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Special Issue "Biodegradable Polymeric Composites: Development and Industrial Applications"

A special issue of Materials (ISSN 1996-1944).

Deadline for manuscript submissions: closed (30 November 2018).

Special Issue Editors

Guest Editor
Dr. Elisa Mele

Department of Materials, Loughborough University, Loughborough, UK
Website | E-Mail
Interests: biocompatible and natural polymers for regenerative medicine; Nanofibrous wound dressings with antimicrobial activity and enhanced cell proliferation; Functional nanocomposites with controlled surface and mechanical properties; Microfluidic devices for biological assays and food safety; Nanofabrication approaches for polymers
Guest Editor
Dr. José Alejandro Heredia-Guerrero

Istituto Italiano di Tecnologia: Genova, Liguria, Italy. https://orcid.org/0000-0002-8251-7577
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Interests: bioplastics, plant cuticle, polymer science, biomimetic systems
Guest Editor
Dr. Athanassia Athanassiou

Smart Materials, Istituto Italiano di Tecnologia, Via Morego 30, Genova, 16163, Italy
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Special Issue Information

Dear Colleagues,

Plastics derived from fossil fuels are extensively used for the large-scale production of commodities, due to the availability of well-developed manufacturing processes and to the possibility of achieving good control over their physicochemical properties. However, once commodity plastics end up in landfills and the oceans, their limited biodegradability is a concern for biodiversity, ecosystems, food security and human health. It has been estimated that 6–12 metric tons of plastic enter the oceans each year, with plastic debris found on coastal areas and in every marine habitat.

The global threat of plastic pollution has stimulated the research of materials that can be broken down to CO2, CH4 and water by the action of microorganisms. These biodegradable polymers can be produced from fossil fuels (polycaprolactone, aromatic or aliphatic co-polyesters), biomasses (polysaccharides, lignin, proteins, cutin) or micro-organisms/biotechnology (polyhydroxy-alkanoates, polylactides). An interesting perspective is represented by composite systems based on this class of polymers for their enhanced properties and retained biodegradability.

In this Special Issue, we aim to publish original work and reviews about the current strategies and technologies for the fabrication of biodegradable polymeric composites and their industrial applications, such as in food packaging and biomedical devices, among others.

Dr. Elisa Mele
Dr. José Alejandro Heredia-Guerrero
Dr. Athanassia Athanassiou
Guest Editors

Manuscript Submission Information

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Keywords

  • Biodegradable polymer composites/nanocomposites
  • Fabrication strategies for biodegradable polymer composites
  • Industrial applications
  • Food packaging
  • Biomedical devices
  • Tissue engineering and drug delivery
  • Membranes and filters for water purification
  • Antimicrobial materials
  • Energy technologies

Published Papers (9 papers)

