Mechanical Performance of Sustainable Bio-Based Compounds

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

Deadline for manuscript submissions: closed (20 December 2022) | Viewed by 107920

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Centro Regionale di Competenza Tecnologie, Napoli, Italy
Interests: polymeric materials and biomaterials; micro- and nano-particles; composites; material characterization; processing behavior; viscoelasticity; rheology; mechanical properties
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Department of Civil Engineering and Architecture (DICAr), University of Catania, Viale Andrea Doria 6, 95125 Catania, Italy
Interests: polymer-based composites; micro- and nanofillers; processability; rheological and mechanical characterization
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The global production of plastic is increasing, representing one of the most popular materials after steel and cement, and is widely spread in countless applications, from commercial and industrial fields to everyday life.

Experts predict, in 2030, millions of tons of plastics will be accumulated and dispersed in nature. Millions of tons of CO2 are also emitted into the atmosphere due to the production of plastics—the most traditional ones being derived from oil—and their final incineration.

In this context, scientific research should focus on alternative solutions for the sustainable development of production processes, including biomass waste valorization, the use of green technologies, avoiding risks for human health, and limiting the environmental impact.

Sustainable bio-based materials are a broad class of organic components from agro-food renewable resources (polysaccharides and proteins), bacterial activities (i.e., polyhydroxyalkanoates), conventional synthesis of bio-derived (i.e., polylactides and polyglycolides), or synthetic (i.e., polycaprolactones, polyesteramides, co-polyester) monomers. This category allows systems to meet current needs without dangerously burdening the future from the ecological, economic, and human point of view (sustainability). Biomaterials can be converted into chemical elements through the action of biological or physical agents (biodegradability), and can be also transformable into natural fertilizers for agriculture, once degraded (compostability). For specific applications, the ability to not be altered by biological fluid contact, reactions with human bodies, and the releasing of harmful species (biocompatibility) is important. Compounds can also be obtained by mixtures of natural lignocellulosic fibers (such as sisal, jute, cotton, linen, hemp, kenaf, jute, bamboo, etc.) and bio-based resins, by offering a possible option for the replacement of harmful glass- and carbon-based fibers in the field of reinforced composites.

Yet, the main restriction to the full development of these bio-based-formulations, in the restoring of the traditional plastics, is represented by the lack of good mechanical characteristics, derived by poor interfacial adhesion between the polar hydrophilic reinforcement and apolar hydrophobic matrix. Different strategies should be studied in order to adapt these systems to our needs and improve their efficiency.

This Special Issue will collect original contributions, both research papers and reviews, showing recent results and/or positive advances in the behavior of new sustainable bio-materials under applied mechanical stress, both in static and dynamic mode, and evaluating the characteristics of resistance, moduli and/or viscoelasticity, in view of potential applications, such as tissue engineering, medical devices, surgical, or dental implants, manufacturing of human parts, agriculture, packaging, textiles, electronics, automotive and aerospace, green buildings, and architecture and construction.

Prof. Dr. Domenico Acierno
Dr. Antonella Patti
Guest Editors

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Keywords

  • Bio-based polymer
  • Green composites
  • Green technologies
  • Low environmental impact
  • Biodegradability
  • Biocompatibility
  • Natural fiber-reinforced composites
  • Biomass waste valorization
  • Mechanical characterization
  • Strength
  • Viscoelasticity
  • Rheological behavior

Published Papers (30 papers)

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Editorial

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4 pages, 210 KiB  
Editorial
Special Issue “Mechanical Performance of Sustainable Bio-Based Compounds”
by Antonella Patti and Domenico Acierno
Polymers 2022, 14(22), 4832; https://doi.org/10.3390/polym14224832 - 10 Nov 2022
Cited by 1 | Viewed by 1084
Abstract
The global production of plastic is increasing, and plastic represents one of the most popular materials, widespread in countless applications in commercial and industrial fields and everyday life [...] Full article
(This article belongs to the Special Issue Mechanical Performance of Sustainable Bio-Based Compounds)

