Sustainable Polymer Technologies

Topic Information

Dear Colleagues,

The Food and Agriculture Organization of the United Nations (FAO) states that approximately one-third of the food addressed to human consumption is currently lost or wasted globally. It also estimates that the direct costs for producers of food going to waste amount to approximately $750 billion every year. In a global context of limited natural resources, it is more effective to reduce food waste than to increase food production. Packaging can definitively play a major role in food waste by extending the shelf life of food items and providing safe food products to consumers. In the last years, polymers have been the key enablers for food preservation and protection due to their balanced properties and high versatility. Then, plastics materials, that is, polymers with additives, have strongly contributed to the needs of global changing demographics and the progress of modern society. However, the plastics economy is still based on a linear model of “make, use, and dispose of,” and most of the plastic packaging material value is lost to the economy after a first short use cycle. Furthermore, hundreds of millions of tons of plastics escape collection systems, ending up in the environment whether as microscopic particles or surviving in a recognizable form for hundreds of years.

The circular economy has recently become a widespread concept that aims to eliminate the concept of waste, rebuild natural capital, and create economic value by using—not consuming—resources effectively. In the food packaging area, the game-changing strategy deals with the promotion of sustainable polymer technologies that decouple plastics from fossil feedstocks, drastically reduce the leakage of plastics into natural systems, and increase the quality and uptake of plastic recycling. Current strategies in circular economy scenarios are steering the development of biopolymers for single-use applications such as food packaging and food contact disposables. Biopolymers comprise a whole family of materials that include either “bio-based” polymers or “biodegradable” polymers as well as polymers featuring both properties. Bio-based polymers refer to any kind of polymer that is produced from renewable resources, which include both naturally occurring polymers (biomacromolecules) and synthetic polymers produced by means of natural monomers. Biodegradable polymers are macromolecular materials whose physical and chemical properties undergo deterioration and completely degrade when exposed to the enzymatic action of microorganisms producing carbon dioxide (aerobic process), methane (anaerobic process), water (aerobic and anaerobic processes), and inorganic compounds and biomass. Bio-based polymers can potentially save fossil resources by using biomass that regenerates annually and contribute to advancing carbon neutrality, whereas biodegradability is an add-on property that offers additional means of recovery at the end of a product’s life.

Today, bio-based polymers are mostly made of carbohydrate-rich plants such as corn or sugar cane, the so-called food crops or “first-generation feedstock”. This is currently the most efficient route for the production of bioplastics because it requires the least amount of land to grow and produces the highest yields. It includes corn, wheat, sugarcane, potato, sugar beet, rice, and edible plants or oils. Nevertheless, this feedstock also shows negative impacts such as deforestation of protected areas and environmental damage caused by bad agricultural practice, which must be avoided. Moreover, the discussion about the use of biomass for industrial purposes is still often linked to the question of whether the conversion of potential food and feedstock into materials is ethically justifiable. Thus, in this scenario, the use of biomass could ultimately ensure the highest value creation and the strongest environmental benefits. Thus, in the near future, innovative technologies should be refocused on non-edible biomass and industrial by-products and wastes as the main source for bioplastics. These novel raw materials represent the so-called second- and third-generation feedstocks that include large amounts of agro-food residues, non-food crops, or cellulosic biomass, which are abundant and currently have low economic value. From the above, the new trend for the development of sustainable polymer technologies will be led by the emergence of new biopolymers made from renewable and non-food sources.

Prof. Dr. Sergio Torres-Giner
Prof. Dr. Maria Vargas
Topic Editors

Keywords

Participating Journals

Journal Name	Impact Factor	CiteScore	Launched Year	First Decision (median)	APC
Applied Sciences applsci	2.7	4.5	2011	16.9 Days	CHF 2400
Foods foods	5.2	5.8	2012	13.1 Days	CHF 2900
Polymers polymers	5.0	6.6	2009	13.7 Days	CHF 2700
Materials materials	3.4	5.2	2008	13.9 Days	CHF 2600

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Published Papers (41 papers)

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14 pages, 3152 KiB  

Open AccessArticle

Sustainable Epoxidized Guayule Natural Rubber, Blends and Composites with Improved Oil Resistance and Greater Stiffness

by Xianjie Ren, Cindy S. Barrera, Janice L. Tardiff and Katrina Cornish

Materials 2022, 15(11), 3946; https://doi.org/10.3390/ma15113946 - 1 Jun 2022

Cited by 3 | Viewed by 1519

Abstract

Production of petroleum-based synthetic rubbers (SRs) causes an enormous carbon footprint for the rubber industry. Carbon footprint would be reduced if natural rubber (NR) could take a larger market share and replace significant quantities of SR. However, some SRs have higher oil resistance [...] Read more.

Production of petroleum-based synthetic rubbers (SRs) causes an enormous carbon footprint for the rubber industry. Carbon footprint would be reduced if natural rubber (NR) could take a larger market share and replace significant quantities of SR. However, some SRs have higher oil resistance than NRs, and, in applications where these properties are needed, chemically modified NR will be required. Epoxidation is a chemical modification of NR which partially converts unsaturated bonds on the backbone of NR to epoxy groups. In this research, epoxidized guayule natural rubber (EGNR)/guayule natural rubber (GNR) blends and GNR were used to make carbon black (CB) filled composites. The processability, mechanical properties, swelling behaviors and dynamic mechanical properties were characterized at various epoxide fractions. Composites made with EGNR/GNR had higher oil resistance, wet traction and stiffness than GNR composites, although tensile strength and elongation at break were reduced by epoxidation. EGNR is expected to lead to the development of new NR products with similar properties to SR, eroding SR markets and increasing the sustainability of the rubber industry. Full article

(This article belongs to the Topic Sustainable Polymer Technologies)

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24 pages, 5825 KiB  

Open AccessArticle

Liquid Guayule Natural Rubber, a Sustainable Processing Aid, Enhances the Processability, Durability and Dynamic Mechanical Properties of Rubber Composites

by Xianjie Ren, Cindy S. Barrera, Janice L. Tardiff, Andres Gil and Katrina Cornish

Materials 2022, 15(10), 3605; https://doi.org/10.3390/ma15103605 - 18 May 2022

Cited by 1 | Viewed by 1559

Abstract

Petroleum-based oils are widely used as processing aids in rubber composites to improve processability but can adversely affect rubber composite performance and increase carbon footprint. In this research, liquid guayule natural rubber (LGNR), produced from guayule natural rubber, was used as a renewable [...] Read more.

Petroleum-based oils are widely used as processing aids in rubber composites to improve processability but can adversely affect rubber composite performance and increase carbon footprint. In this research, liquid guayule natural rubber (LGNR), produced from guayule natural rubber, was used as a renewable processing aid to replace naphthenic oil (NO) in Hevea natural rubber, styrene-butadiene rubber (SBR) and guayule natural rubber (GNR) composites. The rheological properties, thermal stability, glass transition temperature, dynamic mechanical properties, aging, and ozone resistance of rubber composites with and without NO or LGNR were compared. Natural and synthetic rubber composites made with LGNR had similar processability to those made with NO, but had improved thermal stability, mechanical properties after aging, and ozone resistance. This was due to the strong LGNR–filler interaction and additional crosslinks formed between LGNR and the rubber matrices. The glass transition temperature of SBR composites was reduced by LGNR because of its increased molecular mobility. Thus, unlike NO, LGNR processing aid can simultaneously improve rubber composite durability, dynamic performance and renewability. The commercialization of LGNR has the potential to open a new sustainable processing-aid market. Full article

(This article belongs to the Topic Sustainable Polymer Technologies)

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1 pages, 151 KiB  

Open AccessCorrection

Correction: Kong et al. Preparation of Poly Aluminum-Ferric Chloride (PAFC) Coagulant by Extracting Aluminum and Iron Ions from High Iron Content Coal Gangue. Materials 2022, 15, 2253

by Deshun Kong, Zihan Zhou, Shuojiang Song, Shan Feng, Minglei Lian and Rongli Jiang

Materials 2022, 15(9), 3104; https://doi.org/10.3390/ma15093104 - 25 Apr 2022

Cited by 1 | Viewed by 1092

Abstract

Missing Citation [...] Full article

(This article belongs to the Topic Sustainable Polymer Technologies)

26 pages, 1525 KiB  

Open AccessReview

A Review of Polylactic Acid as a Replacement Material for Single-Use Laboratory Components

by Brian Freeland, Eanna McCarthy, Rengesh Balakrishnan, Samantha Fahy, Adam Boland, Keith D. Rochfort, Michal Dabros, Roger Marti, Susan M. Kelleher and Jennifer Gaughran

Materials 2022, 15(9), 2989; https://doi.org/10.3390/ma15092989 - 20 Apr 2022

Cited by 37 | Viewed by 5904

Abstract

Every year, the EU emits 13.4 Mt of CO₂ solely from plastic production, with 99% of all plastics being produced from fossil fuel sources, while those that are produced from renewable sources use food products as feedstocks. In 2019, 29 Mt of [...] Read more.

Every year, the EU emits 13.4 Mt of CO₂ solely from plastic production, with 99% of all plastics being produced from fossil fuel sources, while those that are produced from renewable sources use food products as feedstocks. In 2019, 29 Mt of plastic waste was collected in Europe. It is estimated that 32% was recycled, 43% was incinerated and 25% was sent to landfill. It has been estimated that life-sciences (biology, medicine, etc.) alone create plastic waste of approximately 5.5 Mt/yr, the majority being disposed of by incineration. The vast majority of this plastic waste is made from fossil fuel sources, though there is a growing interest in the possible use of bioplastics as a viable alternative for single-use lab consumables, such as petri dishes, pipette tips, etc. However, to-date only limited bioplastic replacement examples exist. In this review, common polymers used for labware are discussed, along with examining the possibility of replacing these materials with bioplastics, specifically polylactic acid (PLA). The material properties of PLA are described, along with possible functional improvements dure to additives. Finally, the standards and benchmarks needed for assessing bioplastics produced for labware components are reviewed. Full article

(This article belongs to the Topic Sustainable Polymer Technologies)

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18 pages, 4960 KiB  

Open AccessArticle

Development of Low Shrinkage Curing Techniques for Unsaturated Polyester and Vinyl Ester Reinforced Composites

by Iqbal Ahmed Moujdin, Husam Saber Totah, Hani Abdulelah Abulkhair, Abdulmohsen Omar Alsaiari, Amer Ahmed Shaiban and Hussam Adnan Organji

Materials 2022, 15(9), 2972; https://doi.org/10.3390/ma15092972 - 19 Apr 2022

Cited by 8 | Viewed by 1848

Abstract

This work investigated low shrinkage curing techniques and characterization of unsaturated polyester (UPE-8340) and vinyl ester (VE-922) reinforced composite. The reinforced polymeric composite was composed using various amounts (0.1 vol.% to 0.5 vol.%) of methyl ethyl ketone peroxide (MEKP) and the proportion of [...] Read more.

