Advances in Sustainable Polymers: Processing, Modeling, Properties and Applications

A special issue of Polymers (ISSN 2073-4360). This special issue belongs to the section "Polymer Processing and Engineering".

Deadline for manuscript submissions: closed (20 June 2023) | Viewed by 54017

Special Issue Editor


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Guest Editor
Mechanical and Aerospace Engineering Department, College of Engineering, United Arab Emirates University, Al-Ain 15551, United Arab Emirates
Interests: materials science and engineering; materials characterization; polymeric and composite materials; biomaterials and tissue engineering; biomechanics; durability and degradation of polymeric and composite materials; welding of metallic and polymeric materials; corrosion; fatigue and fracture mechanics; renewable energy; finite element method
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Special Issue Information

Dear Colleagues, 

We are living in a world where man-made polymer materials are around. These synthetic materials are necessary parts of our current life and the global economy. It is estimated that the annual output of synthetic materials may reach 1.3 billion tons in 2050 with the annual output increasing year by year. However, the question remains of how to degrade and resue these polymer materials, especially plastics, after their usage is still a challenge. It attracts much more attention from scientists in various fields and from all over the world.

This Special Issue aims to provide a platform for scientists and engineers to showcase the recent development of sustainable polymer materials. The topics of particular interest for this Special Issue include, but are not limited to:

  • Sustainable polymers;
  • Renewable polymers;
  • Eco-friendly polymers;
  • Green polymers;
  • Biomass-derived polymers;
  • Biodegradable polymers;
  • Waste-derived polymers;
  • Recovery and recycling of plastics and polymer composites;
  • Circular economy.

Prof. Dr. Abdel-Hamid I. Mourad
Guest Editor

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Polymers is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • sustainable polymers
  • renewable polymers
  • eco-friendly polymers
  • green polymers
  • biomass-derived polymers
  • biodegradable polymers
  • waste-derived polymers
  • recovery and recycling of plastics and polymer composites
  • circular economy

Published Papers (25 papers)

