Polymers

Editorial

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1 pages, 149 KiB

Open AccessEditorial

Preface to “Advances in Bio-Based and Biodegradable Polymeric Composites”

by Evgenia G. Korzhikova-Vlakh

Polymers 2022, 14(14), 2926; https://doi.org/10.3390/polym14142926 - 20 Jul 2022

Cited by 1 | Viewed by 1137

Abstract

The use of polymers for various purposes is increasing every year [...] Full article

(This article belongs to the Special Issue Advances in Bio-Based and Biodegradable Polymeric Composites)

Research

Jump to: Editorial, Review

20 pages, 5806 KiB

Open AccessArticle

Improving the Processability and Performance of Micronized Fiber-Reinforced Green Composites through the Use of Biobased Additives

by Bruno F. A. Valente, Armando J. D. Silvestre, Carlos Pascoal Neto, Carla Vilela and Carmen S. R. Freire

Polymers 2022, 14(17), 3451; https://doi.org/10.3390/polym14173451 - 24 Aug 2022

Cited by 7 | Viewed by 2773

Abstract

Green composites made of bioplastics reinforced with natural fibers have gained considerable attention over recent years. However, the use of natural fibers in composites usually compromise some key properties, such as the impact strength and the processability of the final materials. In the [...] Read more.

Green composites made of bioplastics reinforced with natural fibers have gained considerable attention over recent years. However, the use of natural fibers in composites usually compromise some key properties, such as the impact strength and the processability of the final materials. In the present study, two distinct additives, namely an epoxidized linseed oil (ELO) and a sugar-based surfactant, viz. GlucoPure^® Sense (GPS), were tested in composite formulations of poly(lactic acid) (PLA) or poly(hydroxybutyrate) (PHB) reinforced with micronized pulp fibers. Both additives showed a plasticizing effect, which led to a decrease in the Young’s and flexural moduli and strengths. At the same time, the elongation and flexural strain at break were considerably improved on some formulations. The melt flow rate was also remarkably improved with the incorporation of the additives. In the PHB-based composites, an increment of 230% was observed upon incorporation of 7.5 wt.% ELO and, in composites based on PLA, an increase of around 155% was achieved with the introduction of 2.5 wt.% GPS. ELO also increased the impact strength to a maximum of 29 kJ m⁻², in formulations with PLA. For most composites, a faster degradation rate was observed on the formulations with the additives, reaching, in the case of PHB composites with GPS, a noteworthy weight loss over 75% under burial testing in compost medium at room temperature. Full article

(This article belongs to the Special Issue Advances in Bio-Based and Biodegradable Polymeric Composites)

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14 pages, 3394 KiB

Open AccessArticle

Improvement in Thermal Stability of Flexible Poly(L-lactide)-b-poly(ethylene glycol)-b-poly(L-lactide) Bioplastic by Blending with Native Cassava Starch

by Yaowalak Srisuwan and Yodthong Baimark

Polymers 2022, 14(15), 3186; https://doi.org/10.3390/polym14153186 - 4 Aug 2022

Cited by 9 | Viewed by 2285

Abstract

High-molecular-weight poly(L-lactide)-b-poly(ethylene glycol)-b-poly(L-lactide) triblock copolymer (PLLA-PEG-PLLA) is a promising candidate for use as a biodegradable bioplastic because of its high flexibility. However, the applications of PLLA-PEG-PLLA have been limited due to its high cost and poor thermal stability compared [...] Read more.

High-molecular-weight poly(L-lactide)-b-poly(ethylene glycol)-b-poly(L-lactide) triblock copolymer (PLLA-PEG-PLLA) is a promising candidate for use as a biodegradable bioplastic because of its high flexibility. However, the applications of PLLA-PEG-PLLA have been limited due to its high cost and poor thermal stability compared to PLLA. In this work, native cassava starch was blended to reduce the production cost and to improve the thermal stability of PLLA-PEG-PLLA. The starch interacted with PEG middle blocks to increase the thermal stability of the PLLA-PEG-PLLA matrix and to enhance phase adhesion between the PLLA-PEG-PLLA matrix and dispersed starch particles. Tensile stress and strain at break of PLLA-PEG-PLLA films decreased and the hydrophilicity increased as the starch content increased. However, all the PLLA-PEG-PLLA/starch films remained more flexible than the pure PLLA film, representing a promising candidate in biomedical, packaging and agricultural applications. Full article

(This article belongs to the Special Issue Advances in Bio-Based and Biodegradable Polymeric Composites)

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14 pages, 2899 KiB

Open AccessArticle

Mechanical, Dynamic-Mechanical, Thermal and Decomposition Behavior of 3D-Printed PLA Reinforced with CaCO₃ Fillers from Natural Resources

by Cristina Pavon, Miguel Aldas, María Dolores Samper, Dana Luca Motoc, Santiago Ferrandiz and Juan López-Martínez

Polymers 2022, 14(13), 2646; https://doi.org/10.3390/polym14132646 - 29 Jun 2022

Cited by 16 | Viewed by 2834

Abstract

This study evaluates the effect of CaCO₃ fillers extracted from waste eggshells on 3D-printed PLA performance. Samples of neat PLA and PLA reinforced with CaCO₃ fillers embedded with different wt.% were prepared using an FDM (fused deposition modeling) technology. The samples [...] Read more.

This study evaluates the effect of CaCO₃ fillers extracted from waste eggshells on 3D-printed PLA performance. Samples of neat PLA and PLA reinforced with CaCO₃ fillers embedded with different wt.% were prepared using an FDM (fused deposition modeling) technology. The samples were examined using mechanical, dynamic mechanical, thermal, and thermal decomposition analyses. The results revealed increasing elastic moduli, tensile strength, and flexure as the filler content increased. The rheological results from the MFR tests showed that the filler content did not influence the PLA-based samples’ processability. Further, the thermal degradation of neat and various CaCO₃-wt.%-reinforced PLA specimens revealed relatively small discrepancies in their exposure to the temperature increase, mainly concerning the eggshell organic components and volatile components, from their processability up to 300 °C. By contrast, the increased filler content positively shifted the peaks along the temperature scale at the maximum degradation rate. Additionally, the weight content of the natural reinforcement strongly influenced the surface wettability and appearance of the samples. Further, the SEM analysis featured both the presence of interlayer disturbances and the interfacial compatibility the PLA with the selected fillers. Full article

(This article belongs to the Special Issue Advances in Bio-Based and Biodegradable Polymeric Composites)

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15 pages, 2394 KiB

Open AccessArticle

Development of Edible Coating from Gelatin Composites with the Addition of Black Tea Extract (Camellia sinensis) on Minimally Processed Watermelon (Citrullus lanatus)

by Salwa Salsabiela, Ambar Sukma Sekarina, Hanifa Bagus, Aulia Audiensi, Farah Azizah, Windy Heristika, Manikharda, Eko Susanto, Heli Siti Halimatul Munawaroh, Pau Loke Show and Andriati Ningrum

Polymers 2022, 14(13), 2628; https://doi.org/10.3390/polym14132628 - 28 Jun 2022

Cited by 11 | Viewed by 2893

Abstract

The purpose of this research was to determine the effect of composite fish gelatin–chitosan edible coatings enriched with black tea extract on the physical, chemical, and fungal decay properties of minimally processed watermelons stored at ±4 °C for 13 days. In this study, [...] Read more.