Research

Jump to: Editorial, Review

15 pages, 4057 KiB  
Article
Supramolecular Structure and Mechanical Performance of κ-Carrageenan–Gelatin Gel
by Anastasiya O. Makarova, Svetlana R. Derkach, Aidar I. Kadyirov, Sufia A. Ziganshina, Mariia A. Kazantseva, Olga S. Zueva, Aidar T. Gubaidullin and Yuriy F. Zuev
Polymers 2022, 14(20), 4347; https://doi.org/10.3390/polym14204347 - 15 Oct 2022
Cited by 12 | Viewed by 1956
Abstract
In this work, by means of complex physicochemical methods the structural features of a composite κ-carrageenan–gelatin system were studied in comparison with initial protein gel. The correlation between the morphology of hydrogels and their mechanical properties was demonstrated through the example of changes [...] Read more.
In this work, by means of complex physicochemical methods the structural features of a composite κ-carrageenan–gelatin system were studied in comparison with initial protein gel. The correlation between the morphology of hydrogels and their mechanical properties was demonstrated through the example of changes in their rheological characteristics. The experiments carried out with PXRD, SAXS, AFM and rheology approaches gave new information on the structure and mechanical performance of κ-carrageenan–gelatin hydrogel. The combination of PXRD, SAXS and AFM results showed that the morphological structures of individual components were not observed in the composite protein–polysaccharide hydrogels. The results of the mechanical testing of initial gelatin and engineered κ-carrageenan–gelatin gel showed the substantially denser parking of polymer chains in the composite system due to a significant increase in intermolecular protein–polysaccharide contacts. Close results were indirectly followed from the SAXS estimations—the driving force for the formation of the common supramolecular structural arrangement of proteins and polysaccharides was the increase in the density of network of macromolecular chains entanglements; therefore, an increase in the energy costs was necessary to change the conformational rearrangements of the studied system. This increase in the macromolecular arrangement led to the growth of the supramolecular associate size and the growth of interchain physical bonds. This led to an increase in the composite gel plasticity, whereas the enlargement of scattering particles made the novel gel system not only more rigid, but also more fragile. Full article
(This article belongs to the Special Issue Mechanical Performance of Sustainable Bio-Based Compounds)
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16 pages, 2846 KiB  
Article
Optimization of the Sustainable Production of Resistant Starch in Rice Bran and Evaluation of Its Physicochemical and Technological Properties
by Ruta Vaitkeviciene, Joana Bendoraitiene, Rimgaile Degutyte, Mantas Svazas and Daiva Zadeike
Polymers 2022, 14(17), 3662; https://doi.org/10.3390/polym14173662 - 3 Sep 2022
Cited by 3 | Viewed by 1922
Abstract
In this study, the optimization of ultrasound (US) (850 kHz, 120 W) processing parameters (temperature, time, and power) for the enhanced production of resistant starch (RS) in rice bran (RB) matrixes was performed. The effect of US cavitation at different temperatures on the [...] Read more.
In this study, the optimization of ultrasound (US) (850 kHz, 120 W) processing parameters (temperature, time, and power) for the enhanced production of resistant starch (RS) in rice bran (RB) matrixes was performed. The effect of US cavitation at different temperatures on the morphology, physicochemical properties, and mechanical performance of RS was evaluated. Ultrasonication at 40–70 °C temperatures affected the chemical structure, reduced the crystallinity of RS from 23.85% to between 18.37 and 4.43%, and increased the mechanical and thermal stability of RS pastes, indicating a higher tendency to retrograde. US treatment significantly (p < 0.05) improved the oil (OAC) and water (WAC) absorption capacities, swelling power (SP), solubility (WS), and reduced the least-gelation concentration (LGC). The mathematical evaluation of the data indicated a significant effect (p < 0.05) of the US parameters on the production of RS. The largest increment of RS (13.46 g/100 g dw) was achieved with US cavitation at 1.8 W/cm2 power, 40.2 °C temperature, and 18 min of processing time. The developed method and technology bring low-temperature US processing of rice milling waste to create a new sustainable food system based on modified rice bran biopolymers. Full article
(This article belongs to the Special Issue Mechanical Performance of Sustainable Bio-Based Compounds)
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18 pages, 4541 KiB  
Article
Environmental Effects on Strength and Failure Strain Distributions of Sheep Wool Fibers
by Olesja Starkova, Alisa Sabalina, Vanda Voikiva and Agnese Osite
Polymers 2022, 14(13), 2651; https://doi.org/10.3390/polym14132651 - 29 Jun 2022
Cited by 6 | Viewed by 1764
Abstract
Sheep wool is an eco-friendly, renewable, and totally recyclable material increasingly used in textiles, filters, insulation, and building materials. Recently, wool fibers have become good alternatives for reinforcement of polymer composites and filaments for 3D printing. Wool fibers are susceptible to environmental degradation [...] Read more.
Sheep wool is an eco-friendly, renewable, and totally recyclable material increasingly used in textiles, filters, insulation, and building materials. Recently, wool fibers have become good alternatives for reinforcement of polymer composites and filaments for 3D printing. Wool fibers are susceptible to environmental degradation that could shorten their lifetime and limit applications. This study reports on the mechanical properties of sheep wool fibers under the impact of humid air and UV irradiation. The results of single fiber tensile tests showed a noticeable gauge length effect on the fibers’ strength and failure strain. Long (50 mm) fibers possessed about 40% lower characteristics than short (10 mm) fibers. Environmental aging decreased the elastic modulus and strength of the fibers. Moisture-saturated fibers possessed up to 43% lower characteristics, while UV aging resulted in up to a twofold reduction of the strength. The most severe degradation effect is observed under the coupled influence of UVs and moisture. The two-parameter Weibull distribution was applied for the fiber strength and failure strain statistical assessment. The model well predicted the gauge length effects. Moisture-saturated and UV-aged fibers were characterized by less extensive strength dependences on the fiber length. The strength and failure strain distributions of aged fibers were horizontally shifted to lower values. The results will contribute to be reliable predictions of the environmental durability of sheep wool fibers and will extend their use in technical applications. Full article
(This article belongs to the Special Issue Mechanical Performance of Sustainable Bio-Based Compounds)
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9 pages, 941 KiB  
Article
Performance Evaluation of Combined Hydrothermal-Mechanical Pretreatment of Lignocellulosic Biomass for Enzymatic Enhancement
by Jiraporn Phojaroen, Thitirat Jiradechakorn, Suchata Kirdponpattara, Malinee Sriariyanun, Jatupol Junthip and Santi Chuetor
Polymers 2022, 14(12), 2313; https://doi.org/10.3390/polym14122313 - 8 Jun 2022
Cited by 18 | Viewed by 2256
Abstract
Pretreatment is a crucial process in a lignocellulosic biorefinery. Corncob is typically considered as a natural renewable carbon source to produce various bio-based products. This study aimed to evaluate the performance of the hydrothermal-mechanical pretreatment of corncob for biofuels and biochemical production. Corncob [...] Read more.
Pretreatment is a crucial process in a lignocellulosic biorefinery. Corncob is typically considered as a natural renewable carbon source to produce various bio-based products. This study aimed to evaluate the performance of the hydrothermal-mechanical pretreatment of corncob for biofuels and biochemical production. Corncob was first pretreated by liquid hot water (LHW) at different temperatures (140–180 °C) and duration (30, 60 min) and then subjected to centrifugal milling to produce bio-powders. To evaluate the performance of this combined pretreatment, the energy efficiency and waste generation were investigated. The results indicated that the maximum fermentable sugars (FS) were 0.488 g/g biomass obtained by LHW at 180 °C, 30 min. In order to evaluate the performance of this combined pretreatment, the energy efficiency and waste generation were 28.3 g of FS/kWh and 7.21 kg of waste/kg FS, respectively. These obtained results indicate that the combined hydrothermal-mechanical pretreatment was an effective pretreatment process to provide high energy efficiency and low waste generation to produce biofuels. In addition, the energy efficiency and waste generation will be useful indicators for process scaling-up into the industrial scale. This combined pretreatment could be a promising pretreatment technology for the production of biofuels and biochemicals from lignocellulosic valorization. Full article
