Renewable and Sustainable Polymers

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

Deadline for manuscript submissions: closed (15 September 2023) | Viewed by 30052

Special Issue Editors


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Guest Editor
College of Materials Science and Engineering, Sichuan University of Science and Engineering, Zigong 643000, China
Interests: carbon-based polymer composites; biodegradable materials; biomass materials; recycling of resources; functional polymer nanocomposites; membrane; plasma surface modification; natural additives; biological resource regeneration and application; 3D printing materials
Special Issues, Collections and Topics in MDPI journals

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Guest Editor
Department of Materials Science and Engineering, National Taiwan University of Science and Technology, Taipei 10607, Taiwan
Interests: biodegradable polymers; biomass composites; optoelectronic materials; sensing materials
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Polymers are widely used and have many advantages. They bring innumerable benefits; however, they are sourced from non-renewable resources. Hence, scientists and researchers have been finding solutions to slow down the depletion of petrochemical resources, produce polymers that respect the environment to a greater extent, avoid the use of toxic compounds, use green technology, and consider the life cycle. All these efforts explain the increasing number of experiments and research in the field of polymers that are recyclable, bio-based, biodegradable, renewable, and more environmentally friendly. Accordingly, the field of polymer research is fully involved in the transition to produce environmentally friendly, green, and carbon-free polymers and toward a more responsible circular economy. The purpose of this Special Issue is to provide a broad overview of scientific papers on the latest progress in the field of “Renewable and Sustainable Polymers”, and it will focus on how renewable resources, green processes, purification engineering, and the use of biomass and industrial by-products from biological refining and transformation can provide the latest and most practical solutions to such new challenges. This Special Issue will cover the latest developments in the following topics: sustainability and recycling, chemical processes, waste utilization, renewable resources, sustainable materials, biomass and natural products, green and cleaning processes, and membranes for wastewater treatment and solvent recovery. 

Prof. Dr. Chi-Hui Tsou
Dr. Chih-Yuan Tsou
Guest Editors

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Keywords

  • recycling
  • green and cleaning process
  • biodegradable polymers
  • renewable resource
  • natural product
  • hydrogel
  • biomass
  • sustainability
  • environmentally friendly
  • membrane separation

Published Papers (12 papers)

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Research

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18 pages, 4897 KiB  
Article
Polymer Packaging through the Blending of Biowaste Oyster Shell and Low-Density Polyethylene: A Sustainable Approach for Enhanced Food Preservation
by Chang-Lei Qu, Shang-Ming Lin, Pranut Potiyaraj, Lei Meng, Chin-San Wu, Li Yuan, Xin Luo, Fei-Fan Ge and Chi-Hui Tsou
Polymers 2023, 15(19), 3977; https://doi.org/10.3390/polym15193977 - 03 Oct 2023
Cited by 2 | Viewed by 1242
Abstract
This research delves into the impact of incorporating thermally treated oyster shell powder (TOS), a biowaste filler, into low-density polyethylene (LDPE) to develop a LDPE/TOS blend, aiming at enhancing food packaging materials. The LDPE/TOS blend portrays advantageous characteristics such as augmented mechanical strength, [...] Read more.
