E-Mail Alert

Add your e-mail address to receive forthcoming issues of this journal:

Journal Browser

Journal Browser

Special Issue "Synthesis and Applications of Biopolymer Composites"

A special issue of International Journal of Molecular Sciences (ISSN 1422-0067). This special issue belongs to the section "Materials Science".

Deadline for manuscript submissions: closed (26 November 2018)

Special Issue Editors

Guest Editor
Prof. Dr. Ana María Díez-Pascual

Analytical Chemistry, Physical Chemistry and Chemical Engineering Department, Faculty of Sciences, Alcalá University, Alcalá de Henares, Spain
Website | E-Mail
Interests: nanomaterials; polymers; nanocomposites; inorganic nanoparticles; antibacterial agents; surfactants; interphases
Guest Editor
Prof. Patrizia Cinelli

Universita di Pisa, Department of Civil and Industrial Engineering, Pisa University, Largo Lucio Lazzarino 1, 56122, Pisa, Italy
E-Mail
Interests: biodegradable polymers, sustainability, biobased, composites, nanocomposites

Special Issue Information

Dear Colleagues,

In recent years, a great deal of attention has been focused on research to replace petroleum-based commodity plastics with biodegradable and biocompatible polymers in a cost-effective manner. However, biopolymers generally present poor mechanical properties, limited processing capability and end-use application. In order to overcome these issues, and develop advanced materials for a wide range of applications, biopolymers can be reinforced with fillers or nanofillers. The nanostructures exhibit higher specific surface area, surface energy and density compared to conventional microfillers, and lead to materials with new and improved properties, hence are advantageous from an application viewpoint.

This Special Issue is planned to bring together a number of original papers and reviews covering (but not restricted to) the following topics:

  • Novel fabrication methods of biopolymer-based composites
  • Structure-property relationships in biopolymer composites
  • Properties of natural polymers, biopolymers, their blends and composites (mechanical, thermal, electrical, optical, chemical, magnetic, etc.)
  • Applications of reinforced polymeric biomaterials
  • Biopolymer composites in electronics
  • Biopolymer composites in water purification
  • Antibacterial activity of biopolymer-based composites
  • Biomedical applications of biopolymer-based composites
  • Biopolymer composites in packaging and food industry
  • Future perspectives for biopolymeric nanomaterials
Prof. Dr. Ana María Díez Pascual
Prof. Patrizia Cinelli
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

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

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1800 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

  • Biopolymers
  • Composites
  • Biodegradability
  • Nanoparticles
  • Mechanical properties
  • Biomedical applications
  • Antibacterial activity

Related Special Issue

Published Papers (19 papers)

View options order results:
result details:
Displaying articles 1-19
Export citation of selected articles as:

Editorial

Jump to: Research

Open AccessEditorial
Synthesis and Applications of Biopolymer Composites
Int. J. Mol. Sci. 2019, 20(9), 2321; https://doi.org/10.3390/ijms20092321
Received: 28 March 2019 / Revised: 1 May 2019 / Accepted: 9 May 2019 / Published: 10 May 2019
PDF Full-text (222 KB) | HTML Full-text | XML Full-text
Abstract
In recent years, there has been a growing demand for a clean and pollution-free environment and an evident target to minimizing fossil fuel [...] Full article
(This article belongs to the Special Issue Synthesis and Applications of Biopolymer Composites)

Research

Jump to: Editorial

Open AccessArticle
PHB is Produced from Glycogen Turn-over during Nitrogen Starvation in Synechocystis sp. PCC 6803
Int. J. Mol. Sci. 2019, 20(8), 1942; https://doi.org/10.3390/ijms20081942
Received: 4 April 2019 / Revised: 17 April 2019 / Accepted: 18 April 2019 / Published: 20 April 2019
PDF Full-text (2148 KB) | HTML Full-text | XML Full-text
Abstract
Polyhydroxybutyrate (PHB) is a polymer of great interest as a substitute for conventional plastics, which are becoming an enormous environmental problem. PHB can be produced directly from CO2 in photoautotrophic cyanobacteria. The model cyanobacterium Synechocystis sp. PCC 6803 produces PHB under conditions [...] Read more.
Polyhydroxybutyrate (PHB) is a polymer of great interest as a substitute for conventional plastics, which are becoming an enormous environmental problem. PHB can be produced directly from CO2 in photoautotrophic cyanobacteria. The model cyanobacterium Synechocystis sp. PCC 6803 produces PHB under conditions of nitrogen starvation. However, it is so far unclear which metabolic pathways provide the precursor molecules for PHB synthesis during nitrogen starvation. In this study, we investigated if PHB could be derived from the main intracellular carbon pool, glycogen. A mutant of the major glycogen phosphorylase, GlgP2 (slr1367 product), was almost completely impaired in PHB synthesis. Conversely, in the absence of glycogen synthase GlgA1 (sll0945 product), cells not only produced less PHB, but were also impaired in acclimation to nitrogen depletion. To analyze the role of the various carbon catabolic pathways (EMP, ED and OPP pathways) for PHB production, mutants of key enzymes of these pathways were analyzed, showing different impact on PHB synthesis. Together, this study clearly indicates that PHB in glycogen-producing Synechocystis sp. PCC 6803 cells is produced from this carbon-pool during nitrogen starvation periods. This knowledge can be used for metabolic engineering to get closer to the overall goal of a sustainable, carbon-neutral bioplastic production. Full article
(This article belongs to the Special Issue Biopolymer Composites 2019)
Figures