The purpose of this research was to determine the effect of composite fish gelatin–chitosan edible coatings enriched with black tea extract on the physical, chemical, and fungal decay properties of minimally processed watermelons stored at ±4 °C for 13 days. In this study, tuna skin gelatin was extracted and used to prepare edible coating solutions which comprised 4% gelatin, 2% chitosan, 2% calcium lactate, 2% glycerol, and black tea extract (0%; 0.25%; 0.50%; 0.75%; 1%). The samples were coated using the layer-by-layer dipping technique. This study showed that composite fish gelatin–chitosan edible coating enriched with black tea extract maintained and improved weight loss, texture (hardness), color, pH, and total soluble solid antioxidant activity and prevented fungal decay on minimally processed watermelons stored at ±4 °C for 13 days. The development in this study of edible film and a coating prepared from fish gelatin–chitosan and the incorporation of black tea extract as an antioxidant or antimicrobial agent can be a new approach to preventing postharvest loss and increasing the shelf life of minimally processed watermelon. Full article

(This article belongs to the Special Issue Advances in Bio-Based and Biodegradable Polymeric Composites)

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20 pages, 2778 KiB

Open AccessArticle

Effective Aging Inhibition of the Thermoplastic Corn Starch Films through the Use of Green Hybrid Filler

by Di Sheng Lai, Azlin Fazlina Osman, Sinar Arzuria Adnan, Ismail Ibrahim, Midhat Nabil Ahmad Salimi and Awad A. Alrashdi

Polymers 2022, 14(13), 2567; https://doi.org/10.3390/polym14132567 - 24 Jun 2022

Cited by 7 | Viewed by 2175

Abstract

Recently, hybrid fillers have been widely used to improve the properties of biopolymers. The synergistic effects of the hybrid fillers can have a positive impact on biopolymers, including thermoplastic corn starch film (TPCS). In this communication, we highlight the effectiveness of hybrid fillers [...] Read more.

Recently, hybrid fillers have been widely used to improve the properties of biopolymers. The synergistic effects of the hybrid fillers can have a positive impact on biopolymers, including thermoplastic corn starch film (TPCS). In this communication, we highlight the effectiveness of hybrid fillers in inhibiting the aging process of TPCS. The TPCS, thermoplastic corn starch composite films (TPCS-C), and hybrid thermoplastic corn starch composite film (TPCS-HC) were stored for 3 months to study the effect of hybrid filler on the starch retrogradation. TPCS-C and TPCS-HC were prepared by casting method with 5 wt% of fillers: nanocellulose (NC) and bentonite (BT). The alteration of the mechanical properties, aging behavior, and crystalline structure of the films were analyzed through the tensile test, Fourier transform infrared (FTIR), X-ray diffraction (XRD), differential scanning calorimetry (DSC), and water absorption analysis. The obtained data were correlated to each other to analyze the retrogradation of the TPCS, which is the main factor that contributes to the aging process of the biopolymer. Results signify that incorporating the hybrid filler (NC + BT) in the TPCS/4BT1NC films has effectively prevented retrogradation of the starch molecules after being stored for 3 months. On the contrary, the virgin TPCS film showed the highest degree of retrogradation resulting in a significant decrement in the film’s flexibility. These findings proved the capability of the green hybrid filler in inhibiting the aging of the TPCS. Full article

(This article belongs to the Special Issue Advances in Bio-Based and Biodegradable Polymeric Composites)

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16 pages, 1737 KiB

Open AccessArticle

Evaluation of the Antimicrobial, Thermal, Mechanical, and Barrier Properties of Corn Starch–Chitosan Biodegradable Films Reinforced with Cellulose Nanocrystals

by Claudio Alonso Díaz-Cruz, Carolina Caicedo, Enrique Javier Jiménez-Regalado, Ramón Díaz de León, Ricardo López-González and Rocio Yaneli Aguirre-Loredo

Polymers 2022, 14(11), 2166; https://doi.org/10.3390/polym14112166 - 26 May 2022

Cited by 20 | Viewed by 2784

Abstract

Packaging materials play an essential role in the preservation and marketing of food and other products. To improve their conservation capacity, antimicrobial agents that inhibit bacterial growth are used. Biopolymers such as starch and chitosan are a sustainable alternative for the generation of [...] Read more.

Packaging materials play an essential role in the preservation and marketing of food and other products. To improve their conservation capacity, antimicrobial agents that inhibit bacterial growth are used. Biopolymers such as starch and chitosan are a sustainable alternative for the generation of films for packaging that can also serve as a support for preservatives and antimicrobial agents. These substances can replace packaging of synthetic origin and maintain good functional properties to ensure the quality of food products. Films based on a mixture of corn starch and chitosan were developed by the casting method and the effect of incorporating cellulose nanocrystals (CNC) at different concentrations (0 to 10% w/w) was studied. The effect of the incorporation of CNC on the rheological, mechanical, thermal and barrier properties, as well as the antimicrobial activity of nanocomposite films, was evaluated. A significant modification of the functional and antimicrobial properties of the starch–chitosan films was observed with an increase in the concentration of nanomaterials. The films with CNC in a range of 0.5 to 5% presented the best performance. In line with the physicochemical characteristics which are desired in antimicrobial materials, this study can serve as a guide for the development this type of packaging for food use. Full article

(This article belongs to the Special Issue Advances in Bio-Based and Biodegradable Polymeric Composites)

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22 pages, 21725 KiB

Open AccessArticle

Physicochemical Properties and Atomic-Scale Interactions in Polyaniline (Emeraldine Base)/Starch Bio-Based Composites: Experimental and Computational Investigations

by Soufiane Boudjelida, Souad Djellali, Hana Ferkous, Yacine Benguerba, Imane Chikouche and Mauro Carraro

Polymers 2022, 14(8), 1505; https://doi.org/10.3390/polym14081505 - 7 Apr 2022

Cited by 16 | Viewed by 2444

Abstract

The processability of conductive polymers still represents a challenge. The use of potato starch as a steric stabilizer for the preparation of stable dispersions of polyaniline (emeraldine base, EB) is described in this paper. Biocomposites are obtained by oxidative polymerization of aniline in [...] Read more.