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Research

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17 pages, 6237 KiB  
Article
Exploring the Potential of Roselle Calyx and Sappan Heartwood Extracts as Natural Colorants in Poly(butylene Succinate) for Biodegradable Packaging Films
by Wordpools Nansu, Sukunya Ross, Amonrut Waisarikit, Gareth M. Ross, Pensri Charoensit, Nungruthai Suphrom and Sararat Mahasaranon
Polymers 2023, 15(20), 4193; https://doi.org/10.3390/polym15204193 - 23 Oct 2023
Cited by 1 | Viewed by 1381
Abstract
Recently, there has been a growing concern among consumers regarding the safety of packaging products, particularly due to the presence of potentially harmful substances like synthetic pigments and inorganic dyes. These substances, which are often used to attract consumer attention, can migrate and [...] Read more.
Recently, there has been a growing concern among consumers regarding the safety of packaging products, particularly due to the presence of potentially harmful substances like synthetic pigments and inorganic dyes. These substances, which are often used to attract consumer attention, can migrate and contaminate products over extended shelf storage periods. To address this issue, the focus of this research was the development of a biodegradable packaging film using poly(butylene succinate) (PBS) incorporated with natural colorants extracted from roselle (RS) and sappan heartwood (SP). RS and SP serve as non-toxic and alternative pigments when compared to synthetic colorants. The biodegradable packaging films were prepared using blown film extrusion, encompassing different weight percentages of RS and SP (0.1%, 0.2%, and 0.3%). The films exhibited distinct colors, with RS films appearing pink to purple and SP films exhibiting an orange hue. The water vapor transmission rate slightly decreased with an increasing content of RS and SP extracts, indicating improved barrier properties. Additionally, the films showed reduced light transmittance, as evidenced by the UV–Vis light barrier results. The degree of crystallinity in the films was enhanced, as confirmed by X-ray diffraction and differential scanning calorimetry techniques. Regarding mechanical properties, the PBS/RS and PBS/SP films exhibited slight increases in tensile strength and elongation compared to neat PBS films. Moreover, the blended films demonstrated higher stability after undergoing an aging test, further highlighting their potential for use in biodegradable packaging applications. The key advantages of these films lie in their non-toxicity, biodegradability, and overall environmental friendliness. Full article
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20 pages, 4786 KiB  
Article
Fabrication of Bio-Nanocomposite Packaging Films with PVA, MMt Clay Nanoparticles, CNCs, and Essential Oils for the Postharvest Preservation of Sapota Fruits
by Senthamil Selvi Poongavanam, Vishnupriya Subramaniyan, Periyar Selvam Sellamuthu, Jayaramudu Jarugala and Emmanuel Rotimi Sadiku
Polymers 2023, 15(17), 3589; https://doi.org/10.3390/polym15173589 - 29 Aug 2023
Cited by 1 | Viewed by 1631
Abstract
Sapota is an important climacteric fruit with limited shelf life. A special system must be employed to extend the shelf life of sapota fruits. In the present study, polyvinyl alcohol (PVA) and montmorillonite clay (MMt)-based bio-nanocomposite films (BNFs) were integrated at various concentrations [...] Read more.
Sapota is an important climacteric fruit with limited shelf life. A special system must be employed to extend the shelf life of sapota fruits. In the present study, polyvinyl alcohol (PVA) and montmorillonite clay (MMt)-based bio-nanocomposite films (BNFs) were integrated at various concentrations (2%, 4%, 6%, and 8%) into cellulose nanocrystals (CNCs), produced from garlic peels (GPs). The BNF loaded with 8% CNC has a better crystallinity index and mechanical properties than the other concentrations of CNC. Therefore, the 8% CNC-incorporated BNF (BNF-8) was selected for further packaging studies. The combined effect of BNF-8 with ajwain essential oil (AO) and oregano essential oil (OO) vapors and BNF-8 with carbendazim (commercial fungicide-CARB) were investigated. In this study, the BNF-based packagings are categorized into five types, viz: BNF+8% CNC (BNF-8), BNF-8+AO, BNF-8+OO, BNF-8+CARB and the non-packaged fruits (control). The shelf-life duration, antioxidant activity, firmness, decay index, and sensory quality were evaluated in order to identify the effectiveness of packaging treatment on sapota fruits. BNF-8+CARB, BNF-8+AO, and BNF-8+OO packaging extended the shelf life of sapota fruits to up to 12 days and maintained the overall physiochemical parameters and sensory qualities of the fruits. Therefore, the BNF-8+AO and BNF-8+OO packaging materials are appropriate alternatives to commercial fungicides for the preservation of sapota during postharvest storage. Full article
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18 pages, 9651 KiB  
Article
Strength and Deformation Characteristics of Fiber and Cement-Modified Waste Slurry
by Jiahao Ye, Ping Jiang, Lejie Chen, Xuhui Zhou, Fei Rao and Xinyi Tang
Polymers 2023, 15(16), 3435; https://doi.org/10.3390/polym15163435 - 17 Aug 2023
Viewed by 953
Abstract
Using fiber and cement to modify waste slurry and apply it to roads is an effective way to recycle waste slurry. A new type of road material, fiber–cement-modified waste slurry (FRCS), was prepared in this study. The static and dynamic characteristics of the [...] Read more.
Using fiber and cement to modify waste slurry and apply it to roads is an effective way to recycle waste slurry. A new type of road material, fiber–cement-modified waste slurry (FRCS), was prepared in this study. The static and dynamic characteristics of the cement soil were studied using an unconfined compressive strength test and dynamic triaxial test. The results show that the optimum fiber content of FRCS is 0.75%. In the unconfined compressive strength test, under this fiber content, the unconfined compressive strength (UCS) of the FRCS is the largest, and the elastic modulus and modulus strength ratio are both the smallest, indicating that the tensile properties of the cement slurry have been enhanced. In the dynamic triaxial test, the hysteretic curve of the FRCS tends to be stable with the increase in the number of cycles, the dynamic elastic modulus of the FRCS decreases first and then increases with the increase in the dosage, while the damping ratio becomes stable after a rapid decline, and the fiber incorporation increases the cumulative strain of the soil–cement under low-stress cycles, indicating that the ductility of the FRCS is improved. In addition, a cumulative strain prediction model of the FRCS is established in this paper, which can provide a reference for the resource application of waste slurry in road engineering. Full article
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13 pages, 4194 KiB  
Article
Improving the Autofluorescence of Lophira alata Woody Cells via the Removal of Extractives
by Zhaoyang Yu, Dongnian Xu, Jinbo Hu, Shanshan Chang, Gonggang Liu, Qiongtao Huang, Jin Han, Ting Li, Yuan Liu and Xiaodong (Alice) Wang
Polymers 2023, 15(15), 3269; https://doi.org/10.3390/polym15153269 - 1 Aug 2023
Viewed by 896
Abstract
The autofluorescence phenomenon is an inherent characteristic of lignified cells. However, in the case of Lophira alata (L. alata), the autofluorescence is nearly imperceptible during occasional fluorescence observations. The aim of this study is to investigate the mechanism behind the quenching [...] Read more.