Graphical abstract

Open AccessArticle
Evaluation of Mechanical and Interfacial Properties of Bio-Composites Based on Poly(Lactic Acid) with Natural Cellulose Fibers
Int. J. Mol. Sci. 2019, 20(4), 960; https://doi.org/10.3390/ijms20040960
Received: 31 December 2018 / Revised: 12 February 2019 / Accepted: 17 February 2019 / Published: 22 February 2019
Cited by 2 | PDF Full-text (4030 KB) | HTML Full-text | XML Full-text
Abstract
The circular economy policy and the interest for sustainable material are inducing a constant expansion of the bio-composites market. The opportunity of using natural fibers in bio-based and biodegradable polymeric matrices, derived from industrial and/or agricultural waste, represents a stimulating challenge in the [...] Read more.
The circular economy policy and the interest for sustainable material are inducing a constant expansion of the bio-composites market. The opportunity of using natural fibers in bio-based and biodegradable polymeric matrices, derived from industrial and/or agricultural waste, represents a stimulating challenge in the replacement of traditional composites based on fossil sources. The coupling of bioplastics with natural fibers in order to lower costs and promote degradability is one of the primary objectives of research, above all in the packaging and agricultural sectors where large amounts of non-recyclable plastics are generated, inducing a serious problem for plastic disposal and potential accumulation in the environment. Among biopolymers, poly(lactic acid) (PLA) is one of the most used compostable, bio-based polymeric matrices, since it exhibits process ability and mechanical properties compatible with a wide range of applications. In this study, two types of cellulosic fibers were processed with PLA in order to obtain bio-composites with different percentages of microfibers (5%, 10%, 20%). The mechanical properties were evaluated (tensile and impact test), and analytical models were applied in order to estimate the adhesion between matrix and fibers and to predict the material’s stiffness. Understanding these properties is of particular importance in order to be able to tune and project the final characteristics of bio-composites. Full article
(This article belongs to the Special Issue Synthesis and Applications of Biopolymer Composites)
Figures

Graphical abstract

Open AccessArticle
Thermal, Mechanical, and Rheological Properties of Biocomposites Made of Poly(lactic acid) and Potato Pulp Powder
Int. J. Mol. Sci. 2019, 20(3), 675; https://doi.org/10.3390/ijms20030675
Received: 31 December 2018 / Revised: 31 January 2019 / Accepted: 1 February 2019 / Published: 5 February 2019
Cited by 3 | PDF Full-text (5070 KB) | HTML Full-text | XML Full-text
Abstract
The thermal, mechanical, and rheological properties of biocomposites of poly(lactic acid) (PLA) with potato pulp powder were investigated in order to (1) quantify how the addition of this filler modifies the structure of the polymeric material and (2) to obtain information on the [...] Read more.
The thermal, mechanical, and rheological properties of biocomposites of poly(lactic acid) (PLA) with potato pulp powder were investigated in order to (1) quantify how the addition of this filler modifies the structure of the polymeric material and (2) to obtain information on the possible miscibility and compatibility between PLA and the potato pulp. The potato pulp powder utilized is a residue of the processing for the production and extraction of starch. The study was conducted by analyzing the effect of the potato pulp concentration on the thermal, mechanical, and rheological properties of the biocomposites. The results showed that the potato pulp powder does not act as reinforcement but as filler for the PLA polymeric matrix. A progressive decrease in elastic modulus, tensile strength, and elongation at break was observed with increasing the potato pulp percentage. This moderate loss of mechanical properties, however, still meets the technical requirements indicated for the production of rigid packaging items. The incorporation of potato pulp powder to PLA offers the possibility to reduce the cost of the final products and promotes a circular economy approach for the valorization of agro-food waste biomass. Full article
(This article belongs to the Special Issue Synthesis and Applications of Biopolymer Composites)
Figures

Graphical abstract

Open AccessArticle
Chitin Nanofibrils in Poly(Lactic Acid) (PLA) Nanocomposites: Dispersion and Thermo-Mechanical Properties
Int. J. Mol. Sci. 2019, 20(3), 504; https://doi.org/10.3390/ijms20030504
Received: 14 December 2018 / Revised: 17 January 2019 / Accepted: 18 January 2019 / Published: 24 January 2019
Cited by 4 | PDF Full-text (9503 KB) | HTML Full-text | XML Full-text
Abstract
Chitin-nanofibrils are obtained in water suspension at low concentration, as nanoparticles normally are, to avoid their aggregation. The addition of the fibrils in molten PLA during extrusion is thus difficult and disadvantageous. In the present paper, the use of poly(ethylene glycol) (PEG) is [...] Read more.
Chitin-nanofibrils are obtained in water suspension at low concentration, as nanoparticles normally are, to avoid their aggregation. The addition of the fibrils in molten PLA during extrusion is thus difficult and disadvantageous. In the present paper, the use of poly(ethylene glycol) (PEG) is proposed to prepare a solid pre-composite by water evaporation. The pre-composite is then added to PLA in the extruder to obtain transparent nanocomposites. The amount of PEG and chitin nanofibrils was varied in the nanocomposites to compare the reinforcement due to nanofibrils and plasticization due to the presence of PEG, as well as for extrapolating, where possible, the properties of reinforcement due to chitin nanofibrils exclusively. Thermal and morphological properties of nanocomposites were also investigated. This study concluded that chitin nanofibrils, added as reinforcing filler up to 12% by weight, do not alter the properties of the PLA based material; hence, this additive can be used in bioplastic items mainly exploiting its intrinsic anti-microbial and skin regenerating properties. Full article
(This article belongs to the Special Issue Synthesis and Applications of Biopolymer Composites)
Figures