This work investigated low shrinkage curing techniques and characterization of unsaturated polyester (UPE-8340) and vinyl ester (VE-922) reinforced composite. The reinforced polymeric composite was composed using various amounts (0.1 vol.% to 0.5 vol.%) of methyl ethyl ketone peroxide (MEKP) and the proportion of UPE and VE (5 vol.%) was kept fixed throughout the study. The epoxy matrix was formed using a 3D printed acrylonitrile butadiene styrene (ABS) dumbbell shape mold and the specimen was cured in the presence of air and an inner gas (carbon dioxide) using a customized ambient closed chamber system. The influence of MEKP on UPE and VE reinforce composites was studied by investigating curing kinetics, shrinkage, tensile properties, contact angle, and thermal stability. The CO₂-cured results show a significant lower shrinkage rate and higher tensile strength and flexural modulus of UPE and VE reinforced composite articles compared with air-cured reinforced composite. These macro-scale results correlate with the air-cured structure, an un-banded smooth surface was observed, and it was found that the lowest amount of MEKP revealed significant improvement in the contact angle of UPET and VE reinforced composites. Full article

(This article belongs to the Topic Sustainable Polymer Technologies)

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19 pages, 4008 KiB  

Open AccessArticle

Non-Isothermal Crystallization of Titanium-Dioxide-Incorporated Rice Straw Fiber/Poly(butylene succinate) Biocomposites

by Tianqi Yue, Huanbo Wang, Yuan Fu, Shiyu Guo, Xuefeng Zhang and Tian Liu

Polymers 2022, 14(7), 1479; https://doi.org/10.3390/polym14071479 - 5 Apr 2022

Cited by 5 | Viewed by 2008

Abstract

In this work, titanium dioxide (TiO₂)-incorporated rice straw fiber (RS)/poly(butylene succinate) (PBS) biocomposites were prepared by injection molding with different TiO₂ powder loadings. The RS/PBS with 1 wt% TiO₂ demonstrated the best mechanical properties, where the flexural strength and [...] Read more.

In this work, titanium dioxide (TiO₂)-incorporated rice straw fiber (RS)/poly(butylene succinate) (PBS) biocomposites were prepared by injection molding with different TiO₂ powder loadings. The RS/PBS with 1 wt% TiO₂ demonstrated the best mechanical properties, where the flexural strength and modulus increased by 30.34% and 28.39%, respectively, compared with RS/PBS. The non-isothermal crystallization of neat PBS, RS/PBS composites, and titanium-dioxide-incorporated RS/PBS composites was investigated by differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The non-isothermal crystallization data were analyzed using several theoretical models. The Avrami and Mo kinetic models described the non-isothermal crystallization behavior of neat PBS and the composites; however, the Ozawa model was inapplicable. The crystallization temperature ($T_c$), half-time of crystallization ($t_{1/2}$), and kinetic parameters ($F_T$) showed that the crystallizability followed the order: TiO₂-incorporated RS/PBS composites > RS/PBS > PBS. The RS/PBS with 1 wt% TiO₂ showed the best crystallization properties. The Friedman model was used to evaluate the effective activation energy of the non-isothermal crystallization of PBS and its composites. Rice straw fiber and TiO₂ acted as nucleating agents for PBS. The XRD results showed that the addition of rice straw fiber and TiO₂ did not substantially affect the crystal parameters of the PBS matrix. Overall, this study shows that RS and TiO₂ can significantly improve the crystallization and mechanical properties of PBS composites. Full article

(This article belongs to the Topic Sustainable Polymer Technologies)

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9 pages, 2511 KiB  

Open AccessCommunication

Enhanced Toughness and Sound Absorption Performance of Bio-Aerogel via Incorporation of Elastomer

by Junshi Shen, Ruofei Hu, Xueliang Jiang, Feng You, Chu Yao, Huan Yang and Peng Yu

Polymers 2022, 14(7), 1344; https://doi.org/10.3390/polym14071344 - 26 Mar 2022

Cited by 1 | Viewed by 1957

Abstract

In this study, Arabic gum/ carboxylic butadiene-acrylonitrite latex aerogels (AG/XNBRL) hybrid aerogel was successfully prepared by a green method, i.e., the combination of latex compounding and vacuum freeze-drying process. After that, the obtained composites were subjected to a high temperature treatment to crosslink [...] Read more.

In this study, Arabic gum/ carboxylic butadiene-acrylonitrite latex aerogels (AG/XNBRL) hybrid aerogel was successfully prepared by a green method, i.e., the combination of latex compounding and vacuum freeze-drying process. After that, the obtained composites were subjected to a high temperature treatment to crosslink the rubber phase. It was found that the AG in the AG/XNBRL hybrid aerogel could act as a framework to improve the dimensional stability of the aerogel, while the XNBRL phase could significantly improve the mechanical flexibility of the ensuing composite. Compared to the AG aerogel which is highly brittle in nature, the AG/XNBRL hybrid aerogel not only exhibits significantly enhanced toughness, but also shows improved thermal stability and sound absorption performances; for instance, the half weight loss (50%) temperature and average sound adsorption coefficient for aerogel containing 30 wt% XNBRL is 344 °C and 0.585, respectively, which are superior to those of neat AG aerogel. Overall, this work provides novel inspiration to prepare the mechanical robust bio-based aerogel for the sound absorption application. Full article

(This article belongs to the Topic Sustainable Polymer Technologies)

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17 pages, 11325 KiB  

Open AccessArticle

Exquisite Energy Savings at Cold Metal Forming of Threads through the Application of Polymers

by Miroslav Píška, Petra Sliwková, Zuzana Vnuková, Martin Petrenec and Eva Sedláková-Valášková

Polymers 2022, 14(6), 1084; https://doi.org/10.3390/polym14061084 - 8 Mar 2022

Cited by 2 | Viewed by 1504

Abstract

One of the global problems today is energy—its production and distribution. As the human population grows, the consumption of energy rises simultaneously. However, the natural sources are limited, and so the focus on power savings becomes more and more important. One of the [...] Read more.

One of the global problems today is energy—its production and distribution. As the human population grows, the consumption of energy rises simultaneously. However, the natural sources are limited, and so the focus on power savings becomes more and more important. One of the ways to reduce consumption is the use of effective lubricants and tribological fluids in industry, especially in processes with high demands on energy but high quality of products as well. Forming is a typical example of such technology, and the application of polymers seems to be a very important challenge, because the application of straight oils or lubricant with extreme pressure additives seems to be prevailing in that field. Nevertheless, the polymer lubricant should fulfill all European standards as well as the environmental and ecological limitations with respect to health and the natural environment and its recycling and disposal. This paper is focused on the forming technology of threads and the application of selected polymers to the forming process. The measured and quantified criteria are torque and force loadings, energy consumption, and quality of the produced surfaces. Kistler dynamometers, scanning electron microscopy, and advanced surface topography with the use of Alicona IF-G5 were applied to assess all aspects of the tribological and energy aspects of six modern process fluids, three lubricating pastes, and two fluid modifications. The results show that the polymer synthetic lubricant (at volume concentration 20% in water) can reduce the total energy consumption by up to 40% per forming cycle (in mean values) at average surface roughness below 0.8 μm. Full article

(This article belongs to the Topic Sustainable Polymer Technologies)

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17 pages, 4550 KiB  

Open AccessReview

Solid State NMR a Powerful Technique for Investigating Sustainable/Renewable Cellulose-Based Materials

by Mustapha El Hariri El Nokab, Mohamed H. Habib, Yasser A. Alassmy, Marwan M. Abduljawad, Khalid M. Alshamrani and Khaled O. Sebakhy

Polymers 2022, 14(5), 1049; https://doi.org/10.3390/polym14051049 - 6 Mar 2022

Cited by 19 | Viewed by 6380

Abstract

Solid state nuclear magnetic resonance (ssNMR) is a powerful and attractive characterization method for obtaining insights into the chemical structure and dynamics of a wide range of materials. Current interest in cellulose-based materials, as sustainable and renewable natural polymer products, requires deep investigation [...] Read more.

Solid state nuclear magnetic resonance (ssNMR) is a powerful and attractive characterization method for obtaining insights into the chemical structure and dynamics of a wide range of materials. Current interest in cellulose-based materials, as sustainable and renewable natural polymer products, requires deep investigation and analysis of the chemical structure, molecular packing, end chain motion, functional modification, and solvent–matrix interactions, which strongly dictate the final product properties and tailor their end applications. In comparison to other spectroscopic techniques, on an atomic level, ssNMR is considered more advanced, especially in the structural analysis of cellulose-based materials; however, due to a dearth in the availability of a broad range of pulse sequences, and time consuming experiments, its capabilities are underestimated. This critical review article presents the comprehensive and up-to-date work done using ssNMR, including the most advanced NMR strategies used to overcome and resolve the structural difficulties present in different types of cellulose-based materials. Full article

(This article belongs to the Topic Sustainable Polymer Technologies)

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16 pages, 1764 KiB  

Open AccessArticle

Design and Study of a Photo-Switchable Polymeric System in the Presence of ZnS Nanoparticles under the Influence of UV Light Irradiation

by Guadalupe del C. Pizarro, Wilson Alavia, Karen González, Héctor Díaz, Oscar G. Marambio, Rudy Martin-Trasanco, Julio Sánchez, Diego P. Oyarzún and Andrónico Neira-Carrillo

Polymers 2022, 14(5), 945; https://doi.org/10.3390/polym14050945 - 26 Feb 2022

Cited by 6 | Viewed by 2913

Abstract

Recent progress in the field of photosensitive materials has prompted a need to develop efficient methods to synthesize materials with basic intermolecular architectural designs and novel properties. Accordingly, in this work we design and study a photoactive polymer as a photo-switchable polymeric system [...] Read more.

Recent progress in the field of photosensitive materials has prompted a need to develop efficient methods to synthesize materials with basic intermolecular architectural designs and novel properties. Accordingly, in this work we design and study a photoactive polymer as a photo-switchable polymeric system in the presence and absence of ZnS nanoparticles (average size < 10 nm) at 5 wt.%. The influence of UV light irradiation on its properties were also studied. The photoactive block copolymer was obtained from styrene (S) and methyl methacrylate (MMA) as monomers and 1-(2-hydroxyethyl)-3,3-dimethylindoline-6-nitrobenzopyran (SP) was grafted to the block copolymer backbone as a photochromic agent. Furthermore, the incorporation of ZnS (NPs) as photo-optical switch component into the system enhances the purple colored photo-emission, with the open form of the spiropyran derivative (merocyanine, MC). The ZnS stabilize the isomeric equilibrium in the MC interconversion of the photochromic agent. The photo-switchable properties of the PS-b-PMMA-SP in the presence of ZnS (NPs) were examined using UV-VIS spectroscopy, Photoluminescence (PL) spectroscopy, optical fluorescence and scanning electronic microscopy (SEM-EDX.). The observed changes in the absorbance, fluorescence and morphology of the system were associated to the reversible interconversion of the two states of the photochromic agent which regulates the radiative deactivation of the luminescent ZnS NPs component. After UV irradiation the photoactive polymer becomes purple in color. Therefore, these basic studies can lead to the development of innovative functional and nanostructured materials with photosensitive character as photosensitive molecular switches. Full article

(This article belongs to the Topic Sustainable Polymer Technologies)

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37 pages, 10387 KiB  

Open AccessReview

π-Conjugated Polymers and Their Application in Organic and Hybrid Organic-Silicon Solar Cells

by Siyabonga B. Mdluli, Morongwa E. Ramoroka, Sodiq T. Yussuf, Kwena D. Modibane, Vivian S. John-Denk and Emmanuel I. Iwuoha

Polymers 2022, 14(4), 716; https://doi.org/10.3390/polym14040716 - 13 Feb 2022

Cited by 23 | Viewed by 7298

Abstract

The evolution and emergence of organic solar cells and hybrid organic-silicon heterojunction solar cells have been deemed as promising sustainable future technologies, owing to the use of π-conjugated polymers. In this regard, the scope of this review article presents a comprehensive summary [...] Read more.