The autofluorescence phenomenon is an inherent characteristic of lignified cells. However, in the case of Lophira alata (L. alata), the autofluorescence is nearly imperceptible during occasional fluorescence observations. The aim of this study is to investigate the mechanism behind the quenching of lignin’s autofluorescence in L. alata by conducting associated experiments. Notably, the autofluorescence image of L. alata observed using optical microscopy appears to be quite indistinct. Abundant extractives are found in the longitudinal parenchyma, fibers, and vessels of L. alata. Remarkably, when subjected to a benzene–alcohol extraction treatment, the autofluorescence of L. alata becomes progressively enhanced under a fluorescence microscope. Additionally, UV–Vis absorption spectra demonstrate that the extractives derived from L. alata exhibit strong light absorption within the wavelength range of 200–500 nm. This suggests that the abundant extractives in L. alata are probably responsible for the autofluorescence quenching observed in the cell walls. Moreover, the presence and quantity of these extractives have a significant impact on the fluorescence intensity of lignin in wood, resulting in a significant decrease therein. In future studies, it would be interesting to explore the role of complex compounds such as polyphenols or terpenoids, which are present in the abundant extractives, in interfering with the fluorescence quenching of lignin in L. alata. Full article
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12 pages, 2058 KiB  
Article
Study on the Biodegradation Process of D-Mannose Glycopolymers in Liquid Media and Soil
by Ana-Maria Pană, Valentin Ordodi, Vasile Gherman, Paula Sfîrloagă and Gabriela-Alina Dumitrel
Polymers 2023, 15(15), 3194; https://doi.org/10.3390/polym15153194 - 27 Jul 2023
Viewed by 652
Abstract
Polymers derived from natural raw materials have become of great interest due to their increased biodegradable features and possible biocompatibility. Our group has successfully synthesized and characterized polymers derived from D-mannose oligomer (M), 2-hydroxy propyl acrylate (HPA), and methacrylate (HPMA) in different weight [...] Read more.
Polymers derived from natural raw materials have become of great interest due to their increased biodegradable features and possible biocompatibility. Our group has successfully synthesized and characterized polymers derived from D-mannose oligomer (M), 2-hydroxy propyl acrylate (HPA), and methacrylate (HPMA) in different weight ratios. Their biodegradation was studied in liquid media with pure Proteus mirabilis inoculum for the samples with the most sugar residue, and the results show that the methacrylate derivative M_HPMA1 lost about 50% of its weight during incubation. SEM/EDX techniques were employed to display the modifications of the samples during the biodegradation process. The glycopolymers were buried in garden soil, and the experiment proved that more than 40% of the weight of the M_HPA1 sample was lost during biodegradation, while the other samples encountered an average of about 32% weight loss. The biodegradation profile was fitted against linear and polynomial mathematical models, which enabled an estimate of about a year for the total degradation of the D-mannose glycopolymers sample in soil. Full article
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13 pages, 2672 KiB  
Article
Influence of Reduction with NaBH4 and HCl in Obtaining Amino Derivatives of Cashew Gum and Cytotoxic Profile
by Francisco das C. M. Brito, Wilton C. Lopes, Fábio O. S. Ribeiro, Raiza Raianne Luz Rodrigues, Klinger Antonio da França Rodrigues, Fabrício dos Santos Machado, Ana Jérsia Araújo, José Delano Barreto Marinho Filho, Antônia Carla J. Oliveira, Edson C. S. Filho, Irisvan S. Ribeiro, Regina C. M. de Paula, Fernando Hallwass, Vicente Gálber F. Viana and Durcilene A. Silva
Polymers 2023, 15(13), 2856; https://doi.org/10.3390/polym15132856 - 28 Jun 2023
Viewed by 1701
Abstract
Tree-exuded gums are natural polymers that represent an abundant raw material in the food and pharmaceutical industries. The cashew gum can be obtained by exudation of trees of the genus Anacardium, a native species of the Brazilian northeast; its polymer consists of monosaccharide [...] Read more.
Tree-exuded gums are natural polymers that represent an abundant raw material in the food and pharmaceutical industries. The cashew gum can be obtained by exudation of trees of the genus Anacardium, a native species of the Brazilian northeast; its polymer consists of monosaccharide units propitious to the action of chemical reactions that tend to improve their intrinsic characteristics among them, as the degree of hydro-solubility. The objective of this work was to modify the exudate gum of Anacardium occidentale (cashew gum (CG)) through an amine reaction. The modification was confirmed by Nuclear Magnetic Resonance (1H NMR), infrared spectroscopy (FTIR), gel permeation chromatography (GPC), zeta potential, and thermogravimetric analysis (TG). In addition, the chemical modification altered the molar mass and surface charge of the CG, and the amino group binding to the CG polymers was confirmed by FTIR spectra. In addition, cytotoxicity tests were performed where cell viability was estimated by an MTT assay on RAW 264.7 macrophages. Through these tests, it was found that the amine caused an increase in the thermal stability of the amino compounds and did not present cytotoxic potential at concentrations below 50.0 mg/L. Full article
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13 pages, 3400 KiB  
Article
Phase Diagram of Pickering Emulsions Stabilized by Cellulose Nanocrystals
by Louise Perrin, Sylvie Desobry-Banon, Guillaume Gillet and Stephane Desobry
Polymers 2023, 15(13), 2783; https://doi.org/10.3390/polym15132783 - 22 Jun 2023
Cited by 2 | Viewed by 1253
Abstract
Cellulose is a promising renewable and biocompatible biopolymer for stabilizing Pickering emulsions (PEs). In the present study, PEs were produced by low-frequency ultrasounds with cellulose nanocrystals (CNCs) and caprylic/capric triglycerides. Phase diagrams allowed to understand mechanisms of formation and long-term stabilization of PEs. [...] Read more.
Cellulose is a promising renewable and biocompatible biopolymer for stabilizing Pickering emulsions (PEs). In the present study, PEs were produced by low-frequency ultrasounds with cellulose nanocrystals (CNCs) and caprylic/capric triglycerides. Phase diagrams allowed to understand mechanisms of formation and long-term stabilization of PEs. Emulsion type, continuous phase viscosity, and yield of oil incorporation were studied after PEs formation. Droplet size, oil release, and stability were measured weekly up to 56 days of storage. Results showed that oil mass fraction above 70% w/w led to unstable W/O PEs. Lower oil mass fraction formed O/W PEs of stability depending on CNC content and oil mass fraction. Droplet size stability increased with CNCs/oil ratio. A very low CNCs/oil ratio led to phase separation and oil release. High CNC content stabilized oil droplets surface, increased aqueous phase viscosity, and prevented creaming. Highly stable PEs were produced for CNC content above 3% (w/w) and oil mass fraction below 50% (w/w). Mechanisms for PEs formation and stabilization were proposed for various CNC contents and oil mass fractions. Full article
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27 pages, 8262 KiB  
Article
The Synergistic Mechanism and Stability Evaluation of Phosphogypsum and Recycled Fine Powder-Based Multi-Source Solid Waste Geopolymer
by Xiaoming Liu and Erping Liu
Polymers 2023, 15(12), 2696; https://doi.org/10.3390/polym15122696 - 15 Jun 2023
Cited by 2 | Viewed by 991
Abstract
Geopolymer prepared from solid waste is a high value-added means. However, when used alone, the geopolymer produced by phosphogypsum has the risk of expansion cracking, while the geopolymer of recycled fine powder has high strength and good density, but its volume shrinkage and [...] Read more.
Geopolymer prepared from solid waste is a high value-added means. However, when used alone, the geopolymer produced by phosphogypsum has the risk of expansion cracking, while the geopolymer of recycled fine powder has high strength and good density, but its volume shrinkage and deformation are large. If the two are combined, the synergistic effect of the phosphogypsum geopolymer and recycled fine powder geopolymer can realize the complementarity of advantages and disadvantages, which provides a possibility for the preparation of stable geopolymers. In this study, the volume stability, water stability and mechanical stability of geopolymers were tested, and the stability synergy mechanism between phosphogypsum, recycled fine powder and slag was analyzed by micro experiments. The results show that the synergistic effect of phosphogypsum, recycled fine powder and slag can not only control the production of ettringite (AFt) but also control the capillary stress in the hydration product, thus improving the volume stability of the geopolymer. The synergistic effect can not only improve the pore structure of the hydration product but also reduce the negative impact of calcium sulfate dihydrate (CaSO4∙2H2O), thus improving the water stability of geopolymers. The softening coefficient of P15R45 with a 45 wt.% recycled fine powder content can reach 1.06, which is 26.2% higher than P35R25 with a 25 wt.% recycled fine powder content. The synergistic work reduces the negative impact of delayed AFt and improves the mechanical stability of the geopolymer. Full article
