Special Issue "Environmentally Friendly Polymers and Polymer Composites"

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

Deadline for manuscript submissions: closed (31 December 2019).

Special Issue Editors

Prof. Dr. Rafael Antonio Balart Gimeno
E-Mail Website
Guest Editor
Technological Institute of Materials (ITM), Universitat Politècnica de València (UPV)
Interests: aliphatic polyesters; blends; compatibilization; advanced characterization; functional additives; green composites; biobased materials; circular economy
Special Issues and Collections in MDPI journals
Prof. Dr. Nestor Montañés Muñoz
E-Mail Website
Guest Editor
Technological Institute of Materials (ITM), Universitat Politècnica de València (UPV)
Interests: FESEM & TEM characterization; polymer processing; polyester; compatibilizer; environmentally friendly additives; wood plastic composites; extrusion
Special Issues and Collections in MDPI journals
Dr. Franco Dominici
E-Mail Website
Guest Editor
Dipartimento di Ingegneria Civile e Ambientale, Università di Perugia, Italy
Interests: high performance polymers; nanoparticle additives for plastic formulations; biodegradation of polymers; polymer composites
Prof. Dr. Sergio Torres-Giner
E-Mail Website
Guest Editor
Novel Materials and Nanotechnology Group, Institute of Agrochemistry and Food Technology (IATA), Spanish Council for Scientific Research (CSIC), Paterna 46980, Spain
Interests: bio-based and biodegradable polymers; green composites; polymerization of biopolymers; processing of bioplastics; sustainable polymer technologies; nanofibers obtained by electrospinning; controlled release of active compounds in plastic formulations; biopolymers for food packaging applications; plastics towards a Circular Economy
Special Issues and Collections in MDPI journals
Prof. Dr. Teodomiro Boronat Vitoria
E-Mail Website
Guest Editor
Technological Institute of Materials (ITM), Universitat Politècnica de València (UPV)
Interests: polymer manufacturing; rheology; injection moulding; mathematical modeling; Thermal characterizacion
Special Issues and Collections in MDPI journals

Special Issue Information

Dear Colleagues,

In the last few years, the problems related to plastic wastes have been aggravated. Conventional plastics are obtained from fossil fuels and are not, in general, biodegradable (or disintegrable in controlled compost soil). Our society is, every day, much more sensitive with regards to the environment and topics such as petroleum depletion, sustainable development, Circular Economy, waste management, and related issues, are gaining relevance.

For these reasons, important research in the field of environmental-friendly polymers and polymer composites has been observed in the last decade. These investigations include a wide range of materials that show environmental efficiency at different stages of the Life Cycle. e.g., only at the origin (polymers from renewable resources such as bio-based polyethylene-bioPE, polyamides-bioPA, polycarbonate-bioPC, and others), and only at the end (disintegrable petroleum-derived polymers, such as poly e-caprolactone-PCL, polyvinyl alcohol-PVA, polyglycolic acid-PGA, polybutylene succinate-PBS and copolymers).

In addition, important research is being conducted from a third stand point, which considers environmental efficiency at both the origin and the end of the Life Cycle. These investigations include the potential of polysaccharide-derived polymers (starch, cellulose, quitin and their derivatives such as starch-derived PLA, quitosan, and so on). Moreover, research on protein-based polymer formulations is also an interesting challenge for the polymer and composites industries as natural proteins, such as gluten, casein, ovalbumin, and collagen could be potentially used in industrial formulations. Finally, the industrial use of bacterial polyesters such as polyhydroxybutyrate-PHB, polyhydroxybutyrate-co-valerate-PHBV and other polyhydroxyalkanoates-PHAs, represents a challenging topic.

This Special Issue is intended to compile the most recent research works in any polymer or polymer composite with a marked environmental efficiency with the main aim of using them at industrial scale. Research on any biobased polymer, biodegradable polymer or both biobased/biodegradable polymer (and new additives or blends) is welcome. All manufacturing processes, e.g., injection molding, extrusion, electrospinning, cast film, melt spinning, rotational moulding, hot-press moulding, 3D printing, and so on, fit this Special Issue and could help to reveal the real potential of these materials. In addition, original research on polymer-based composites in which, the matrix, the reinforcement/filler or both could be obtained from renewable resources is welcome, e.g., research on natural fiber reinforced plastics (NFRPs) and wood plastic composites (WPCs).