The evolution and emergence of organic solar cells and hybrid organic-silicon heterojunction solar cells have been deemed as promising sustainable future technologies, owing to the use of π-conjugated polymers. In this regard, the scope of this review article presents a comprehensive summary of the applications of π-conjugated polymers as hole transporting layers (HTLs) or emitters in both organic solar cells and organic-silicon hybrid heterojunction solar cells. The different techniques used to synthesize these polymers are discussed in detail, including their electronic band structure and doping mechanisms. The general architecture and principle of operating heterojunction solar cells is addressed. In both discussed solar cell types, incorporation of π-conjugated polymers as HTLs have seen a dramatic increase in efficiencies attained by these devices, owing to the high transmittance in the visible to near-infrared region, reduced carrier recombination, high conductivity, and high hole mobilities possessed by the p-type polymeric materials. However, these cells suffer from long-term stability due to photo-oxidation and parasitic absorptions at the anode interface that results in total degradation of the polymeric p-type materials. Although great progress has been seen in the incorporation of conjugated polymers in the various solar cell types, there is still a long way to go for cells incorporating polymeric materials to realize commercialization and large-scale industrial production due to the shortcomings in the stability of the polymers. This review therefore discusses the progress in using polymeric materials as HTLs in organic solar cells and hybrid organic-silicon heterojunction solar cells with the intention to provide insight on the quest of producing highly efficient but less expensive solar cells. Full article

(This article belongs to the Topic Sustainable Polymer Technologies)

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15 pages, 18013 KiB  

Open AccessArticle

PVP/Highly Dispersed AgNPs Nanofibers Using Ultrasonic-Assisted Electrospinning

by Li Zhu, Wanying Zhu, Xin Hu, Yingying Lin, Siti Machmudah, Wahyudiono, Hideki Kanda and Motonobu Goto

Polymers 2022, 14(3), 599; https://doi.org/10.3390/polym14030599 - 2 Feb 2022

Cited by 10 | Viewed by 2434

Abstract

Silver nanoparticles (AgNPs) are novel materials with antibacterial, antifungal, and antiviral activities over a wide range. This study aimed to prepare polyvinylpyrrolidone (PVP) electrospinning composites with uniformly distributed AgNPs. In this study, starch-capped ~2 nm primary AgNPs were first synthesized using Atmospheric pressure [...] Read more.

Silver nanoparticles (AgNPs) are novel materials with antibacterial, antifungal, and antiviral activities over a wide range. This study aimed to prepare polyvinylpyrrolidone (PVP) electrospinning composites with uniformly distributed AgNPs. In this study, starch-capped ~2 nm primary AgNPs were first synthesized using Atmospheric pressure Pulsed Discharge Plasma (APDP) at AC 10 kV and 10 kHz. Then, 0.6 wt.% AgNPs were mixed into a 10 wt.% PVP ethanol-based polymer solution and coiled through an Ultrasonic-assisted Electrospinning device (US-ES) with a 50 W and 50 kHz ultrasonic generator. At 12 kV and a distance of 10 cm, this work successfully fabricated AgNPs-PVP electrospun fibers. The electrospun products were characterized using Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), High-Resolution TEM (HR-TEM), Fourier Transform Infrared Spectroscopy (FT-IR), X-ray Diffraction (XRD), Thermogravimetric (TG), and X-ray Photoelectron Spectroscopy (XPS) methods. Full article

(This article belongs to the Topic Sustainable Polymer Technologies)

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17 pages, 4691 KiB  

Open AccessArticle

A New Green Composite Based on Plasticized Polylactic Acid Mixed with Date Palm Waste for Single-Use Plastics Applications

by Noran Mousa, Emmanuel Galiwango, Sabeera Haris, Ali H. Al-Marzouqi, Basim Abu-Jdayil and Yousuf L. Caires

Polymers 2022, 14(3), 574; https://doi.org/10.3390/polym14030574 - 31 Jan 2022

Cited by 16 | Viewed by 3927

Abstract

Petroleum-based plastic is widely used in almost all fields. However, it causes serious threats to the environment owing to its non-biodegradable properties, which necessitates finding biodegradable alternatives. Here, date palm rachis (DPR) waste was used as a filler (30, 40, and 50 wt%) [...] Read more.

Petroleum-based plastic is widely used in almost all fields. However, it causes serious threats to the environment owing to its non-biodegradable properties, which necessitates finding biodegradable alternatives. Here, date palm rachis (DPR) waste was used as a filler (30, 40, and 50 wt%) to form a biodegradable composite with polylactic acid (PLA) and achieve cost–performance balance. DPR–PLA composites were prepared using a melt-mixing extruder at 180 °C by varying mixing time, DPR composition, and plasticizer type and composition. The biodegradable testing specimens were prepared by compression molding and analyzed using physical, thermal, and mechanical characterizations. Scanning electron microscopy images indicated a uniform dispersion of DPR (90 μm) in the PLA matrix. The esterification reaction resulting from this interaction between DPR and PLA was confirmed by Fourier transform infrared spectroscopy. The 30 wt% DPR–PLA composite was considered the optimal composite with the lowest melt flow index (16 g/10 min). This work confirmed the superior effect of addition of 10 wt% of triethyl citrate (TEC) compared with polybutylene adipate terephthalate (PBAT) by the improvement in the elongation at break of the optimal composite from 2.10% to 4.20%. Moreover, the addition of 10 wt% of PBAT to the optimal composite resulted in a lower tensile strength (21.80 MPa) than that of the composite with 10 wt% of TEC (33.20 MPa). These results show the potential of using the proposed composite as an alternative material for single-use plastics such as cutlery. Full article

(This article belongs to the Topic Sustainable Polymer Technologies)

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14 pages, 8131 KiB  

Open AccessArticle

Influence of Chitin Nanocrystals on the Crystallinity and Mechanical Properties of Poly(hydroxybutyrate) Biopolymer

by Marta Zaccone, Mitul Kumar Patel, Laurens De Brauwer, Rakesh Nair, Maria Luana Montalbano, Marco Monti and Kristiina Oksman

Polymers 2022, 14(3), 562; https://doi.org/10.3390/polym14030562 - 29 Jan 2022

Cited by 10 | Viewed by 2583

Abstract

This study focuses on the use of pilot-scale produced polyhydroxy butyrate (PHB) biopolymer and chitin nanocrystals (ChNCs) in two different concentrated (1 and 5 wt.%) nanocomposites. The nanocomposites were compounded using a twin-screw extruder and calendered into sheets. The crystallization was studied using [...] Read more.

This study focuses on the use of pilot-scale produced polyhydroxy butyrate (PHB) biopolymer and chitin nanocrystals (ChNCs) in two different concentrated (1 and 5 wt.%) nanocomposites. The nanocomposites were compounded using a twin-screw extruder and calendered into sheets. The crystallization was studied using polarized optical microscopy and differential scanning calorimetry, the thermal properties were studied using thermogravimetric analysis, the viscosity was studied using a shear rheometer, the mechanical properties were studied using conventional tensile testing, and the morphology of the prepared material was studied using optical microscopy and scanning electron microscopy. The results showed that the addition of ChNCs significantly affected the crystallization of PHB, resulting in slower crystallization, lower overall crystallinity, and smaller crystal size. Furthermore, the addition of ChNCs resulted in increased viscosity in the final formulations. The calendering process resulted in slightly aligned sheets and the nanocomposites with 5 wt.% ChNCs evaluated along the machine direction showed the highest mechanical properties, the strength increased from 24 to 33 MPa, while the transversal direction with lower initial strength at 14 MPa was improved to 21 MPa. Full article

(This article belongs to the Topic Sustainable Polymer Technologies)

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20 pages, 21729 KiB  

Open AccessArticle

Methods for Predicting Ethylene/Cyclic Olefin Copolymerization Rates Promoted by Single-Site Metallocene: Kinetics Is the Key

by Amjad Ali, Ahmad Naveed, Tahir Rasheed, Tariq Aziz, Muhammad Imran, Ze-Kun Zhang, Muhammad Wajid Ullah, Ameer Ali Kubar, Aziz Ur Rehman, Zhiqiang Fan and Li Guo

Polymers 2022, 14(3), 459; https://doi.org/10.3390/polym14030459 - 24 Jan 2022

Cited by 6 | Viewed by 2832

Abstract

In toluene at 50 °C, the vinyl addition polymerization of 4-vinyl-cyclohexene (VCH) comonomers with ethylene is investigated using symmetrical metallocene (rac-Et(Ind)₂ZrCl₂) combined with borate/TIBA. To demonstrate the polymerizations’ living character, cyclic VCH with linear-exocyclic_π and endocyclic [...] Read more.