The processability of conductive polymers still represents a challenge. The use of potato starch as a steric stabilizer for the preparation of stable dispersions of polyaniline (emeraldine base, EB) is described in this paper. Biocomposites are obtained by oxidative polymerization of aniline in aqueous solutions containing different ratios of aniline and starch (% w/w). PANI-EB/Starch biocomposites are subjected to structural analysis (UV-Visible, RAMAN, ATR, XRD), thermal analysis (TGA, DSC), morphological analysis (SEM, Laser Granulometry), and electrochemical analysis using cyclic voltammetry. The samples were also tested for their solubility using various organic solvents. The results showed that, with respect to starch particles, PANI/starch biocomposites exhibit an overall decrease in particles size, which improves both their aqueous dispersion and solubility in organic solvents. Although X-ray diffraction and DSC analyses indicated a loss of crystallinity in biocomposites, the cyclic voltammetry tests revealed that all PANI-EB/Starch biocomposites possess improved redox exchange properties. Finally, the weak interactions at the atomic-level interactions between amylopectin–aniline and amylopectin–PANI were disclosed by the computational studies using DFT, COSMO-RS, and AIM methods. Full article

(This article belongs to the Special Issue Advances in Bio-Based and Biodegradable Polymeric Composites)

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8 pages, 1385 KiB

Open AccessCommunication

A Potential of New Untreated Bio-Reinforcement from Caesalpinia sappan L. Wood Fiber for Polybutylene Succinate Composite Film

by Ekkachai Martwong, Yvette Tran, Nattawadee Natsrita, Chaithip Kaewpang, Kittisak Kongsuk, Yeampon Nakaramontri and Nathapong Sukhawipat

Polymers 2022, 14(3), 499; https://doi.org/10.3390/polym14030499 - 26 Jan 2022

Cited by 3 | Viewed by 2505

Abstract

Natural cellulose-based Caesalpinia sappan L. wood fiber (CSWF) has been demonstrated to have significant promise as a new untreated bio-reinforcement of the polybutylene succinate (PBS) composite film. The morphology, mechanical characteristics, and biodegradation were investigated. The morphology, the fiber distribution, and the fiber [...] Read more.

Natural cellulose-based Caesalpinia sappan L. wood fiber (CSWF) has been demonstrated to have significant promise as a new untreated bio-reinforcement of the polybutylene succinate (PBS) composite film. The morphology, mechanical characteristics, and biodegradation were investigated. The morphology, the fiber distribution, and the fiber aggregation has been discussed. The properties of the composite have been improved by the addition of CSWF from 5 phr to 10 phr, while with the addition of 15 phr, the properties were dropped. The result showed that CSWF could be used as a new reinforcement without any treatment, and 10 phr of CSWF was the best formulation of a new biocomposite film. The PBS/CSWF10 composite film had the highest mechanical strength, with a tensile strength of 12.21 N/mm² and an elongation at break of 21.01%, respectively. It was completely degraded by soil bury in three months. Therefore, the PBS/CSWF10 composite film has the potential to be a green with a promising short-term degradation. Full article

(This article belongs to the Special Issue Advances in Bio-Based and Biodegradable Polymeric Composites)

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19 pages, 3850 KiB

Open AccessArticle

Hydrothermal Ageing Effect on Reinforcement Efficiency of Nanofibrillated Cellulose/Biobased Poly(butylene succinate) Composites

by Olesja Starkova, Oskars Platnieks, Alisa Sabalina and Sergejs Gaidukovs

Polymers 2022, 14(2), 221; https://doi.org/10.3390/polym14020221 - 6 Jan 2022

Cited by 12 | Viewed by 2081

Abstract

Nanofibrillated cellulose (NFC) is a sustainable functional nanomaterial known for its high strength, stiffness, and biocompatibility. It has become a key building block for the next-generation of lightweight, advanced materials for applications such as consumer products, biomedical, energy storage, coatings, construction, and automotive. [...] Read more.

Nanofibrillated cellulose (NFC) is a sustainable functional nanomaterial known for its high strength, stiffness, and biocompatibility. It has become a key building block for the next-generation of lightweight, advanced materials for applications such as consumer products, biomedical, energy storage, coatings, construction, and automotive. Tunable and predictable durability under environmental impact is required for high performance applications. Bio-based poly (butylene succinate) (PBS) composites containing up to 50% NFC content were designed and aged in distilled water or at high relative humidity (RH98%). PBS/NFC composites are characterized by up to 10-fold increased water absorption capacity and diffusivity and the data are correlated with model calculations. Aged samples exhibited decreased crystallinity and melting temperature. Incorporation of NFC into PBS showed up to a 2.6-fold enhancement of the elastic modulus, although accompanied by a loss of strength by 40% and 8-fold reduction in the strain at failure of maximally loaded composites. Hydrothermal ageing had almost no influence on the tensile characteristics of PBS; however, there were considerable degradation effects in PBS/NFC composites. Altered reinforcement efficiency is manifested through a 3.7-fold decreased effective elastic moduli of NFC determined by applying the Halpin–Tsai model and a proportional reduction of the storage moduli of composites. The adhesion efficiency in composites was reduced by hydrothermal ageing, as measured Puckanszky’s adhesion parameter for the strength, which decreased from 3 to 0.8. For the loss factor, Kubat’s adhesion parameter was increased by an order. PBS filled with 20 wt.% NFC is identified as the most efficient composition, for which negative environmental degradation effects are counterbalanced with the positive reinforcement effect. The PBS matrix can be used to protect the NFC network from water. Full article

(This article belongs to the Special Issue Advances in Bio-Based and Biodegradable Polymeric Composites)

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14 pages, 4226 KiB

Open AccessArticle

Crystallization Behavior and Electrical Properties of Nanoparticle-Reinforced Poly(lactic Acid)-Based Films

by Mei-Xian Li, Yu Ren, Dasom Lee and Sung-Woong Choi

Polymers 2022, 14(1), 177; https://doi.org/10.3390/polym14010177 - 2 Jan 2022

Cited by 8 | Viewed by 2455

Abstract

Graphene oxide (GO) and multiwalled carbon nanotubes with silver particles (MWNT-Ag) of different concentrations were used as nanofillers to prepare poly(lactic acid) (PLA) nanoparticle films through the solvent casting method. In this study, the effects of nanoparticles on the crystallization behavior, relationships between [...] Read more.