Graphical abstract

Open AccessArticle
Processability and Degradability of PHA-Based Composites in Terrestrial Environments
Int. J. Mol. Sci. 2019, 20(2), 284; https://doi.org/10.3390/ijms20020284
Received: 21 December 2018 / Revised: 7 January 2019 / Accepted: 9 January 2019 / Published: 12 January 2019
Cited by 2 | PDF Full-text (3679 KB) | HTML Full-text | XML Full-text
Abstract
In this work, composites based on poly(3-hydroxybutyrate-3-hydroxyvalerate) (PHB-HV) and waste wood sawdust (SD) fibers, a byproduct of the wood industry, were produced by melt extrusion and characterized in terms of processability, thermal stability, morphology, and mechanical properties in order to discriminate the formulations [...] Read more.
In this work, composites based on poly(3-hydroxybutyrate-3-hydroxyvalerate) (PHB-HV) and waste wood sawdust (SD) fibers, a byproduct of the wood industry, were produced by melt extrusion and characterized in terms of processability, thermal stability, morphology, and mechanical properties in order to discriminate the formulations suitable for injection molding. Given their application in agriculture and/or plant nursery, the biodegradability of the optimized composites was investigated under controlled composting conditions in accordance with standard methods (ASTM D5338-98 and ISO 20200-2004). The optimized PHB-HV/SD composites were used for the production of pots by injection molding and their performance was qualitatively monitored in a plant nursery and underground for 14 months. This study presents a sustainable option of valuation of wood factory residues and lowering the production cost of PHB-HV-based compounds without affecting their mechanical properties, improving their impact resistance and biodegradability rates in terrestrial environments. Full article
(This article belongs to the Special Issue Synthesis and Applications of Biopolymer Composites)
Figures

Figure 1

Open AccessArticle
Impact of pH Modification on Protein Polymerization and Structure–Function Relationships in Potato Protein and Wheat Gluten Composites
Int. J. Mol. Sci. 2019, 20(1), 58; https://doi.org/10.3390/ijms20010058
Received: 12 November 2018 / Revised: 17 December 2018 / Accepted: 20 December 2018 / Published: 24 December 2018
Cited by 1 | PDF Full-text (1977 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Wheat gluten (WG) and potato protein (PP) were modified to a basic pH by NaOH to impact macromolecular and structural properties. Films were processed by compression molding (at 130 and 150 °C) of WG, PP, their chemically modified versions (MWG, MPP) and of [...] Read more.
Wheat gluten (WG) and potato protein (PP) were modified to a basic pH by NaOH to impact macromolecular and structural properties. Films were processed by compression molding (at 130 and 150 °C) of WG, PP, their chemically modified versions (MWG, MPP) and of their blends in different ratios to study the impact of chemical modification on structure, processing and tensile properties. The modification changed the molecular and secondary structure of both protein powders, through unfolding and re-polymerization, resulting in less cross-linked proteins. The β-sheet formation due to NaOH modification increased for WG and decreased for PP. Processing resulted in cross-linking of the proteins, shown by a decrease in extractability; to a higher degree for WG than for PP, despite higher β-sheet content in PP. Compression molding of MPP resulted in an increase in protein cross-linking and improved maximum stress and extensibility as compared to PP at 130 °C. The highest degree of cross-linking with improved maximum stress and extensibility was found for WG/MPP blends compared to WG/PP and MWG/MPP at 130 °C. To conclude, chemical modification of PP changed the protein structures produced under harsh industrial conditions and made the protein more reactive and attractive for use in bio-based materials processing, no such positive gains were seen for WG. Full article
(This article belongs to the Special Issue Synthesis and Applications of Biopolymer Composites)
Figures