This research delves into the impact of incorporating thermally treated oyster shell powder (TOS), a biowaste filler, into low-density polyethylene (LDPE) to develop a LDPE/TOS blend, aiming at enhancing food packaging materials. The LDPE/TOS blend portrays advantageous characteristics such as augmented mechanical strength, thermostability, crystallinity, water absorption, and improved hydrophobicity with TOS content up to 50%. Microstructure analysis reveals a transition from a sparse to a more interconnected structure, contributing to the amplified tensile strength. The blend demonstrates increased barrier properties against water vapor transmission, which is attributed to elongated diffusion paths induced by the TOS particles. Application of the blend material in vegetable preservation trials manifested a substantial reduction in water loss compared to pure LDPE or no packaging. This biowaste-based blend film extends the shelf-life of chicken significantly when compared to that of pure LDPE. Importantly, the LDPE/TOS blend exhibits excellent antibacterial properties against both Escherichia coli and Staphylococcus aureus. Full article
(This article belongs to the Special Issue Renewable and Sustainable Polymers)
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21 pages, 3714 KiB  
Article
Analytical Pyrolysis of Pinus radiata and Eucalyptus globulus: Effects of Microwave Pretreatment on Pyrolytic Vapours Composition
by Diego Venegas-Vásconez, Luis E. Arteaga-Pérez, María Graciela Aguayo, Romina Romero-Carrillo, Víctor H. Guerrero, Luis Tipanluisa-Sarchi and Serguei Alejandro-Martín
Polymers 2023, 15(18), 3790; https://doi.org/10.3390/polym15183790 - 17 Sep 2023
Cited by 1 | Viewed by 1025
Abstract
Pinus radiata (PR) and Eucalyptus globulus (EG) are the most planted species in Chile. This research aims to evaluate the pyrolysis behaviour of PR and EG from the Bío Bío region in Chile. Biomass samples were subjected to microwave pretreatment considering power (259, [...] Read more.
Pinus radiata (PR) and Eucalyptus globulus (EG) are the most planted species in Chile. This research aims to evaluate the pyrolysis behaviour of PR and EG from the Bío Bío region in Chile. Biomass samples were subjected to microwave pretreatment considering power (259, 462, 595, and 700 W) and time (1, 2, 3, and 5 min). The maximum temperature reached was 147.69 °C for PR and 130.71 °C for EG in the 700 W-5 min condition, which caused the rearrangement of the cellulose crystalline chains through vibration and an increase in the internal energy of the biomass and the decomposition of lignin due to reaching its glass transition temperature. Thermogravimetric analysis revealed an activation energy (Ea) reduction from 201.71 to 174.91 kJ·mol−1 in PR and from 174.80 to 158.51 kJ·mol−1 in EG, compared to the untreated condition (WOT) for the 700 W-5 min condition, which indicates that microwave pretreatment improves the activity of the components and the decomposition of structural compounds for subsequent pyrolysis. Functional groups were identified by Fourier transform infrared spectroscopy (FTIR). A decrease in oxygenated compounds such as acids (from 21.97 to 17.34% w·w−1 and from 27.72 to 24.13% w·w−1) and phenols (from 34.41 to 31.95% w·w−1 and from 21.73 to 20.24% w·w−1) in PR and EG, respectively, was observed in comparison to the WOT for the 700 W-5 min condition, after analytical pyrolysis. Such results demonstrate the positive influence of the pretreatment on the reduction in oxygenated compounds obtained from biomass pyrolysis. Full article
(This article belongs to the Special Issue Renewable and Sustainable Polymers)
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15 pages, 2942 KiB  
Article
Degradation of PET Bottles by an Engineered Ideonella sakaiensis PETase
by Maria Eduarda Sevilla, Mario D. Garcia, Yunierkis Perez-Castillo, Vinicio Armijos-Jaramillo, Santiago Casado, Karla Vizuete, Alexis Debut and Liliana Cerda-Mejía
Polymers 2023, 15(7), 1779; https://doi.org/10.3390/polym15071779 - 03 Apr 2023
Cited by 6 | Viewed by 8901
Abstract
Extensive plastic production has become a serious environmental and health problem due to the lack of efficient treatment of plastic waste. Polyethylene terephthalate (PET) is one of the most used polymers and is accumulating in landfills or elsewhere in nature at alarming rates. [...] Read more.