Graphene oxide (GO) and multiwalled carbon nanotubes with silver particles (MWNT-Ag) of different concentrations were used as nanofillers to prepare poly(lactic acid) (PLA) nanoparticle films through the solvent casting method. In this study, the effects of nanoparticles on the crystallization behavior, relationships between the dispersion and electrical properties, and hydrolytic degradation behaviors were investigated for the PLA/MWNT-Ag and PLA/rGO films. Differential scanning calorimetry was used to evaluate the crystallization behaviors of the PLA/MWNT-Ag and PLA/reduced GO (rGO) films. Electron probe microanalysis was performed to characterize the dispersion of MWNT-Ag, and X-ray diffraction and Raman spectroscopy were used to determine the degree of dispersion of rGO in the PLA matrix. The results showed that nanoparticles enhanced the crystallization kinetics of PLA as well as the hydrolytic degradation rate. From the measurement of electrical properties, the electrical conductivity of PLA/MWNT-Ag 1.0 wt% was much higher than that of the pure PLA and PLA/rGO films, showing that MANT and Ag nanoparticles contribute greatly to enhancing the electrical conductivity of the PLA/MWNT-Ag films. Full article

(This article belongs to the Special Issue Advances in Bio-Based and Biodegradable Polymeric Composites)

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24 pages, 3472 KiB

Open AccessArticle

Biodegradation of Polylactic Acid-Based Bio Composites Reinforced with Chitosan and Essential Oils as Anti-Microbial Material for Food Packaging

by Teuku Rihayat, Agung Efriyo Hadi, Nurhanifa Aidy, Aida Safitri, Januar Parlaungan Siregar, Tezara Cionita, Agustinus Purna Irawan, Mohammad Hazim Mohamad Hamdan and Deni Fajar Fitriyana

Polymers 2021, 13(22), 4019; https://doi.org/10.3390/polym13224019 - 20 Nov 2021

Cited by 17 | Viewed by 4213

Abstract

This study aims to produce and investigate the potential of biodegradable Polylactic Acid (PLA)-based composites mixed with chitosan and Turmeric Essential Oil (TEO) as an anti-microbial biomaterial. PLA has good barrier properties for moisture, so it is suitable for use as a raw [...] Read more.

This study aims to produce and investigate the potential of biodegradable Polylactic Acid (PLA)-based composites mixed with chitosan and Turmeric Essential Oil (TEO) as an anti-microbial biomaterial. PLA has good barrier properties for moisture, so it is suitable for use as a raw material for making packaging and is included in the GRAS (Generally Recognized As Safe). Chitosan is a non-toxic and antibacterial cationic polysaccharide that needs to be improved in its ability to fight microbes. TEO must be added to increase antibacterial properties due to a large number of hydroxyl (-OH) and carbonyl functional groups. The samples were prepared in three different variations: 2 g of chitosan, 0 mL TEO and 0 mL glycerol (Biofilm 1), 3 g of chitosan, 0.3 mL TEO and 0.5 mL of glycerol (Biofilm 2), and 4 g of chitosan, 0.3 of TEO and 0.5 mL of glycerol (Biofilm 3). The final product was characterized by its functional group through Fourier transform infrared (FTIR); the functional groups contained by the addition of TEO are C-H, C=O, O-H, and N-H with the extraction method, and as indicated by the emergence of a wide band at 3503 cm⁻¹, turmeric essential oil interacts with the polymer matrix by creating intermolecular hydrogen bonds between their terminal hydroxyl group and the carbonyl groups of the ester moieties of both PLA and Chitosan. Thermogravimetric analysis (TGA) of PLA as biofilms, the maximum temperature of a biofilm was observed at 315.74 °C in the variation of 4 g chitosan, 0.3 mL TEO, and 0.5 mL glycerol (Biofilm 3). Morphological conditions analyzed under scanning electron microscopy (SEM) showed that the addition of TEO inside the chitosan interlayer bound chitosan molecules to produce solid particles. Chitosan and TEO showed increased anti-bacterial activity in the anti-microbial test. Furthermore, after 12 days of exposure to open areas, the biofilms generated were able to resist S. aureus and E. coli bacteria. Full article

(This article belongs to the Special Issue Advances in Bio-Based and Biodegradable Polymeric Composites)

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14 pages, 72970 KiB

Open AccessArticle

Electrospun Polymer-Fungicide Nanocomposites for Grapevine Protection

by Nasko Nachev, Mariya Spasova, Petya Tsekova, Nevena Manolova, Iliya Rashkov and Mladen Naydenov

Polymers 2021, 13(21), 3673; https://doi.org/10.3390/polym13213673 - 25 Oct 2021

Cited by 5 | Viewed by 2724

Abstract

Nowadays, diseases in plants are a worldwide problem. Fungi represent the largest number of plant pathogens and are responsible for a range of serious plant diseases. Esca is a grapevine disease caused mainly by fungal pathogens Phaeomoniella chlamydospora (P. chlamydospora) and [...] Read more.

Nowadays, diseases in plants are a worldwide problem. Fungi represent the largest number of plant pathogens and are responsible for a range of serious plant diseases. Esca is a grapevine disease caused mainly by fungal pathogens Phaeomoniella chlamydospora (P. chlamydospora) and Phaeoacremonium aleophilum (P. aleophilum). The currently proposed methods to fight esca are not curative. In this study, polymer composites based on biodegradable polymer containing chemical fungicides with antifungal activity were successfully prepared by electrospinning. The obtained materials were hydrophobic with good mechanical properties. In vitro studies demonstrated that the fungicide release was higher from PLLA/K5N8Q fibrous mats (ca. 72% for 50 h) compared to the released drug amount from PLLA/5-Cl8Q materials (ca. 52% for 50 h), which is due to the better water-solubility of the salt. The antifungal activity of the fibrous materials against P. chlamydospora and P. aleophilum was studied as well. The incorporation of the fungicide in the biodegradable fibers resulted in the inhibition of fungal growth. The obtained materials are perspective candidates for the protection of vines from the penetration and growth of fungal pathogens. Full article

(This article belongs to the Special Issue Advances in Bio-Based and Biodegradable Polymeric Composites)

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20 pages, 6177 KiB

Open AccessArticle

Chitosan/Poly Vinyl Alcohol/Graphene Oxide Based pH-Responsive Composite Hydrogel Films: Drug Release, Anti-Microbial and Cell Viability Studies

by Muhammad Umar Aslam Khan, Zahida Yaqoob, Mohamed Nainar Mohamed Ansari, Saiful Izwan Abd Razak, Mohsin Ali Raza, Amna Sajjad, Sajjad Haider and Fauzi Mh Busra

Polymers 2021, 13(18), 3124; https://doi.org/10.3390/polym13183124 - 16 Sep 2021

Cited by 72 | Viewed by 7457

Abstract

The composite hydrogels were produced using the solution casting method due to the non-toxic and biocompatible nature of chitosan (CS)/polyvinyl alcohol (PVA). The best composition was chosen and crosslinked with tetraethyl orthosilicate (TEOS), after which different amounts of graphene oxide (GO) were added [...] Read more.