In toluene at 50 °C, the vinyl addition polymerization of 4-vinyl-cyclohexene (VCH) comonomers with ethylene is investigated using symmetrical metallocene (rac-Et(Ind)₂ZrCl₂) combined with borate/TIBA. To demonstrate the polymerizations’ living character, cyclic VCH with linear-exocyclic_π and endocyclic_π bonds produces monomodal polymers, but the dispersity (Ɖ) was broader. The copolymers obtained can be dissolved in conventional organic solvent and have excellent thermal stability and crystalline temperature (ΔH_m), and their melting temperature (Tm) varies from 109 to 126 °C, and ΔH_m ranges from 80 to 128 (J/g). Secondly, the distribution of polymeric catalysts engaged in polymer chain synthesis and the nature of the dormant state are two of the most essential yet fundamentally unknown aspects. Comprehensive and exhaustive kinetics of E/VCH have shown numerous different kinetic aspects that are interpreted as manifestations of polymeric catalysts or of the instability of several types of active center [Zr]/[C*] fluctuations and formation rates of chain propagation R_pE, R_pVCH, and propagation rate constants k_pE and k_pVCH, the quantitative relationship between R_pE, R_pVCH and k_pE, k_pVCH and catalyst structures, their constituent polymer Mw, and their reactivity response to the endocyclic and exocyclic bonds of VCH. The kinetic parameters R_pE, R_pVCH, k_pE, and k_pVCH, which are the apparent rates for the metallocene-catalyzed E/VCH, R_pE, and kpE values, are much more significant than R_pVCH and kpVCH at 120 s, R_pE and R_pVCH 39.63 and 0.78, and the k_pE and kpVCH values are 6461 and 93 L/mol·s, respectively, and minor diffusion barriers are recommended in the early stages. Compared with previously reported PE, R_pE and k_pE values are 34.2 and 7080 L/mol·s. VCH increases the R_pE in the initial stage, as we are expecting; this means that the exocyclic bond of VCH is more active at the initial level, and that the chain transfer reaction of cyclic internal π double is increased with the reaction time. The t_p versus R_p, k_p, and [Zr]/[C*] fraction count may be fitted to a model that invokes deactivation of growing polymer chains. At t_p 120–360 s higher, the incorporation rate of VCH suppresses E insertion, resulting in reduced molecular weight. Full article

(This article belongs to the Topic Sustainable Polymer Technologies)

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12 pages, 5406 KiB  

Open AccessArticle

Polyacrylonitrile Nanofibers Containing Viroblock as Promising Material for Protective Clothing

by Mujtaba Hussain, Abdul Salam, Muhammad Fahad Arain, Azeem Ullah, Anh-Tuan Dao, Hai Vu-Manh, Duy-Nam Phan, Aamir Shabbir Ansari, Muhammad Qamar Khan, Zafar Javed and Ick-Soo Kim

Appl. Sci. 2021, 11(23), 11469; https://doi.org/10.3390/app112311469 - 3 Dec 2021

Cited by 5 | Viewed by 2087

Abstract

Antimicrobial viroblock/polyacrylonitrile nanofiber webs fabricated using the electrospinning method were assessed in terms of the antimicrobial activity against infectious agents as a potential material used in mask production. Viroblock (VB) is an amalgam of lipid vesicle and silver. Lipid vesicle depletes the virus [...] Read more.

Antimicrobial viroblock/polyacrylonitrile nanofiber webs fabricated using the electrospinning method were assessed in terms of the antimicrobial activity against infectious agents as a potential material used in mask production. Viroblock (VB) is an amalgam of lipid vesicle and silver. Lipid vesicle depletes the virus outer membrane, which contains cholesterol, while silver ions penetrate the virus, interact with sulfur-bearing moieties, and possess the virus bactericidal property. VB, having anti-coronavirus and anti-influenza properties, was prepared in four different concentrations, 0.5 wt%, 1 wt%, 1.5 wt%, and 2 wt%, in regard to nanofiber weight. The resultant nanofibers were characterized by scanning electron microscope (SEM), Fourier transform infrared (FTIR), thermogravimetric analysis (TGA), water contact angle, water content, and thermogravimetric analysis (TGA). Moreover, all nanofibrous samples were evaluated for cell proliferation assay and ATCC antibacterial tests. Based on characterization results and cytotoxicity, the developed composite nanofibers-based webs showed good promise for utilization in anti-viral masks. Particularly, 2 wt% VB/PAN nanofibers have the highest antibacterial properties against negative and positive bacteria along with excellent cell viability. Full article

(This article belongs to the Topic Sustainable Polymer Technologies)

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17 pages, 3838 KiB  

Open AccessArticle

Application of Amberlite IRA 402 Resin Adsorption and Laccase Treatment for Acid Blue 113 Removal from Aqueous Media

by Nicoleta Mirela Marin and Ioana Stanculescu

Polymers 2021, 13(22), 3991; https://doi.org/10.3390/polym13223991 - 18 Nov 2021

Cited by 11 | Viewed by 2969

Abstract

Despite Acid Blue 113 (AB 113)’s extensive use and negative environmental impact, very few studies have focused on its efficient and environmentally friendly removal. This research aims the removal of AB 113 from environmental aqueous media and its consequent enzymatic biodegradation. A strongly [...] Read more.

Despite Acid Blue 113 (AB 113)’s extensive use and negative environmental impact, very few studies have focused on its efficient and environmentally friendly removal. This research aims the removal of AB 113 from environmental aqueous media and its consequent enzymatic biodegradation. A strongly basic anion exchange resin in Cl⁻ form, Amberlite IRA 402 (IRA 402(Cl⁻)) was used for AB 113 adsorption and a laccase was used to further biodegrade it. For the first time, two novel, efficient and environmentally friendly physical–chemical and biological assays for AB 113 wastewater removal and subsequent biodegradation were combined. The adsorption of AB 113 onto IRA 402(Cl⁻) was tested in batch and continuous flux modes. Influence of contact time, concentration and desorption in acidic media were evaluated. The kinetic data were best modulated by the Lagergren model with R² = 0.9275. The Langmuir isotherm model best fitted the experimental data, and the maximum adsorption capacity was 130 mg/g. Dye, resin and AB113 loaded resin were characterized by thermogravimetry and FTIR to evaluate their physical chemical properties modification. Based on the performed studies, a consecutive methodology is proposed, incorporating the ion exchange process in the first stage and the biodegradation process in the second. Thus, in the second stage the residual concentration of AB 113 is reduced by an efficient bio-degradation process produced by the laccase at pH = 4. Full article

(This article belongs to the Topic Sustainable Polymer Technologies)

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15 pages, 5566 KiB  

Open AccessArticle

Efficient Congo Red Removal Using Porous Cellulose/Gelatin/Sepiolite Gel Beads: Assembly, Characterization, and Adsorption Mechanism

by Chenlu Jiao, Die Liu, Nana Wei, Jiannan Gao, Fan Fu, Tao Liu and Jian Wang

Polymers 2021, 13(22), 3890; https://doi.org/10.3390/polym13223890 - 10 Nov 2021

Cited by 9 | Viewed by 2053

Abstract

Porous sustainable cellulose/gelatin/sepiolite gel beads were fabricated via an efficient ‘hydrophilic assembly–floating droplet’ two-step method to remove Congo red (CR) from wastewater. The beads comprised microcrystalline cellulose and gelatin, forming a dual network framework, and sepiolite, which acted as a functional component to [...] Read more.

Porous sustainable cellulose/gelatin/sepiolite gel beads were fabricated via an efficient ‘hydrophilic assembly–floating droplet’ two-step method to remove Congo red (CR) from wastewater. The beads comprised microcrystalline cellulose and gelatin, forming a dual network framework, and sepiolite, which acted as a functional component to reinforce the network. The as-prepared gel beads were characterized using FTIR, SEM, XRD, and TGA, with the results indicating a highly porous structure that was also thermally stable. A batch adsorption experiment for CR was performed and evaluated as a function of pH, sepiolite addition, contact time, temperature, and initial concentration. The kinetics and isotherm data obtained were in agreement with the pseudo-second-order kinetic model and the Langmuir isotherm, with a maximum monolayer capacity of 279.3 mg·g⁻¹ for CR at 303 K. Moreover, thermodynamic analysis demonstrated the spontaneous and endothermic nature of the dye uptake. Importantly, even when subjected to five regeneration cycles, the gel beads retained 87% of their original adsorption value, suggesting their suitability as an efficient and reusable material for dye wastewater treatments. Full article

(This article belongs to the Topic Sustainable Polymer Technologies)

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15 pages, 1631 KiB  

Open AccessArticle

Cationic Lignin Polymers as Flocculant for Municipal Wastewater

by Courtney Moore, Weijue Gao and Pedram Fatehi

Polymers 2021, 13(22), 3871; https://doi.org/10.3390/polym13223871 - 9 Nov 2021

Cited by 9 | Viewed by 2999

Abstract

The radical polymerization of acid-washed and unwashed softwood kraft lignin with [2-(methacryloyloxy) ethyl] trimethylammonium chloride (METAC) was attempted to investigate the production of lignin-based flocculants for simulated wastewater. The incorporation of METAC onto lignin resulted in a cationic charge density (2.3–3.3 meq/g), increased [...] Read more.

The radical polymerization of acid-washed and unwashed softwood kraft lignin with [2-(methacryloyloxy) ethyl] trimethylammonium chloride (METAC) was attempted to investigate the production of lignin-based flocculants for simulated wastewater. The incorporation of METAC onto lignin resulted in a cationic charge density (2.3–3.3 meq/g), increased water solubility (89–96% in neutral pH), and increased molecular weight (70,000–210,000 g/mol) of lignin. The lignin–METAC polymers generated from acid-washed lignin had higher molecular weights than those generated from unwashed lignin. The lignin–METAC polymers showed lower resistance to thermal decomposition than unmodified lignin due to the inclusion of PolyMETAC. The unmodified acid-washed lignin samples did not significantly affect the COD of the wastewater, while the unmodified unwashed lignin samples contributed to the COD, implying that unmodified lignin was not suitable for wastewater treatment. The flocculation of wastewater with lignin–METAC led to the chemical oxygen demand (COD) reduction of 17–23% and total organic carbon (TOC) drop of 51–60%. The lignin–METAC polymer with the highest molecular weight (produced from acid-washed lignin) reached the highest COD removal, while lignin–METAC polymer with the highest charge density (produced from unwashed lignin) reached the highest TOC removal. Focused beam reflectance measurement (FBRM) studies revealed that the lignin–METAC polymer produced from acid-washed lignin with a high molecular weight generated larger and more flocs in wastewater than the lignin–METAC polymer produced from unwashed lignin. The comparison of theoretical and experimental dosages required for neutralizing the charges of wastewater demonstrated that charge neutralization was the main flocculation mechanism, although a bridging mechanism was also involved for component removals from wastewater. The use of 1 mg/L of alum along with 65 mg/L lignin–METAC in a dual coagulation–flocculation system led to higher average phosphorous (42%) and COD (44%) removals than the singular flocculation system only using 65 mg/L of lignin–METAC (with phosphorous removals of 3.4% and COD removals of 18.7%). However, lignin–METAC flocculant slightly increased the ammonia–nitrogen content in both singular flocculation and dual coagulation–flocculation systems due to the residual ammonia content of lignin–METAC. The coagulation–flocculation system determined that the use of lignin–METAC (65 mg/L) could reduce the alum dosage significantly while maintaining a similar organic content reduction of 44% for wastewater. Full article

(This article belongs to the Topic Sustainable Polymer Technologies)

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18 pages, 3650 KiB  

Open AccessArticle

Assessment of the Antigenotoxic Effects of Alginate and ZnO/Alginate–Nanocomposites Extracted from Brown Alga Fucus vesiculosus in Mice

by Ragaa A. Hamouda, Asmaa S. Salman, Asrar A. Alharbi, Reem Hasaballah Alhasani and Maha M. Elshamy

Polymers 2021, 13(21), 3839; https://doi.org/10.3390/polym13213839 - 6 Nov 2021

Cited by 10 | Viewed by 2331

Abstract

Mitomycin C (MMC) is an alkylating chemotherapy drug that could induce DNA damage and genetic alteration. It has been used as a model mutagen for in vivo and in vitro studies. The current study aimed to evaluate the protective role of Zinc oxide [...] Read more.