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Research

Open AccessArticle
Photodegradation and Biodegradation of Poly(Lactic) Acid Containing Orotic Acid as a Nucleation Agent
Materials 2019, 12(3), 481; https://doi.org/10.3390/ma12030481
Received: 11 January 2019 / Revised: 31 January 2019 / Accepted: 2 February 2019 / Published: 4 February 2019
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Abstract
Orotic acid is a natural heterocyclic compound that acts as a nucleation agent in poly(lactic acid) (PLA). PLA materials with increasing orotic acid content were prepared and characterized. It was found that crystallinity of about 28% was reached with 0.3% content of the [...] Read more.
Orotic acid is a natural heterocyclic compound that acts as a nucleation agent in poly(lactic acid) (PLA). PLA materials with increasing orotic acid content were prepared and characterized. It was found that crystallinity of about 28% was reached with 0.3% content of the agent. Further enhancement in the content of the agent did not provoke any additional significant increase of crystallinity. Subsequently, it was investigated whether the orotic acid content affected photodegradation of PLA and, in the next phase, its biodegradation. The results of rheological measurements showed that the compound slightly accelerates photodegradation of the material, which was accompanied by the cleavage of PLA chains. Previous photodegradation was shown to accelerate the subsequent biodegradation by shortening the lag phase of the process, where the explanation is probably in the reduction of the polymer molecular weight during the photodegradation. Moreover, the presence of orotic acid in both initial and photodegraded samples was found to influence biodegradation positively by shortening the lag phase and increasing the observed maximal rate of the biodegradation. Full article
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Open AccessArticle
Functional Chitosan Derivative and Chitin as Decolorization Materials for Methylene Blue and Methyl Orange from Aqueous Solution
Materials 2019, 12(3), 361; https://doi.org/10.3390/ma12030361
Received: 8 December 2018 / Revised: 18 January 2019 / Accepted: 22 January 2019 / Published: 24 January 2019
Cited by 2 | PDF Full-text (2749 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Dyes are classified as one of the major pollutants of water. They have negative impacts not only on environment but also on human health. In fact, wastewater that contains these harmful substances requires many types of treatments. Therefore, alternative methods and adsorption agents [...] Read more.
Dyes are classified as one of the major pollutants of water. They have negative impacts not only on environment but also on human health. In fact, wastewater that contains these harmful substances requires many types of treatments. Therefore, alternative methods and adsorption agents are needed. Herein, we propose to evaluate the decolorization of methylene blue (MB) and methyl orange (MO) as two models of soluble dyes from water using chitin and chitosan-graft-polyacrylamide. Furthermore, the applicability of these biomacromolecules as alternative adsorption agents, their sticking probability and desorption were also examined. Experimental parameters such as dye concentration, contact time, pH solution, adsorbent dosage and temperature were thoroughly examined for the grafted chitosan and chitin. The activation energy ( E a ) and the thermodynamic variables (i.e., standard Gibb’s free energy ( Δ G 0 ), standard enthalpy ( Δ H 0 ), and standard entropy ( Δ S 0 )) were determined using the Van’t Hoff and Arrhenius equations. The sticking probability ( S *) model for MB and MO removal by chitin and the chitosan derivative demonstrated that both dyes were successfully removed under the proposed conditions. Desorption studies of MB and MO showed the reusability of both materials, suggesting their application for removing dyes from aqueous solution. Full article
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Open AccessArticle
3D Arrays of Super-Hydrophobic Microtubes from Polypore Mushrooms as Naturally-Derived Systems for Oil Absorption
Materials 2019, 12(1), 132; https://doi.org/10.3390/ma12010132
Received: 28 November 2018 / Revised: 20 December 2018 / Accepted: 27 December 2018 / Published: 3 January 2019
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Abstract
Porous materials derived from natural resources, such as Luffa sponges, pomelo peel and jute fibres, have recently emerged as oil adsorbents for water purification, due to their suitability, low environmental impact, biodegradability and low cost. Here we show, for the first time, that [...] Read more.
Porous materials derived from natural resources, such as Luffa sponges, pomelo peel and jute fibres, have recently emerged as oil adsorbents for water purification, due to their suitability, low environmental impact, biodegradability and low cost. Here we show, for the first time, that the porosity of the fruiting body of polypore mushrooms can be used to absorb oils and organic solvents while repelling water. We engineered the surface properties of Ganoderma applanatum fungi, of which the fruiting body consists of a regular array of long capillaries embedded in a fibrous matrix, with paraffin wax, octadecyltrichlorosilane (OTS) and trichloro(1H,1H,2H,2H-perfluorooctyl)silane. Morphological and wettability analyses of the modified fungus revealed that the OTS treatment was effective in preserving the 3D porosity of the natural material, inducing super-hydrophobicity (water contact angle higher than 150°) and improving oil sorption capacity (1.8–3.1 g/g). The treated fungus was also inserted into fluidic networks as a filtration element, and its ability to separate water from chloroform was demonstrated. Full article
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Open AccessArticle
Hybrid Composites of Polylactide with Basalt and Carbon Fibers and Their Thermal Treatment
Materials 2019, 12(1), 95; https://doi.org/10.3390/ma12010095
Received: 30 November 2018 / Revised: 21 December 2018 / Accepted: 24 December 2018 / Published: 28 December 2018