The composite hydrogels were produced using the solution casting method due to the non-toxic and biocompatible nature of chitosan (CS)/polyvinyl alcohol (PVA). The best composition was chosen and crosslinked with tetraethyl orthosilicate (TEOS), after which different amounts of graphene oxide (GO) were added to develop composite hydrogels. Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), atomic force microscopy (AFM) and contact angle was used to analyze the hydrogels. The samples were also evaluated for swelling abilities in various mediums. The drug release profile was studied in phosphate-buffered saline (PBS) at a pH of 7.4. To predict the mechanism of drug release, the data were fitted into kinetic models. Finally, antibacterial activity and cell viability data were obtained. FTIR studies revealed the successful synthesis of CS/PVA hydrogels and GO/CS/PVA in hydrogel composite. SEM showed no phase separation of the polymers, whereas AFM showed a decrease in surface roughness with an increase in GO content. 100 µL of crosslinker was the critical concentration at which the sample displayed excellent swelling and preserved its structure. Both the crosslinked and composite hydrogel showed good swelling. The most acceptable mechanism of drug release is diffusion-controlled, and it obeys Fick’s law of diffusion for drug released. The best fitting of the zero-order, Hixson-Crowell and Higuchi models supported our assumption. The GO/CS/PVA hydrogel composite showed better antibacterial and cell viability behaviors. They can be better biomaterials in biomedical applications. Full article

(This article belongs to the Special Issue Advances in Bio-Based and Biodegradable Polymeric Composites)

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18 pages, 4774 KiB

Open AccessArticle

Polymerizable Choline- and Imidazolium-Based Ionic Liquids Reinforced with Bacterial Cellulose for 3D-Printing

by Michael A. Smirnov, Veronika S. Fedotova, Maria P. Sokolova, Alexandra L. Nikolaeva, Vladimir Yu. Elokhovsky and Mikko Karttunen

Polymers 2021, 13(18), 3044; https://doi.org/10.3390/polym13183044 - 9 Sep 2021

Cited by 20 | Viewed by 4144

Abstract

In this work, a novel approach is demonstrated for 3D-printing of bacterial cellulose (BC) reinforced UV-curable ion gels using two-component solvents based on 1-butyl-3-methylimidazolium chloride or choline chloride combined with acrylic acid. Preservation of cellulose’s crystalline and nanofibrous structure is demonstrated using wide-angle [...] Read more.

In this work, a novel approach is demonstrated for 3D-printing of bacterial cellulose (BC) reinforced UV-curable ion gels using two-component solvents based on 1-butyl-3-methylimidazolium chloride or choline chloride combined with acrylic acid. Preservation of cellulose’s crystalline and nanofibrous structure is demonstrated using wide-angle X-ray diffraction (WAXD) and atomic force microscopy (AFM). Rheological measurements reveal that cholinium-based systems, in comparison with imidazolium-based ones, are characterised with lower viscosity at low shear rates and improved stability against phase separation at high shear rates. Grafting of poly(acrylic acid) onto the surfaces of cellulose nanofibers during UV-induced polymerization of acrylic acid results in higher elongation at break for choline chloride-based compositions: 175% in comparison with 94% for imidazolium-based systems as well as enhanced mechanical properties in compression mode. As a result, cholinium-based BC ion gels containing acrylic acid can be considered as more suitable for 3D-printing of objects with improved mechanical properties due to increased dispersion stability and filler/matrix interaction. Full article

(This article belongs to the Special Issue Advances in Bio-Based and Biodegradable Polymeric Composites)

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24 pages, 4594 KiB

Open AccessArticle

Barrier Properties and Hydrophobicity of Biodegradable Poly(lactic acid) Composites Reinforced with Recycled Chinese Spirits Distiller’s Grains

by Zhi-Jun Chen, Chi-Hui Tsou, Meng-Lin Tsai, Jipeng Guo, Manuel Reyes De Guzman, Tao Yang, Chen Gao, Yan Lei, Pei-Wen Gan, Shuang Chen, Lian-Jie Tu, Chang-Lei Qu, Ruo-Yao Wang and Chin-San Wu

Polymers 2021, 13(17), 2861; https://doi.org/10.3390/polym13172861 - 26 Aug 2021

Cited by 16 | Viewed by 2414

Abstract

Adding natural biomass to poly(lactic acid) (PLA) as a reinforcing filler is a way to change the properties of PLA. This paper is about preparing PLA/biomass composites by physically melting and blending Chinese Spirits distiller’s grains (CSDG) biomass and PLA to optimize the [...] Read more.

Adding natural biomass to poly(lactic acid) (PLA) as a reinforcing filler is a way to change the properties of PLA. This paper is about preparing PLA/biomass composites by physically melting and blending Chinese Spirits distiller’s grains (CSDG) biomass and PLA to optimize the composite performance. Composites of modified PLA (MPLA) with varying amounts of CSDG were also prepared by the melt-mixing method, and unmodified PLA/CSDG composites were used as a control group for comparative analysis. The functional groups of MPLA enhanced the compatibility between the polymer substrate and CSDG. The composite water vapor/oxygen barrier and mechanical properties were studied. It was found that the barrier and mechanical properties of MPLA/CSDG composites were significantly improved. SEM was adopted to examine the tensile section structure of the composites, and the compatibility between the filler and the matrix was analyzed. An appropriate amount of CSDG had a better dispersibility in the matrix, and it further improved the interfacial bonding force, which in turn improved the composite mechanical properties. X-ray diffraction, thermogravimetric analysis, and differential scanning calorimetry were conducted to determine the crystalline properties and to analyze the stability of the composites. It was found that the CSDG content had a significant effect on the crystallinity. Barrier and biodegradation mechanisms were also discussed. Full article

(This article belongs to the Special Issue Advances in Bio-Based and Biodegradable Polymeric Composites)

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17 pages, 5523 KiB

Open AccessArticle

Aminated Graphene-Graft-Oligo(Glutamic Acid) /Poly(ε-Caprolactone) Composites: Preparation, Characterization and Biological Evaluation

by Mariia Stepanova, Olga Solomakha, Maxim Rabchinskii, Ilia Averianov, Iosif Gofman, Yuliya Nashchekina, Grigorii Antonov, Aleksey Smirnov, Boris Ber, Aleksey Nashchekin and Evgenia Korzhikova-Vlakh

Polymers 2021, 13(16), 2628; https://doi.org/10.3390/polym13162628 - 7 Aug 2021

Cited by 10 | Viewed by 2500

Abstract

Biodegradable and biocompatible composites are of great interest as biomedical materials for various regeneration processes such as the regeneration of bones, cartilage and soft tissues. Modification of the filler surface can improve its compatibility with the polymer matrix, and, as a result, the [...] Read more.