(This article belongs to the Special Issue Mechanical Performance of Sustainable Bio-Based Compounds)
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21 pages, 4517 KiB  
Article
Impact of Drying Regimes and Different Coating Layers on Carboxymethyl Cellulose Cross-Linked with Citric Acid on Cotton Thread Fibers for Wound Dressing Modification
by Mohamad Khalid Khairunnisa-Atiqah, Kushairi Mohd Salleh, A. H. Ainul Hafiza, Nyak Syazwani Nyak Mazlan, Marhaini Mostapha and Sarani Zakaria
Polymers 2022, 14(6), 1217; https://doi.org/10.3390/polym14061217 - 17 Mar 2022
Cited by 5 | Viewed by 2136
Abstract
The oldest preservation techniques used are drying techniques, which are employed to remove moisture and prevent microorganisms’ growths, prolonging a material’s shelf life. This study evaluates the effects of drying methods on carboxymethyl cellulose (CMC) + citric acid (CA) coating layers on cotton [...] Read more.
The oldest preservation techniques used are drying techniques, which are employed to remove moisture and prevent microorganisms’ growths, prolonging a material’s shelf life. This study evaluates the effects of drying methods on carboxymethyl cellulose (CMC) + citric acid (CA) coating layers on cotton threads. For this reason, cotton threads were washed and then coated with different layers of CMC cross-linked with CA, followed by drying using an oven (OD), infrared (IR), and a combination of oven + IR (OIR) drying methods at 65 °C. Our investigations revealed that CMC + CA yields a pliable biopolymer. The differences in drying regimes and coating layers of CMC + CA have a significant effect on the coated cotton thread strength and absorption capability. The study concluded that the IR drying regime is more effective to dry a single-layered cotton thread with a single layer of CMC + CA coating to enhance desirable properties for wound dressing modification. Full article
(This article belongs to the Special Issue Mechanical Performance of Sustainable Bio-Based Compounds)
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17 pages, 7441 KiB  
Article
The Effect of Salinized Nano ZrO2 Particles on the Microstructure, Hardness, and Wear Behavior of Acrylic Denture Tooth Nanocomposite
by Kawkb M. El-Tamimi, Dalia A. Bayoumi, Mohamed M. Z. Ahmed, Ibrahim Albaijan and Mohammed E. El-Sayed
Polymers 2022, 14(2), 302; https://doi.org/10.3390/polym14020302 - 12 Jan 2022
Cited by 13 | Viewed by 1884
Abstract
The wear of acrylic denture teeth is a serious problem that can change the vertical dimensions of dentures. This study evaluates the effect of adding salinized nano ZrO2 particles on the microstructure, hardness, and wear resistance of acrylic denture teeth. Heat polymerizing [...] Read more.
The wear of acrylic denture teeth is a serious problem that can change the vertical dimensions of dentures. This study evaluates the effect of adding salinized nano ZrO2 particles on the microstructure, hardness, and wear resistance of acrylic denture teeth. Heat polymerizing polymethyl methacrylate resin was mixed with salinized ZrO2 at concentrations of 5 wt.% and 10 wt.%. Acrylic resin specimens without filler addition were used as a control group. SEM/EDS analyses were performed and the Vickers’ hardness was evaluated. Two-body wear testing was performed using a chewing simulator with a human enamel antagonist. After subjecting the samples to 37,500 cycles, both height loss and weight loss were used to evaluate the wear behavior. The microstructural investigation of the reinforced-denture teeth indicates sound nanocomposite preparation using the applied regime without porosity or macro defects. The addition of zirconium oxide nanofillers to PMMA at both 5% and 10% increased the microhardness, with values of up to 49.7 HV. The wear mechanism in the acrylic base material without nanoparticle addition was found to be fatigue wear; a high density of microcracks were found. The addition of 5 wt.% ZrO2 improved the wear resistance. Increasing the nanoparticles to 10 wt.% ZrO2 further improved the wear resistance, with no microcracks found. Full article
(This article belongs to the Special Issue Mechanical Performance of Sustainable Bio-Based Compounds)
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19 pages, 7997 KiB  
Article
Evaluation of Particleboards Made from Giant Reed (Arundo donax L.) Bonded with Cement and Potato Starch
by Aranzazu Alejandra Ferrandez-García, Teresa Garcia Ortuño, Manuel Ferrandez-Villena, Antonio Ferrandez-Garcia and Maria Teresa Ferrandez-García
Polymers 2022, 14(1), 111; https://doi.org/10.3390/polym14010111 - 29 Dec 2021
Cited by 6 | Viewed by 1736
Abstract
There is a general concern about the rationalization of resources and the management of waste. Plant residues can contribute to the development of new non-polluting construction materials. The objective of this study was to valorize a plant residue such as the giant reed [...] Read more.
There is a general concern about the rationalization of resources and the management of waste. Plant residues can contribute to the development of new non-polluting construction materials. The objective of this study was to valorize a plant residue such as the giant reed and obtain a particleboard with cement using potato starch as a plasticizer in a manufacturing process involving compression and heat. The influence of cement and starch in different proportions and its stability over time were analyzed. Finally, their physical and mechanical properties were evaluated and compared to European Standards. High-quality sustainable particleboards (boards with high structural performance) were obtained and can be classified as P6 according to European Standards. Mechanical properties were improved by increasing the starch content and pressing time, whereas greater resistance to water was obtained by increasing the cement content. Giant reed particles seem to tolerate the alkalinity of the cement since there was no sign of degradation of its fibers. The use of these residues in the manufacture of construction materials offers a very attractive alternative in terms of price, technology and sustainability. Full article
(This article belongs to the Special Issue Mechanical Performance of Sustainable Bio-Based Compounds)
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13 pages, 3720 KiB  
Article
Characterization of Polyhydroxybutyrate-Based Composites Prepared by Injection Molding
by Marcos M. Hernandez, Nevin S. Gupta, Kwan-Soo Lee, Aaron C. Pital, Babetta L. Marrone, Carl N. Iverson and Joseph H. Dumont
Polymers 2021, 13(24), 4444; https://doi.org/10.3390/polym13244444 - 18 Dec 2021
Cited by 3 | Viewed by 2424
Abstract
The waste generated by single-use plastics is often non-recyclable and non-biodegradable, inevitably ending up in our landfills, ecosystems, and food chain. Through the introduction of biodegradable polymers as substitutes for common plastics, we can decrease our impact on the planet. In this study, [...] Read more.
The waste generated by single-use plastics is often non-recyclable and non-biodegradable, inevitably ending up in our landfills, ecosystems, and food chain. Through the introduction of biodegradable polymers as substitutes for common plastics, we can decrease our impact on the planet. In this study, we evaluate the changes in mechanical and thermal properties of polyhydroxybutyrate-based composites with various additives: Microspheres, carbon fibers or polyethylene glycol (2000, 10,000, and 20,000 MW). The mixtures were injection molded using an in-house mold attached to a commercial extruder. The resulting samples were characterized using microscopy and a series of spectroscopic, thermal, and mechanical techniques. We have shown that the addition of carbon fibers and microspheres had minimal impact on thermal stability, whereas polyethylene glycol showed slight improvements at higher molecular weights. All of the composite samples showed a decrease in hardness and compressibility. The findings described in this study will improve our understanding of polyhydroxybutyrate-based composites prepared by injection molding, enabling advancements in integrating biodegradable plastics into everyday products. Full article
(This article belongs to the Special Issue Mechanical Performance of Sustainable Bio-Based Compounds)