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Abstract
In this research, polylactide was hybrid-reinforced and heat-treated in order to obtain durable structural materials with the use of eco-friendly components. Differential scanning calorimetry (DSC) analysis, tensile tests at various temperatures, Vicat tests, impact tests, and microscopic observations were conducted on the annealed [...] Read more.
In this research, polylactide was hybrid-reinforced and heat-treated in order to obtain durable structural materials with the use of eco-friendly components. Differential scanning calorimetry (DSC) analysis, tensile tests at various temperatures, Vicat tests, impact tests, and microscopic observations were conducted on the annealed and non-heat-treated specimens. The theoretical and true density, as well as water absorption, were also determined. The simultaneous introduction of chopped carbon and basalt fibers in equal mass fractions of 7.5% and 12.5% resulted in satisfactory increases in stiffness and tensile strength. The reinforcing effect was more efficient for the heat-treated composites, especially at elevated temperatures. Heat treatment significantly increased the degree of crystallinity of the matrix, improving heat resistance and reducing water absorption. It also reduced the stress concentrations in the injection-molded specimens. Full article
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Open AccessFeature PaperArticle
Valorization of Tomato Processing by-Products: Fatty Acid Extraction and Production of Bio-Based Materials
Materials 2018, 11(11), 2211; https://doi.org/10.3390/ma11112211
Received: 17 October 2018 / Revised: 5 November 2018 / Accepted: 6 November 2018 / Published: 7 November 2018
Cited by 3 | PDF Full-text (1344 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
A method consisting of the alkaline hydrolysis of tomato pomace by-products has been optimized to obtain a mixture of unsaturated and polyhydroxylated fatty acids as well as a non-hydrolysable secondary residue. Reaction rates and the activation energy of the hydrolysis were calculated to [...] Read more.
A method consisting of the alkaline hydrolysis of tomato pomace by-products has been optimized to obtain a mixture of unsaturated and polyhydroxylated fatty acids as well as a non-hydrolysable secondary residue. Reaction rates and the activation energy of the hydrolysis were calculated to reduce costs associated with chemicals and energy consumption. Lipid and non-hydrolysable fractions were chemically (infrared (IR) spectroscopy, gas chromatography/mass spectrometry (GC-MS)) and thermally (differential scanning calorimetry (DSC), thermogravimetric analysis (TGA)) characterized. In addition, the fatty acid mixture was used to produce cutin-based polyesters. Freestanding films were prepared by non-catalyzed melt-polycondensation and characterized by Attenuated Total Reflected-Fourier Transform Infrared (ATR-FTIR) spectroscopy, solid-state nuclear magnetic resonance (NMR), DSC, TGA, Water Contact Angles (WCA), and tensile tests. These bio-based polymers were hydrophobic, insoluble, infusible, and thermally stable, their physical properties being tunable by controlling the presence of unsaturated fatty acids and oxygen in the reaction. The participation of an oxidative crosslinking side reaction is proposed to be responsible for such modifications. Full article
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Open AccessArticle
Significance of a Non-Thermal Plasma Treatment on LDPE Biodegradation with Pseudomonas Aeruginosa
Materials 2018, 11(10), 1925; https://doi.org/10.3390/ma11101925
Received: 19 August 2018 / Revised: 1 October 2018 / Accepted: 5 October 2018 / Published: 10 October 2018
Cited by 1 | PDF Full-text (4532 KB) | HTML Full-text | XML Full-text
Abstract
The use of plastics has spanned across almost all aspects of day to day life. Although their uses are invaluable, they contribute to the generation of a lot of waste products that end up in the environment and end up polluting natural habitats [...] Read more.
The use of plastics has spanned across almost all aspects of day to day life. Although their uses are invaluable, they contribute to the generation of a lot of waste products that end up in the environment and end up polluting natural habitats such as forests and the ocean. By treating low-density polyethylene (LDPE) samples with non-thermal plasma in ambient air and with an addition of ≈4% CO2, the biodegradation of the samples can be increased due to an increase in oxidative species causing better cell adhesion and acceptance on the polymer sample surface. It was, however, found that the use of this slight addition of CO2 aided in the biodegradation of the LDPE samples more than with solely ambient air as the carbon bonds measured from Raman spectroscopy were seen to decrease even more with this change in gas composition and chemistry. The results show that the largest increase of polymer degradation occurs when a voltage of 32 kV is applied over 300 s and with a mixture of ambient air and CO2 in the ratio 25:1. Full article
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Open AccessArticle
3D-Printed PCL/PLA Composite Stents: Towards a New Solution to Cardiovascular Problems
Materials 2018, 11(9), 1679; https://doi.org/10.3390/ma11091679
Received: 31 July 2018 / Revised: 4 September 2018 / Accepted: 9 September 2018 / Published: 11 September 2018
Cited by 3 | PDF Full-text (3867 KB) | HTML Full-text | XML Full-text
Abstract
Biodegradable stents (BRS) offer enormous potential but first they must meet five specific requirements: (i) their manufacturing process must be precise; (ii) degradation should have minimal toxicity; (iii) the rate of degradation should match the recovery rate of vascular tissue; (iv) ideally, they [...] Read more.