Graphical abstract

Open AccessArticle
Study on Thermal Decomposition Behaviors of Terpolymers of Carbon Dioxide, Propylene Oxide, and Cyclohexene Oxide
Int. J. Mol. Sci. 2018, 19(12), 3723; https://doi.org/10.3390/ijms19123723
Received: 20 September 2018 / Revised: 12 November 2018 / Accepted: 13 November 2018 / Published: 23 November 2018
Cited by 1 | PDF Full-text (3780 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The terpolymerization of carbon dioxide (CO2), propylene oxide (PO), and cyclohexene oxide (CHO) were performed by both random polymerization and block polymerization to synthesize the random poly (propylene cyclohexene carbonate) (PPCHC), di-block polymers of poly (propylene carbonate–cyclohexyl carbonate) (PPC-PCHC), and tri-block [...] Read more.
The terpolymerization of carbon dioxide (CO2), propylene oxide (PO), and cyclohexene oxide (CHO) were performed by both random polymerization and block polymerization to synthesize the random poly (propylene cyclohexene carbonate) (PPCHC), di-block polymers of poly (propylene carbonate–cyclohexyl carbonate) (PPC-PCHC), and tri-block polymers of poly (cyclohexyl carbonate–propylene carbonate–cyclohexyl carbonate) (PCHC-PPC-PCHC). The kinetics of the thermal degradation of the terpolymers was investigated by the multiple heating rate method (Kissinger-Akahira-Sunose (KAS) method), the single heating rate method (Coats-Redfern method), and the Isoconversional kinetic analysis method proposed by Vyazovkin with the data from thermogravimetric analysis under dynamic conditions. The values of ln k vs. T−1 for the thermal decomposition of four polymers demonstrate the thermal stability of PPC and PPC-PCHC are poorer than PPCHC and PCHC-PPC-PCHC. In addition, for PPCHC and PCHC-PPC-PCHC, there is an intersection between the two rate constant lines, which means that, for thermal stability of PPCHC, it is more stable than PCHC-PPC-PCHC at the temperature less than 309 °C and less stable when the decomposed temperature is more than 309 °C. Pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) and thermogravimetric analysis/infrared spectrometry (TG/FTIR) techniques were applied to investigate the thermal degradation behavior of the polymers. The results showed that unzipping was the main degradation mechanism of all polymers so the final pyrolysates were cyclic propylene carbonate and cyclic cyclohexene carbonate. For the block copolymers, the main chain scission reaction first occurs at PC-PC linkages initiating an unzipping reaction of PPC chain and then, at CHC–CHC linkages, initiating an unzipping reaction of the PCHC chain. That is why the T−5% of di-block and tri-block polymers were not much higher than that of PPC while two maximum decomposition temperatures were observed for both the block copolymer and the second one were much higher than that of PPC. For PPCHC, the random arranged bulky cyclohexane groups in the polymer chain can effectively suppress the backbiting process and retard the unzipping reaction. Thus, it exhibited much higher T−5% than that of PPC and block copolymers. Full article
(This article belongs to the Special Issue Synthesis and Applications of Biopolymer Composites)
Figures

Graphical abstract

Open AccessArticle
Characterization of Ecklonia cava Alginate Films Containing Cinnamon Essential Oils
Int. J. Mol. Sci. 2018, 19(11), 3545; https://doi.org/10.3390/ijms19113545
Received: 27 October 2018 / Revised: 7 November 2018 / Accepted: 8 November 2018 / Published: 10 November 2018
Cited by 2 | PDF Full-text (4545 KB) | HTML Full-text | XML Full-text
Abstract
In this study, Ecklonia cava alginate (ECA) was used as a base material for biodegradable films. Calcium chloride (CaCl2) was used as a cross-linking agent, and various concentrations (0%, 0.4%, 0.7%, and 1.0%) of cinnamon leaf oil (CLO) or cinnamon bark [...] Read more.
In this study, Ecklonia cava alginate (ECA) was used as a base material for biodegradable films. Calcium chloride (CaCl2) was used as a cross-linking agent, and various concentrations (0%, 0.4%, 0.7%, and 1.0%) of cinnamon leaf oil (CLO) or cinnamon bark oil (CBO) were incorporated to prepare active films. The ECA film containing 3% CaCl2 had a tensile strength (TS) of 17.82 MPa and an elongation at break (E) of 10.36%, which were higher than those of the film without CaCl2. As the content of essential oils (EOs) increased, TS decreased and E increased. Addition of CLO or CBO also provided antioxidant and antimicrobial activities to the ECA films. The antioxidant activity of the ECA film with CBO was higher than that of the film containing CLO. In particular, the scavenging activities of the 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radicals in the ECA film containing 1% CBO were 50.45% and 99.37%, respectively. In contrast, the antimicrobial activities against Escherichia coli O157:H7, Salmonella Typhimurium, Staphylococcus aureus, and Listeria monocytogenes were superior in the ECA films with CLO. These results suggest that ECA films containing CLO or CBO can be applied as new active packaging materials. Full article
(This article belongs to the Special Issue Synthesis and Applications of Biopolymer Composites)
Figures