The potential transfer of this research to industry could only be possible by increasing our knowledge about these materials, which includes an in depth knowledge of their mechanical properties (mathematical models and simulation), thermal behavior, use of environmentally friendly additives and fillers, advanced morphology characterization, manufacturing conditions and optimization of the processing window, rheology studies, compatibilization, interface phenomena, degradation/biodegradation and its kinetics, functional additives, and so on.

We hope all the research works included in this Special Issue help scientist to transfer new materials for industrial purposes, as well as to give an overall view of the potential of these environmentally friendly materials.

Prof. Dr. Rafael Balart
Prof. Dr. Nestor Montanes
Dr. Franco Dominici
Prof. Dr. Sergio Torres-Giner
Prof. Dr. Teodomiro Boronat Vitoria
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 2000 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

  • Environmentally friendly
  • Bio-based polymers
  • Natural fiber reinforced polymers (NFRPs)
  • Wood plastic composites (WPCs)
  • Petroleum-derived biodegradable polyesters
  • Polysaccharide-derived polymers and composites
  • Protein-derived polymers and composites
  • Bacterial polyesters and composites
  • Biobased additives and fillers
  • Characterization (mechanical, thermal, electrical, piezoelectric, physical, chemical, morphology, etc.)
  • Manufacturing (injection moulding, extrusion, reactive extrusion, 3D printing, melt spinning, rotational moulding, electrospinning, thermoforming, hot-press moulding, etc.)
  • Engineering parts, films, fibers, components

Published Papers (15 papers)