Mitomycin C (MMC) is an alkylating chemotherapy drug that could induce DNA damage and genetic alteration. It has been used as a model mutagen for in vivo and in vitro studies. The current study aimed to evaluate the protective role of Zinc oxide alginate–nanocomposites (ZnO-Alg/NCMs) against MMC–induced genotoxicity in mice. Animals were treated as follows: the control group, the groups treated with Algin (400 mg/kg b.w), the groups treated with ZnO-Alg/NCMs (400 mg/kg b.w), the group treated with MMC, and the groups treated with MMC plus Algin or ZnO-Alg/NCMs. Pre-treatment with Algin and ZnO-Alg/NCMs was repeated for one or seven days. Zinc oxide alginate-nanocomposites (ZnO-Alg/NCMs) were synthesized with the aim of incorporating the intrinsic properties of their constituents as an antigenotoxic substance. In this study, alginate was extracted from the brown marine alga Fucus vesiculosus, Zinc oxide nanoparticles were synthesized by using water extract of the same alga, and loaded in alginate to synthesize ZnO-Alg/NCMs. ZnO-NPs and ZnO-Alg/NCMs were characterized by TEM, SEM, EDX, and Zeta potential. The obtained results confirmed that by TEM and SEM, ZnO-NPs are rod shaped which modified, when loaded in alginate matrix, into spherical shape. The physical stability of ZnO-Alg/NCMs was reported to be higher than ZnO-NPs due to the presence of more negative charges on ZnO-Alg/NCMs. The EDX analysis indicated that the amount of zinc was higher in ZnO-NPs than ZnO-Alg/NCMs. The in vivo results showed that treatment with MMC induced genotoxic disturbances. The combined treatment with Algin and ZnO-Alg/NCMs succeeded in inducing significant protection against MMC. It could be concluded that ZnO-Algin/NCMs is a promising candidate to protect against MMC–induced genotoxicity. Full article

(This article belongs to the Topic Sustainable Polymer Technologies)

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3 pages, 212 KiB  

Open AccessCorrection

Correction: Bodea et al. Optimization of Moist and Oven-Dried Bacterial Cellulose Production for Functional Properties. Polymers 2021, 13, 2088

by Ioana M. Bodea, Florin I. Beteg, Carmen R. Pop, Adriana P. David, Mircea Cristian Dudescu, Cristian Vilău, Andreea Stănilă, Ancuța M. Rotar and Giorgiana M. Cătunescu

Polymers 2021, 13(21), 3821; https://doi.org/10.3390/polym13213821 - 5 Nov 2021

Cited by 1 | Viewed by 1169

Abstract

The authors wish to make a change to the published paper [...] Full article

(This article belongs to the Topic Sustainable Polymer Technologies)

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17 pages, 3406 KiB  

Open AccessArticle

Cocoa Nanoparticles to Improve the Physicochemical and Functional Properties of Whey Protein-Based Films to Extend the Shelf Life of Muffins

by Sergio de Jesús Calva-Estrada, Maribel Jimenez-Fernandez, Alba Adriana Vallejo-Cardona, Gustavo Adolfo Castillo-Herrera and Eugenia del Carmen Lugo-Cervantes

Foods 2021, 10(11), 2672; https://doi.org/10.3390/foods10112672 - 3 Nov 2021

Cited by 6 | Viewed by 2339

Abstract

A novel nanocomposite whey protein-based film with nanoemulsified cocoa liquor (CL) was prepared using one-stage microfluidization to evaluate the emulsion properties and the effect of CL on the film properties by response surface methodology (RSM). The results indicated that the number of cycles [...] Read more.

A novel nanocomposite whey protein-based film with nanoemulsified cocoa liquor (CL) was prepared using one-stage microfluidization to evaluate the emulsion properties and the effect of CL on the film properties by response surface methodology (RSM). The results indicated that the number of cycles by microfluidization had a significant effect (p < 0.05) on the particle size and polydispersity of the nanoemulsion, with a polyphenol retention of approximately 83%. CL decreased the solubility (<21.87%) and water vapor permeability (WVP) (<1.57 g mm h⁻¹ m⁻² kPa⁻¹) of the film. FTIR analysis indicated that CL modified the secondary protein structure of the whey protein and decreased the mechanical properties of the film. These results demonstrate that applying the film as a coating is feasible and effective to improve the shelf life of bakery products with a high moisture content. This nanocomposite film is easy to produce and has potential applications in the food industry. Full article

(This article belongs to the Topic Sustainable Polymer Technologies)

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15 pages, 3076 KiB  

Open AccessArticle

Food Xanthan Polysaccharide Sulfation Process with Sulfamic Acid

by Aleksandr S. Kazachenko, Natalya Yu. Vasilieva, Valentina S. Borovkova, Olga Yu. Fetisova, Noureddine Issaoui, Yuriy N. Malyar, Evgeniy V. Elsuf’ev, Anton A. Karacharov, Andrey M. Skripnikov, Angelina V. Miroshnikova, Anna S. Kazachenko, Dmitry V. Zimonin and Vladislav A. Ionin

Foods 2021, 10(11), 2571; https://doi.org/10.3390/foods10112571 - 25 Oct 2021

Cited by 30 | Viewed by 2351

Abstract

Xanthan is an important polysaccharide with many beneficial properties. Sulfated xanthan derivatives have anticoagulant and antithrombotic activity. This work proposes a new method for the synthesis of xanthan sulfates using sulfamic acid. Various N-substituted ureas have been investigated as process activators. It was [...] Read more.

Xanthan is an important polysaccharide with many beneficial properties. Sulfated xanthan derivatives have anticoagulant and antithrombotic activity. This work proposes a new method for the synthesis of xanthan sulfates using sulfamic acid. Various N-substituted ureas have been investigated as process activators. It was found that urea has the greatest activating ability. BBD of xanthan sulfation process with sulfamic acid in 1,4-dioxane has been carried out. It was shown that the optimal conditions for the sulfation of xanthan (13.1 wt% sulfur content) are: the amount of sulfating complex per 1 g of xanthan is 3.5 mmol, temperature 90 °C, duration 2.3 h. Sulfated xanthan with the maximum sulfur content was analyzed by physicochemical methods. Thus, in the FTIR spectrum of xanthan sulfate, in comparison with the initial xanthanum, absorption bands appear at 1247 cm⁻¹, which corresponds to the vibrations of the sulfate group. It was shown by GPC chromatography that the starting xanthan gum has a bimodal molecular weight distribution of particles, including a high molecular weight fraction with M_w > 1000 kDa and an LMW fraction with M_w < 600 kDa. It was found that the Mw of sulfated xanthan gum has a lower value (~612 kDa) in comparison with the original xanthan gum, and a narrower molecular weight distribution and is characterized by lower PD values. It was shown by thermal analysis that the main decomposition of xanthan sulfate, in contrast to the initial xanthan, occurs in two stages. The DTG curve has two pronounced peaks, with maxima at 226 and 286 °C. Full article

(This article belongs to the Topic Sustainable Polymer Technologies)

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15 pages, 2265 KiB  

Open AccessArticle

Antibacterial Properties of Coaxial Spinning Membrane of Methyl ferulate/zein and Its Preservation Effect on Sea Bass

by Tingting Li, Yue Shen, Haitao Chen, Yuchen Xu, Dangfeng Wang, Fangchao Cui, Yujuan Han and Jianrong Li

Foods 2021, 10(10), 2385; https://doi.org/10.3390/foods10102385 - 8 Oct 2021

Cited by 18 | Viewed by 2059

Abstract

Methyl ferulate is a new natural antibacterial agent with strong activity and low toxicity. It has good application prospects in food preservation. In this paper, the antibacterial activity of methyl ferulate against Shigella putrefaciens was verified, and it was embedded into zein by [...] Read more.

Methyl ferulate is a new natural antibacterial agent with strong activity and low toxicity. It has good application prospects in food preservation. In this paper, the antibacterial activity of methyl ferulate against Shigella putrefaciens was verified, and it was embedded into zein by electrospinning technology to prepare fiber membranes. The addition of methyl ferulate could improve the tensile strength of zein fiber membrane and decrease the crystallinity of the membrane, which was mainly a physical combination. The fiber membrane improved the thermal stability of methyl ferulate. The water contact angle (WCA) decreased to 54.85°. The results showed that methyl ferulate in fiber membrane could be released slowly, gradually exerting its antibacterial activity. After coating perch with methyl ferulate/zein fiber membrane, the growth of microorganisms in perch meat was inhibited, and the pH value and total volatile basic nitrogen (TVB-N)content were effectively increased. In a word, methyl ferulate had antibacterial activity in the fiber film, which was able to achieve a sustained release effect in the process of fish packaging, prolonging its antibacterial activity, and having preservation effect on sea bass; thus, it could be used in food packaging. Full article

(This article belongs to the Topic Sustainable Polymer Technologies)

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28 pages, 6993 KiB  

Open AccessReview

Material Anisotropy in Additively Manufactured Polymers and Polymer Composites: A Review

by Nima Zohdi and Richard (Chunhui) Yang

Polymers 2021, 13(19), 3368; https://doi.org/10.3390/polym13193368 - 30 Sep 2021

Cited by 63 | Viewed by 6804

Abstract

Additive manufacturing (AM) is a sustainable and innovative manufacturing technology to fabricate products with specific properties and complex shapes for additive manufacturable materials including polymers, steels, titanium, copper, ceramics, composites, etc. This technology can well facilitate consumer needs on products with complex geometry [...] Read more.

Additive manufacturing (AM) is a sustainable and innovative manufacturing technology to fabricate products with specific properties and complex shapes for additive manufacturable materials including polymers, steels, titanium, copper, ceramics, composites, etc. This technology can well facilitate consumer needs on products with complex geometry and shape, high strength and lightweight. It is sustainable with having a layer-by-layer manufacturing process contrary to the traditional material removal technology—subtractive manufacturing. However, there are still challenges on the AM technologies, which created barriers for their further applications in engineering fields. For example, materials properties including mechanical, electrical, and thermal properties of the additively manufactured products are greatly affected by using different ways of AM methods and it was found as the material anisotropy phenomenon. In this study, a detailed literature review is conducted to investigate research work conducted on the material anisotropy phenomenon of additively manufactured materials. Based on research findings on material anisotropy phenomenon reported in the literature, this review paper aims to understand the nature of this phenomenon, address main factors and parameters influencing its severity on thermal, electrical and mechanical properties of 3D printed parts, and also, explore potential methods to minimise or mitigate this unwanted anisotropy. The outcomes of this study would be able to shed a light on improving additive manufacturing technologies and material properties of additively manufactured materials. Full article

(This article belongs to the Topic Sustainable Polymer Technologies)

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11 pages, 16605 KiB  

Open AccessArticle

Fabrication and Characterization of Composite Biofilm of Konjac Glucomannan/Sodium Lignosulfonate/ε-Polylysine with Reinforced Mechanical Strength and Antibacterial Ability

by Xiaowei Xu and Jie Pang

Polymers 2021, 13(19), 3367; https://doi.org/10.3390/polym13193367 - 30 Sep 2021

Cited by 2 | Viewed by 1767

Abstract

In order to enforce the mechanical strength and antibacterial ability of biofilm and explore the underlying mechanism, sodium lignosulfonate (SL) and ε-polylysine (ε-PL) were introduced to fabricate the composite film of konjac glucomannan (KGM)/SL/ε-PL in the present study. According to our previous method, [...] Read more.