Extensive plastic production has become a serious environmental and health problem due to the lack of efficient treatment of plastic waste. Polyethylene terephthalate (PET) is one of the most used polymers and is accumulating in landfills or elsewhere in nature at alarming rates. In recent years, enzymatic degradation of PET by Ideonella sakaiensis PETase (IsPETase), a cutinase-like enzyme, has emerged as a promising strategy to completely depolymerize this polymer into its building blocks. Here, inspired by the architecture of cutinases and lipases homologous to IsPETase and using 3D structure information of the enzyme, we rationally designed three mutations in IsPETase active site for enhancing its PET-degrading activity. In particular, the S238Y mutant, located nearby the catalytic triad, showed a degradation activity increased by 3.3-fold in comparison to the wild-type enzyme. Importantly, this structural modification favoured the function of the enzyme in breaking down highly crystallized (~31%) PET, which is found in commercial soft drink bottles. In addition, microscopical analysis of enzyme-treated PET samples showed that IsPETase acts better when the smooth surface of highly crystalline PET is altered by mechanical stress. These results represent important progress in the accomplishment of a sustainable and complete degradation of PET pollution. Full article
(This article belongs to the Special Issue Renewable and Sustainable Polymers)
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10 pages, 1065 KiB  
Article
Life Cycle Assessment of Functionalized Bionanocompounds with Ice Nucleation Protein for Freezing Applications
by Olga P. Fuentes and Johann F. Osma
Polymers 2023, 15(6), 1457; https://doi.org/10.3390/polym15061457 - 15 Mar 2023
Viewed by 1324
Abstract
The objective of this study was to assess the effectiveness of functionalized bionanocompounds with ice nucleation protein (INP) as a novel approach for freezing applications in terms of how much energy is used during each step of freezing when water bionanocompound solutions were [...] Read more.
The objective of this study was to assess the effectiveness of functionalized bionanocompounds with ice nucleation protein (INP) as a novel approach for freezing applications in terms of how much energy is used during each step of freezing when water bionanocompound solutions were compared with pure water. According to the results of the manufacturing analysis, water required 28 times less energy than the silica + INA bionanocompound and 14 times less than the magnetite + INA bionanocompound. These findings showed that water used the least energy during the manufacturing process. In order to determine the associated environmental implications, an analysis of the operating stage was also conducted, taking the defrosting time of each bionanocompound during a 4 h work cycle into account. Our results showed that bionanocompounds may substantially reduce the environmental effects by achieving a 91% reduction in the impact after their use during all four work cycles in the operation stage. Additionally, given the energy and raw materials needed in this process, this improvement was more significant than at the manufacturing stage. The results from both stages indicated that, when compared with water, the magnetite + INA bionanocompound and the silica + INA bionanocompound would save an estimated 7% and 47% of total energy, respectively. The study’s findings also demonstrated the great potential for using bionanocompounds in freezing applications to reduce the effects on the environment and human health. Full article
(This article belongs to the Special Issue Renewable and Sustainable Polymers)
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23 pages, 4251 KiB  
Article
Exclusive Biosynthesis of Pullulan Using Taguchi’s Approach and Decision Tree Learning Algorithm by a Novel Endophytic Aureobasidium pullulans Strain
by WesamEldin I. A. Saber, Abdulaziz A. Al-Askar and Khalid M. Ghoneem
Polymers 2023, 15(6), 1419; https://doi.org/10.3390/polym15061419 - 13 Mar 2023
Cited by 3 | Viewed by 1872
Abstract
Pullulan is a biodegradable, renewable, and environmentally friendly hydrogel biopolymer, with potential uses in food, medicine, and cosmetics. New endophytic Aureobasidium pullulans (accession number; OP924554) was used for the biosynthesis of pullulan. Innovatively, the fermentation process was optimized using both Taguchi’s approach and [...] Read more.