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Open AccessArticle
Improved Toughness in Lignin/Natural Fiber Composites Plasticized with Epoxidized and Maleinized Linseed Oils
Materials 2020, 13(3), 600; https://doi.org/10.3390/ma13030600 - 28 Jan 2020
Abstract
The use of maleinized (MLO) and epoxidized (ELO) linseed oils as potential biobased plasticizers for lignin/natural fiber composites formulations with improved toughness was evaluated. Arboform®, a lignin/natural fiber commercial composite, was used as a reference matrix for the formulations. The plasticizer [...] Read more.
The use of maleinized (MLO) and epoxidized (ELO) linseed oils as potential biobased plasticizers for lignin/natural fiber composites formulations with improved toughness was evaluated. Arboform®, a lignin/natural fiber commercial composite, was used as a reference matrix for the formulations. The plasticizer content varied in the range 0–15 wt % and mechanical, thermal and morphological characterizations were used to assess the potential of these environmentally friendly modifiers. Results from impact tests show a general increase in the impact-absorbed energy for all the samples modified with bio-oils. The addition of 2.5 wt % of ELO to Arboform (5.4 kJ/m2) was able to double the quantity of absorbed energy (11.1 kJ/m2) and this value slightly decreased for samples containing 5 and 10 wt %. A similar result was obtained with the addition of MLO at 5 wt %, with an improvement of 118%. The results of tensile and flexural tests also show that ELO and MLO addition increased the tensile strength as the percentage of both oils increased, even if higher values were obtained with lower percentages of maleinized oil due to the possible presence of ester bonds formed between multiple maleic groups present in MLO and the hydroxyl groups of the matrix. Thermal characterization confirmed that the mobility of polymer chains was easier in the presence of ELO molecules. On the other hand, MLO presence delayed the crystallization event, predominantly acting as an anti-nucleating agent, interrupting the folding or packing process. Both chemically modified vegetable oils also efficiently improved the thermal stability of the neat matrix. Full article
(This article belongs to the Special Issue Environmentally Friendly Polymers and Polymer Composites)
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Open AccessArticle
Development and Characterization of Bacterial Cellulose Reinforced with Natural Rubber
Materials 2019, 12(14), 2323; https://doi.org/10.3390/ma12142323 - 21 Jul 2019
Abstract
Films of bacterial cellulose (BC) reinforced by natural rubber (NR) with remarkably high mechanical strength were developed by combining the prominent mechanical properties of multilayer BC nanofibrous structural networks and the high elastic hydrocarbon polymer of NR. BC pellicle was immersed in a [...] Read more.
Films of bacterial cellulose (BC) reinforced by natural rubber (NR) with remarkably high mechanical strength were developed by combining the prominent mechanical properties of multilayer BC nanofibrous structural networks and the high elastic hydrocarbon polymer of NR. BC pellicle was immersed in a diluted NR latex (NRL) suspension in the presence of ethanol aqueous solution. Effects of NRL concentrations (0.5%–10% dry rubber content, DRC) and immersion temperatures (30–70 °C) on the film characteristics were studied. It was revealed that the combination of nanocellulose fibrous networks and NR polymer provided a synergistic effect on the mechanical properties of NR–BC films. In comparison with BC films, the tensile strength and elongation at break of the NR–BC films were considerably improved ~4-fold. The NR–BC films also exhibited improved water resistance over that of BC films and possessed a high resistance to non-polar solvents such as toluene. NR–BC films were biodegradable and could be degraded completely within 5–6 weeks in soil. Full article
(This article belongs to the Special Issue Environmentally Friendly Polymers and Polymer Composites)
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Open AccessArticle
Reactive Melt Mixing of Poly(3-Hydroxybutyrate)/Rice Husk Flour Composites with Purified Biosustainably Produced Poly(3-Hydroxybutyrate-co-3-Hydroxyvalerate)
Materials 2019, 12(13), 2152; https://doi.org/10.3390/ma12132152 - 04 Jul 2019
Cited by 2
Abstract
Novel green composites based on commercial poly(3-hydroxybutyrate) (PHB) filled with 10 wt % rice husk flour (RHF) were melt-compounded in a mini-mixer unit using triglycidyl isocyanurate (TGIC) as compatibilizer and dicumyl peroxide (DCP) as initiator. Purified poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) produced by mixed [...] Read more.
Novel green composites based on commercial poly(3-hydroxybutyrate) (PHB) filled with 10 wt % rice husk flour (RHF) were melt-compounded in a mini-mixer unit using triglycidyl isocyanurate (TGIC) as compatibilizer and dicumyl peroxide (DCP) as initiator. Purified poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) produced by mixed bacterial cultures derived from fruit pulp waste was then incorporated into the green composite in contents in the 5–50 wt % range. Films for testing were obtained thereafter by thermo-compression and characterized. Results showed that the incorporation of up to 20 wt % of biowaste derived PHBV yielded green composite films with a high contact transparency, relatively low crystallinity, high thermal stability, improved mechanical ductility, and medium barrier performance to water vapor and aroma. This study puts forth the potential use of purified biosustainably produced PHBV as a cost-effective additive to develop more affordable and waste valorized food packaging articles. Full article