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16 pages, 4776 KiB  
Article
Extraction and Characterization of Natural Cellulosic Fiber from Pandanus amaryllifolius Leaves
by Z. N. Diyana, R. Jumaidin, M. Z. Selamat, R. H. Alamjuri and Fahmi Asyadi Md Yusof
Polymers 2021, 13(23), 4171; https://doi.org/10.3390/polym13234171 - 29 Nov 2021
Cited by 18 | Viewed by 10512
Abstract
Pandanus amaryllifolius is a member of Pandanaceae family and is abundant in south-east Asian countries including Malaysia, Thailand, Indonesia and India. In this study, Pandanus amaryllifolius fibres were extracted via a water retting extraction process and were investigated as potential fibre reinforcement in [...] Read more.
Pandanus amaryllifolius is a member of Pandanaceae family and is abundant in south-east Asian countries including Malaysia, Thailand, Indonesia and India. In this study, Pandanus amaryllifolius fibres were extracted via a water retting extraction process and were investigated as potential fibre reinforcement in polymer composite. Several tests were carried out to investigate the characterization of Pandanus amaryllifolius fibre such as chemical composition analysis which revealed Pandanus amaryllifolius fibre’s cellulose, hemicellulose and lignin content of 48.79%, 19.95% and 18.64% respectively. Material functional groups were analysed by using Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction analysis confirming the presence of cellulose and amorphous substances in the fibre. The morphology of extracted Pandanus amaryllifolius fibre was studied using a scanning electron microscope (SEM). Further mechanical behaviour of fibre was investigated using a single fibre test with 5 kN cell load and tensile strength was found to be 45.61 ± 16.09 MPa for an average fibre diameter of 368.57 ± 50.47 μm. Meanwhile, moisture content analysis indicated a 6.00% moisture absorption rate of Pandanus amaryllifolius fibre. The thermogravimetric analysis justified the thermal stability of Pandanus amaryllifolius fibre up to 210 °C, which is within polymerization process temperature conditions. Overall, the finding shows that Pandanus amaryllifolius fibre may be used as alternative reinforcement particularly for a bio-based polymer matrix. Full article
(This article belongs to the Special Issue Mechanical Performance of Sustainable Bio-Based Compounds)
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21 pages, 7670 KiB  
Article
Improvements of Arboblend V2 Nature Characteristics through Depositing Thin Ceramic Layers
by Simona-Nicoleta Mazurchevici, Alina Marguta, Bogdan Istrate, Marcelin Benchea, Mihai Boca and Dumitru Nedelcu
Polymers 2021, 13(21), 3765; https://doi.org/10.3390/polym13213765 - 30 Oct 2021
Cited by 6 | Viewed by 1502
Abstract
The paper aims to investigate the behavior of Arboblend V2 Nature biopolymer samples covered with three ceramic powders, Amdry 6420 (Cr2O3), Metco 143 (ZrO2 18TiO2 10Y2O3) and Metco 136F (Cr2O3 [...] Read more.
The paper aims to investigate the behavior of Arboblend V2 Nature biopolymer samples covered with three ceramic powders, Amdry 6420 (Cr2O3), Metco 143 (ZrO2 18TiO2 10Y2O3) and Metco 136F (Cr2O3-xSiO2-yTiO2). The coated samples were obtained by injection molding, and the micropowder deposition was achieved by using the Atmospheric Plasma Spray (APS) method, with varied thickness layers. The present study will only describe the results for nine-layer deposition because, as the number of layers’ increases, the surface quality and mechanical/thermal characteristics such as wear, hardness and thermal resistance are also increased. The followed determinations were conducted: the adhesion strength, hardness on a microscopic scale by micro-indentation, thermal analysis and structural and morphological analysis. The structural analysis has highlighted a uniform deposition for the ZrO2 18TiO2 10Y2O3 layer, but for the layers that contained Cr2O3 ceramic microparticles, the deposition was not completely uniform. The thermal analysis revealed structural stability up to a temperature of 230 °C, the major degradation of the biopolymer matrix taking place at a temperature around 344 °C. The samples’ crystalline structure as well as the presence of the Cr2O3 compound significantly influenced the micro-indentation and scratch analysis responses. The novelty of this study is given by itself the coating of the Arboblend V2 Nature biopolymer (as base material), with ceramic microparticles as the micropowder coating material. Following the undertaken study, the increase in the mechanical, tribological and thermal characteristics of the samples recommend all three coated biopolymer samples as suitable for operating in harsh conditions, such as the automotive industry, in order to replace plastic materials. Full article
(This article belongs to the Special Issue Mechanical Performance of Sustainable Bio-Based Compounds)
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25 pages, 8010 KiB  
Article
Physical, Mechanical, and Morphological Properties of Treated Sugar Palm/Glass Reinforced Poly(Lactic Acid) Hybrid Composites
by S. F. K. Sherwani, E. S. Zainudin, S. M. Sapuan, Z. Leman and A. Khalina
Polymers 2021, 13(21), 3620; https://doi.org/10.3390/polym13213620 - 20 Oct 2021
Cited by 5 | Viewed by 1549
Abstract
This research was performed to evaluate the physical, mechanical, and morphological properties of treated sugar palm fiber (SPF)/glass fiber (GF) reinforced poly(lactic acid) (PLA) hybrid composites. Morphological investigations of tensile and flexural fractured samples of composites were conducted with the help of scanning [...] Read more.
This research was performed to evaluate the physical, mechanical, and morphological properties of treated sugar palm fiber (SPF)/glass fiber (GF) reinforced poly(lactic acid) (PLA) hybrid composites. Morphological investigations of tensile and flexural fractured samples of composites were conducted with the help of scanning electron microscopy (SEM). Alkaline and benzoyl chloride (BC) treatments of SPFs were performed. A constant weight fraction of 30% total fiber loading and 70% poly(lactic acid) were considered. The composites were initially prepared by a Brabender Plastograph, followed by a hot-pressing machine. The results reported that the best tensile and flexural strengths of 26.3 MPa and 27.3 MPa were recorded after alkaline treatment of SPF, while the highest values of tensile and flexural moduli of 607 MPa and 1847 MPa were recorded after BC treatment of SPF for SPF/GF/PLA hybrid composites. The novel SPF/GF/PLA hybrid composites could be suitable for fabricating automotive components. Full article
(This article belongs to the Special Issue Mechanical Performance of Sustainable Bio-Based Compounds)
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13 pages, 28041 KiB  
Article
Crazing Effect on the Bio-Based Conducting Polymer Film
by Pei-Yi Wong, Akiyoshi Takeno, Shinya Takahashi, Sook-Wai Phang and Azizah Baharum
Polymers 2021, 13(19), 3425; https://doi.org/10.3390/polym13193425 - 6 Oct 2021
Cited by 5 | Viewed by 2254
Abstract
The biodegradability problem of polymer waste is one of the fatal pollutFions to the environment. Enzymes play an essential role in increasing the biodegradability of polymers. In a previous study, antistatic polymer film based on poly(lactic acid) (PLA) as a matrix and polyaniline [...] Read more.
The biodegradability problem of polymer waste is one of the fatal pollutFions to the environment. Enzymes play an essential role in increasing the biodegradability of polymers. In a previous study, antistatic polymer film based on poly(lactic acid) (PLA) as a matrix and polyaniline (PAni) as a conductive filler, was prepared. To solve the problem of polymer wastes pollution, a crazing technique was applied to the prepared polymer film (PLA/PAni) to enhance the action of enzymes in the biodegradation of polymer. This research studied the biodegradation test based on crazed and non-crazed PLA/PAni films by enzymes. The presence of crazes in PLA/PAni film was evaluated using an optical microscope and scanning electron microscopy (SEM). The optical microscope displayed the crazed in the lamellae form, while the SEM image revealed microcracks in the fibrils form. Meanwhile, the tensile strength of the crazed PLA/PAni film was recorded as 19.25 MPa, which is almost comparable to the original PLA/PAni film with a tensile strength of 20.02 MPa. However, the Young modulus decreased progressively from 1113 MPa for PLA/PAni to 651 MPa for crazed PLA/PAni film, while the tensile strain increased 150% after crazing. The significant decrement in the Young modulus and increment in the tensile strain was due to the craze propagation. The entanglement was reduced and the chain mobility along the polymer chain increased, thus leading to lower resistance to deformation of the polymer chain and becoming more flexible. The presence of crazes in PLA/PAni film showed a substantial change in weight loss with increasing the time of degradation. The weight loss of crazed PLA/PAni film increased to 42%, higher than that of non-crazed PLA/PAni film with only 31%. The nucleation of crazes increases the fragmentation and depolymerization of PLA/PAni film that induced microbial attack and led to higher weight loss. In conclusion, the presence of crazes in PLA/PAni film significantly improved enzymes’ action, speeding up the polymer film’s biodegradability. Full article