Pullulan is a biodegradable, renewable, and environmentally friendly hydrogel biopolymer, with potential uses in food, medicine, and cosmetics. New endophytic Aureobasidium pullulans (accession number; OP924554) was used for the biosynthesis of pullulan. Innovatively, the fermentation process was optimized using both Taguchi’s approach and the decision tree learning algorithm for the determination of important variables for pullulan biosynthesis. The relative importance of the seven tested variables that were obtained by Taguchi and the decision tree model was accurate and followed each other’s, confirming the accuracy of the experimental design. The decision tree model was more economical by reducing the quantity of medium sucrose content by 33% without a negative reduction in the biosynthesis of pullulan. The optimum nutritional conditions (g/L) were sucrose (60 or 40), K2HPO4 (6.0), NaCl (1.5), MgSO4 (0.3), and yeast extract (1.0) at pH 5.5, and short incubation time (48 h), yielding 7.23% pullulan. The spectroscopic characterization (FT-IR and 1H-NMR spectroscopy) confirmed the structure of the obtained pullulan. This is the first report on using Taguchi and the decision tree for pullulan production by a new endophyte. Further research is encouraged for additional studies on using artificial intelligence to maximize fermentation conditions. Full article
(This article belongs to the Special Issue Renewable and Sustainable Polymers)
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22 pages, 4898 KiB  
Article
Nanoparticles Based on Chondroitin Sulfate from Tuna Heads and Chitooligosaccharides for Enhanced Water Solubility and Sustained Release of Curcumin
by Yaowapha Waiprib, Pattarachat Ingrungruengluet and Wanchai Worawattanamateekul
Polymers 2023, 15(4), 834; https://doi.org/10.3390/polym15040834 - 08 Feb 2023
Cited by 2 | Viewed by 2062
Abstract
This study aimed to separate chondroitin sulfate (CS) from the heads of skipjack tuna (Katsuwonus pelamis) and yellowfin tuna (Thunnus albacares), by-products derived from canned tuna processing, via a biological process. The use of 1% w/w papain [...] Read more.
This study aimed to separate chondroitin sulfate (CS) from the heads of skipjack tuna (Katsuwonus pelamis) and yellowfin tuna (Thunnus albacares), by-products derived from canned tuna processing, via a biological process. The use of 1% w/w papain and an incubation time of 48 h resulted in a degree of hydrolysis of 93.75 ± 2.94% and a CS content of 59.53 ± 1.77 mg/100 g. The FTIR spectra of extracted CS products exhibited identical functional groups found in commercially available CS. The molecular weights of CS extracted from skipjack and yellowfin tuna heads were 11.0 kDa and 7.7 kDa, respectively. Subsequently, a CH:CS ratio of 3:2 for CS and chitooligosaccharides (CH) was chosen as the optimal ratio for the preparation of spherical nanoparticles, with %EE, mean particle size, PDI, and zeta potential values of 50.89 ± 0.66%, 128.90 ± 3.29 nm, 0.27 ± 0.04, and −12.47 ± 2.06, respectively. The CU content was enhanced to 127.21 ± 1.66 μg/mL. The release of CU from this particular nanosystem involved mainly a drug diffusion mechanism, with a burst release in the first 3 h followed by a sustained release of CU over 24 h. The DPPH and ABTS scavenging activity results confirmed the efficient encapsulation of CU into CHCS nanoparticles. This study will provide a theoretical basis for CS derived from tuna head cartilages to be used as a functional component with specific functional properties in food and biomedical applications. Full article
(This article belongs to the Special Issue Renewable and Sustainable Polymers)
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11 pages, 3090 KiB  
Article
Utilization of Corncob as an Immobilization Matrix for a Xylanolytic Yeast Strain
by Maham Aftab, Uroosa Ejaz, Rami Adel Pashameah, Aimen Fatima, Jaweria Syed, Immad Ansari, Muhammad Sohail, Samah A. AlSubhi, Eman Alzahrani and Zeinhom M. El-Bahy
Polymers 2023, 15(3), 683; https://doi.org/10.3390/polym15030683 - 29 Jan 2023
Cited by 2 | Viewed by 1664
Abstract
Immobilization of microbial cells for the production of industrially important enzymes has been reported to offer the advantages of recyclability, higher yields and cost effectiveness. The search for an appropriate matrix that is affordable and easy to prepare is a significant topic in [...] Read more.