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10 pages, 2226 KiB  
Article
Influence of Incorporating Recycled Windshield Glass, PVB-Foil, and Rubber Granulates on the Properties of Geopolymer Composites and Concretes
by Van Su Le, Katarzyna Ewa Buczkowska, Roberto Ercoli, Kinga Pławecka, Narcisa Mihaela Marian and Petr Louda
Polymers 2023, 15(9), 2122; https://doi.org/10.3390/polym15092122 - 29 Apr 2023
Cited by 1 | Viewed by 1514
Abstract
Waste materials from the automotive industries were re-used as aggregates into metakaolin-based geopolymer (GP), geopolymer mortar (GM), and Bauhaus B20-based concrete composite (C). Specifically, the study evaluates the ability of windshield silica glass (W), PVB-Foils (P), and rubber granulates (G) to impact the [...] Read more.
Waste materials from the automotive industries were re-used as aggregates into metakaolin-based geopolymer (GP), geopolymer mortar (GM), and Bauhaus B20-based concrete composite (C). Specifically, the study evaluates the ability of windshield silica glass (W), PVB-Foils (P), and rubber granulates (G) to impact the mechanical and thermal properties. The addition of the recovered materials into the experimental geopolymers outperformed the commercially available B20. The flexural strength reached values of 7.37 ± 0.51 MPa in concrete with silica glass, 4.06 ± 0.32 in geopolymer malt with PVB-Foils, and 6.99 ± 0.82 MPa in pure geopolymer with rubber granulates; whereas the highest compressive strengths (бc) were obtained by the addition of PVB-Foils in pure geopolymer, geopolymer malt, and concrete (43.16 ± 0.31 MPa, 46.22 ± 2.06 MPa, and 27.24 ± 1.28 MPa, respectively). As well PVB-Foils were able to increase the impact strength (бi) at 5.15 ± 0.28 J/cm2 in pure geopolymer, 5.48 ± 0.41 J/cm2 in geopolymer malt, and 3.19 ± 0.14 J/cm2 in concrete, furnishing a significant improvement over the reference materials. Moreover, a correlation between density and thermal conductivity (λ) was also obtained to provide the suitability of these materials in applications such as insulation or energy storage. These findings serve as a basis for further research on the use of waste materials in the creation of new, environmentally friendly composites. Full article
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12 pages, 2936 KiB  
Article
Simulation of Wood Polymer Composites with Finite Element Analysis
by Satya Guha Nukala, Ing Kong, Akesh Babu Kakarla, Vipulkumar Ishvarbhai Patel and Hossam Abuel-Naga
Polymers 2023, 15(9), 1977; https://doi.org/10.3390/polym15091977 - 22 Apr 2023
Cited by 1 | Viewed by 2516
Abstract
Wood is a cellulosic material that is most abundantly available in nature. Wood has been extensively used as reinforcement in polymer composite materials. Wood polymer composite (WPC) is an environmentally friendly and sustainable material exploited in building and construction within the marine, packaging, [...] Read more.
Wood is a cellulosic material that is most abundantly available in nature. Wood has been extensively used as reinforcement in polymer composite materials. Wood polymer composite (WPC) is an environmentally friendly and sustainable material exploited in building and construction within the marine, packaging, housewares, aerospace, and automotive industries. However, the precision of testing equipment for finding the properties of WPCs becomes less feasible compared to experimental analysis due to a high degree of differences in the measurement of properties such as stress, strain and deformation. Thus, evaluating the mechanical properties of WPCs using finite element analysis (FEA) can aid in overcoming the inadequacies in measuring physical properties prior to experimental analyses. Furthermore, the prediction of mechanical properties using simulation tools has evolved to analyze novel material performance under various conditions. The current study aimed to examine the mechanical properties of saw dust-reinforced recycled polypropylene (rPP) through experimentation and FEA. A model was developed using SolidWorks, and simulation was performed in ANSYS to predict the mechanical properties of the WPCs. To validate the obtained results, the simulated static tension test results were confirmed with experimental tension tests, and both assessments were well in accordance with each other. Using FEA to predict material properties could be a cost-effective technique in studying new materials under varied load conditions. Full article
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21 pages, 2894 KiB  
Article
Characterization and Process Optimization for Enhanced Production of Polyhydroxybutyrate (PHB)-Based Biodegradable Polymer from Bacillus flexus Isolated from Municipal Solid Waste Landfill Site
by Mohd Adnan, Arif Jamal Siddiqui, Syed Amir Ashraf, Mejdi Snoussi, Riadh Badraoui, Angum M. M. Ibrahim, Mousa Alreshidi, Manojkumar Sachidanandan and Mitesh Patel
Polymers 2023, 15(6), 1407; https://doi.org/10.3390/polym15061407 - 12 Mar 2023
Cited by 6 | Viewed by 3825
Abstract
In recent years, there has been a growing interest in bio-based degradable plastics as an alternative to synthetic plastic. Polyhyroxybutyrate (PHB) is a macromolecule produced by bacteria as a part of their metabolism. Bacteria accumulate them as reserve materials when growing under different [...] Read more.
In recent years, there has been a growing interest in bio-based degradable plastics as an alternative to synthetic plastic. Polyhyroxybutyrate (PHB) is a macromolecule produced by bacteria as a part of their metabolism. Bacteria accumulate them as reserve materials when growing under different stress conditions. PHBs can be selected as alternatives for the production of biodegradable plastics because of their fast degradation properties when exposed to natural environmental conditions. Hence, the present study was undertaken in order to isolate the potential PHB-producing bacteria isolated from the municipal solid waste landfill site soil samples collected from the Ha’il region of Saudi Arabia to assess the production of PHB using agro-residues as a carbon source and to evaluate the growth of PHB production. In order to screen the isolates for producing PHB, a dye-based procedure was initially employed. Based on the 16S rRNA analysis of the isolates, Bacillus flexus (B. flexus) accumulated the highest amount of PHB of all the isolates. By using a UV–Vis spectrophotometer and Fourier-transform infrared spectrophotometer (FT-IR), in which a sharp absorption band at 1721.93 cm−1 (C=O stretching of ester), 1273.23 cm−1 (–CH group), multiple bands between 1000 and 1300 cm−1 (stretching of the C–O bond), 2939.53 cm−1 (–CH3 stretching), 2880.39 cm−1 (–CH2 stretching) and 3510.02 cm−1 (terminal –OH group), the extracted polymer was characterized and confirmed its structure as PHB. The highest PHB production by B. flexus was obtained after 48 h of incubation (3.9 g/L) at pH 7.0 (3.7 g/L), 35 °C (3.5 g/L) with glucose (4.1 g/L) and peptone (3.4 g/L) as carbon and nitrogen sources, respectively. As a result of the use of various cheap agricultural wastes, such as rice bran, barley bran, wheat bran, orange peel and banana peel as carbon sources, the strain was found to be capable of accumulating PHB. Using response surface methodology (RSM) for optimization of PHB synthesis using a Box–Behnken design (BBD) proved to be highly effective in increasing the polymer yield of the synthesis. With the optimum conditions obtained from RSM, PHB content can be increased by approximately 1.3-fold when compared to an unoptimized medium, resulting in a significant reduction in production costs. Thus, isolate B. flexus is a highly promising candidate for the production of industrial-size quantities of PHB from agricultural wastes and is capable of removing the environmental concerns associated with synthetic plastics from the industrial production process. Moreover, the successful production of bioplastics using a microbial culture provides a promising avenue for the large-scale production of biodegradable and renewable plastics with potential applications in various industries, including packaging, agriculture and medicine. Full article