Figure 1

Open AccessArticle
Exploring the Structural Transformation Mechanism of Chinese and Thailand Silk Fibroin Fibers and Formic-Acid Fabricated Silk Films
Int. J. Mol. Sci. 2018, 19(11), 3309; https://doi.org/10.3390/ijms19113309
Received: 19 September 2018 / Revised: 13 October 2018 / Accepted: 22 October 2018 / Published: 24 October 2018
Cited by 1 | PDF Full-text (1329 KB) | HTML Full-text | XML Full-text
Abstract
Silk fibroin (SF) is a protein polymer derived from insects, which has unique mechanical properties and tunable biodegradation rate due to its variable structures. Here, the variability of structural, thermal, and mechanical properties of two domesticated silk films (Chinese and Thailand B. [...] Read more.
Silk fibroin (SF) is a protein polymer derived from insects, which has unique mechanical properties and tunable biodegradation rate due to its variable structures. Here, the variability of structural, thermal, and mechanical properties of two domesticated silk films (Chinese and Thailand B. Mori) regenerated from formic acid solution, as well as their original fibers, were compared and investigated using dynamic mechanical analysis (DMA) and Fourier transform infrared spectrometry (FTIR). Four relaxation events appeared clearly during the temperature region of 25 °C to 280 °C in DMA curves, and their disorder degree (fdis) and glass transition temperature (Tg) were predicted using Group Interaction Modeling (GIM). Compared with Thai (Thailand) regenerated silks, Chin (Chinese) silks possess a lower Tg, higher fdis, and better elasticity and mechanical strength. As the calcium chloride content in the initial processing solvent increases (1%–6%), the Tg of the final SF samples gradually decrease, while their fdis increase. Besides, SF with more non-crystalline structures shows high plasticity. Two α- relaxations in the glass transition region of tan δ curve were identified due to the structural transition of silk protein. These findings provide a new perspective for the design of advanced protein biomaterials with different secondary structures, and facilitate a comprehensive understanding of the structure-property relationship of various biopolymers in the future. Full article
(This article belongs to the Special Issue Synthesis and Applications of Biopolymer Composites)
Figures

Graphical abstract

Open AccessArticle
Amphiphilic Polymeric Micelles Based on Deoxycholic Acid and Folic Acid Modified Chitosan for the Delivery of Paclitaxel
Int. J. Mol. Sci. 2018, 19(10), 3132; https://doi.org/10.3390/ijms19103132
Received: 14 September 2018 / Revised: 9 October 2018 / Accepted: 10 October 2018 / Published: 12 October 2018
Cited by 1 | PDF Full-text (2545 KB) | HTML Full-text | XML Full-text
Abstract
The present investigation aimed to develop a tumor-targeting drug delivery system for paclitaxel (PTX). The hydrophobic deoxycholic acid (DA) and active targeting ligand folic acid (FA) were used to modify water-soluble chitosan (CS). As an amphiphilic polymer, the conjugate FA-CS-DA was synthesized and [...] Read more.
The present investigation aimed to develop a tumor-targeting drug delivery system for paclitaxel (PTX). The hydrophobic deoxycholic acid (DA) and active targeting ligand folic acid (FA) were used to modify water-soluble chitosan (CS). As an amphiphilic polymer, the conjugate FA-CS-DA was synthesized and characterized by Proton nuclear magnetic resonance (1H-NMR) and Fourier-transform infrared spectroscopy (FTIR) analysis. The degree of substitutions of DA and FA were calculated as 15.8% and 8.0%, respectively. In aqueous medium, the conjugate could self-assemble into micelles with the critical micelle concentration of 6.6 × 10−3 mg/mL. Under a transmission electron microscope (TEM), the PTX-loaded micelles exhibited a spherical shape. The particle size determined by dynamic light scattering was 126 nm, and the zeta potential was +19.3 mV. The drug loading efficiency and entrapment efficiency were 9.1% and 81.2%, respectively. X-Ray Diffraction (XRD) analysis showed that the PTX was encapsulated in the micelles in a molecular or amorphous state. In vitro and in vivo antitumor evaluations demonstrated the excellent antitumor activity of PTX-loaded micelles. It was suggested that FA-CS-DA was a safe and effective carrier for the intravenous delivery of paclitaxel. Full article
(This article belongs to the Special Issue Synthesis and Applications of Biopolymer Composites)
Figures

Graphical abstract

Open AccessArticle
Degradation Studies Realized on Natural Rubber and Plasticized Potato Starch Based Eco-Composites Obtained by Peroxide Cross-Linking
Int. J. Mol. Sci. 2018, 19(10), 2862; https://doi.org/10.3390/ijms19102862
Received: 2 August 2018 / Revised: 14 September 2018 / Accepted: 18 September 2018 / Published: 20 September 2018
Cited by 1 | PDF Full-text (5127 KB) | HTML Full-text | XML Full-text
Abstract
The obtaining and characterization of some environmental-friendly composites that are based on natural rubber and plasticized starch, as filler, are presented. These were obtained by peroxide cross-linking in the presence of a polyfunctional monomer used here as cross-linking co-agent, trimethylolpropane trimethacrylate. The influence [...] Read more.
The obtaining and characterization of some environmental-friendly composites that are based on natural rubber and plasticized starch, as filler, are presented. These were obtained by peroxide cross-linking in the presence of a polyfunctional monomer used here as cross-linking co-agent, trimethylolpropane trimethacrylate. The influence of plasticized starch amount on the composites physical and mechanical characteristics, gel fraction and cross-link density, water uptake, structure and morphology before and after accelerated (thermal) degradation, and natural (for one year in temperate climate) ageing, was studied. Differences of two orders of magnitude between the degradation/aging methods were registered in the case of some mechanical characteristics, by increasing the plasticized starch amount. The cross-link density, water uptake and mass loss were also significant affected by the plasticized starch amount increasing and exposing for one year to natural ageing in temperate climate. Based on the results of Fourier Transform Infrared Spectroscopy (FTIR) and cross-link density measurements, reaction mechanisms attributed to degradation induced by accelerated and natural ageing were done. SEM micrographs have confirmed in addition that by incorporating a quantity of hydrophilic starch amount over 20 phr and by exposing the composites to natural ageing, and then degradability can be enhanced by comparing with thermal degradation. Full article
(This article belongs to the Special Issue Synthesis and Applications of Biopolymer Composites)
Figures