(This article belongs to the Special Issue Mechanical Performance of Sustainable Bio-Based Compounds)
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15 pages, 2445 KiB  
Article
Influence of Newly Organosolv Lignin-Based Interface Modifier on Mechanical and Thermal Properties, and Enzymatic Degradation of Polylactic Acid/Chitosan Biocomposites
by Faisal Amri Tanjung, Yalun Arifin and Retna Astuti Kuswardani
Polymers 2021, 13(19), 3355; https://doi.org/10.3390/polym13193355 - 30 Sep 2021
Cited by 1 | Viewed by 1627
Abstract
This article aimed to study the effects of chitosan fiber and a newly modifying agent, based on organosolv lignin, on mechanical and thermal performances and the enzymatic degradation of PLA/chitosan biocomposites. A newly modifying agent based on polyacrylic acid-grafted organosolv lignin (PAA-g-OSL) was [...] Read more.
This article aimed to study the effects of chitosan fiber and a newly modifying agent, based on organosolv lignin, on mechanical and thermal performances and the enzymatic degradation of PLA/chitosan biocomposites. A newly modifying agent based on polyacrylic acid-grafted organosolv lignin (PAA-g-OSL) was synthesized via free radical copolymerization using t-butyl peroxide as the initiator. The biocomposites were prepared using an internal mixer and the hot-pressed method at various fiber loadings. The results demonstrate that the addition of chitosan fiber into PLA biocomposites remarkably decreases tensile strength and elongation at break. However, it improves the Young’s modulus. The modified biocomposites clearly demonstrat an improvement in tensile strength by approximately 20%, with respect to the unmodified ones, upon the presence of PAA-g-OSL. Moreover, the thermal stability of the modified biocomposites was enhanced significantly, indicating the effectiveness of the thermal protective barrier of the lignin’s aromatic structure belonging to the modifying agent during pyrolysis. In addition, a slower biodegradation rate was exhibited by the modified biocomposites, relative to the unmodified ones, that confirms the positive effects of their improved interfacial interaction, resulting in a decreased area that was degraded through enzyme hydrolysis. Full article
(This article belongs to the Special Issue Mechanical Performance of Sustainable Bio-Based Compounds)
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19 pages, 2965 KiB  
Article
Gellan Gum Hydrogels Filled Edible Oil Microemulsion for Biomedical Materials: Phase Diagram, Mechanical Behavior, and In Vivo Studies
by Muhammad Zulhelmi Muktar, Muhammad Ameerul Amin Bakar, Khairul Anuar Mat Amin, Laili Che Rose, Wan Iryani Wan Ismail, Mohd Hasmizam Razali, Saiful Izwan Abd Razak and Marc in het Panhuis
Polymers 2021, 13(19), 3281; https://doi.org/10.3390/polym13193281 - 26 Sep 2021
Cited by 8 | Viewed by 2786
Abstract
The demand for wound care products, especially advanced and active wound care products is huge. In this study, gellan gum (GG) and virgin coconut oil (VCO) were utilized to develop microemulsion-based hydrogel for wound dressing materials. A ternary phase diagram was constructed to [...] Read more.
The demand for wound care products, especially advanced and active wound care products is huge. In this study, gellan gum (GG) and virgin coconut oil (VCO) were utilized to develop microemulsion-based hydrogel for wound dressing materials. A ternary phase diagram was constructed to obtain an optimized ratio of VCO, water, and surfactant to produce VCO microemulsion. The VCO microemulsion was incorporated into gellan gum (GG) hydrogel (GVCO) and their chemical interaction, mechanical performance, physical properties, and thermal behavior were examined. The stress-at-break (σ) and Young’s modulus (YM) of GVCO hydrogel films were increased along with thermal behavior with the inclusion of VCO microemulsion. The swelling degree of GVCO hydrogel decreased as the VCO microemulsion increased and the water vapor transmission rate of GVCO hydrogels was comparable to commercial dressing in the range of 332–391 g m−2 d−1. The qualitative antibacterial activities do not show any inhibition against Gram-negative (Escherichia coli and Klebsiella pneumoniae) and Gram-positive (Staphylococcus aureus and Bacillus subtilis) bacteria. In vivo studies on Sprague–Dawley rats show the wound contraction of GVCO hydrogel is best (95 ± 2%) after the 14th day compared to a commercial dressing of Smith and Nephew Opsite post-op waterproof dressing, and this result is supported by the ultrasound images of wound skin and histological evaluation of the wound. The findings suggest that GVCO hydrogel has the potential to be developed as a biomedical material. Full article
(This article belongs to the Special Issue Mechanical Performance of Sustainable Bio-Based Compounds)
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11 pages, 2076 KiB  
Article
Characterization of 3D Printing on Jute Fabrics
by Edgar Adrián Franco-Urquiza, Yael Ramírez Escamilla and Perla Itzel Alcántara Llanas
Polymers 2021, 13(19), 3202; https://doi.org/10.3390/polym13193202 - 22 Sep 2021
Cited by 19 | Viewed by 2417
Abstract
This work evaluates the feasibility to manufacture polylactic acid (PLA) composites using jute fiber fabrics. For characterization, PLA-fused filament was successfully deposed onto jute fabrics to print dog-bone tensile specimens (Type I specimen from ASTM D638). The jute fabrics were chemically modified, treated [...] Read more.
This work evaluates the feasibility to manufacture polylactic acid (PLA) composites using jute fiber fabrics. For characterization, PLA-fused filament was successfully deposed onto jute fabrics to print dog-bone tensile specimens (Type I specimen from ASTM D638). The jute fabrics were chemically modified, treated with flame retardant additives, and sprayed with aerosol adhesive to improve the mechanical properties of PLA/Jute fabric composites. The elastic modulus and the strength of PLA were higher than PLA composites, and the plastic deformation of the PLA composites was slightly lower than PLA. Tomography scans revealed the fabrics were well oriented and some adherence between jute fabrics and PLA. Viscoelastic properties of PLA composites resulted in the reduction in storage modulus and the reduction in intensity in the damping factor attributed to segmental motions with no variations in the glass transition temperature. Flame retardant and spray adhesive on jute fabrics promoted better response to time of burning than PLA and PLA with modified fibers. The results presented in this work lead to the need for a more detailed investigation of the effect of plant fiber fabrics as reinforcement of 3D printed objects for industrial applications. Full article
(This article belongs to the Special Issue Mechanical Performance of Sustainable Bio-Based Compounds)
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19 pages, 5423 KiB  
Article
Potency of Urea-Treated Halloysite Nanotubes for the Simultaneous Boosting of Mechanical Properties and Crystallization of Epoxidized Natural Rubber Composites
by Indra Surya, Kamaruddin Waesateh, Sitisaiyidah Saiwari, Hanafi Ismail, Nadras Othman and Nabil Hayeemasae
Polymers 2021, 13(18), 3068; https://doi.org/10.3390/polym13183068 - 11 Sep 2021
Cited by 12 | Viewed by 1980
Abstract
Halloysite nanotubes (HNTs) are naturally occurring tubular clay made of aluminosilicate sheets rolled several times. HNT has been used to reinforce many rubbers. However, the narrow diameter of this configuration causes HNT to have poor interfacial contact with the rubber matrix. Therefore, increasing [...] Read more.