(This article belongs to the Special Issue Environmentally Friendly Polymers and Polymer Composites)
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Open AccessArticle
The Use of Cashew Nut Shell Liquid (CNSL) in PP/HIPS Blends: Morphological, Thermal, Mechanical and Rheological Properties
Materials 2019, 12(12), 1904; https://doi.org/10.3390/ma12121904 - 13 Jun 2019
Abstract
Polypropylene (PP) and high impact polystyrene (HIPS) are two polymers that are frequently found in disposable waste. Both of these polymers are restricted from being separated in several ways. An easier way to reuse them in new applications, without the need for separation, [...] Read more.
Polypropylene (PP) and high impact polystyrene (HIPS) are two polymers that are frequently found in disposable waste. Both of these polymers are restricted from being separated in several ways. An easier way to reuse them in new applications, without the need for separation, would require them to be less immiscible. In this work, cashew nut shell liquid (CNSL), a sub-product of the cashew agroindustry, was added as a third component to PP-HIPS mixtures and its effect as a compatibilizing agent was investigated. Morphological results showed that CNSL acted as an emulsifier by promoting reduction in the domains of the dispersive phase, HIPS, thus stabilizing the blends morphology. Differential scanning calorimetry (DSC) analysis suggests that CNSL is preferably incorporated in the HIPS phase. Its plasticizing effect leads to more flexible materials, but no significant effect could be detected on impact resistance or elongation at break. Full article
(This article belongs to the Special Issue Environmentally Friendly Polymers and Polymer Composites)
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Open AccessArticle
Optimization of the Loading of an Environmentally Friendly Compatibilizer Derived from Linseed Oil in Poly(Lactic Acid)/Diatomaceous Earth Composites
Materials 2019, 12(10), 1627; https://doi.org/10.3390/ma12101627 - 17 May 2019
Cited by 2
Abstract
Maleinized linseed oil (MLO) has been successfully used as biobased compatibilizer in polyester blends. Its efficiency as compatibilizer in polymer composites with organic and inorganic fillers, compared to other traditional fillers, has also been proved. The goal of this work is to optimize [...] Read more.
Maleinized linseed oil (MLO) has been successfully used as biobased compatibilizer in polyester blends. Its efficiency as compatibilizer in polymer composites with organic and inorganic fillers, compared to other traditional fillers, has also been proved. The goal of this work is to optimize the amount of MLO on poly(lactic acid)/diatomaceous earth (PLA/DE) composites to open new potential to these materials in the active packaging industry without compromising the environmental efficiency of these composites. The amount of DE remains constant at 10 wt% and MLO varies from 1 to 15 phr (weight parts of MLO per 100 g of PLA/DE composite). The effect of MLO on mechanical, thermal, thermomechanical and morphological properties is described in this work. The obtained results show a clear embrittlement of the uncompatibilized PLA/DE composites, which is progressively reduced by the addition of MLO. MLO shows good miscibility at low concentrations (lower than 5 phr) while above 5 phr, a clear phase separation phenomenon can be detected, with the formation of rounded microvoids and shapes which have a positive effect on impact strength. Full article
(This article belongs to the Special Issue Environmentally Friendly Polymers and Polymer Composites)
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Open AccessArticle
Origanum majorana L. Essential Oil-Associated Polymeric Nano Dendrimer for Antifungal Activity against Phytophthora infestans
Materials 2019, 12(9), 1446; https://doi.org/10.3390/ma12091446 - 04 May 2019
Cited by 1
Abstract
In this study, the introduction of Origanum majorana L. essential oil into a polyamidoamine (PAMAM) G4.0 dendrimer was performed for creation of a potential nanocide against Phytophthora infestans. The characteristics of marjoram oil and PAMAM G4.0 was analyzed using transmission electron spectroscopy [...] Read more.
In this study, the introduction of Origanum majorana L. essential oil into a polyamidoamine (PAMAM) G4.0 dendrimer was performed for creation of a potential nanocide against Phytophthora infestans. The characteristics of marjoram oil and PAMAM G4.0 was analyzed using transmission electron spectroscopy (TEM), nuclear magnetic resonance spectroscopy (1H-NMR) and gas chromatography mass spectrometry (GC-MS). The success of combining marjoram oil with PAMAM G4.0 was evaluated by FT-IR, TGA analysis, and the antifungal activity of this system was also investigated. The results showed that the antifungal activity of oil/PAMAM G4.0 was high and significantly higher than only PAMAM G4.0 or marjoram essential oil. These results indicated that the nanocide oil/PAMAM G4.0 helped strengthen and prolong the antifungal properties of the oil. Full article
(This article belongs to the Special Issue Environmentally Friendly Polymers and Polymer Composites)
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Open AccessArticle
The Influence of Non-Uniformities on the Mechanical Behavior of Hemp-Reinforced Composite Materials with a Dammar Matrix
Materials 2019, 12(8), 1232; https://doi.org/10.3390/ma12081232 - 15 Apr 2019