Biodegradable and biocompatible composites are of great interest as biomedical materials for various regeneration processes such as the regeneration of bones, cartilage and soft tissues. Modification of the filler surface can improve its compatibility with the polymer matrix, and, as a result, the characteristics and properties of composite materials. This work is devoted to the synthesis and modification of aminated graphene with oligomers of glutamic acid and their use for the preparation of composite materials based on poly(ε-caprolactone). Ring-opening polymerization of N-carboxyanhydride of glutamic acid γ-benzyl ester was used to graft oligomers of glutamic acid from the surface of aminated graphene. The success of the modification was confirmed by Fourier-transform infrared and X-ray photoelectron spectroscopy as well as thermogravimetric analysis. In addition, the dispersions of neat and modified aminated graphene were analyzed by dynamic and electrophoretic light scattering to monitor changes in the characteristics due to modification. The poly(ε-caprolactone) films filled with neat and modified aminated graphene were manufactured and carefully characterized for their mechanical and biological properties. Grafting of glutamic acid oligomers from the surface of aminated graphene improved the distribution of the filler in the polymer matrix that, in turn, positively affected the mechanical properties of composite materials in comparison to ones containing the unmodified filler. Moreover, the modification improved the biocompatibility of the filler with human MG-63 osteoblast-like cells. Full article

(This article belongs to the Special Issue Advances in Bio-Based and Biodegradable Polymeric Composites)

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22 pages, 7199 KiB

Open AccessArticle

Biomimetic Hierarchical Structuring of PLA by Ultra-Short Laser Pulses for Processing of Tissue Engineered Matrices: Study of Cellular and Antibacterial Behavior

by Albena Daskalova, Liliya Angelova, Emil Filipov, Dante Aceti, Rosica Mincheva, Xavier Carrete, Halima Kerdjoudj, Marie Dubus, Julie Chevrier, Anton Trifonov and Ivan Buchvarov

Polymers 2021, 13(15), 2577; https://doi.org/10.3390/polym13152577 - 3 Aug 2021

Cited by 14 | Viewed by 3328

Abstract

The influence of ultra-short laser modification on the surface morphology and possible chemical alteration of poly-lactic acid (PLA) matrix in respect to the optimization of cellular and antibacterial behavior were investigated in this study. Scanning electron microscopy (SEM) morphological examination of the processed [...] Read more.

The influence of ultra-short laser modification on the surface morphology and possible chemical alteration of poly-lactic acid (PLA) matrix in respect to the optimization of cellular and antibacterial behavior were investigated in this study. Scanning electron microscopy (SEM) morphological examination of the processed PLA surface showed the formation of diverse hierarchical surface microstructures, generated by irradiation with a range of laser fluences (F) and scanning velocities (V) values. By controlling the laser parameters, diverse surface roughness can be achieved, thus influencing cellular dynamics. This surface feedback can be applied to finely tune and control diverse biomaterial surface properties like wettability, reflectivity, and biomimetics. The triggering of thermal effects, leading to the ejection of material with subsequent solidification and formation of raised rims and 3D-like hollow structures along the processed zones, demonstrated a direct correlation to the wettability of the PLA. A transition from superhydrophobic (θ > 150°) to super hydrophilic (θ < 20°) surfaces can be achieved by the creation of grooves with V = 0.6 mm/s, F = 1.7 J/cm². The achieved hierarchical architecture affected morphology and thickness of the processed samples which were linked to the nature of ultra-short laser-material interaction effects, namely the precipitation of temperature distribution during material processing can be strongly minimized with ultrashort pulses leading to non-thermal and spatially localized effects that can facilitate volume ablation without collateral thermal damage The obtained modification zones were analyzed employing Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), Energy dispersive X-ray analysis (EDX), and optical profilometer. The modification of the PLA surface resulted in an increased roughness value for treatment with lower velocities (V = 0.6 mm/s). Thus, the substrate gains a 3D-like architecture and forms a natural matrix by microprocessing with V = 0.6 mm/s, F = 1.7 J/cm², and V = 3.8 mm/s, F = 0.8 J/cm². The tests performed with Mesenchymal stem cells (MSCs) demonstrated that the ultra-short laser surface modification altered the cell orientation and promoted cell growth. The topographical design was tested also for the effectiveness of bacterial attachment concerning chosen parameters for the creation of an array with defined geometrical patterns. Full article

(This article belongs to the Special Issue Advances in Bio-Based and Biodegradable Polymeric Composites)

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12 pages, 1796 KiB

Open AccessArticle

Improvement of the UV Barrier and Antibacterial Properties of Crosslinked Pectin/Zinc Oxide Bionanocomposite Films

by Karina Dyasti Hari, Coralia V. Garcia, Gye-Hwa Shin and Jun-Tae Kim

Polymers 2021, 13(15), 2403; https://doi.org/10.3390/polym13152403 - 22 Jul 2021

Cited by 41 | Viewed by 4126

Abstract

Pectin-based antibacterial bionanocomposite films were prepared by crosslinking with calcium chloride (CaCl₂) and mixing with zinc oxide nanoparticles (ZnO-NPs) at various concentrations (0.5%, 1%, and 1.5% w/w, based on pectin). Crosslinking with 1% CaCl₂ significantly (p < 0.05) [...] Read more.

Pectin-based antibacterial bionanocomposite films were prepared by crosslinking with calcium chloride (CaCl₂) and mixing with zinc oxide nanoparticles (ZnO-NPs) at various concentrations (0.5%, 1%, and 1.5% w/w, based on pectin). Crosslinking with 1% CaCl₂ significantly (p < 0.05) improved the tensile strength of the pectin films, although their elongation at break was decreased. The UV-light barrier property of the pectin/ZnO bionanocomposite films was significantly (p < 0.05) improved with increasing ZnO-NP concentrations. In addition, the bionanocomposite films incorporating 1.5% ZnO-NPs showed excellent antibacterial effects against both Escherichia coli and Staphylococcus aureus, inhibiting over 99% of the bacteria. Therefore, the developed crosslinked pectin/ZnO bionanocomposite films show great potential as active packaging materials with excellent UV-blocking and antibacterial properties. Full article

(This article belongs to the Special Issue Advances in Bio-Based and Biodegradable Polymeric Composites)

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11 pages, 3937 KiB

Open AccessArticle

Characterization of Chitosan Extracted from Fish Scales of the Colombian Endemic Species Prochilodus magdalenae as a Novel Source for Antibacterial Starch-Based Films

by Carlos Molina-Ramírez, Paulina Mazo, Robin Zuluaga, Piedad Gañán and Juan Álvarez-Caballero

Polymers 2021, 13(13), 2079; https://doi.org/10.3390/polym13132079 - 24 Jun 2021

Cited by 23 | Viewed by 4350

Abstract

Scales of Prochilodus magdalenae, a Colombian endemic fish species, were used to obtain chitosan for application as an antibacterial agent integrated into starch-based films. Analysis of its composition during the demineralization and deproteinization process indicated that minerals and protein were both removed [...] Read more.