Halloysite nanotubes (HNTs) are naturally occurring tubular clay made of aluminosilicate sheets rolled several times. HNT has been used to reinforce many rubbers. However, the narrow diameter of this configuration causes HNT to have poor interfacial contact with the rubber matrix. Therefore, increasing the distance between layers could improve interfacial contact with the matrix. In this work, Epoxidized Natural Rubber (ENR)/HNT was the focus. The HNT layer distance was successfully increased by a urea-mechanochemical process. Attachment of urea onto HNT was verified by FTIR, where new peaks appeared around 3505 cm−1 and 3396 cm−1, corresponding to urea’s functionalities. The intercalation of urea to the distance gallery of HNT was revealed by XRD. It was also found that the use of urea-treated HNT improved the modulus, tensile strength, and tear strength of the composites. This was clearly responsible for interactions between ENR and urea-treated HNT. It was further verified by observing the Payne effect. The value of the Payne effect was found to be reduced at 62.38% after using urea for treatment. As for the strain-induced crystallization (SIC) of the composites, the stress–strain curves correlated well with the results from synchrotron wide-angle X-ray scattering. Full article
(This article belongs to the Special Issue Mechanical Performance of Sustainable Bio-Based Compounds)
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15 pages, 3592 KiB  
Article
Improving Mechanical Properties of PLA/Starch Blends Using Masterbatch Containing Vegetable Oil Based Active Ingredients
by Bianka Nagy, Norbert Miskolczi and Zoltán Eller
Polymers 2021, 13(17), 2981; https://doi.org/10.3390/polym13172981 - 2 Sep 2021
Cited by 11 | Viewed by 2101
Abstract
The aim of this research was to increase the compatibility between PLA and starch with vegetable oil-based additives. Based on tensile results, it can be stated, that Charpy impact strength could be improved for 70/30 and 60/40 blends in both unconditioned and conditioned [...] Read more.
The aim of this research was to increase the compatibility between PLA and starch with vegetable oil-based additives. Based on tensile results, it can be stated, that Charpy impact strength could be improved for 70/30 and 60/40 blends in both unconditioned and conditioned cases, regardless of vegetable oil, while no advantageous change in impact strength was obtained with PLA-g-MA. Considering sample with the highest starch concentration (50%), the flexural modulus was improved by using sunflower oil-based additive, Charpy impact strength and elongation at break was increased using rapeseed oil-based additive in both conditioned and unconditioned cases. SEM images confirmed the improvement of compatibility between components. Full article
(This article belongs to the Special Issue Mechanical Performance of Sustainable Bio-Based Compounds)
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15 pages, 4509 KiB  
Article
Interfacial Adhesion and Mechanical Properties of Wood-Polymer Hybrid Composites Prepared by Injection Molding
by Alexander Stadlmann, Andreas Mautner, Maximilian Pramreiter, Alexander Bismarck and Ulrich Müller
Polymers 2021, 13(17), 2849; https://doi.org/10.3390/polym13172849 - 25 Aug 2021
Cited by 11 | Viewed by 2215
Abstract
Birch (Betula pendula Roth.) and beech (Fagus sylvatica L.) solid wood and plywood were overmolded with polyamide 6 (PA 6) and polypropylene (PP) to investigate their mechanical properties and interfacial adhesion. In the case of PA 6, maximum tensile shear strengths [...] Read more.
Birch (Betula pendula Roth.) and beech (Fagus sylvatica L.) solid wood and plywood were overmolded with polyamide 6 (PA 6) and polypropylene (PP) to investigate their mechanical properties and interfacial adhesion. In the case of PA 6, maximum tensile shear strengths values of more than 8 to 9 MPa were obtained for birch and beech, respectively. The values are comparable to bond strengths of commercial joints bonded with formaldehyde-containing amino-plastics. Perpendicular to the wood elements, bond strength values of 3 MPa was achieved for PA 6. The penetration of the polymers into the wood structure results in a non-densified interphase and subsequent plastic deformation of the wood structure beyond the interphase. These compressed areas influenced the interfacial adhesion and mechanical interlocking. SEM and XPS analysis revealed different interpenetration behavior of the polymers into the wood structure, with chemical interaction confirmed only for wood and PA 6 but not PP. Full article
(This article belongs to the Special Issue Mechanical Performance of Sustainable Bio-Based Compounds)
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19 pages, 8315 KiB  
Article
Properties of Wood–Plastic Composites Manufactured from Two Different Wood Feedstocks: Wood Flour and Wood Pellets
by Geeta Pokhrel, Douglas J. Gardner and Yousoo Han
Polymers 2021, 13(16), 2769; https://doi.org/10.3390/polym13162769 - 18 Aug 2021
Cited by 20 | Viewed by 6582
Abstract
Driven by the motive of minimizing the transportation costs of raw materials to manufacture wood–plastic composites (WPCs), Part I and the current Part II of this paper series explore the utilization of an alternative wood feedstock, i.e., pellets. Part I of this study [...] Read more.
Driven by the motive of minimizing the transportation costs of raw materials to manufacture wood–plastic composites (WPCs), Part I and the current Part II of this paper series explore the utilization of an alternative wood feedstock, i.e., pellets. Part I of this study reported on the characteristics of wood flour and wood pellets manufactured from secondary processing mill residues. Part II reports on the physical and mechanical properties of polypropylene (PP)-based WPCs made using the two different wood feedstocks, i.e., wood flour and wood pellets. WPCs were made from 40-mesh wood flour and wood pellets from four different wood species (white cedar, white pine, spruce-fir and red maple) in the presence and absence of the coupling agent maleic anhydride polypropylene (MAPP). With MAPP, the weight percentage of wood filler was 20%, PP 78%, MAPP 2% and without MAPP, formulation by weight percentage of wood filler was 20% and PP 80%. Fluorescent images showed wood particles’ distribution in the PP polymer matrix was similar for both wood flour and ground wood pellets. Dispersion of particles was higher with ground wood pellets in the PP matrix. On average, the density of composite products from wood pellets was higher, tensile strength, tensile modulus and impact strength were lower than the composites made from wood flour. Flexural properties of the control composites made with pellets were higher and with MAPP were lower than the composites made from wood flour. However, the overall mechanical property differences were low (0.5–10%) depending on the particular WPC formulations. Statistical analysis also showed there was no significant differences in the material property values of the composites made from wood flour and wood pellets. In some situations, WPC properties were better using wood pellets rather than using wood flour. We expect if the material properties of WPCs from wood flour versus wood pellets are similar and with a greater reduction in transportation costs for wood pellet feedstocks, this would be beneficial to WPC manufacturers and consumers. Full article
(This article belongs to the Special Issue Mechanical Performance of Sustainable Bio-Based Compounds)
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16 pages, 5480 KiB  
Article
Lignin Inter-Diffusion Underlying Improved Mechanical Performance of Hot-Pressed Paper Webs
by Amanda Mattsson, Tove Joelsson, Arttu Miettinen, Jukka A. Ketoja, Gunilla Pettersson and Per Engstrand
Polymers 2021, 13(15), 2485; https://doi.org/10.3390/polym13152485 - 28 Jul 2021
Cited by 10 | Viewed by 3305
Abstract
Broader use of bio-based fibres in packaging becomes possible when the mechanical properties of fibre materials exceed those of conventional paperboard. Hot-pressing provides an efficient method to improve both the wet and dry strength of lignin-containing paper webs. Here we study varied pressing [...] Read more.
Broader use of bio-based fibres in packaging becomes possible when the mechanical properties of fibre materials exceed those of conventional paperboard. Hot-pressing provides an efficient method to improve both the wet and dry strength of lignin-containing paper webs. Here we study varied pressing conditions for webs formed with thermomechanical pulp (TMP). The results are compared against similar data for a wide range of other fibre types. In addition to standard strength and structural measurements, we characterise the induced structural changes with X-ray microtomography and scanning electron microscopy. The wet strength generally increases monotonously up to a very high pressing temperature of 270 °C. The stronger bonding of wet fibres can be explained by the inter-diffusion of lignin macromolecules with an activation energy around 26 kJ mol−1 after lignin softening. The associated exponential acceleration of diffusion with temperature dominates over other factors such as process dynamics or final material density in setting wet strength. The optimum pressing temperature for dry strength is generally lower, around 200 °C, beyond which hemicellulose degradation begins. By varying the solids content prior to hot-pressing for the TMP sheets, the highest wet strength is achieved for the completely dry web, while no strong correlation was observed for the dry strength. Full article