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22 pages, 8893 KiB  
Article
Utilization of Mechanically Recycled Carbon Fibers in Vinyl Ester Composites
by Khaled AlHarmoodi, Amir Hussain Idrisi, Abdel-Hamid Ismail Mourad and Basim Abu-Jdayil
Polymers 2023, 15(4), 1016; https://doi.org/10.3390/polym15041016 - 17 Feb 2023
Viewed by 1794
Abstract
As we enter the twenty-first century, the aviation sector is expected to thrive as flying becomes the primary mode of transportation between states or nations. With such a demand, there is a corresponding need to manufacture aircraft components. The study focused on recycling [...] Read more.
As we enter the twenty-first century, the aviation sector is expected to thrive as flying becomes the primary mode of transportation between states or nations. With such a demand, there is a corresponding need to manufacture aircraft components. The study focused on recycling carbon fiber composites received from the STRATA company, which were cut-off/waste material generated during the manufacture of airplane components. The cut-offs were then reduced to powder form using a standard face milling machine in three sizes (90, 150, and 250 µm). After, the powder was utilized to fabricate vinyl ester composites with four weight percentages (10%, 20%, 30%, and 40%). The results demonstrate that the tensile strength of all composites had risen by 30.2%, 21.3%, and 17.6% for 90, 150, and 250 µm respective with the addition of 20 wt% of reinforcement. Furthermore, subsequently decreased with the additional reinforcement for all particle sizes. The compressive strength increased by 30% from 187.5 MPa to 244 MPa with 10 wt% of recycled carbon powder composite of 90μm particle size. However, samples prepared with 150 μm and 250 μm fiber size show approximately 17% and 1% increase in the compression strength with the addition of 10wt% of recycled carbon powder. A similar trend was observed for the flexural strength with an highest increase of 9% for 90 µm particle size with addition of 20 wt% reinforcement. Nonetheless, the SEM images revealed that the fiber–matrix bonding was weak, proved through the clean pullout fibers at the fracture surfaces. Full article
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20 pages, 5206 KiB  
Article
Scalable Continuous Manufacturing Process of Stereocomplex PLA by Twin-Screw Extrusion
by Mohammed Alhaj and Ramani Narayan
Polymers 2023, 15(4), 922; https://doi.org/10.3390/polym15040922 - 12 Feb 2023
Cited by 2 | Viewed by 2611
Abstract
A scalable continuous manufacturing method to produce stereocomplex PLA was developed and optimized by melt-blending a 1:1 blend of high molecular weight poly(L-lactide) (PLLA) and high molecular weight poly(D-lactide) (PDLA) in a co-rotating twin-screw extruder. Thermal characteristics of stereocomplex formation were characterized via [...] Read more.
A scalable continuous manufacturing method to produce stereocomplex PLA was developed and optimized by melt-blending a 1:1 blend of high molecular weight poly(L-lactide) (PLLA) and high molecular weight poly(D-lactide) (PDLA) in a co-rotating twin-screw extruder. Thermal characteristics of stereocomplex formation were characterized via DSC to identify the optimal temperature profile and time for processing stereocomplex PLA. At the proper temperature window, high stereocomplex formation is achieved as the twin-screw extruder allows for alignment of the chains; this is due to stretching of the polymer chains in the extruder. The extruder processing conditions were optimized and used to produce >95% of stereocomplex PLA conversion (melting peak temperature Tpm = 240 °C). ATR-FTIR depicts the formation of stereocomplex crystallites based on the absorption band at 908 cm−1 (β helix). The only peaks observed for stereocomplex PLA’s WAXD profile were at 2θ values of 12, 21, and 24°, verifying >99% of stereocomplex formation. The total crystallinity of stereocomplex PLA ranges from 56 to 64%. A significant improvement in the tensile behavior was observed in comparison to the homopolymers, resulting in a polymer of high strength and toughness. These results lead us to propose stereocomplex PLA as a potential additive/fiber that can reinforce the material properties of neat PLA. Full article
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18 pages, 6730 KiB  
Article
Study on Mechanical Properties and Micro Characterization of Fibre Reinforced Ecological Cementitious Coal Gangue Materials
by Shuai Pang, Xiangdong Zhang, Kaixin Zhu, Jiaze Li and Lijuan Su
Polymers 2023, 15(3), 700; https://doi.org/10.3390/polym15030700 - 30 Jan 2023
Cited by 4 | Viewed by 1524
Abstract
Eco-gelled coal gangue materials (EGCGMs) are usually produced using coal gangue, slag, and fly ash in a highly alkaline environment. Herein, to improve the mechanical properties of such materials, polypropylene fibers were uniformly mixed with them. An unconfined compressive strength test and a [...] Read more.
Eco-gelled coal gangue materials (EGCGMs) are usually produced using coal gangue, slag, and fly ash in a highly alkaline environment. Herein, to improve the mechanical properties of such materials, polypropylene fibers were uniformly mixed with them. An unconfined compressive strength test and a three-point bending test of the fiber-reinforced EGCGMs under different conditions were conducted. Based on the performance degradation control technology of the fiber structure, the interface mechanism of the composite materials was analyzed from the micro level using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD). In the mechanical test, the 28 d UCS and flexural properties of the fiber-reinforced EGCGMs were analyzed using the Box–Behnken design response surface design method and orthogonal design method, respectively. The order of significance was as follows: sodium hydroxide, fiber length, and fiber content. Within the scope of the experimental study, when the NaOH content is 3, the fiber content is 5 ‰, and the fiber length is 9 mm, the mechanical properties are the best. Based on the microscopic equipment, it was discovered that the amorphous ecological glue condensation product formed by the reaction of slag and fly ash in the alkaline environment was filled between the coal gangue particles and the fibers, and several polymerization products accumulated to form a honeycomb network topology. The distribution of fibers in the EGCGM matrix could be primarily divided into single embedded and network occurrences. The fiber inhibits the crack initiation and development of the matrix through the crack resistance effect, and improves the brittleness characteristics through the bridging effect during the failure process, which promotes the ductility of the ecological cementitious coal gangue matrix.The results presented herein can provide a theoretical basis for improving the mechanical properties of alkali-activated geopolymers. Full article
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19 pages, 6794 KiB  
Article
CVD Deposited Epoxy Copolymers as Protective Coatings for Optical Surfaces
by Merve Karabıyık, Gizem Cihanoğlu and Özgenç Ebil
Polymers 2023, 15(3), 652; https://doi.org/10.3390/polym15030652 - 27 Jan 2023
Cited by 1 | Viewed by 1972
Abstract
Copolymer thin films of glycidyl methacrylate (GMA), ethylene glycol dimethacrylate (EGDMA) and 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane (V4D4) were synthesized via initiated chemical vapor deposition (iCVD) as protective coatings for optical surfaces. Chemical durability in various solvents, corrosion resistance, adhesion to substrate, thermal resistance and optical transmittance [...] Read more.