Scales of Prochilodus magdalenae, a Colombian endemic fish species, were used to obtain chitosan for application as an antibacterial agent integrated into starch-based films. Analysis of its composition during the demineralization and deproteinization process indicated that minerals and protein were both removed successfully. At this point, mild conditions for the deacetylation process were employed, namely, 2, 4, and 6 wt.% NaOH at room temperature for 16 h. Chitosan processed under 2 wt.% NaOH had low molecular weight, with the lowest value of 107.18 ± 24.99 kDa, which was closely related to its antibacterial activity. Finally, this chitosan was integrated into a banana starch-based film, and its antibacterial activity was assayed in Escherichia coli and Staphylococcus aureus cultures, with positive results in the former culture, especially due to the low-molecular-weight characteristic of chitosan. Full article

(This article belongs to the Special Issue Advances in Bio-Based and Biodegradable Polymeric Composites)

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16 pages, 2232 KiB

Open AccessArticle

Preparation of a Dmap-Catalysis Lignin Epoxide and the Study of Its High Mechanical-Strength Epoxy Resins with High-Biomass Content

by Lingxia Song, Yeyun Meng, Peng Lv, Weiqu Liu and Hao Pang

Polymers 2021, 13(5), 750; https://doi.org/10.3390/polym13050750 - 28 Feb 2021

Cited by 8 | Viewed by 3056

Abstract

The depletion of limited petroleum resources used for the fabrication of epoxy resins calls for the development of biomass-based epoxides as promising alternatives to petroleum-derived epoxides. However, it is challenging to obtain an epoxy resin with both high lignin content and excellent mechanical [...] Read more.

The depletion of limited petroleum resources used for the fabrication of epoxy resins calls for the development of biomass-based epoxides as promising alternatives to petroleum-derived epoxides. However, it is challenging to obtain an epoxy resin with both high lignin content and excellent mechanical performance. Herein, a 4-dimethylaminopyridine (DMAP)-lignin epoxide with a certain epoxy value and a small molecular weight is obtained by the catalysis of DMAP for the macromolecular lignin. It was discovered that compared to the prepared composite resin of benzyltriethylammonium chloride (BTEAC)-lignin epoxide, there is a better low-temperature storage modulus for the DMAP-lignin epoxide resin and its composite resins with high-biomass contents, and higher tensile strength for its composite resins. In particular, the DMAP-lignin epoxide/ bisphenol A diglycidyl ether (BADGE) (DB) composite resin with DMAP-lignin epoxide replacement of 80 wt% BADGE, containing up to 58.0 wt% the lignin epoxide, exhibits the tensile strength of 76.3 ± 3.2 MPa. Its tensile strength is 110.2% of BTEAC-lignin epoxide/BADGE (BB) composite resins and is comparable to that of petroleum-based epoxy resins. There are good application prospects for the DB composite resin in the engineering plastics, functional composite, grouting, and other fields. Full article

(This article belongs to the Special Issue Advances in Bio-Based and Biodegradable Polymeric Composites)

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Review

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55 pages, 64781 KiB

Open AccessReview

Modification of Cellulose Micro- and Nanomaterials to Improve Properties of Aliphatic Polyesters/Cellulose Composites: A Review

by Mariia Stepanova and Evgenia Korzhikova-Vlakh

Polymers 2022, 14(7), 1477; https://doi.org/10.3390/polym14071477 - 5 Apr 2022

Cited by 47 | Viewed by 5826

Abstract

Aliphatic polyesters/cellulose composites have attracted a lot attention due to the perspectives of their application in biomedicine and the production of disposable materials, food packaging, etc. Both aliphatic polyesters and cellulose are biocompatible and biodegradable polymers, which makes them highly promising for the [...] Read more.

Aliphatic polyesters/cellulose composites have attracted a lot attention due to the perspectives of their application in biomedicine and the production of disposable materials, food packaging, etc. Both aliphatic polyesters and cellulose are biocompatible and biodegradable polymers, which makes them highly promising for the production of “green” composite materials. However, the main challenge in obtaining composites with favorable properties is the poor compatibility of these polymers. Unlike cellulose, which is very hydrophilic, aliphatic polyesters exhibit strong hydrophobic properties. In recent times, the modification of cellulose micro- and nanomaterials is widely considered as a tool to enhance interfacial biocompatibility with aliphatic polyesters and, consequently, improve the properties of composites. This review summarizes the main types and properties of cellulose micro- and nanomaterials as well as aliphatic polyesters used to produce composites with cellulose. In addition, the methods for noncovalent and covalent modification of cellulose materials with small molecules, polymers and nanoparticles have been comprehensively overviewed and discussed. Composite fabrication techniques, as well as the effect of cellulose modification on the mechanical and thermal properties, rate of degradation, and biological compatibility have been also analyzed. Full article

(This article belongs to the Special Issue Advances in Bio-Based and Biodegradable Polymeric Composites)

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29 pages, 12757 KiB

Open AccessReview

A Review on Antimicrobial Packaging from Biodegradable Polymer Composites

by Siti Hasnah Kamarudin, Marwah Rayung, Falah Abu, So’bah Ahmad, Fatirah Fadil, Azrena Abdul Karim, Mohd Nurazzi Norizan, Norshahida Sarifuddin, Mohd Shaiful Zaidi Mat Desa, Mohd Salahuddin Mohd Basri, Hayati Samsudin and Luqman Chuah Abdullah

Polymers 2022, 14(1), 174; https://doi.org/10.3390/polym14010174 - 2 Jan 2022

Cited by 66 | Viewed by 7292

Abstract

The development of antimicrobial packaging has been growing rapidly due to an increase in awareness and demands for sustainable active packaging that could preserve the quality and prolong the shelf life of foods and products. The addition of highly efficient antibacterial nanoparticles, antifungals, [...] Read more.

The development of antimicrobial packaging has been growing rapidly due to an increase in awareness and demands for sustainable active packaging that could preserve the quality and prolong the shelf life of foods and products. The addition of highly efficient antibacterial nanoparticles, antifungals, and antioxidants to biodegradable and environmentally friendly green polymers has become a significant advancement trend for the packaging evolution. Impregnation of antimicrobial agents into the packaging film is essential for impeding or destroying the pathogenic microorganisms causing food illness and deterioration. Higher safety and quality as well as an extended shelf life of sustainable active packaging desired by the industry are further enhanced by applying the different types of antimicrobial packaging systems. Antimicrobial packaging not only can offer a wide range of advantages, but also preserves the environment through usage of renewable and biodegradable polymers instead of common synthetic polymers, thus reducing plastic pollution generated by humankind. This review intended to provide a summary of current trends and applications of antimicrobial, biodegradable films in the packaging industry as well as the innovation of nanotechnology to increase efficiency of novel, bio-based packaging systems. Full article

(This article belongs to the Special Issue Advances in Bio-Based and Biodegradable Polymeric Composites)

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20 pages, 2710 KiB

Open AccessReview

Waste Natural Polymers as Potential Fillers for Biodegradable Latex-Based Composites: A Review

by D. N. Syuhada and A. R. Azura

Polymers 2021, 13(20), 3600; https://doi.org/10.3390/polym13203600 - 19 Oct 2021

Cited by 17 | Viewed by 3757

Abstract

In recent years, biodegradable composites have become important in various fields because of the increasing awareness of the global environment. Waste natural polymers have received much attention as renewable, biodegradable, non-toxic and low-cost filler in polymer composites. In order to exploit the high [...] Read more.