(This article belongs to the Special Issue Mechanical Performance of Sustainable Bio-Based Compounds)
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14 pages, 4302 KiB  
Article
Rotational Rheology of Wood Flour Composites Based on Recycled Polyethylene
by Antonella Patti, Gianluca Cicala and Stefano Acierno
Polymers 2021, 13(14), 2226; https://doi.org/10.3390/polym13142226 - 6 Jul 2021
Cited by 15 | Viewed by 2181
Abstract
In this paper, we study the effect of the addition of wood flour as a filler in a recycled polyethylene (r-PE) in view of its potential applications in 3D printing. The composites, prepared by melt mixing, are characterized with torque measurements performed during [...] Read more.
In this paper, we study the effect of the addition of wood flour as a filler in a recycled polyethylene (r-PE) in view of its potential applications in 3D printing. The composites, prepared by melt mixing, are characterized with torque measurements performed during the compounding, dynamic rotational rheology, and infrared spectroscopy. Data show that the introduction of wood results in increased viscosity and in sensible viscous heating during the compounding. The r-PE appear to be stable at temperatures up to 180 °C while at higher temperatures the material shows a rheological response characterized by time-increasing viscoelastic moduli that suggests a thermal degradation governed by crosslinking reactions. The compounds (with wood loading up to 50% in wt.) also shows thermal stability at temperatures up to 180 °C. The viscoelastic behavior and the infrared spectra of the r-PE matrix suggests the presence of branches in the macromolecular structure due to the process. Although the addition of wood particles determines increased viscoelastic moduli, a solid-like viscoelastic response is not shown even for the highest wood concentrations. This behavior, due to a poor compatibility and weak interfacial adhesion between the two phases, is however promising in view of common processing technologies as extrusion or injection molding. Full article
(This article belongs to the Special Issue Mechanical Performance of Sustainable Bio-Based Compounds)
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16 pages, 4190 KiB  
Article
Flow Characteristics, Mechanical, Thermal, and Thermomechanical Properties, and 3D Printability of Biodegradable Polylactide Containing Boehmite at Different Loadings
by Dimakatso Makwakwa, Vincent Ojijo, Jayita Bandyopadhyay and Suprakas Sinha Ray
Polymers 2021, 13(12), 2019; https://doi.org/10.3390/polym13122019 - 21 Jun 2021
Cited by 7 | Viewed by 2581
Abstract
This work investigates the effects of modification of polylactide (PLA) using dicumyl peroxide (DCP) as a crosslinker and Joncryl as a chain extender on boehmite distribution. The PLA/boehmite (PLA/BA) composites at various concentrations were prepared via a twin-screw extruder. Transmission electron microscopy showed [...] Read more.
This work investigates the effects of modification of polylactide (PLA) using dicumyl peroxide (DCP) as a crosslinker and Joncryl as a chain extender on boehmite distribution. The PLA/boehmite (PLA/BA) composites at various concentrations were prepared via a twin-screw extruder. Transmission electron microscopy showed more agglomerations of BA particles when Joncryl and DCP were added individually to the PLA matrix, with lesser agglomeration upon simultaneous addition of DCP and Joncryl, which led to an enhancement of 10.7% of the heat distortion temperature and 8.8% of the modulus. The existence of fine dispersed BA particles in the BA3 sample improved the cold crystallization by 4 °C. Moreover, the maximum reinforcing effect in increasing the storage modulus of the prepared system was observed upon concurrent addition of DCP and Joncryl, with minimum reinforcing effect upon individual addition of DCP and Joncryl. In general, a bio-based PLA composite base BA with enhanced properties was successfully prepared for various applications. Full article
(This article belongs to the Special Issue Mechanical Performance of Sustainable Bio-Based Compounds)
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15 pages, 3171 KiB  
Article
Influence of Different Percentages of Binders on the Physico-Mechanical Properties of Rhizophora spp. Particleboard as Natural-Based Tissue-Equivalent Phantom for Radiation Dosimetry Applications
by Siti Hajar Zuber, Nurul Ab. Aziz Hashikin, Mohd Fahmi Mohd Yusof, Mohd Zahri Abdul Aziz and Rokiah Hashim
Polymers 2021, 13(11), 1868; https://doi.org/10.3390/polym13111868 - 4 Jun 2021
Cited by 3 | Viewed by 2173
Abstract
Rhizophora spp. particleboard with the incorporation of lignin and soy flour as binders were fabricated and the influence of different percentages of lignin and soy flour (0%, 6% and 12%) on the physico-mechanical properties of the particleboard were studied. The samples were characterised [...] Read more.
Rhizophora spp. particleboard with the incorporation of lignin and soy flour as binders were fabricated and the influence of different percentages of lignin and soy flour (0%, 6% and 12%) on the physico-mechanical properties of the particleboard were studied. The samples were characterised by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), X-ray fluorescence (XRF) and internal bonding. The results stipulated that the addition of binders in the fabrication of the particleboard did not change the functional groups according to the FTIR spectrum. For XRD, addition of binders did not reveal any major transformation within the composites. SEM and EDX analyses for all percentages of binders added showed no apparent disparity; however, it is important to note that the incorporation of binders allows better bonding between the molecules. In XRF analysis, lower percentage of chlorine in the adhesive-bonded samples may be advantageous in maintaining the natural properties of the particleboard. In internal bonding, increased internal bond strength in samples with binders may indicate better structural integrity and physico-mechanical strength. In conclusion, the incorporation of lignin and soy flour as binders may potentially strengthen and fortify the particleboard, thus, can be a reliable phantom in radiation dosimetry applications. Full article
(This article belongs to the Special Issue Mechanical Performance of Sustainable Bio-Based Compounds)
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9 pages, 2518 KiB  
Article
Effect of Moisture Content on the Processing and Mechanical Properties of a Biodegradable Polyester
by Vincenzo Titone, Antonio Correnti and Francesco Paolo La Mantia
Polymers 2021, 13(10), 1616; https://doi.org/10.3390/polym13101616 - 17 May 2021
Cited by 17 | Viewed by 2450
Abstract
This work is focused on the influence of moisture content on the processing and mechanical properties of a biodegradable polyester used for applications in injection molding. The pellets of the biodegradable polyester were exposed under different relative humidity conditions at a constant temperature [...] Read more.
This work is focused on the influence of moisture content on the processing and mechanical properties of a biodegradable polyester used for applications in injection molding. The pellets of the biodegradable polyester were exposed under different relative humidity conditions at a constant temperature before being compression molded. The compression-molded specimens were again placed under the above conditions before the mechanical testing. With all these samples, it is possible to determine the effect of moisture content on the processing and mechanical properties separately, as well as the combined effect of moisture content on the mechanical properties. The results obtained showed that the amount of absorbed water—both before processing and before mechanical testing—causes an increase in elongation at break and a slight reduction of the elastic modulus and tensile strength. These changes have been associated with possible hydrolytic degradation during the compression molding process and, in particular, with the plasticizing action of the moisture absorbed by the specimens. Full article
(This article belongs to the Special Issue Mechanical Performance of Sustainable Bio-Based Compounds)
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Review