Abstract
As a result of manufacture, composite materials can appear to have variations to their properties due to the existence of structural changes. In this paper, we studied the influence of material irregularity on the mechanical behavior of two categories of bars for which [...] Read more.
As a result of manufacture, composite materials can appear to have variations to their properties due to the existence of structural changes. In this paper, we studied the influence of material irregularity on the mechanical behavior of two categories of bars for which we have used hemp fabric as a reinforcing material. The common matrix is a hybrid resin based on Dammar and epoxy resin. We molded two types of bars within each of the previously mentioned categories. The first type, also called “ideal bar”, was made of layers in which the volume proportion and the orientation of the reinforcing material was the same in each section. The ideal bar does not show variations of mechanical properties along it. The second type of bar was molded to have one or two layers where, between certain sections, the reinforcing material was interrupted in several segments. We have determined some mechanical properties, the characteristic curves (strain-stress), the tensile strength, and elongation at break for all the sample sets on trial. Moreover, we have studied the influence of the non-uniformities on the mechanical behavior of the composites by entering certain quality factors that have been calculated after experimental determinations. Full article
(This article belongs to the Special Issue Environmentally Friendly Polymers and Polymer Composites)
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Open AccessFeature PaperArticle
Chitosan Nanoparticles Rescue Rotenone-Mediated Cell Death
Materials 2019, 12(7), 1176; https://doi.org/10.3390/ma12071176 - 11 Apr 2019
Abstract
The aim of the present investigation was to study the anti-oxidant effect of chitosan nanoparticles on a human SH-SY5Y neuroblastoma cell line using a rotenone model to generate reactive oxygen species. Chitosan nanoparticles were synthesized using an ionotropic gelation method. The obtained nanoparticles [...] Read more.
The aim of the present investigation was to study the anti-oxidant effect of chitosan nanoparticles on a human SH-SY5Y neuroblastoma cell line using a rotenone model to generate reactive oxygen species. Chitosan nanoparticles were synthesized using an ionotropic gelation method. The obtained nanoparticles were characterized using various analytical techniques such as Dynamic Light Scattering, Scanning Electron Microscopy, Transmission Electron Microscopy, Fourier Transmission Infrared spectroscopy and Atomic Force Microscopy. Incubation of SH-SY5Y cells with 50 µM rotenone resulted in 35–50% cell death within 24 h of incubation time. Annexin V/Propidium iodide dual staining verified that the majority of neuronal cell death occurred via the apoptotic pathway. The incubation of cells with chitosan nanoparticles reduced rotenone-initiated cytotoxicity and apoptotic cell death. Given that rotenone insult to cells causes oxidative stress, our results suggest that Chitosan nanoparticles have antioxidant and anti-apoptotic properties. Chitosan can not only serve as a novel therapeutic drug in the near future but also as a carrier for combo-therapy. Full article
(This article belongs to the Special Issue Environmentally Friendly Polymers and Polymer Composites)
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Open AccessArticle
Size Distribution and Characteristics of Chitin Microgels Prepared via Emulsified Reverse-Micelles
Materials 2019, 12(7), 1160; https://doi.org/10.3390/ma12071160 - 10 Apr 2019
Abstract
Chitin was extracted from local snow crab shell waste and used as a raw material in the fabrication of porous spherical microgels. The chitin microgels were obtained using a batch process of emulsification and, afterward, gelation. The effects of chitin concentrations, oil and [...] Read more.
Chitin was extracted from local snow crab shell waste and used as a raw material in the fabrication of porous spherical microgels. The chitin microgels were obtained using a batch process of emulsification and, afterward, gelation. The effects of chitin concentrations, oil and water phase ratios (O:W), surfactants, and gelation on the size distribution and morphology of the microgels were investigated. The extracted chitin possessed α-chitin with a degree of acetylation of ~60% and crystallinity of 70%, as confirmed by Fourier Transform Infrared Spectroscopy (FTIR) and X-Ray Powder Diffraction (XRD). In the reverse-micellar emulsification, different chitin concentrations in NaOH solution were used as aqueous phases, and n-hexane media containing Span 80-based surfactants were used as dispersion phases. Various HCl solutions were used as gelling agents. Microgels with sizes ranging from ~5–200 μm were obtained relying on these studied parameters. Under the condition of 3% w/w chitin solution using O:W of 15:1 at 5% w/w of Span 80 (hydrophilic-lipophilic balance; HLB of 4.3), the gelation in the emulsified reverse micelles was better controlled and capable of forming spherical microgel particles with a size of 7.1 ± 0.3 μm, when 800 μL of 1 M HCl was added. The prepared chitin microgel exhibited macro-pore morphology and swelling behavior sensitive to the acidic pH. Full article
(This article belongs to the Special Issue Environmentally Friendly Polymers and Polymer Composites)
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Open AccessArticle