Graphical abstract

Open AccessArticle
The Degradation Properties of MgO Whiskers/PLLA Composite In Vitro
Int. J. Mol. Sci. 2018, 19(9), 2740; https://doi.org/10.3390/ijms19092740
Received: 14 August 2018 / Revised: 28 August 2018 / Accepted: 30 August 2018 / Published: 13 September 2018
Cited by 2 | PDF Full-text (4910 KB) | HTML Full-text | XML Full-text
Abstract
In this study, composite films of stearic acid–modified magnesium oxide whiskers (Sa–w-MgO)/poly-l-lactic acid (PLLA) were prepared through solution casting, and the in vitro degradation properties and cytocompatibility of the composites with different whisker contents were investigated. The results showed that the [...] Read more.
In this study, composite films of stearic acid–modified magnesium oxide whiskers (Sa–w-MgO)/poly-l-lactic acid (PLLA) were prepared through solution casting, and the in vitro degradation properties and cytocompatibility of the composites with different whisker contents were investigated. The results showed that the degradation behavior of the composite samples depended significantly on the whisker content, and the degradation rate increased with the addition of MgO content. Furthermore, the degradation of the composites with higher contents of whiskers was influenced more severely by the hydrophilicity and pH value, leading to more final weight loss, but the decomposition rate decreased gradually. Furthermore, the pH value of the phosphate buffer solution (PBS) was obviously regulated by the dissolution of MgO whiskers through neutralization of the acidic product of PLLA degradation. The cytocompatibility of the composites also increased remarkably, as determined from the cell viability results, and was higher than that of PLLA at the chosen whisker content. This was beneficial for the cell affinity of the material, as it notably led to an enhanced biocompatibility of the PLLA, in favor of promoting cell proliferation, which significantly improved its bioactivity, as well. Full article
(This article belongs to the Special Issue Synthesis and Applications of Biopolymer Composites)
Figures

Graphical abstract

Open AccessArticle
Toughness Enhancement of PHBV/TPU/Cellulose Compounds with Reactive Additives for Compostable Injected Parts in Industrial Applications
Int. J. Mol. Sci. 2018, 19(7), 2102; https://doi.org/10.3390/ijms19072102
Received: 25 June 2018 / Revised: 16 July 2018 / Accepted: 17 July 2018 / Published: 19 July 2018
Cited by 1 | PDF Full-text (4846 KB) | HTML Full-text | XML Full-text
Abstract
Poly(3-hydroxybutyrate-co-3-valerate), PHBV, is a bacterial thermoplastic biopolyester that possesses interesting thermal and mechanical properties. As it is fully biodegradable, it could be an alternative to the use of commodities in single-use applications or in those intended for composting at their end of life. [...] Read more.
Poly(3-hydroxybutyrate-co-3-valerate), PHBV, is a bacterial thermoplastic biopolyester that possesses interesting thermal and mechanical properties. As it is fully biodegradable, it could be an alternative to the use of commodities in single-use applications or in those intended for composting at their end of life. Two big drawbacks of PHBV are its low impact toughness and its high cost, which limit its potential applications. In this work, we proposed the use of a PHBV-based compound with purified α-cellulose fibres and a thermoplastic polyurethane (TPU), with the purpose of improving the performance of PHBV in terms of balanced heat resistance, stiffness, and toughness. Three reactive agents with different functionalities have been tested in these compounds: hexametylene diisocianate (HMDI), a commercial multi-epoxy-functionalized styrene-co-glycidyl methacrylate oligomer (Joncryl® ADR-4368), and triglycidyl isocyanurate (TGIC). The results indicate that the reactive agents play a main role of compatibilizers among the phases of the PHBV/TPU/cellulose compounds. HMDI showed the highest ability to compatibilize the cellulose and the PHBV in the compounds, with the topmost values of deformation at break, static toughness, and impact strength. Joncryl® and TGIC, on the other hand, seemed to enhance the compatibility between the fibres and the polymer matrix as well as the TPU within the PHBV. Full article
(This article belongs to the Special Issue Synthesis and Applications of Biopolymer Composites)
Figures

