Synthesis, Characterization and Applications of Natural Polymers

A special issue of Polymers (ISSN 2073-4360). This special issue belongs to the section "Biomacromolecules, Biobased and Biodegradable Polymers".

Deadline for manuscript submissions: 5 August 2024 | Viewed by 5624

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Faculty of Agricultural Sciences, São Paulo State University (UNESP), Botucatu 18610-034, Brazil
Interests: foods science and technology
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Faculty of Engineering, Federal University of Grande Dourados, Dourados, Brazil
Interests: biopolymers; biodegradable polymers; blends and polymer composites

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Department of Materials Science and Engineering, Universitat Politècnica de Catalunya (UPC BarcelonaTech), 08222 Terrassa, Spain
Interests: edible packaging; edible coatings; food packaging; starch
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Special Issue Information

Dear Colleagues,

This Special Issue of Polymers on the “Synthesis, Characterization, and Applications of Natural Polymers” is dedicated to the dissemination of relevant research articles that demonstrate advances in the area in this broad field. The production, characterization, and use of natural polymers have increased in recent years, and they are widely used in various fields of the pharmaceutical, food, medical, and cosmetic industries and in everyday life. To obtain these polymers, several modifications are carried out, to obtain the desired properties, in addition to being considered from renewable sources. It is my pleasure to invite you to submit your manuscript and contribute significantly to this edition.

Prof. Dr. Vitor Augusto dos Santos Garcia
Dr. Silvia Maria Martelli
Prof. Dr. Farayde Matta Fakhouri
Guest Editors

Manuscript Submission Information

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

Keywords

  • natural polymers
  • applications
  • polymer synthesis
  • films
  • delivery system
  • oral films

Published Papers (4 papers)