Immobilization of microbial cells for the production of industrially important enzymes has been reported to offer the advantages of recyclability, higher yields and cost effectiveness. The search for an appropriate matrix that is affordable and easy to prepare is a significant topic in microbial biotechnology. Here, an abundant type of agro-industrial waste—corncob—was utilized as an immobilization matrix for the production of xylanase from an indigenous yeast strain, Saccharomyces cerevisiae MK-157. This is the first report describing xylanase production from immobilized S. cerevisiae. To render the corncob matrix more porous, alkaline pretreatment was undertaken and yeast cells were immobilized on the matrix by cultivating at 30 °C for 48 h in Sabouraud dextrose broth. After incubation, the immobilized matrix was transferred to mineral salt medium containing 1% xylan and incubated at 30 °C for 24 h. Xylanase production was determined in cell-free culture supernatant and the matrix was recycled for up to seven cycles. Moreover, xylanase-mediated saccharification was carried out using sugarcane bagasse as a substrate and the release of reducing sugars was monitored. The results showed that the immobilized yeast produced 4.97 IU mL−1 xylanase in the first production cycle, indicating a >tenfold increase compared to the free cells. Xylanase production further increased to its maximum levels (9.23 IU mL−1) in the fourth production cycle. Nonetheless, the cells retained 100% productivity for up to seven cycles. The volumetric and specific productivity of xylanase were also the highest in the fourth cycle. Scanning electron microscopy images revealed the rough surface of the untreated corncob, which became more porous after alkaline pretreatment. Immobilized yeast cells were also visible on the corncob pieces. The saccharification of a natural resource—sugarcane bagasse—using xylanase preparation yielded 26 mg L−1 of reducing sugars. Therefore, it can be concluded that yeast strains can yield sufficient quantities of xylanase, allowing possible biotechnological applications. Moreover, corncob can serve as a cost-effective matrix for industrially important yeast strains. Full article
(This article belongs to the Special Issue Renewable and Sustainable Polymers)
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15 pages, 3524 KiB  
Article
Synthesis of Cellulose Nanoparticles from Ionic Liquid Solutions for Biomedical Applications
by Marta G. Fuster, Imane Moulefera, M. Noelia Muñoz, Mercedes G. Montalbán and Gloria Víllora
Polymers 2023, 15(2), 382; https://doi.org/10.3390/polym15020382 - 11 Jan 2023
Cited by 7 | Viewed by 2156
Abstract
A method for the synthesis of cellulose nanoparticles using the ionic liquid 1-ethyl-3-methylimidazolium acetate has been optimised. The use of a highly biocompatible biopolymer such as cellulose, together with the use of an ionic liquid, makes this method a promising way to obtain [...] Read more.
A method for the synthesis of cellulose nanoparticles using the ionic liquid 1-ethyl-3-methylimidazolium acetate has been optimised. The use of a highly biocompatible biopolymer such as cellulose, together with the use of an ionic liquid, makes this method a promising way to obtain nanoparticles with good capability for drug carrying. The operating conditions of the synthesis have been optimised based on the average hydrodynamic diameter, the polydispersity index, determined by Dynamic Light Scattering (DLS) and the Z-potential, obtained by phase analysis light scattering (PALS), to obtain cellulose nanoparticles suitable for use in biomedicine. The obtained cellulose nanoparticles have been characterised by Fourier transform infrared spectroscopy (FTIR) with attenuated total reflectance (ATR), field emission scanning electron microscopy (FESEM) and thermogravimetric analysis (TGA/DTA). Finally, cell viability studies have been performed with a cancer cell line (HeLa) and with a healthy cell line (EA.hy926). These have shown that the cellulose nanoparticles obtained are not cytotoxic in the concentration range of the studied nanoparticles. The results obtained in this work constitute a starting point for future studies on the use of cellulose nanoparticles, synthesised from ionic liquids, for biomedical applications such as targeted drug release or controlled drug release. Full article
(This article belongs to the Special Issue Renewable and Sustainable Polymers)
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12 pages, 3168 KiB  
Article
Encapsulation of Thymol and Eugenol Essential Oils Using Unmodified Cellulose: Preparation and Characterization
by Koranit Shlosman, Dmitry M. Rein, Rotem Shemesh, Na’ama Koifman, Ayelet Caspi and Yachin Cohen
Polymers 2023, 15(1), 95; https://doi.org/10.3390/polym15010095 - 26 Dec 2022
Cited by 6 | Viewed by 2298
Abstract
Essential oils (EOs) are volatile natural organic compounds, which possess pesticidal properties. However, they are vulnerable to heat and light, limiting their range of applications. Encapsulation of EOs is a useful approach to overcome some of these limitations. In this study, a novel [...] Read more.