Graphical abstract

Open AccessArticle
Biodegradable and Toughened Composite of Poly(Propylene Carbonate)/Thermoplastic Polyurethane (PPC/TPU): Effect of Hydrogen Bonding
Int. J. Mol. Sci. 2018, 19(7), 2032; https://doi.org/10.3390/ijms19072032
Received: 25 May 2018 / Revised: 21 June 2018 / Accepted: 30 June 2018 / Published: 13 July 2018
Cited by 1 | PDF Full-text (16781 KB) | HTML Full-text | XML Full-text
Abstract
The blends of Poly(propylene carbonate) (PPC) and polyester-based thermoplastic polyurethane (TPU) were melt compounded in an internal mixer. The compatibility, thermal behaviors, mechanical properties and toughening mechanism of the blends were investigated using Fourier transform infrared spectra (FTIR), tensile tests, impact tests, differential [...] Read more.
The blends of Poly(propylene carbonate) (PPC) and polyester-based thermoplastic polyurethane (TPU) were melt compounded in an internal mixer. The compatibility, thermal behaviors, mechanical properties and toughening mechanism of the blends were investigated using Fourier transform infrared spectra (FTIR), tensile tests, impact tests, differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and dynamic mechanical analysis technologies. FTIR and SEM examination reveal strong interfacial adhesion between PPC matrix and suspended TPU particles. Dynamic mechanical analyzer (DMA) characterize the glass transition temperature, secondary motion and low temperature properties. By the incorporation of TPU, the thermal stabilities are greatly enhanced and the mechanical properties are obviously improved for the PPC/TPU blends. Moreover, PPC/TPU blends exhibit a brittle-ductile transition with the addition of 20 wt % TPU. It is considered that the enhanced toughness results in the shear yielding occurred in both PPC matrix and TPU particles of the blends. Full article
(This article belongs to the Special Issue Synthesis and Applications of Biopolymer Composites)
Figures

Figure 1

Open AccessArticle
Effect of Surfactant Type and Sonication Energy on the Electrical Conductivity Properties of Nanocellulose-CNT Nanocomposite Films
Int. J. Mol. Sci. 2018, 19(6), 1819; https://doi.org/10.3390/ijms19061819
Received: 15 May 2018 / Revised: 6 June 2018 / Accepted: 15 June 2018 / Published: 20 June 2018
Cited by 4 | PDF Full-text (2727 KB) | HTML Full-text | XML Full-text
Abstract
We present a detailed study on the influence of sonication energy and surfactant type on the electrical conductivity of nanocellulose-carbon nanotube (NFC-CNT) nanocomposite films. The study was made using a minimum amount of processing steps, chemicals and materials, to optimize the conductivity properties [...] Read more.
We present a detailed study on the influence of sonication energy and surfactant type on the electrical conductivity of nanocellulose-carbon nanotube (NFC-CNT) nanocomposite films. The study was made using a minimum amount of processing steps, chemicals and materials, to optimize the conductivity properties of free-standing flexible nanocomposite films. In general, the NFC-CNT film preparation process is sensitive concerning the dispersing phase of CNTs into a solution with NFC. In our study, we used sonication to carry out the dispersing phase of processing in the presence of surfactant. In the final phase, the films were prepared from the dispersion using centrifugal cast molding. The solid films were analyzed regarding their electrical conductivity using a four-probe measuring technique. We also characterized how conductivity properties were enhanced when surfactant was removed from nanocomposite films; to our knowledge this has not been reported previously. The results of our study indicated that the optimization of the surfactant type clearly affected the formation of freestanding films. The effect of sonication energy was significant in terms of conductivity. Using a relatively low 16 wt. % concentration of multiwall carbon nanotubes we achieved the highest conductivity value of 8.4 S/cm for nanocellulose-CNT films ever published in the current literature. This was achieved by optimizing the surfactant type and sonication energy per dry mass. Additionally, to further increase the conductivity, we defined a preparation step to remove the used surfactant from the final nanocomposite structure. Full article
(This article belongs to the Special Issue Synthesis and Applications of Biopolymer Composites)
Figures

Graphical abstract

Open AccessArticle
Morphological Study of Chitosan/Poly (Vinyl Alcohol) Nanofibers Prepared by Electrospinning, Collected on Reticulated Vitreous Carbon
Int. J. Mol. Sci. 2018, 19(6), 1718; https://doi.org/10.3390/ijms19061718
Received: 3 May 2018 / Revised: 30 May 2018 / Accepted: 1 June 2018 / Published: 9 June 2018
Cited by 2 | PDF Full-text (7540 KB) | HTML Full-text | XML Full-text
Abstract
In this work, chitosan (CS)/poly (vinyl alcohol) (PVA) nanofibers were prepared by using the electrospinning method. Different CS concentrations (0.5, 1, 2, and 3 wt %), maintaining the PVA concentration at 8 wt %, were tested. Likewise, the studied electrospinning experimental parameters were: [...] Read more.
In this work, chitosan (CS)/poly (vinyl alcohol) (PVA) nanofibers were prepared by using the electrospinning method. Different CS concentrations (0.5, 1, 2, and 3 wt %), maintaining the PVA concentration at 8 wt %, were tested. Likewise, the studied electrospinning experimental parameters were: syringe/collector distance, solution flow and voltage. Subsequently, the electrospun fibers were collected on a reticulated vitreous carbon (RVC) support for 0.25, 0.5, 1, 1.5, and 2 h. The morphology and diameter of the CS/PVA nanofibers were characterized by scanning electron microscopy (SEM), finding diameters in the order of 132 and 212 nm; the best results (uniform fibers) were obtained from the solution with 2 wt % of chitosan and a voltage, distance, and flow rate of 16 kV, 20 cm, and 0.13 mL/h, respectively. Afterwards, a treatment with an ethanolic NaOH solution was performed, observing a change in the fiber morphology and a diameter decrease (117 ± 9 nm). Full article
(This article belongs to the Special Issue Synthesis and Applications of Biopolymer Composites)
Figures