Biodegradable stents (BRS) offer enormous potential but first they must meet five specific requirements: (i) their manufacturing process must be precise; (ii) degradation should have minimal toxicity; (iii) the rate of degradation should match the recovery rate of vascular tissue; (iv) ideally, they should induce rapid endothelialization to restore the functions of vascular tissue, but at the same time reduce the risk of restenosis; and (v) their mechanical behavior should comply with medical requirements, namely, the flexibility required to facilitate placement but also sufficient radial rigidity to support the vessel. Although the first three requirements have been comprehensively studied, the last two have been overlooked. One possible way of addressing these issues would be to fabricate composite stents using materials that have different mechanical, biological, or medical properties, for instance, Polylactide Acid (PLA) or Polycaprolactone (PCL). However, fashioning such stents using the traditional stent manufacturing process known as laser cutting would be impossible. Our work, therefore, aims to produce PCL/PLA composite stents using a novel 3D tubular printer based on Fused Deposition Modelling (FDM). The cell geometry (shape and area) and the materials (PCL and PLA) of the stents were analyzed and correlated with 3T3 cell proliferation, degradation rates, dynamic mechanical and radial expansion tests to determine the best parameters for a stent that will satisfy the five strict BRS requirements. Results proved that the 3D-printing process was highly suitable for producing composite stents (approximately 85–95% accuracy). Both PCL and PLA demonstrated their biocompatibility with PCL stents presenting an average cell proliferation of 12.46% and PLA 8.28% after only 3 days. Furthermore, the PCL/PLA composite stents demonstrated their potential in degradation, dynamic mechanical and expansion tests. Moreover, and regardless of the order of the layers, the composite stents showed (virtually) medium levels of degradation rates and mechanical modulus. Radially, they exhibited the virtues of PCL in the expansion step (elasticity) and those of PLA in the recoil step (rigidity). Results have clearly demonstrated that composite PCL/PLA stents are a highly promising solution to fulfilling the rigorous BRS requirements. Full article
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Open AccessArticle
Effect of Antibacterial Plant Extracts on the Morphology of Electrospun Poly(Lactic Acid) Fibres
Materials 2018, 11(6), 923; https://doi.org/10.3390/ma11060923
Received: 15 May 2018 / Revised: 26 May 2018 / Accepted: 28 May 2018 / Published: 30 May 2018
Cited by 2 | PDF Full-text (3594 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Essential oils (EOs) of clary sage and black pepper induce changes in the morphology of poly(lactic acid) (PLA) electrospun fibres. The chemical composition of the oils is analysed by gas chromatography-mass spectrometry and Fourier-transform infrared spectroscopy; while the evaporation rate of the EOs [...] Read more.
Essential oils (EOs) of clary sage and black pepper induce changes in the morphology of poly(lactic acid) (PLA) electrospun fibres. The chemical composition of the oils is analysed by gas chromatography-mass spectrometry and Fourier-transform infrared spectroscopy; while the evaporation rate of the EOs and their main chemical components is characterised by Thermogravimetric Analysis. The addition of EOs generate thermodynamic instabilities during the electrospinning process, leading to the formation of fibres with either wrinkled (for clary sage oil) or nano-textured surfaces (for black pepper oil). The morphology of the PLA-EOs fibres is investigated by Scanning Electron Microscopy. Together with a well-defined structure, the fibres produced also possess antibacterial activity, as demonstrated by viability loss tests conducted on E. coli and S. epidermidis. Bacteria inactivation efficiency of 76 and 100% is reported for the composite PLA/essential oils electrospun mats. The composite mats produced are promising in the biomedical field, where nanotopography offers physical cues to regulate cell behaviour, and the delivery of therapeutic compounds (essential oils) limits microbial growth. Full article
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Open AccessFeature PaperArticle
Protein-Based Nanoparticle Preparation via Nanoprecipitation Method
Materials 2018, 11(3), 394; https://doi.org/10.3390/ma11030394
Received: 31 January 2018 / Revised: 1 March 2018 / Accepted: 4 March 2018 / Published: 7 March 2018
Cited by 7 | PDF Full-text (10098 KB) | HTML Full-text | XML Full-text
Abstract
Nanoparticles are nowadays largely investigated in the field of drug delivery. Among nanoparticles, protein-based particles are of paramount importance since they are natural, biodegradable, biocompatible, and nontoxic. There are several methods to prepare proteins containing nanoparticles, but only a few studies have been [...] Read more.
Nanoparticles are nowadays largely investigated in the field of drug delivery. Among nanoparticles, protein-based particles are of paramount importance since they are natural, biodegradable, biocompatible, and nontoxic. There are several methods to prepare proteins containing nanoparticles, but only a few studies have been dedicated to the preparation of protein- based nanoparticles. Then, the aim of this work was to report on the preparation of bovine serum albumin (BSA)-based nanoparticles using a well-defined nanoprecipitation process. Special attention has been dedicated to a systematic study in order to understand separately the effect of each operating parameter of the method (such as protein concentration, solvent/non-solvent volume ratio, non-solvent injection rate, ionic strength of the buffer solution, pH, and cross-linking) on the colloidal properties of the obtained nanoparticles. In addition, the mixing processes (batch or drop-wise) were also investigated. Using a well-defined formulation, submicron protein-based nanoparticles have been obtained. All prepared particles have been characterized in terms of size, size distribution, morphology, and electrokinetic properties. In addition, the stability of nanoparticles was investigated using Ultraviolet (UV) scan and electrophoresis, and the optimal conditions for preparing BSA nanoparticles by the nanoprecipitation method were concluded. Full article
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