Essential oils (EOs) are volatile natural organic compounds, which possess pesticidal properties. However, they are vulnerable to heat and light, limiting their range of applications. Encapsulation of EOs is a useful approach to overcome some of these limitations. In this study, a novel emulsification technique is utilized for encapsulation of thymol (TY) and eugenol (EU) (EOs) within microcapsules with an unmodified cellulose shell. Use of low cost materials and processes can be beneficial in agricultural applications. In the encapsulation process, unmodified cellulose was dissolved in 7% aqueous NaOH at low temperature, regenerated to form a dispersion of cellulose hydrogels, which was rigorously mixed with the EOs by mechanical mixing followed by high-pressure homogenization (HPH). Cellulose:EO ratios of 1:1 and 1:8 utilizing homogenization pressures of 5000, 10,000 and 20,000 psi applied in a microfluidizer were studied. Light microscopy, high-resolution cryogenic scanning electron microscopy (cryo-SEM) and Fourier transform infrared spectroscopy (FTIR) revealed successful fabrication of EO-loaded capsules in size range of 1 to ~8 µm. Stability analyses showed highly stabilized oil in water (O/W) emulsions with instability index close to 0. The emulsions exhibited anti-mold activity in post-harvest alfalfa plants, with potency affected by the cellulose:EO ratio as well as the EO type; TY showed the highest anti-mold activity. Taken together, this study showed potential for anti-fungal activity of cellulose-encapsulated EOs in post-harvest hay. Full article
(This article belongs to the Special Issue Renewable and Sustainable Polymers)
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11 pages, 3074 KiB  
Article
Sustainable Sheep Wool/Soy Protein Biocomposites for Sound Absorption
by Marta Urdanpilleta, Itsaso Leceta, Pedro Guerrero and Koro de la Caba
Polymers 2022, 14(23), 5231; https://doi.org/10.3390/polym14235231 - 01 Dec 2022
Cited by 4 | Viewed by 1634
Abstract
The wool fibers of the Latxa sheep breed were combined with a soy protein isolate (SPI) matrix to develop sustainable biocomposites with acoustic properties, adding value to Latxa sheep wool, which is currently considered a residue. Samples with 7, 10, 15, and 20 [...] Read more.
The wool fibers of the Latxa sheep breed were combined with a soy protein isolate (SPI) matrix to develop sustainable biocomposites with acoustic properties, adding value to Latxa sheep wool, which is currently considered a residue. Samples with 7, 10, 15, and 20 wt % wool were prepared by freeze drying in order to develop porous structures, as shown by SEM analysis. Additionally, XRD analysis provided the evidence of a change toward a more amorphous structure with the incorporation of wool fibers due to the interactions between the soy protein and keratin present in wool fibers, as shown by the relative intensity changes in the FTIR bands. The biocomposites were analyzed in a Kundt’s tube to obtain their sound absorption coefficient at normal incidence. The results showed an acoustic absorption coefficient that well-surpassed 0.9 for frequencies above 1000 Hz. This performance is comparable to that of the conventional synthetic materials present in the market and, thus, sheep wool/SPI biocomposites are suitable to be used as acoustic absorbers in the building industry, highlighting the potential of replacing not only synthetic fibers but also synthetic polymers, with natural materials to enhance the sustainability of the building sector. Full article
(This article belongs to the Special Issue Renewable and Sustainable Polymers)
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14 pages, 5308 KiB  
Article
Using Sodium Polyacrylate to Gel-Spin Lignin/Poly(Vinyl Alcohol) Fiber at High Lignin Content
by Manik Chandra Biswas and Ericka Ford
Polymers 2022, 14(13), 2736; https://doi.org/10.3390/polym14132736 - 04 Jul 2022
Cited by 3 | Viewed by 2500
Abstract
Lignin is the world’s most naturally abundant aromatic polymer, which makes it a sustainable raw material for engineered polymers and fiber manufacturing. Dry-jet gel-spinning was used to fabricate poly(vinyl alcohol) (PVA) fibers having 30% or more of the lignin biopolymer. To achieve this [...] Read more.