Copolymer thin films of glycidyl methacrylate (GMA), ethylene glycol dimethacrylate (EGDMA) and 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane (V4D4) were synthesized via initiated chemical vapor deposition (iCVD) as protective coatings for optical surfaces. Chemical durability in various solvents, corrosion resistance, adhesion to substrate, thermal resistance and optical transmittance of the films were evaluated. Crosslinked thin films exhibited high chemical resistance to strong organic solvents and excellent adhesion to substrates. Poly(GMA-co-EGDMA) and poly(GMA-co-V4D4) copolymers demonstrated protection against water (<1% thickness loss), high salt resistance (<1.5% thickness loss), and high optical transparency (~90% in visible spectrum) making them ideal coating materials for optical surfaces. Combining increased mechanical properties of GMA and chemical durability V4D4, the iCVD process provides a fast and low-cost alternative for the fabrication of protective coatings. Full article
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12 pages, 2627 KiB  
Article
Ultra-High-Capacity Lithium Metal Batteries Based on Multi-Electron Redox Reaction of Organopolysulfides including Conductive Organic Moieties
by Takeshi Shimizu, Naoki Tanifuji, Kosuke Nishio, Yuma Tanaka, Yuta Tsukaguchi, Kentaro Tsubouchi, Fumiya Nakamura, Naoko Shokura, Mariko Noguchi, Hiroki Fujimori, Hiromi Kimura-Suda, Yusuke Date, Kaoru Aoki and Hirofumi Yoshikawa
Polymers 2023, 15(2), 335; https://doi.org/10.3390/polym15020335 - 9 Jan 2023
Cited by 1 | Viewed by 1876
Abstract
Recently, organic polysulfides have been synthesized as cathode active materials exceeding the battery performance of sulfur. However, the conventional organic polysulfides have exhibited capacities lower than the theoretical capacity of sulfur because the π-organic moieties do not conjugate with the sulfur chains. In [...] Read more.
Recently, organic polysulfides have been synthesized as cathode active materials exceeding the battery performance of sulfur. However, the conventional organic polysulfides have exhibited capacities lower than the theoretical capacity of sulfur because the π-organic moieties do not conjugate with the sulfur chains. In this work, the organopolysulfides, synthesized via inverse vulcanization using disulfide compounds, exhibited higher capacities equal to the theoretical capacity of sulfur because of enhanced electronic conductivity based on the conjugation between organic moieties and sulfur chains. Furthermore, the organopolysulfide including 1,3-dhitiol-2-thione moiety exhibited the highest capacity because of the enhanced electronic conductivity. This finding will pave the way to develop next-generation rechargeable batteries. Full article
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13 pages, 4521 KiB  
Article
Green Copolymers and Nanocomposites from Myrcene and Limonene Using Algerian Nano-Clay as Nano-Reinforcing Filler
by Hodhaifa Derdar, Geoffrey Robert Mitchell, Artur Mateus, Sarra Chaibedraa, Zinelabidine Otmane Elabed, Vidhura Subash Mahendra, Zakaria Cherifi, Khaldoun Bachari, Redouane Chebout, Rachid Meghabar, Amine Harrane and Mohammed Belbachir
Polymers 2022, 14(23), 5271; https://doi.org/10.3390/polym14235271 - 2 Dec 2022
Viewed by 1964
Abstract
In this work, we report a new facile method for the preparation of myrcene-limonene copolymers and nanocomposites using a Lewis acid as a catalyst (AlCl3) and organo-modified clay as a nano-reinforcing filler. The copolymer (myr-co-lim) was prepared by cationic copolymerization using [...] Read more.
In this work, we report a new facile method for the preparation of myrcene-limonene copolymers and nanocomposites using a Lewis acid as a catalyst (AlCl3) and organo-modified clay as a nano-reinforcing filler. The copolymer (myr-co-lim) was prepared by cationic copolymerization using AlCl3 as a catalyst. The structure of the obtained copolymer is studied and confirmed by Fourier Transform Infrared spectroscopy, Nuclear Magnetic Resonance spectroscopy, and Differential Scanning Calorimetry. By improving the dispersion of the matrix polymer in sheets of the organoclay, Maghnite-CTA+ (Mag-CTA+), an Algerian natural organophilic clay, was used to preparenanocomposites of linear copolymer (myr-co-lim). In order to identify and assess their structural, morphological, and thermal properties, the effect of the organoclay, used in varyingamounts (1, 4, 7, and 10% by weight), and the preparation process were investigated. The Mag-CTA+ is an organophylic montmorillonite silicate clay prepared through a direct exchange process in which they were used as green nano-reinforcing filler. The X-ray diffraction of the resulting nanocomposites revealed a considerable alteration in the interlayer spacing of Mag-CTA+. As a result, interlayer expansion and myr-co-lim exfoliation between layers of Mag-CTA+ were observed. Thermogravimetric analysis provided information on the synthesized nanocomposites’ thermal properties. Fourier transform infrared spectroscopy and scanning electronic microscopy, respectively, were used to determine the structure and morphology of the produced nanocomposites (myr-co-lim/Mag). The intercalation of myr-co-lim in the Mag-CTA+ sheets has been supported by the results, and the optimum amount of organoclay needed to create a nanocomposite with high thermal stability is 10% by weight. Finally, a new method for the preparation of copolymer and nanocomposites from myrcene and limonene in a short reaction time was developed. Full article
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19 pages, 1163 KiB  
Article
Effect of 3-Hydroxyvalerate Content on Thermal, Mechanical, and Rheological Properties of Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) Biopolymers Produced from Fermented Dairy Manure
by Maryam Abbasi, Dikshya Pokhrel, Erik R. Coats, Nicholas M. Guho and Armando G. McDonald
Polymers 2022, 14(19), 4140; https://doi.org/10.3390/polym14194140 - 3 Oct 2022
Cited by 11 | Viewed by 2915
Abstract
Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) with various 3-hydroxyvalerate (3HV) contents biosynthesized by mixed microbial consortia (MMC) fed fermented dairy manure at the large-scale level was assessed over a 3-month period. The thermal, mechanical, and rheological behavior and the chemical structure of the extracted PHBV biopolymers were [...] Read more.
Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) with various 3-hydroxyvalerate (3HV) contents biosynthesized by mixed microbial consortia (MMC) fed fermented dairy manure at the large-scale level was assessed over a 3-month period. The thermal, mechanical, and rheological behavior and the chemical structure of the extracted PHBV biopolymers were studied. The recovery of crude PHBV extracted in a large Soxhlet extractor with CHCl3 for 24 h ranged between 20.6% to 31.8% and purified to yield between 8.9% to 26.9% all based on original biomass. 13C-NMR spectroscopy revealed that the extracted PHBVs have a random distribution of 3HV and 3-hydroxybutyrate (3HB) units and with 3HV content between 16% and 24%. The glass transition temperature (Tg) of the extracted PHBVs varied between −0.7 and −7.4 °C. Some of the extracted PHBVs showed two melting temperatures (Tm) which the lower Tm1 ranged between 126.1 °C and 159.7 °C and the higher Tm2 varied between 152.1 °C and 170.1 °C. The weight average molar mass of extracted PHBVs was wide ranging from 6.49 × 105 g·mol−1 to 28.0 × 105 g·mol−1. The flexural and tensile properties were also determined. The extracted polymers showed a reverse relationship between the 3HV content and Young’s modulus, tensile strength, flexural modulus, and flexural strength properties. Full article
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18 pages, 2580 KiB  
Article
Polyhydroxybutyrate (PHB)-Based Biodegradable Polymer from Agromyces indicus: Enhanced Production, Characterization, and Optimization
by Mohd Adnan, Arif Jamal Siddiqui, Syed Amir Ashraf, Mejdi Snoussi, Riadh Badraoui, Mousa Alreshidi, Abdelbaset Mohamed Elasbali, Waleed Abu Al-Soud, Salem Hussain Alharethi, Manojkumar Sachidanandan and Mitesh Patel
Polymers 2022, 14(19), 3982; https://doi.org/10.3390/polym14193982 - 23 Sep 2022
Cited by 12 | Viewed by 4781
Abstract