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Research

22 pages, 5929 KiB  
Article
Development of Polylactic Acid Films with Alkali- and Acetylation-Treated Flax and Hemp Fillers via Solution Casting Technique
by Anamol Pokharel, Kehinde James Falua, Amin Babaei-Ghazvini, Mostafa Nikkhah Dafchahi, Lope G. Tabil, Venkatesh Meda and Bishnu Acharya
Polymers 2024, 16(7), 996; https://doi.org/10.3390/polym16070996 - 05 Apr 2024
Viewed by 354
Abstract
This study aims to enhance value addition to agricultural byproducts to produce composites by the solution casting technique. It is well known that PLA is moisture-sensitive and deforms at high temperatures, which limits its use in some applications. When blending with plant-based fibers, [...] Read more.
This study aims to enhance value addition to agricultural byproducts to produce composites by the solution casting technique. It is well known that PLA is moisture-sensitive and deforms at high temperatures, which limits its use in some applications. When blending with plant-based fibers, the weak point is the poor filler–matrix interface. For this reason, surface modification was carried out on hemp and flax fibers via acetylation and alkaline treatments. The fibers were milled to obtain two particle sizes of <75 μm and 149–210 μm and were blended with poly (lactic) acid at different loadings (0, 2.5%, 5%, 10%, 20%, and 30%) to form a composite film The films were characterized for their spectroscopy, physical, and mechanical properties. All the film specimens showed C–O/O–H groups and the π–π interaction in untreated flax fillers showed lignin phenolic rings in the films. It was noticed that the maximum degradation temperature occurred at 362.5 °C. The highest WVPs for untreated, alkali-treated, and acetylation-treated composites were 20 × 10−7 g·m/m2 Pa·s (PLA/hemp30), 7.0 × 10−7 g·m/m2 Pa·s (PLA/hemp30), and 22 × 10−7 g·m/m2 Pa·s (PLA/hemp30), respectively. Increasing the filler content caused an increase in the color difference of the composite film compared with that of the neat PLA. Alkali-treated PLA/flax composites showed significant improvement in their tensile strength, elongation at break, and Young’s modulus at a 2.5 or 5% filler loading. An increase in the filler loadings caused a significant increase in the moisture absorbed, whereas the water contact angle decreased with an increasing filler concentration. Flax- and hemp-induced PLA-based composite films with 5 wt.% loadings showed a more stable compromise in all the examined properties and are expected to provide unique industrial applications with satisfactory performance. Full article
(This article belongs to the Special Issue Synthesis, Characterization and Applications of Natural Polymers)
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21 pages, 5304 KiB  
Article
Influence of Alkali Treatment of Jatropha Curcas L. Filler on the Service Life of Hybrid Adhesive Bonds under Low Cycle Loading
by Viktor Kolář, Petr Hrabě, Miroslav Müller, Monika Hromasová, David Herák and Hadi Sutanto
Polymers 2023, 15(2), 395; https://doi.org/10.3390/polym15020395 - 12 Jan 2023
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Abstract
The aim of this research was to evaluate the effect of untreated and 5% aqueous NaOH solution-treated filler of the plant Jatropha Curcas L. on the mechanical properties of adhesive bonds, especially in terms of their service life at different amplitudes of cyclic [...] Read more.
The aim of this research was to evaluate the effect of untreated and 5% aqueous NaOH solution-treated filler of the plant Jatropha Curcas L. on the mechanical properties of adhesive bonds, especially in terms of their service life at different amplitudes of cyclic loading. As a result of the presence of phorbol ester, which is toxic, Jatropha oilseed cake cannot be used as livestock feed. The secondary aim was to find other possibilities for the utilization of natural waste materials. Another use is as a filler in polymer composites, that is, in composite adhesive layers. The cyclic loading of the adhesive bonds was carried out for 1000 cycles in two amplitudes, that is, 5–30% of the maximum force and 5–50% of the maximum force, which was obtained by the static tensile testing of the adhesive bonds with unmodified filler. The static tensile test showed an increase in the shear strength of the adhesive bonds with alkali-treated filler compared to the untreated filler by 3–41%. The cyclic test results did not show a statistically significant effect of the alkaline treatment of the filler surface on the service life of the adhesive bonds. Positive changes in the strain value between adhesive bonds with treated and untreated filler were demonstrated at cyclic stress amplitudes of 5–50%. SEM analysis showed the presence of interlayer defects in the layers of the tested materials, which are related to the oil-based filler used. Full article
(This article belongs to the Special Issue Synthesis, Characterization and Applications of Natural Polymers)
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12 pages, 4332 KiB  
Article
Comparison of the Degree of Acetylation of Chitin Nanocrystals Measured by Various Analysis Methods
by Murat Yanat, Ivanna Colijn, Kieke de Boer and Karin Schroën
Polymers 2023, 15(2), 294; https://doi.org/10.3390/polym15020294 - 06 Jan 2023
Cited by 5 | Viewed by 1937
Abstract
Chitin and its derivate chitosan have versatile properties and have been used in various applications. One key parameter determining the functionality of chitin-based materials is the degree of acetylation (DA). For DA determination, NMR and FTIR spectroscopy are often considered to be the [...] Read more.
Chitin and its derivate chitosan have versatile properties and have been used in various applications. One key parameter determining the functionality of chitin-based materials is the degree of acetylation (DA). For DA determination, NMR and FTIR spectroscopy are often considered to be the gold standard, but these techniques may not always be available and are rather time-consuming and costly. The first derivative UV method has been suggested, although accurate measurements can be challenging for materials with high degrees of acetylation, due to hydroxymethylfurfural (HMF) formation and other side reactions occurring. In this paper, we re-evaluated the first derivate UV method for chitin and chitosan powder, chitin nanocrystals, and deacetylated chitin nanocrystals. Our results showed that the first derivative UV method is capable of measuring DA with high accuracy (>0.9), leading to values comparable to those obtained by 1H NMR, 13C NMR, and FTIR. Moreover, by-product formation could either be suppressed by selecting the proper experimental conditions, or be compensated. For chitin nanocrystals, DA calculation deviations up to 20% due to by-product formation can be avoided with the correction that we propose. We conclude that the first derivative UV method is an accessible method for DA quantification, provided that sample solubility is warranted. Full article
(This article belongs to the Special Issue Synthesis, Characterization and Applications of Natural Polymers)
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10 pages, 2585 KiB  
Article
Assessment of Acute Oral Toxicity of Thiolated Gum Ghatti in Rats
by Vivek Puri, Ameya Sharma, Pradeep Kumar, Kamal Dua, Kampanart Huanbutta, Inderbir Singh and Tanikan Sangnim
Polymers 2022, 14(18), 3836; https://doi.org/10.3390/polym14183836 - 14 Sep 2022
Cited by 2 | Viewed by 1538
Abstract
Various drug delivery systems were developed using a modified form of gum ghatti. Modifying gum ghatti using thioglycolic acid improves its mucoadhesive property, and hence, it is a suitable approach for the fabrication and development of controlled drug delivery systems. In accordance with [...] Read more.
Various drug delivery systems were developed using a modified form of gum ghatti. Modifying gum ghatti using thioglycolic acid improves its mucoadhesive property, and hence, it is a suitable approach for the fabrication and development of controlled drug delivery systems. In accordance with regulatory guidelines, namely, the Organization for Economic Co-operation and Development’s (OECD) 423 guidelines, an acute oral dose toxicity study was performed to examine the toxicological effects of gum ghattiin an animal (Wistar rat) after a single oral dose administration of pure gum ghatti and thiolated gum ghatti. Orally administered pure and thiolated gum ghatti do not reveal any considerable change in the behavioral pattern, food intake, body weight, hematology, or clinical symptoms of treated animals. Furthermore, histopathological studies showed no pathological mutations in the vital organs of Wistar rats after the oral administration of single doses of both types of gumghatti (i.e., 300 mg/kg and 2000 mg/kg body weight). Whole blood clotting studies showed the low absorbance value of the modified gum (thiolated gum ghatti) in contrast to the pure gum and control, hence demonstrating its excellent clotting capability. The aforementioned toxicological study suggested that the oral administration of a single dose of pure and thiolated gum ghatti did not produce any toxicological effects in Wistar rats. Consequently, it could be a suitable and safe candidate for formulating various drug delivery systems. Full article
(This article belongs to the Special Issue Synthesis, Characterization and Applications of Natural Polymers)
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