In recent years, biodegradable composites have become important in various fields because of the increasing awareness of the global environment. Waste natural polymers have received much attention as renewable, biodegradable, non-toxic and low-cost filler in polymer composites. In order to exploit the high potential for residual natural loading in latex composites, different types of surface modification techniques have been applied. This review discusses the preparation and characterization of the modified waste natural fillers for latex-based composites. The potency of the waste natural filler for the latex-based composites was explored with a focus on the mechanical, thermal, biodegradability and filler–latex interaction. This review also offers an update on the possible application of the waste natural filler towards the biodegradability of the latex-based composites for a more sustainable future. Full article

(This article belongs to the Special Issue Advances in Bio-Based and Biodegradable Polymeric Composites)

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26 pages, 4117 KiB

Open AccessReview

Advocating Electrically Conductive Scaffolds with Low Immunogenicity for Biomedical Applications: A Review

by Dania Adila Ahmad Ruzaidi, Mohd Muzamir Mahat, Saiful Arifin Shafiee, Zarif Mohamed Sofian, Awis Sukarni Mohmad Sabere, Rosmamuhamadani Ramli, Hazwanee Osman, Hairul Hisham Hamzah, Zaidah Zainal Ariffin and Kishor Kumar Sadasivuni

Polymers 2021, 13(19), 3395; https://doi.org/10.3390/polym13193395 - 2 Oct 2021

Cited by 16 | Viewed by 3490

Abstract

Scaffolds support and promote the formation of new functional tissues through cellular interactions with living cells. Various types of scaffolds have found their way into biomedical science, particularly in tissue engineering. Scaffolds with a superior tissue regenerative capacity must be biocompatible and biodegradable, [...] Read more.

Scaffolds support and promote the formation of new functional tissues through cellular interactions with living cells. Various types of scaffolds have found their way into biomedical science, particularly in tissue engineering. Scaffolds with a superior tissue regenerative capacity must be biocompatible and biodegradable, and must possess excellent functionality and bioactivity. The different polymers that are used in fabricating scaffolds can influence these parameters. Polysaccharide-based polymers, such as collagen and chitosan, exhibit exceptional biocompatibility and biodegradability, while the degradability of synthetic polymers can be improved using chemical modifications. However, these modifications require multiple steps of chemical reactions to be carried out, which could potentially compromise the end product’s biosafety. At present, conducting polymers, such as poly(3,4-ethylenedioxythiophene) poly(4-styrenesulfonate) (PEDOT: PSS), polyaniline, and polypyrrole, are often incorporated into matrix scaffolds to produce electrically conductive scaffold composites. However, this will reduce the biodegradability rate of scaffolds and, therefore, agitate their biocompatibility. This article discusses the current trends in fabricating electrically conductive scaffolds, and provides some insight regarding how their immunogenicity performance can be interlinked with their physical and biodegradability properties. Full article

(This article belongs to the Special Issue Advances in Bio-Based and Biodegradable Polymeric Composites)

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41 pages, 7508 KiB

Open AccessReview

Polyaniline/Biopolymer Composite Systems for Humidity Sensor Applications: A Review

by Yuriy A. Anisimov, Richard W. Evitts, Duncan E. Cree and Lee D. Wilson

Polymers 2021, 13(16), 2722; https://doi.org/10.3390/polym13162722 - 14 Aug 2021

Cited by 37 | Viewed by 6001

Abstract

The development of polyaniline (PANI)/biomaterial composites as humidity sensor materials represents an emerging area of advanced materials with promising applications. The increasing attention to biopolymer materials as desiccants for humidity sensor components can be explained by their sustainability and propensity to absorb water. [...] Read more.

The development of polyaniline (PANI)/biomaterial composites as humidity sensor materials represents an emerging area of advanced materials with promising applications. The increasing attention to biopolymer materials as desiccants for humidity sensor components can be explained by their sustainability and propensity to absorb water. This review represents a literature survey, covering the last decade, which is focused on the interrelationship between the core properties and moisture responsiveness of multicomponent polymer/biomaterial composites. This contribution provides an overview of humidity-sensing materials and the corresponding sensors that emphasize the resistive (impedance) type of PANI devices. The key physicochemical properties that affect moisture sensitivity include the following: swelling, water vapor adsorption capacity, porosity, electrical conductivity, and enthalpies of adsorption and vaporization. Some key features of humidity-sensing materials involve the response time, recovery time, and hysteresis error. This work presents a discussion on various types of humidity-responsive composite materials that contain PANI and biopolymers, such as cellulose, chitosan and structurally related systems, along with a brief overview of carbonaceous and ceramic materials. The effect of additive components, such as polyvinyl alcohol (PVA), for film fabrication and their adsorption properties are also discussed. The mechanisms of hydration and proton transfer, as well as the relationship with conductivity is discussed. The literature survey on hydration reveals that the textural properties (surface area and pore structure) of a material, along with the hydrophile–lipophile balance (HLB) play a crucial role. The role of HLB is important in PANI/biopolymer materials for understanding hydration phenomena and hydrophobic effects. Fundamental aspects of hydration studies that are relevant to humidity sensor materials are reviewed. The experimental design of humidity sensor materials is described, and their relevant physicochemical characterization methods are covered, along with some perspectives on future directions in research on PANI-based humidity sensors. Full article

(This article belongs to the Special Issue Advances in Bio-Based and Biodegradable Polymeric Composites)

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19 pages, 1335 KiB

Open AccessReview

Recent Progress of Rice Husk Reinforced Polymer Composites: A Review

by Mohamed Azlan Suhot, Mohamad Zaki Hassan, Sa’ardin Abdul Aziz and Mohd Yusof Md Daud

Polymers 2021, 13(15), 2391; https://doi.org/10.3390/polym13152391 - 21 Jul 2021

Cited by 52 | Viewed by 9993

Abstract

Recently, because of the rising population, carbon overloading, and environmental distress, human beings have needed to increase awareness and responsibility for the reduction of agricultural waste. The utilization of agricultural waste as a filler material in reinforced polymers is a fascinating discovery. This [...] Read more.

Recently, because of the rising population, carbon overloading, and environmental distress, human beings have needed to increase awareness and responsibility for the reduction of agricultural waste. The utilization of agricultural waste as a filler material in reinforced polymers is a fascinating discovery. This review paper attempts to study the physical, mechanical, and thermal behavior of rice husk (RH) as a fiber for reinforcing various synthetic polymers, based on recent studies, conducted between 2017 and 2021. It also highlights that advanced modification techniques could further improve the performance of composites by tailoring the physical and chemical substances of the fiber or matrix. The thermal properties, including flame-retardance and thermal behavior, are also discussed. The characteristics of the fiber–matrix interaction between RH and the polymer matrix provide essential insights into the future-ready applications of this agricultural waste fiber. The way forward in researching RH polymer composites is finally reviewed. Full article

(This article belongs to the Special Issue Advances in Bio-Based and Biodegradable Polymeric Composites)

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