Figure 1

Open AccessArticle
Polymeric Micelles Based on Modified Glycol Chitosan for Paclitaxel Delivery: Preparation, Characterization and Evaluation
Int. J. Mol. Sci. 2018, 19(6), 1550; https://doi.org/10.3390/ijms19061550
Received: 22 April 2018 / Revised: 15 May 2018 / Accepted: 15 May 2018 / Published: 23 May 2018
Cited by 5 | PDF Full-text (2045 KB) | HTML Full-text | XML Full-text
Abstract
Amphiphilic polymer of α-tocopherol succinate modified glycol chitosan (TS-GC) was successfully constructed by conjugating α-tocopherol succinate to the skeleton of glycol chitosan and characterized by Fourier-transform infrared (FT-IR) and proton nuclear magnetic resonance (1H-NMR). In aqueous milieu, the conjugates self-assembled to [...] Read more.
Amphiphilic polymer of α-tocopherol succinate modified glycol chitosan (TS-GC) was successfully constructed by conjugating α-tocopherol succinate to the skeleton of glycol chitosan and characterized by Fourier-transform infrared (FT-IR) and proton nuclear magnetic resonance (1H-NMR). In aqueous milieu, the conjugates self-assembled to micelles with the critical aggregation concentration of 7.2 × 10−3 mg/mL. Transmission electron microscope (TEM) observation and dynamic light scattering (DLS) measurements were carried out to determine the physicochemical properties of the micelles. The results revealed that paclitaxel (PTX)-loaded TS-GC micelles were spherical in shape. Moreover, the PTX-loaded micelles showed increased particle sizes (35 nm vs. 142 nm) and a little reduced zeta potential (+19 mV vs. +16 mV) compared with blank micelles. The X-ray diffraction (XRD) spectra demonstrated that PTX existed inside the micelles in amorphous or molecular state. In vitro and in vivo tests showed that the PTX-loaded TS-GC micelles had advantages over the Cremophor EL-based formulation in terms of low toxicity level and increased dose, which suggested the potential of the polymer as carriers for PTX to improve their delivery properties. Full article
(This article belongs to the Special Issue Synthesis and Applications of Biopolymer Composites)
Figures

Figure 1

Open AccessArticle
Structure/Function Analysis of Cotton-Based Peptide-Cellulose Conjugates: Spatiotemporal/Kinetic Assessment of Protease Aerogels Compared to Nanocrystalline and Paper Cellulose
Int. J. Mol. Sci. 2018, 19(3), 840; https://doi.org/10.3390/ijms19030840
Received: 2 January 2018 / Revised: 24 February 2018 / Accepted: 25 February 2018 / Published: 13 March 2018
Cited by 7 | PDF Full-text (3833 KB) | HTML Full-text | XML Full-text
Abstract
Nanocellulose has high specific surface area, hydration properties, and ease of derivatization to prepare protease sensors. A Human Neutrophil Elastase sensor designed with a nanocellulose aerogel transducer surface derived from cotton is compared with cotton filter paper, and nanocrystalline cellulose versions of the [...] Read more.
Nanocellulose has high specific surface area, hydration properties, and ease of derivatization to prepare protease sensors. A Human Neutrophil Elastase sensor designed with a nanocellulose aerogel transducer surface derived from cotton is compared with cotton filter paper, and nanocrystalline cellulose versions of the sensor. X-ray crystallography was employed along with Michaelis–Menten enzyme kinetics, and circular dichroism to contrast the structure/function relations of the peptide-cellulose conjugate conformation to enzyme/substrate binding and turnover rates. The nanocellulosic aerogel was found to have a cellulose II structure. The spatiotemporal relation of crystallite surface to peptide-cellulose conformation is discussed in light of observed enzyme kinetics. A higher substrate binding affinity (Km) of elastase was observed with the nanocellulose aerogel and nanocrystalline peptide-cellulose conjugates than with the solution-based elastase substrate. An increased Km observed for the nanocellulosic aerogel sensor yields a higher enzyme efficiency (kcat/Km), attributable to binding of the serine protease to the negatively charged cellulose surface. The effect of crystallite size and β-turn peptide conformation are related to the peptide-cellulose kinetics. Models demonstrating the orientation of cellulose to peptide O6-hydroxymethyl rotamers of the conjugates at the surface of the cellulose crystal suggest the relative accessibility of the peptide-cellulose conjugates for enzyme active site binding. Full article
(This article belongs to the Special Issue Synthesis and Applications of Biopolymer Composites)
Figures

Graphical abstract

Int. J. Mol. Sci. EISSN 1422-0067 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
Back to Top