Lignin is the world’s most naturally abundant aromatic polymer, which makes it a sustainable raw material for engineered polymers and fiber manufacturing. Dry-jet gel-spinning was used to fabricate poly(vinyl alcohol) (PVA) fibers having 30% or more of the lignin biopolymer. To achieve this goal, 0.45 wt.% of aqueous sodium polyacrylate (SPA, at 0.55 wt.% solids) was added to spinning dopes of PVA dissolved in dimethylsulfoxide (DMSO). SPA served to enable the spinning of fibers having high lignin content (i.e., above 30%) while eliminating the aging of as-spun gel fiber prior to elevated temperature drawing. SPA impedes the migration of acetone soluble lignin from the skin of as-spun gel fibers, because SPA is insoluble in acetone, which is also a nonsolvent coagulant for PVA. PVA fibers having 30% lignin exhibited the highest tenacity of 1.3 cN/dtex (centinewton/decitex) and specific modulus 35.7 cN/dtex. The drawn fiber of 70% lignin to PVA, showed tenacity and specific modulus values of 0.94 cN/dtex and 35.3 cN/dtex, respectively. Fourier Transform Infrared (FTIR) spectroscopy showed evidence of hydrogen bonding between lignin and PVA among the drawn fibers. The modification of PVA/lignin dopes with SPA, therefore, allowed for the fabrication of gel-spun biobased fibers without the previously required step of gel aging. Full article
(This article belongs to the Special Issue Renewable and Sustainable Polymers)
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Review

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25 pages, 7402 KiB  
Review
Thermal, Morphological and Mechanical Properties of Multifunctional Composites Based on Biodegradable Polymers/Bentonite Clay: A Review
by António Benjamim Mapossa, Afonso Henrique da Silva Júnior, Carlos Rafael Silva de Oliveira and Washington Mhike
Polymers 2023, 15(16), 3443; https://doi.org/10.3390/polym15163443 - 17 Aug 2023
Cited by 7 | Viewed by 1809
Abstract
The extensive use of non-biodegradable plastic products has resulted in significant environmental problems caused by their accumulation in landfills and their proliferation into water bodies. Biodegradable polymers offer a potential solution to mitigate these issues through the utilization of renewable resources which are [...] Read more.
The extensive use of non-biodegradable plastic products has resulted in significant environmental problems caused by their accumulation in landfills and their proliferation into water bodies. Biodegradable polymers offer a potential solution to mitigate these issues through the utilization of renewable resources which are abundantly available and biodegradable, making them environmentally friendly. However, biodegradable polymers face challenges such as relatively low mechanical strength and thermal resistance, relatively inferior gas barrier properties, low processability, and economic viability. To overcome these limitations, researchers are investigating the incorporation of nanofillers, specifically bentonite clay, into biodegradable polymeric matrices. Bentonite clay is an aluminum phyllosilicate with interesting properties such as a high cation exchange capacity, a large surface area, and environmental compatibility. However, achieving complete dispersion of nanoclays in polymeric matrices remains a challenge due to these materials’ hydrophilic and hydrophobic nature. Several methods are employed to prepare polymer–clay nanocomposites, including solution casting, melt extrusion, spraying, inkjet printing, and electrospinning. Biodegradable polymeric nanocomposites are versatile and promising in various industrial applications such as electromagnetic shielding, energy storage, electronics, and flexible electronics. Additionally, combining bentonite clay with other fillers such as graphene can significantly reduce production costs compared to the exclusive use of carbon nanotubes or metallic fillers in the matrix. This work reviews the development of bentonite clay-based composites with biodegradable polymers for multifunctional applications. The composition, structure, preparation methods, and characterization techniques of these nanocomposites are discussed, along with the challenges and future directions in this field. Full article
(This article belongs to the Special Issue Renewable and Sustainable Polymers)
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