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28 pages, 1891 KiB  
Review
Factors Affecting Mechanical Properties of Reinforced Bioplastics: A Review
by Jet Yin Boey, Chee Keong Lee and Guan Seng Tay
Polymers 2022, 14(18), 3737; https://doi.org/10.3390/polym14183737 - 7 Sep 2022
Cited by 38 | Viewed by 10045
Abstract
The short life cycle and recalcitrant nature of petroleum-based plastics have been associated with plastic waste accumulation due to their composition rather than worldwide overproduction. The drive to replace single-use products has sparked a considerable amount of research work to discover sustainable options [...] Read more.
The short life cycle and recalcitrant nature of petroleum-based plastics have been associated with plastic waste accumulation due to their composition rather than worldwide overproduction. The drive to replace single-use products has sparked a considerable amount of research work to discover sustainable options for petroleum-based plastics. Bioplastics open up a new horizon in plastics manufacturing operations and industrial sectors because of their low environmental impact, superior biodegradability, and contribution to sustainable goals. Their mechanical properties regarding tensile, flexural, hardness, and impact strength vary substantially. Various attempts have been made to augment their mechanical characteristics and capacities by incorporating reinforcement materials, such as inorganic and lignocellulosic fibres. This review summarizes the research on the properties of bioplastics modified by fibre reinforcement, with a focus on mechanical performance. The mechanical properties of reinforced bioplastics are significantly driven by parameters such as filler type, filler percentage, and aspect ratio. Fibre treatment aims to promote fibre–matrix adhesion by changing their physical, chemical, thermal, and mechanical properties. A general overview of how different filler treatments affect the mechanical properties of the composite is also presented. Lastly, the application of natural fibre-reinforced bioplastics in the automobile, construction, and packaging industries is discussed. Full article
(This article belongs to the Special Issue Mechanical Performance of Sustainable Bio-Based Compounds)
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32 pages, 2498 KiB  
Review
Small Diameter Cell-Free Tissue-Engineered Vascular Grafts: Biomaterials and Manufacture Techniques to Reach Suitable Mechanical Properties
by María A. Rodríguez-Soto, Camilo A. Polanía-Sandoval, Andrés M. Aragón-Rivera, Daniel Buitrago, María Ayala-Velásquez, Alejandro Velandia-Sánchez, Gabriela Peralta Peluffo, Juan C. Cruz, Carolina Muñoz Camargo, Jaime Camacho-Mackenzie, Juan Guillermo Barrera-Carvajal and Juan Carlos Briceño
Polymers 2022, 14(17), 3440; https://doi.org/10.3390/polym14173440 - 23 Aug 2022
Cited by 7 | Viewed by 4082
Abstract
Vascular grafts (VGs) are medical devices intended to replace the function of a blood vessel. Available VGs in the market present low patency rates for small diameter applications setting the VG failure. This event arises from the inadequate response of the cells interacting [...] Read more.
Vascular grafts (VGs) are medical devices intended to replace the function of a blood vessel. Available VGs in the market present low patency rates for small diameter applications setting the VG failure. This event arises from the inadequate response of the cells interacting with the biomaterial in the context of operative conditions generating chronic inflammation and a lack of regenerative signals where stenosis or aneurysms can occur. Tissue Engineered Vascular grafts (TEVGs) aim to induce the regeneration of the native vessel to overcome these limitations. Besides the biochemical stimuli, the biomaterial and the particular micro and macrostructure of the graft will determine the specific behavior under pulsatile pressure. The TEVG must support blood flow withstanding the exerted pressure, allowing the proper compliance required for the biomechanical stimulation needed for regeneration. Although the international standards outline the specific requirements to evaluate vascular grafts, the challenge remains in choosing the proper biomaterial and manufacturing TEVGs with good quality features to perform satisfactorily. In this review, we aim to recognize the best strategies to reach suitable mechanical properties in cell-free TEVGs according to the reported success of different approaches in clinical trials and pre-clinical trials. Full article
(This article belongs to the Special Issue Mechanical Performance of Sustainable Bio-Based Compounds)
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27 pages, 2784 KiB  
Review
Towards the Sustainability of the Plastic Industry through Biopolymers: Properties and Potential Applications to the Textiles World
by Antonella Patti and Domenico Acierno
Polymers 2022, 14(4), 692; https://doi.org/10.3390/polym14040692 - 11 Feb 2022
Cited by 44 | Viewed by 9156
Abstract
This study aims to provide an overview of the latest research studies on the use of biopolymers in various textile processes, from spinning processes to dyeing and finishing treatment, proposed as a possible solution to reduce the environmental impact of the textile industry. [...] Read more.
This study aims to provide an overview of the latest research studies on the use of biopolymers in various textile processes, from spinning processes to dyeing and finishing treatment, proposed as a possible solution to reduce the environmental impact of the textile industry. Recently, awareness of various polluting aspects of textile production, based on petroleum derivatives, has grown significantly. Environmental issues resulting from greenhouse gas emissions, and waste accumulation in nature and landfills, have pushed research activities toward more sustainable, low-impact alternatives. Polymers derived from renewable resources and/or with biodegradable characteristics were investigated as follows: (i) as constituent materials in yarn production, in view of their superior ability to be decomposed compared with common synthetic petroleum-derived plastics, positive antibacterial activities, good breathability, and mechanical properties; (ii) in textile finishing to act as biological catalysts; (iii) to impart specific functional properties to treated textiles; (iv) in 3D printing technologies on fabric surfaces to replace traditionally more pollutive dye-based and inkjet printing; and (v) in the implants for the treatment of dye-contaminated water. Finally, current projects led by well-known companies on the development of new materials for the textile market are presented. Full article
(This article belongs to the Special Issue Mechanical Performance of Sustainable Bio-Based Compounds)
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37 pages, 3479 KiB  
Review
Progress in the Valorization of Fruit and Vegetable Wastes: Active Packaging, Biocomposites, By-Products, and Innovative Technologies Used for Bioactive Compound Extraction
by Mohd Salahuddin Mohd Basri, Nor Nadiah Abdul Karim Shah, Alifdalino Sulaiman, Intan Syafinaz Mohamed Amin Tawakkal, Mohd Zuhair Mohd Nor, Siti Hajar Ariffin, Nur Hamizah Abdul Ghani and Faiqa Shazeaa Mohd Salleh
Polymers 2021, 13(20), 3503; https://doi.org/10.3390/polym13203503 - 12 Oct 2021
Cited by 41 | Viewed by 10879
Abstract
According to the Food Wastage Footprint and Climate Change Report, about 15% of all fruits and 25% of all vegetables are wasted at the base of the food production chain. The significant losses and wastes in the fresh and processing industries is becoming [...] Read more.
According to the Food Wastage Footprint and Climate Change Report, about 15% of all fruits and 25% of all vegetables are wasted at the base of the food production chain. The significant losses and wastes in the fresh and processing industries is becoming a serious environmental issue, mainly due to the microbial degradation impacts. There has been a recent surge in research and innovation related to food, packaging, and pharmaceutical applications to address these problems. The underutilized wastes (seed, skin, rind, and pomace) potentially present good sources of valuable bioactive compounds, including functional nutrients, amylopectin, phytochemicals, vitamins, enzymes, dietary fibers, and oils. Fruit and vegetable wastes (FVW) are rich in nutrients and extra nutritional compounds that contribute to the development of animal feed, bioactive ingredients, and ethanol production. In the development of active packaging films, pectin and other biopolymers are commonly used. In addition, the most recent research studies dealing with FVW have enhanced the physical, mechanical, antioxidant, and antimicrobial properties of packaging and biocomposite systems. Innovative technologies that can be used for sensitive bioactive compound extraction and fortification will be crucial in valorizing FVW completely; thus, this article aims to report the progress made in terms of the valorization of FVW and to emphasize the applications of FVW in active packaging and biocomposites, their by-products, and the innovative technologies (both thermal and non-thermal) that can be used for bioactive compounds extraction. Full article
(This article belongs to the Special Issue Mechanical Performance of Sustainable Bio-Based Compounds)
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27 pages, 3689 KiB  
Review
Durability of Biodegradable Polymer Nanocomposites
by Tatjana Glaskova-Kuzmina, Olesja Starkova, Sergejs Gaidukovs, Oskars Platnieks and Gerda Gaidukova
Polymers 2021, 13(19), 3375; https://doi.org/10.3390/polym13193375 - 30 Sep 2021
Cited by 28 | Viewed by 5047
Abstract
Biodegradable polymers (BP) are often regarded as the materials of the future, which address the rising environmental concerns. The advancement of biorefineries and sustainable technologies has yielded various BP with excellent properties comparable to commodity plastics. Water resistance, high dimensional stability, processability and [...] Read more.
Biodegradable polymers (BP) are often regarded as the materials of the future, which address the rising environmental concerns. The advancement of biorefineries and sustainable technologies has yielded various BP with excellent properties comparable to commodity plastics. Water resistance, high dimensional stability, processability and excellent physicochemical properties limit the reviewed materials to biodegradable polyesters and modified compositions of starch and cellulose, both known for their abundance and relatively low price. The addition of different nanofillers and preparation of polymer nanocomposites can effectively improve BP with controlled functional properties and change the rate of degradation. The lack of data on the durability of biodegradable polymer nanocomposites (BPN) has been the motivation for the current review that summarizes recent literature data on environmental ageing of BPN and the role of nanofillers, their basic engineering properties and potential applications. Various durability tests discussed thermal ageing, photo-oxidative ageing, water absorption, hygrothermal ageing and creep testing. It was discussed that incorporating nanofillers into BP could attenuate the loss of mechanical properties and improve durability. Although, in the case of poor dispersion, the addition of the nanofillers can lead to even faster degradation, depending on the structural integrity and the state of interfacial adhesion. Selected models that describe the durability performance of BPN were considered in the review. These can be applied as a practical tool to design BPN with tailored property degradationand durability. Full article
(This article belongs to the Special Issue Mechanical Performance of Sustainable Bio-Based Compounds)
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