In order to enforce the mechanical strength and antibacterial ability of biofilm and explore the underlying mechanism, sodium lignosulfonate (SL) and ε-polylysine (ε-PL) were introduced to fabricate the composite film of konjac glucomannan (KGM)/SL/ε-PL in the present study. According to our previous method, 1% (w/v) of KGM was the optimal concentration for the film preparation method, on the basis of which the amount of SL and ε-PL were screened by mechanical properties enforcement of film. The structure, mechanical performance and thermal stability of the film were characterized by SEM, FTIR, TGA and tensile strength tests. The optimized composite film was comprised of KGM 1% (w/v), SL 0.2% (w/v), and ε-PL 0.375% (w/v). The tensile strength (105.97 ± 4.58 MPa, p < 0.05) and elongation at break (95.71 ± 5.02%, p < 0.05) of the KGM/SL/ε-PL composite film was greatly improved compared with that of KGM. Meanwhile, the thermal stability and antibacterial property of film were also enhanced by the presence of SL and ε-PL. In co-culturation mode, the KGM/SL/ε-PL composite film showed good inhibitory effect on Escherichia coli (22.50 ± 0.31 mm, p < 0.05) and Staphylococcus aureus (19.69 ± 0.36 mm, p < 0.05) by determining the inhibition zone diameter. It was revealed that KGM/SL/ε-PL composite film shows enhanced mechanical strength and reliable antibacterial activities and it could be a potential candidate in the field of food packaging. Full article

(This article belongs to the Topic Sustainable Polymer Technologies)

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23 pages, 32787 KiB  

Open AccessArticle

Molecularly Imprinted Chitosan-Based Thin Films with Selectivity for Nicotine Derivatives for Application as a Bio-Sensor and Filter

by Obinna Ofoegbu, David Chukwuebuka Ike, Gaber El-Saber Batiha, Hassan Fouad, Roongnapa S. Srichana and Ian Nicholls

Polymers 2021, 13(19), 3363; https://doi.org/10.3390/polym13193363 - 30 Sep 2021

Cited by 5 | Viewed by 2037

Abstract

This study reports the feasible use of chitosan as a thin film biosensor on the very sensitive quartz crystal micro balance system for detection of blends of multiple templates within a single matrix. The development of chitosan-based thin film materials with selectivity for [...] Read more.

This study reports the feasible use of chitosan as a thin film biosensor on the very sensitive quartz crystal micro balance system for detection of blends of multiple templates within a single matrix. The development of chitosan-based thin film materials with selectivity for nicotine derivatives is described. The molecular imprinting of a combination of nicotine derivatives in N-diacryloyl pipiradine-chitosan-methacrylic acid copolymer films on quartz crystal resonators was used to generate thin films with selectivity for nicotine and a range of nicotine analogues, particularly 3-phenylpyridine. The polymers were characterized by spectroscopic and microscopic evaluations; surface area, pore size, pore volume using Breuner-Emmet-Teller method. Temperature characteristics were also studied. The swelling and structure consistency of the Chitosan was achieved by grafting with methylmethacrylic acid and cross-linking with N-diacrylol pipiradine. A blend of 0.002 g (0.04 mmol) of Chitosan, 8.5 μL Methylmethacrylic Acid and 1.0 mg N-diacrylol pipradine (BAP) presented the best blend formulation. Detections were made within a time interval of 99 s, and blend templates were detected at a concentration of 0.5 mM from the Quartz crystal microbalance resonator analysis. The successful crosslinking of the biopolymers ensured successful control of the swelling and agglomeration of the chitosan, giving it the utility potential for use as thin film sensor. This successful crosslinking also created successful dual multiple templating on the chitosan matrix, even for aerosolized templates. The products can be used in environments with temperature ranges between 60 °C and 250 °C. Full article

(This article belongs to the Topic Sustainable Polymer Technologies)

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14 pages, 38565 KiB  

Open AccessArticle

High-Temperature-Induced Shape Memory Copolyimide

by Yucheng Zi, Dongxu Pei, Jianhua Wang, Shengli Qi, Guofeng Tian and Dezhen Wu

Polymers 2021, 13(19), 3222; https://doi.org/10.3390/polym13193222 - 23 Sep 2021

Cited by 9 | Viewed by 2186

Abstract

A series of polyimide (PI) films with a high-temperature-induced shape memory effect and tunable properties were prepared via the facile random copolymerization of 4,4′-oxydianiline (ODA) with 4,4′-(hexafluoroisopropyl)diphthalic anhydride (6FDA) and 4,4′-oxydiphthalic anhydride (ODPA). The trigger temperature can be controlled from 294 to 326 [...] Read more.

A series of polyimide (PI) films with a high-temperature-induced shape memory effect and tunable properties were prepared via the facile random copolymerization of 4,4′-oxydianiline (ODA) with 4,4′-(hexafluoroisopropyl)diphthalic anhydride (6FDA) and 4,4′-oxydiphthalic anhydride (ODPA). The trigger temperature can be controlled from 294 to 326 °C by adjusting the ratio of monomers. The effects of monomer rigidity on the chain mobility, physical properties, and shape memory performance of as-prepared copolyimide were systematically investigated. The introduction of ODPA could enhance the mobility of PI macromolecular chains, which made chain entanglement more likely to occur and increased the physical crosslinking density, thereby improving the PI’s shape recovery up to 97%. Meanwhile, the existence of 6FDA enabled PI films to set quickly at low temperatures with a shape fixation of 98%. The shape memory cycling characteristics of the polyimide films are also studied, and the relationship between the PI chemical structure and the film properties are further discussed. Full article

(This article belongs to the Topic Sustainable Polymer Technologies)

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14 pages, 1830 KiB  

Open AccessArticle

Use of Dicyclopentadiene and Methyl Dicyclopentadiene for the Synthesis of Unsaturated Polyester Resins

by Alexandre Perrot, Jan Hyršl, Jan Bandžuch, Simona Waňousová, Jiří Hájek, Jan Jenčík and Tomáš Herink

Polymers 2021, 13(18), 3135; https://doi.org/10.3390/polym13183135 - 16 Sep 2021

Cited by 7 | Viewed by 4407

Abstract

Dicyclopentadiene (DCPD) modified unsaturated polyester resins (UPRs) are mostly used for hulls, decks, and bathroom facilities. Main advantages of these polymers over orthophthalic or isophthalic polyesters are their relatively low shrinking, reduced styrene emission, lower cost, and fast curing in thin layers. On [...] Read more.

Dicyclopentadiene (DCPD) modified unsaturated polyester resins (UPRs) are mostly used for hulls, decks, and bathroom facilities. Main advantages of these polymers over orthophthalic or isophthalic polyesters are their relatively low shrinking, reduced styrene emission, lower cost, and fast curing in thin layers. On the other hand, once cured, these materials are more brittle and have lower glass transition temperatures and lower chemical resistance due to their different chemical constitutions. DCPD UPRs with standard grades are usually produced with high-quality DCPD (over a 85% purity) using the so-called “water process”, a synthesis consisting of two reaction steps. An adduct of maleic anhydride with DCPD is firstly formed with water, and then, it reacts with the other esterification monomers such as acids and glycols. DCPD raw materials used in this study were prepared by a unique distillation process developed by ORLEN Unipetrol and University of Chemistry and Technology, Prague. This technology allows producing a wide spectrum of DCPD quality by adjusting the content of another norbornene dimer: methyl dicyclopentadiene (MeDCPD). The influence of MeDCPD on unsaturated polyester properties was examined throughout this study. It has been discovered that in low concentrations, MeDCPD had a slight influence on flexural mechanical properties whereas its concentrations up to 65% led to a softer and brittle material. Nevertheless, by adjusting the unsaturation degree, it has been shown that MeDCPD may be successfully implanted in UPR formulation. Full article

(This article belongs to the Topic Sustainable Polymer Technologies)

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19 pages, 7768 KiB  

Open AccessArticle

Comparative Analysis of the Chemical Composition and Physicochemical Properties of the Mucilage Extracted from Fresh and Dehydrated Opuntia ficus indica Cladodes

by Michelle Quintero-García, Elsa Gutiérrez-Cortez, Moustapha Bah, Alejandra Rojas-Molina, María de los Angeles Cornejo-Villegas, Alicia Del Real and Isela Rojas-Molina

Foods 2021, 10(9), 2137; https://doi.org/10.3390/foods10092137 - 10 Sep 2021

Cited by 15 | Viewed by 3391

Abstract

The development of sustainable extraction methods to obtain natural products constitutes a challenge for the food industry. The aim of this work was to compare yield, separation efficiency, chemical composition, and physicochemical properties of the mucilage extracted from fresh cladodes (FNM) and mucilage [...] Read more.

The development of sustainable extraction methods to obtain natural products constitutes a challenge for the food industry. The aim of this work was to compare yield, separation efficiency, chemical composition, and physicochemical properties of the mucilage extracted from fresh cladodes (FNM) and mucilage extracted from dehydrated cladodes (DNM) of O. ficus indica. Suspensions of fresh and dehydrated cladodes (4% w/w) were prepared for mucilage extraction by using a mechanical separation process. Subsequently, the separated mucilage was precipitated with ethyl alcohol (1:2 v/v) then, yield and separation efficiency were determined. The mucilage was characterized by measuring Z potential, viscosity, color, and texture attributes. Additionally, chemical proximate analysis, scanning electron microscopy, and thermogravimetric analysis (TGA) were conducted. No significant differences (p < 0.05) were detected in the yield and separation efficiencies between samples. Nevertheless, the dehydration process of cladodes prior to mucilage extraction increased protein, ashes, nitrogen free extract, and calcium content. The viscosity was higher in DNM than in FNM. The TGA revealed a different thermal behavior between samples. In addition, the DNM showed lower L (darkness/lightness), cohesiveness, adhesiveness, and springiness values than those of FNM. These results support that differences found between the chemical and physicochemical properties of DNM and those of FNM will determine the applications of the mucilage obtained from the O. ficus indica cladodes in the food, pharmaceutical, and cosmetic industries. Full article

(This article belongs to the Topic Sustainable Polymer Technologies)

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27 pages, 1747 KiB  

Open AccessArticle

Kinetic, Thermodynamic, Physicochemical, and Economical Characterization of Pectin from Mangifera indica L. cv. Haden Residues

by Sergio Valdivia-Rivera, Iván Emanuel Herrera-Pool, Teresa Ayora-Talavera, Manuel Alejandro Lizardi-Jiménez, Ulises García-Cruz, Juan Carlos Cuevas-Bernardino, José Manuel Cervantes-Uc and Neith Pacheco

Foods 2021, 10(9), 2093; https://doi.org/10.3390/foods10092093 - 4 Sep 2021

Cited by 14 | Viewed by 3069

Abstract

The effect of temperature (60, 70, 80, and 90 °C) and time (30, 45, 60, 75, and 90 min) on citric acid extraction of Haden mango (Mangifera indica L. cv. Haden) peel pectin was evaluated in the present study. In order to [...] Read more.