Recently, there has been significant interest in bio-based degradable plastics owing to their potential as a green and sustainable alternative to synthetic plastics due to their biodegradable properties. Polyhydroxybutyrate (PHB) is a biodegradable polymer that is produced by bacteria and archaea as carbon [...] Read more.
Recently, there has been significant interest in bio-based degradable plastics owing to their potential as a green and sustainable alternative to synthetic plastics due to their biodegradable properties. Polyhydroxybutyrate (PHB) is a biodegradable polymer that is produced by bacteria and archaea as carbon and energy reserves. Due to its rapid degradation in natural environments, it can be considered a biodegradable plastic alternative. In the present study, a dye-based procedure was used to screen PHB-producing bacteria isolated from mangrove soil samples. Among the seven isolates, Agromyces indicus (A. indicus), identified by means of 16S rRNA analysis, accumulated the highest amount of PHB. The extracted polymer was characterized by a UV–Vis spectrophotometer, Fourier-transform infrared (FTIR) spectroscopy, and for the presence of the phbB gene, which confirmed the structure of the polymer as PHB. The maximum PHB production by A. indicus was achieved after 96 h of incubation at a pH of 8.0 and 35 °C in the presence of 2% NaCl, with glucose and peptone as the carbon and nitrogen sources, respectively. The strain was found to be capable of accumulating PHB when various cheap agricultural wastes, such as rice, barley, corn, and wheat bran, were used as the carbon sources. The response surface methodology (RSM) through the central composite design (CCD) for optimizing the PHB synthesis was found to be highly efficient at augmenting the polymer yields. As a result of the optimum conditions obtained from the RSM, this strain can increase the PHB content by approximately 1.4-fold when compared with an unoptimized medium, which would substantially lower the production cost. Therefore, the isolate A. indicus strain B2 may be regarded as one of the best candidates for the industrial production of PHB from agricultural wastes, and it can remove the environmental concerns associated with synthetic plastic. Full article
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15 pages, 3321 KiB  
Article
Formulation of Modified-Release Bilayer Tablets of Atorvastatin and Ezetimibe: An In-Vitro and In-Vivo Analysis
by Iqra Mubeen, Muhammad Zaman, Muhammad Farooq, Asim Mehmood, Fahad Khan Azeez, Wajiha Rehman, Sohail Akhtar, Mueen Ahmad Chaudhry, Muhammad Hammad Butt, Qurat-ul-ain Shamim, Sherjeel Adnan, Muhammad Rizwan Khan and Atta-ur-Rehman
Polymers 2022, 14(18), 3770; https://doi.org/10.3390/polym14183770 - 9 Sep 2022
Cited by 2 | Viewed by 2228
Abstract
The objective of this work was to formulate co-loaded bilayer tablets containing ezetimibe (EZB) and atorvastatin (ATC). ATC loaded in the immediate-release (IR) layer is an HMG CoA reductase inhibitor, while EZB, added in the sustained-release (SR) layer, is a lipid-lowering agent. This [...] Read more.
The objective of this work was to formulate co-loaded bilayer tablets containing ezetimibe (EZB) and atorvastatin (ATC). ATC loaded in the immediate-release (IR) layer is an HMG CoA reductase inhibitor, while EZB, added in the sustained-release (SR) layer, is a lipid-lowering agent. This study was conducted to evaluate the effects of polymer on the formulation and characterization of bilayer tablets, as well as the therapeutic impact of the concurrent use of both drugs having a sequential release pattern. To obtain the optimized results, four different formulations with variable compositions were developed and evaluated for different parameters. The drug release studies were carried out using a type II dissolution apparatus, using phosphate buffer solution (PBS) of 1.2 pH for IR of EZB for an initial 2 h, followed by 24 h studies for ATC in PBS 6.8 pH. The IR layer showed rapid drug release (96%) in 2 h, while 80% of the ATC was released in 24 h from the SR layer. Locally obtained, 6-week-old female albino rats were selected for in vivo studies. Both preventive and curative models were applied to check the effects of the drug combination on the lipid profile, atherosclerosis and physiology of different organs. Studies have shown that the administration of both drugs with different release patterns has a better therapeutic effect (p < 0.05), both in preventing and in curing hyperlipidemia. Conclusively, through the sequential release of ATC and EZB, a better therapeutic response could be obtained. Full article
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21 pages, 8155 KiB  
Article
Obtaining Ultrafine Dispersions of Silver Particles in Poly(vinyl Alcohol) Matrix Using Mechanical Alloying
by Deize Basílio dos Santos de Aguiar, Denilson José Marcolino de Aguiar, Josiane de Fátima Padilha de Paula and Osvaldo Mitsuyuki Cintho
Polymers 2022, 14(17), 3588; https://doi.org/10.3390/polym14173588 - 30 Aug 2022
Cited by 1 | Viewed by 1411
Abstract
Mechanical alloying was performed to obtain a composite material with a homogeneous dispersion of silver particles in a poly(vinyl alcohol) (PVA) matrix. Silver is a bactericidal material, and PVA is a widely used biocompatible polymer. Therefore, this mix can lead to a potentially [...] Read more.
Mechanical alloying was performed to obtain a composite material with a homogeneous dispersion of silver particles in a poly(vinyl alcohol) (PVA) matrix. Silver is a bactericidal material, and PVA is a widely used biocompatible polymer. Therefore, this mix can lead to a potentially functional biomaterial. This study focuses on the combination of both materials, processed by mechanical alloying, which has a promising application potential. The silver (Ag) used was ultrafine, measuring between 200 and 400 nanometers, produced from silver nitrate (AgNO3) redox. The Attritor high–energy, water–cooled ball mill was used to mill PVA for 4 h, at 600 rpm speed rotation and 38:1 power milling. Mechanical alloying was demonstrated to cause particle refinement in PVA with a timespan of 1 h. A slight additional particle decrease occurred for long–time milling. A milling time of 4 h was used to disperse the silver particles in the polymer matrix homogeneously. Hot pressing films were produced from the obtained dispersion powders. The microstructural features were studied using several material characterization techniques. Antimicrobial Susceptibility Tests (AST), conducted in an in–vitro assay, showed a hydrophilic character of the films and a protection against bacterial growth, making the process a promising path for the production of surface protective polymeric films. Full article
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17 pages, 9664 KiB  
Article
A Sustainable Approach to a Cleaner Production of Antimicrobial and Biocompatible Protein Fibers
by Angela Danila, Mariana Costea, Lenuta Profire, Cristina Mihaela Rimbu, Mihaela Baican, Florentina Lupascu, Simona-Maria Tatarusanu, Bianca-Stefania Profire and Emil-Ioan Muresan
Polymers 2022, 14(15), 3194; https://doi.org/10.3390/polym14153194 - 5 Aug 2022
Cited by 1 | Viewed by 1854
Abstract
This study presents the production, characterization, and application of celandine (Chelidonium majus L.) extracts (aqueous, acidic, alcoholic, and ultrasound) on wool fibers and their characterization. The study aims to obtain an ecologically dyed wool support that possesses biocompatible and antimicrobial activities. The [...] Read more.
This study presents the production, characterization, and application of celandine (Chelidonium majus L.) extracts (aqueous, acidic, alcoholic, and ultrasound) on wool fibers and their characterization. The study aims to obtain an ecologically dyed wool support that possesses biocompatible and antimicrobial activities. The plant extracts were characterized based on pH, total polyphenol content, and berberine content. Ecologically dyed wool supports were characterized based on scanning electron microscopy, levelness index, color measurements, contact angle indirect biocompatibility, and antibacterial analysis. According to the obtained results, celandine extract can be considered a potential candidate for the sustainable dyeing and functionalization of wool fibers. Full article
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Review