The effect of temperature (60, 70, 80, and 90 °C) and time (30, 45, 60, 75, and 90 min) on citric acid extraction of Haden mango (Mangifera indica L. cv. Haden) peel pectin was evaluated in the present study. In order to obtain a better understanding of both the extraction process and the characteristics of the pectin (obtained from an agro-industrial waste) for a future scaling process, the following characterizations were performed: (1) Kinetic, with the maximum extraction times and yields at all evaluated temperatures; (2) thermodynamic, obtaining activation energies, enthalpies, entropies, and Gibbs free energies for each stage of the process; (3) physicochemical (chemical analysis, monosaccharide composition, degree of esterification, galacturonic acid content, free acidity, Fourier-transform infrared spectroscopy, thermogravimetric and derivative thermogravimetric analyses); and (4) economical, of the pectin with the highest yield. The Haden mango peel pectin was found to be characterized by a high-esterified degree (81.81 ± 0.00%), regular galacturonic acid content (71.57 ± 1.26%), low protein (0.83 ± 0.05%) and high ash (3.53 ± 0.02%) content, low mean viscometric molecular weight (55.91 kDa), and high equivalent weight (3657.55 ± 8.41), which makes it potentially useful for food applications. Full article

(This article belongs to the Topic Sustainable Polymer Technologies)

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8 pages, 1356 KiB  

Open AccessArticle

Effect of Modified Silica Fume Using MPTMS for the Enhanced EPDM Foam Insulation

by Rudeerat Suntako

Polymers 2021, 13(17), 2996; https://doi.org/10.3390/polym13172996 - 3 Sep 2021

Cited by 6 | Viewed by 2203

Abstract

Silica fume (SF) is a by-product from the production of silicon metal, which has a relatively high silica concentration. The surface modified silica fume (mSF) is treated with (3-mercaptopropyl) trimethoxysilane (MPTMS) as filler in ethylene propylene diene monomer (EPDM) foam. The FTIR spectra [...] Read more.

Silica fume (SF) is a by-product from the production of silicon metal, which has a relatively high silica concentration. The surface modified silica fume (mSF) is treated with (3-mercaptopropyl) trimethoxysilane (MPTMS) as filler in ethylene propylene diene monomer (EPDM) foam. The FTIR spectra of mSF clearly indicated that MPTMS can be successfully bonded to the SF surface. The reinforcing efficiency of mSF-filled EPDM foam insulation indicated that the mechanical properties such as hardness, tensile strength, modulus, and compression set enhanced higher than in case of SF and calcium carbonate. While the cure characteristics such as the maximum torque (M_H), the minimum torque (M_L) and the differential torque (M_H-M_L) are increasing in proportion to increasing filler contents, mainly with mSF. For the cure behavior, the mSF-filled EPDM foam insulation showed the fastest cure time (t_c90) and scorch time (t_s2) due to reduced accelerator adsorption. Whereas, the calcium carbonate-filled EPDM foam insulation increased the cure time (t_c90) and scorch time (t_s2), therefore, it also prevents compound scorching. The results indicated that the mSF with MPTMS can be used as an alternative filler for EPDM foam insulation. Full article

(This article belongs to the Topic Sustainable Polymer Technologies)

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14 pages, 8144 KiB  

Open AccessArticle

Preparation and Characterization of Cellulose Acetate Film Reinforced with Cellulose Nanofibril

by Azelia Wulan Cindradewi, Rajkumar Bandi, Chan-Woo Park, Ji-Soo Park, Eun-Ah Lee, Jeong-Ki Kim, Gu-Joong Kwon, Song-Yi Han and Seung-Hwan Lee

Polymers 2021, 13(17), 2990; https://doi.org/10.3390/polym13172990 - 3 Sep 2021

Cited by 27 | Viewed by 8893

Abstract

In this study, cellulose acetate (CA)/cellulose nanofibril (CNF) film was prepared via solvent casting. CNF was used as reinforcement to increase tensile properties of CA film. CNF ratio was varied into 3, 5, and 10 phr (parts per hundred rubbers). Triacetin (TA) and [...] Read more.

In this study, cellulose acetate (CA)/cellulose nanofibril (CNF) film was prepared via solvent casting. CNF was used as reinforcement to increase tensile properties of CA film. CNF ratio was varied into 3, 5, and 10 phr (parts per hundred rubbers). Triacetin (TA) and triethyl citrate (TC) were used as two different eco-friendly plasticizers. Two different types of solvent, which are acetone and N-methyl-2-pyrrolidone (NMP), were also used. CA/CNF film was prepared by mixing CA and CNF in acetone or NMP with 10% concentration and stirred for 24 h. Then, the solution was cast in a polytetrafluoroethylene (PTFE) dish followed by solvent evaporation for 12 h at room temperature for acetone and 24 h at 80 °C in an oven dryer for NMP. The effect of solvent type, plasticizers type, and CNF amount on film properties was studied. Good dispersion in NMP was evident from the morphological study of fractured surface and visible light transmittance. The results showed that CNF has a better dispersion in NMP which leads to a significant increase in tensile strength and elastic modulus up to 38% and 65%, respectively, compared with those of neat CA. CNF addition up to 5 phr loading increased the mechanical properties of the film composites. Full article

(This article belongs to the Topic Sustainable Polymer Technologies)

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13 pages, 4680 KiB  

Open AccessArticle

Wet-Spun Composite Filaments from Lignocellulose Nanofibrils/Alginate and Their Physico-Mechanical Properties

by Ji-Soo Park, Song-Yi Han, Rajkumar Bandi, Eun-Ah Lee, Azelia-Wulan Cindradewi, Jeong-Ki Kim, Gu-Joong Kwon, Young-Ho Seo, Won-Jae Youe, Jaegyoung Gwon, Chan-Woo Park and Seung-Hwan Lee

Polymers 2021, 13(17), 2974; https://doi.org/10.3390/polym13172974 - 1 Sep 2021

Cited by 3 | Viewed by 2738

Abstract

Lignocellulose nanofibrils (LCNFs) with different lignin contents were prepared using choline chloride (ChCl)/lactic acid (LA), deep eutectic solvent (DES) pretreatment, and subsequent mechanical defibrillation. The LCNFs had a diameter of 15.3–18.2 nm, which was similar to the diameter of commercial pure cellulose nanofibrils [...] Read more.

Lignocellulose nanofibrils (LCNFs) with different lignin contents were prepared using choline chloride (ChCl)/lactic acid (LA), deep eutectic solvent (DES) pretreatment, and subsequent mechanical defibrillation. The LCNFs had a diameter of 15.3–18.2 nm, which was similar to the diameter of commercial pure cellulose nanofibrils (PCNFs). The LCNFs and PCNFs were wet-spun in CaCl₂ solution for filament fabrication. The addition of sodium alginate (AL) significantly improved the wet-spinnability of the LCNFs. As the AL content increased, the average diameter of the composite filaments increased, and the orientation index decreased. The increase in AL content improved the wet-spinnability of CNFs but deteriorated the tensile properties. The increase in the spinning rate resulted in an increase in the orientation index, which improved the tensile strength and elastic modulus. Full article

(This article belongs to the Topic Sustainable Polymer Technologies)

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10 pages, 4980 KiB  

Open AccessArticle

Physical-Mechanical Properties of Bamboo Fiber Composites Using Filament Winding

by Wenfu Zhang, Cuicui Wang, Shaohua Gu, Haixia Yu, Haitao Cheng and Ge Wang

Polymers 2021, 13(17), 2913; https://doi.org/10.3390/polym13172913 - 29 Aug 2021

Cited by 19 | Viewed by 3032

Abstract

In order to study the performance of the bamboo fiber composites prepared by filament winding, composites reinforced with jute fiber and glass fiber were used as control samples. The structure and mechanical properties of the composites were investigated by scanning electric microscope (SEM), [...] Read more.

In order to study the performance of the bamboo fiber composites prepared by filament winding, composites reinforced with jute fiber and glass fiber were used as control samples. The structure and mechanical properties of the composites were investigated by scanning electric microscope (SEM), tensile testing, bending testing, and dynamic mechanical analysis. The results demonstrated that the bamboo fiber composites exhibited lower density (0.974 g/cm³) and mechanical properties in comparison of to fiber composite and glass fiber composite, because the inner tissue structure of bamboo fiber was preserved without resin adsorbed into the cell cavity of fibrous parenchyma. The bamboo fibers in composites were pulled out, while the fibers in the surface of composites were torn, resulting in the lowest mechanical performance of bamboo fiber composites. The glass transition temperature of twisting bamboo fiber Naval Ordnance Laboratory (TBF-NOL) composite (165.89 °C) was the highest in general, which indicated that the TBF circumferential composite had the best plasticizing properties and better elasticity, the reason being that the fiber-reinforced epoxy circumferential composite interface joint is a physical connection, which restricts the movement of the molecular chain of the epoxy matrix, making the composite have a higher storage modulus (6000 MPa). In addition, The TBF-NOL had the least frequency dependence, and the circumferential composite prepared by TBF had the least performance variability. Therefore, the surface and internal structures of the bamboo fiber should be further processed and improved by decreasing the twisting bamboo fiber (TBF) diameter and increasing the specific surface area of the TBF and joint surface between fibers and resin, to improve the comprehensive properties of bamboo fiber composites. Full article

(This article belongs to the Topic Sustainable Polymer Technologies)

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18 pages, 17420 KiB  

Open AccessArticle

Comparative Study of Fire Resistance and Anti-Ageing Properties of Intumescent Fire-Retardant Coatings Reinforced with Conch Shell Bio-Filler

by Feiyue Wang, Hui Liu, Long Yan and Yuwei Feng

Polymers 2021, 13(16), 2620; https://doi.org/10.3390/polym13162620 - 6 Aug 2021

Cited by 13 | Viewed by 2999

Abstract

Conch shell bio-filler (CSBF) was prepared by washing, ultrasonicating, and pulverizing of conch shells and then was applied in waterborne intumescent fire-retardant coatings. The influence of CSBF on fire resistance and anti-ageing properties of intumescent fire-retardant coatings were studied by using different analytical [...] Read more.