Jump to: Research

24 pages, 13374 KiB  
Review
Advancements in Performance Optimization of Electrospun Polyethylene Oxide-Based Solid-State Electrolytes for Lithium-Ion Batteries
by Xiuhong Li, Yichen Deng, Kai Li, Zhiyong Yang, Xinyu Hu, Yong Liu and Zheng Zhang
Polymers 2023, 15(18), 3727; https://doi.org/10.3390/polym15183727 - 11 Sep 2023
Cited by 3 | Viewed by 1782
Abstract
Polyethylene oxide (PEO)-based solid-state electrolytes for lithium-ion batteries have garnered significant interest due to their enhanced potential window, high energy density, and improved safety features. However, the issues such as low ionic conductivity at ambient temperature, substantial ionic conductivity fluctuations with temperature changes, [...] Read more.
Polyethylene oxide (PEO)-based solid-state electrolytes for lithium-ion batteries have garnered significant interest due to their enhanced potential window, high energy density, and improved safety features. However, the issues such as low ionic conductivity at ambient temperature, substantial ionic conductivity fluctuations with temperature changes, and inadequate electrolyte interfacial compatibility hinder their widespread applications. Electrospinning is a popular approach for fabricating solid-state electrolytes owing to its superior advantages of adjustable component constitution and the unique internal fiber structure of the resultant electrolytes. Thus, this technique has been extensively adopted in related studies. This review provides an overview of recent advancements in optimizing the performance of PEO solid-state electrolytes via electrospinning technology. Initially, the impacts of different lithium salts and their concentrations on the performance of electrospun PEO-based solid-state electrolytes were compared. Subsequently, research pertaining to the effects of various additives on these electrolytes was reviewed. Furthermore, investigations concerning the enhancement of electrospun solid-state electrolytes via modifications of PEO molecular chains are herein detailed, and lastly, the prevalent challenges and future directions of PEO-based solid-state electrolytes for lithium-ion batteries are summarized. Full article
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33 pages, 10705 KiB  
Review
Review on the Degradation of Poly(lactic acid) during Melt Processing
by Ineke Velghe, Bart Buffel, Veerle Vandeginste, Wim Thielemans and Frederik Desplentere
Polymers 2023, 15(9), 2047; https://doi.org/10.3390/polym15092047 - 25 Apr 2023
Cited by 14 | Viewed by 3226
Abstract
This review paper presents an overview of the state of the art on process-induced degradation of poly(lactic acid) (PLA) and the relative importance of different processing variables. The sensitivity of PLA to degradation, especially during melt processing, is considered a significant challenge as [...] Read more.
This review paper presents an overview of the state of the art on process-induced degradation of poly(lactic acid) (PLA) and the relative importance of different processing variables. The sensitivity of PLA to degradation, especially during melt processing, is considered a significant challenge as it may result in deterioration of its properties. The focus of this review is on degradation during melt processing techniques such as injection molding and extrusion, and therefore it does not deal with biodegradation. Firstly, the general processing and fundamental variables that determine the degradation are discussed. Secondly, the material properties (for example rheological, thermal, and mechanical) are presented that can be used to monitor and quantify the degradation. Thirdly, the effects of different processing variables on the extent of degradation are reviewed. Fourthly, additives are discussed for melt stabilization of PLA. Although current literature reports the degradation reactions and clearly indicates the effect of degradation on PLA’s properties, there are still knowledge gaps in how to select and predict the processing conditions that minimize process-induced degradation to save raw materials and time during production. Full article
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40 pages, 4529 KiB  
Review
Plasma Surface Engineering of Natural and Sustainable Polymeric Derivatives and Their Potential Applications
by Renjith Rajan Pillai and Vinoy Thomas
Polymers 2023, 15(2), 400; https://doi.org/10.3390/polym15020400 - 12 Jan 2023
Cited by 21 | Viewed by 3912
Abstract
Recently, natural as well as synthetic polymers have been receiving significant attention as candidates to replace non-renewable materials. With the exponential developments in the world each day, the collateral damage to the environment is incessant. Increased demands for reducing pollution and energy consumption [...] Read more.
Recently, natural as well as synthetic polymers have been receiving significant attention as candidates to replace non-renewable materials. With the exponential developments in the world each day, the collateral damage to the environment is incessant. Increased demands for reducing pollution and energy consumption are the driving force behind the research related to surface-modified natural fibers (NFs), polymers, and various derivatives of them such as natural-fiber-reinforced polymer composites. Natural fibers have received special attention for industrial applications due to their favorable characteristics, such as low cost, abundance, light weight, and biodegradable nature. Even though NFs offer many potential applications, they still face some challenges in terms of durability, strength, and processing. Many of these have been addressed by various surface modification methodologies and compositing with polymers. Among different surface treatment strategies, low-temperature plasma (LTP) surface treatment has recently received special attention for tailoring surface properties of different materials, including NFs and synthetic polymers, without affecting any of the bulk properties of these materials. Hence, it is very important to get an overview of the latest developments in this field. The present article attempts to give an overview of different materials such as NFs, synthetic polymers, and composites. Special attention was placed on the low-temperature plasma-based surface engineering of these materials for diverse applications, which include but are not limited to environmental remediation, packaging, biomedical devices, and sensor development. Full article
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