Conch shell bio-filler (CSBF) was prepared by washing, ultrasonicating, and pulverizing of conch shells and then was applied in waterborne intumescent fire-retardant coatings. The influence of CSBF on fire resistance and anti-ageing properties of intumescent fire-retardant coatings were studied by using different analytical methods. The fire protection and smoke density tests showed that when the mass fraction of CSBF was 3%, the resulting FRC3 coating had the optimum synergistic flame-retardant and smoke-suppression effects concomitant with a flame-spread rating of 10.7, equilibrium backside temperature of 152.4 °C at 900 s, and smoke-density rating value of 10.4%, which were attributed to the establishment of a more dense and stable intumescent char layer against heat and mass transfer. Thermogravimetric analysis indicated that the presence of CSBF increased the thermal stability and char-forming performance of the coatings, and the char residue of FRC3 rose to 34.6% at 800 °C from 28.6% of FRC0 without CSBF. The accelerated ageing test suggested that the incorporation of CSBF reduced the migration and decomposition of the flame retardants and the yellowing, blistering, and powdering phenomenon, thus improving the structural stability of the coating, resulting in better durability of flame retardancy and smoke-suppression performance. Full article

(This article belongs to the Topic Sustainable Polymer Technologies)

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15 pages, 2869 KiB  

Open AccessArticle

Insight into the Effect of Ice Addition on the Gel Properties of Nemipterus virgatus Surimi Gel Combined with Water Migration

by Haiqiang Chen, Yiqian Zou, Aimei Zhou, Jie Xiao and Soottawat Benjakul

Foods 2021, 10(8), 1815; https://doi.org/10.3390/foods10081815 - 5 Aug 2021

Cited by 19 | Viewed by 2340

Abstract

The effect of the amount of ice added (20–60%) on the gel properties and water migration of Nemipterus virgatus surimi gel obtained with two-stage heat treatment was studied. The gel strength and water-holding capability (WHC) of the surimi gel with 30% ice added [...] Read more.

The effect of the amount of ice added (20–60%) on the gel properties and water migration of Nemipterus virgatus surimi gel obtained with two-stage heat treatment was studied. The gel strength and water-holding capability (WHC) of the surimi gel with 30% ice added were significantly higher than those of other treatment groups (p < 0.05). The addition of 30% ice was conducive to the increase of protein β-sheet proportion during heat treatment, exposing more reactive sulfhydryl groups. These promoted the combination of protein-protein through disulfide bonds and hydrophobic-hydrophobic interactions, forming an ordered three-dimensional gel network structure. Meanwhile, the increase in hydrogen bonds promoted the protein-water interaction. Low-field nuclear magnetic resonance analysis showed that more bound water was locked in the gel system, reducing the migration of immobile water to free water and finally showing better gel properties. When the amount of ice added was insufficient (20%), the gel structure lacked the support of immobile water, resulting in deterioration of gel strength. However, excessive addition of ice (>30%) was not conducive to the combination of protein-protein and protein-water, forming a large and rough gel structure, resulting in the migration of immobile water to free water and ultimately exhibited weak gel properties. Full article

(This article belongs to the Topic Sustainable Polymer Technologies)

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15 pages, 2721 KiB  

Open AccessArticle

Changes in Properties of Soy Protein Isolate Edible Films Stored at Different Temperatures: Studies on Water and Glycerol Migration

by Hong Zhang, Lechuan Wang, Hanyu Li, Yujie Chi, Huajiang Zhang, Ning Xia, Yanqiu Ma, Longwei Jiang and Xiaonan Zhang

Foods 2021, 10(8), 1797; https://doi.org/10.3390/foods10081797 - 4 Aug 2021

Cited by 12 | Viewed by 2641

Abstract

Plasticizers and the water migration of edible protein films during storage can result in changes in film properties, while specific changing processes need to be further explored. In this study, glycerol-plasticized soy protein isolate (SPI) films were stored at 25 °C, 4 °C, [...] Read more.

Plasticizers and the water migration of edible protein films during storage can result in changes in film properties, while specific changing processes need to be further explored. In this study, glycerol-plasticized soy protein isolate (SPI) films were stored at 25 °C, 4 °C, and −18 °C for 6 weeks (relative humidity (RH), 40–50%). The glycerol migration was monitored by the glycerol migration rate and differential scanning calorimetry (DSC). Water content, low-field nuclear magnetic resonance (LF-NMR), and thermogravimetric analysis (TGA) were used to analyze the water state. The results showed that significant pores and cracks were observed after storage at 25 °C. The proportion of bound water gradually increased, and the glycerol migration rate also reached 1.3% and 0.7% at 25 °C and 4 °C, respectively. The results proved that increasing the storage temperature accelerated the loss of water and glycerol, and decreased the mechanical properties of the SPI film. Full article

(This article belongs to the Topic Sustainable Polymer Technologies)

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17 pages, 7543 KiB  

Open AccessArticle

Nano-Metal Organic Framework for Enhanced Mechanical, Flame Retardant and Ultraviolet-Blue Light Shielding Properties of Transparent Cellulose-Based Bioplastics

by Lijian Sun, Limei Li, Xianhui An and Xueren Qian

Polymers 2021, 13(15), 2433; https://doi.org/10.3390/polym13152433 - 23 Jul 2021

Cited by 12 | Viewed by 3299

Abstract

From the perspective of sustainable development and practical applications, there has been a great need for the design of multifunctional transparent cellulose-based composite films. We herein propose a novel concept of improving the mechanical, fire-resistant and ultraviolet (UV)-blue light shielding properties of cellulose-based [...] Read more.

From the perspective of sustainable development and practical applications, there has been a great need for the design of multifunctional transparent cellulose-based composite films. We herein propose a novel concept of improving the mechanical, fire-resistant and ultraviolet (UV)-blue light shielding properties of cellulose-based composite bioplastic films though in situ embedding nano-metal organic framework (MIL-125(Ti)-NH₂) into regenerated cellulose gel. Regenerated cellulose hydrogel (CH) with a porous structure acts as a nanoreactor and stabilizer to facilitate the growth and anchorage of MIL-125(Ti)-NH₂ nanoparticles (MNPs). Subsequently, hot-pressing induces the formation of transparent MIL-125(Ti)-NH₂@cellulose bioplastics (MNP@CBPs). As expected, the MNP@CBPs exhibit exceptional UV-blue light shielding capability, while retaining satisfactory optical transmittance. Meanwhile, with the incorporation of MNPs, the mechanical strength of MNP@CBPs is increased by 6.5~25.9%. In addition, MNPs enhance the flame retardant effect of the MNP@CBPs. The limited oxygen index (LOI) of the MNP@CBPs increased from 21.95 to 27.01%. The hot-pressing process improves the resistance of the MNP@CBPs to the penetration of water/non-aqueous liquids. This simple strategy would direct sustainable multifunctional MNP@CBPs toward diversified applications: food containers or packaging materials that can reduce or eliminate food spoilage, screen protectors for blocking harmful light, and promising candidates for protective plastic products, among others. Full article

(This article belongs to the Topic Sustainable Polymer Technologies)

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25 pages, 4885 KiB  

Open AccessArticle

Optimization of Moist and Oven-Dried Bacterial Cellulose Production for Functional Properties

by Ioana M. Bodea, Florin I. Beteg, Carmen R. Pop, Adriana P. David, Mircea Cristian Dudescu, Cristian Vilău, Andreea Stănilă, Ancuța M. Rotar and Giorgiana M. Cătunescu

Polymers 2021, 13(13), 2088; https://doi.org/10.3390/polym13132088 - 24 Jun 2021

Cited by 12 | Viewed by 3735 | Correction

Abstract

Bacterial cellulose (BC) is a natural polymer with properties suitable for tissue engineering and possible applications in scaffold production. However, current procedures have limitations in obtaining BC pellicles with the desired structural, physical, and mechanical properties. Thus, this study analyzed the optimal culture [...] Read more.

Bacterial cellulose (BC) is a natural polymer with properties suitable for tissue engineering and possible applications in scaffold production. However, current procedures have limitations in obtaining BC pellicles with the desired structural, physical, and mechanical properties. Thus, this study analyzed the optimal culture conditions of BC membranes and two types of processing: draining and oven-drying. The aim was to obtain BC membranes with properties suitable for a wound dressing material. Two studies were carried out. In the preliminary study, the medium (100 mL) was inoculated with varying volumes (1, 2, 3, 4, and 5 mL) and incubated statically for different periods (3, 6, 9, 12, and 18 days), using a full factorial experimental design. Thickness, uniformity, weight, and yield were evaluated. In the optimization study, a Box–Behnken design was used. Two independent variables were used: inoculum volume (X₁: 1, 3, and 5 mL) and fermentation period (X₂: 6, 12, and 18 d) to determine the target response variables: thickness, swelling ratio, drug release, fiber diameter, tensile strength, and Young’s modulus for both dry and moist BC membranes. The mathematical modelling of the effect of the two independent variables was performed by response surface methodology (RSM). The obtained models were validated with new experimental values and confirmed for all tested properties, except Young’s modulus of oven-dried BC. Thus, the optimal properties in terms of a scaffold material of the moist BC were obtained with an inoculum volume of 5% (v/v) and 16 d of fermentation. While, for the oven-dried membranes, optimal properties were obtained with a 4% (v/v) and 14 d of fermentation. Full article

(This article belongs to the Topic Sustainable Polymer Technologies)

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13 pages, 2655 KiB  

Open AccessArticle

Improving the Dyeability and Anti-Wrinkle Properties of Cotton Fabric via Oxidized Raffinose

by Jiangfei Lou, Jinfang Zhang, Dan Wang and Xuerong Fan

Appl. Sci. 2021, 11(10), 4641; https://doi.org/10.3390/app11104641 - 19 May 2021

Cited by 4 | Viewed by 2665

Abstract

In the anti-wrinkle finishing of cotton fabrics, the decreased dyeability of the finished fabrics has always been a difficult problem. A new anti-wrinkle finishing mode was developed to solve this problem by changing the finishing sequence of fabric dyeing and anti-wrinkle. In this [...] Read more.

In the anti-wrinkle finishing of cotton fabrics, the decreased dyeability of the finished fabrics has always been a difficult problem. A new anti-wrinkle finishing mode was developed to solve this problem by changing the finishing sequence of fabric dyeing and anti-wrinkle. In this research, the partial oxidization of raffinose with sodium periodate generated multiple aldehydes, which acted as multifunctional cross-linkers and endowed cotton fabrics with anti-wrinkle and hydrophilic properties. The structural characteristics of oxyRa were analyzed by FTIR and ¹³C-NMR. Through response surface methodology (RSM), the finishing model of oxyRa was established from the influencing factors of catalyst concentration, pH, curing temperature and time, and the optimized finishing process: the catalyst concentration was 20.12 g/L, pH was 4.32, curing temperature was 150 °C and curing time was 120 s. Under this condition, the predicted wrinkle recovery angle (WRA) of the finished fabric was up to 249.76°, Tensile strength (TS) was 75.62%, Whiteness index (WI) was 70.69. Importantly, comparing the anti-wrinkle and dyeing performance of the fabric with anti-wrinkle and then dyeing and anti-wrinkle after dyeing, the oxyRa-treated fabrics showed better dyeing properties compared with previously reported dimethyldihydroxyethylene urea (DMDHEU), glutaraldehyde (GA), and 1,2,3,4-butanetetracarboxylic acid (BTCA). Analysis of the combined mechanism of different finishing agents and cellulose, demonstrated the reason why oxyRa can be used to change the order of dyeing and anti-wrinkle finishing. Full article

(This article belongs to the Topic Sustainable Polymer Technologies)

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