Fully Biodegradable Composites: Thermal, Flammability, Moisture Absorption and Mechanical Properties of Natural Fibre-Reinforced Composites with Nano-Hydroxyapatite
Materials 2019, 12(7), 1145; https://doi.org/10.3390/ma12071145 - 08 Apr 2019
Cited by 3
Abstract
Natural fibre-reinforced poly(lactic acid) (PLA) laminates were prepared by a conventional film stacking method from PLA films and natural fabrics with a cross ply layup of [0/90/0/90/0/90], followed by hot compression. Natural fibre (NF) nano-hydroxyapatite (nHA) filled composites were produced by the same [...] Read more.
Natural fibre-reinforced poly(lactic acid) (PLA) laminates were prepared by a conventional film stacking method from PLA films and natural fabrics with a cross ply layup of [0/90/0/90/0/90], followed by hot compression. Natural fibre (NF) nano-hydroxyapatite (nHA) filled composites were produced by the same manufacturing technique with matrix films that had varying concentrations of nHA in the PLA. Their flammability, thermal, moisture absorption and mechanical properties were analysed in terms of the amount of nHA. The flame behavior of neat PLA and composites evaluated by the UL-94 test demonstrated that only the composite containing the highest quantity of nHA (i.e., 40 wt% nHA in matrix) was found to achieve an FH-1 rating and exhibited no recorded burn rate, whereas other composites obtained only an FH-3. The thermal degradation temperature and mass residue were also observed, via thermogravimetric analysis, to increase when increasing concentrations of nHA were added to the NF composite. The tensile strength, tensile modulus and flexural modulus of the neat resin were found to increase significantly with the introduction of flax fibre. Conversely, moisture absorption was found to increase and mechanical properties to decrease with both the presence of NF and increasing concentrations of nHA, and subsequent mechanical properties experienced an obvious reduction. Full article
(This article belongs to the Special Issue Environmentally Friendly Polymers and Polymer Composites)
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Open AccessArticle
Optimization of Maleinized Linseed Oil Loading as a Biobased Compatibilizer in Poly(Butylene Succinate) Composites with Almond Shell Flour
Materials 2019, 12(5), 685; https://doi.org/10.3390/ma12050685 - 26 Feb 2019
Cited by 1
Abstract
Green composites of poly(butylene succinate) (PBS) were manufactured with almond shell flour (ASF) by reactive compatibilization with maleinized linseed oil *MLO) by extrusion and subsequent injection molding. ASF was kept constant at 30 wt %, while the effect of different MLO loading on [...] Read more.
Green composites of poly(butylene succinate) (PBS) were manufactured with almond shell flour (ASF) by reactive compatibilization with maleinized linseed oil *MLO) by extrusion and subsequent injection molding. ASF was kept constant at 30 wt %, while the effect of different MLO loading on mechanical, thermal, thermomechanical, and morphology properties was studied. Uncompatibilized PBS/ASF composites show a remarkable decrease in mechanical properties due to the nonexistent polymer‒filler interaction, as evidenced by field emission scanning electron microscopy (FESEM). MLO provides a plasticization effect on PBS/ASF composites but, in addition, acts as a compatibilizer agent since the maleic anhydride groups contained in MLO are likely to react with hydroxyl groups in both PBS end chains and ASF particles. This compatibilizing effect is observed by FESEM with a reduction of the gap between the filler particles and the surrounding PBS matrix. In addition, the Tg of PBS increases from −28 °C to −12 °C with an MLO content of 10 wt %, thus indicating compatibilization. MLO has been validated as an environmentally friendly additive to PBS/ASF composites to give materials with high environmental efficiency. Full article
(This article belongs to the Special Issue Environmentally Friendly Polymers and Polymer Composites)
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Open AccessFeature PaperArticle
Toughened Poly (Lactic Acid)—PLA Formulations by Binary Blends with Poly(Butylene Succinate-co-Adipate)—PBSA and Their Shape Memory Behaviour
Materials 2019, 12(4), 622; https://doi.org/10.3390/ma12040622 - 19 Feb 2019
Cited by 4
Abstract
This study reports the effect of poly(butylene succinate-co-adipate) (PBSA) on the mechanical performance and shape memory behavior of poly(lactic acid) (PLA) specimens that were manufactured by injection molding and hot-press molding. The poor miscibility between PLA and PBSA was minimized by [...] Read more.
This study reports the effect of poly(butylene succinate-co-adipate) (PBSA) on the mechanical performance and shape memory behavior of poly(lactic acid) (PLA) specimens that were manufactured by injection molding and hot-press molding. The poor miscibility between PLA and PBSA was minimized by the addition of an epoxy styrene-acrylic oligomer (ESAO), which was commercially named Joncryl®. It was incorporated during the extrusion process. Tensile, impact strength, and hardness tests were carried out following international standards. PLA/PBSA blends with improved mechanical properties were obtained, which highlighted the sample that was compatibilized with ESAO, leading to a remarkable enhancement in elongation at break, but showing poor shape memory behaviour. Field Emission Scanning Electron Microscopy (FESEM) images showed how the ductile properties were improved, while PBSA loading increased, thus leading to minimizing the brittleness of neat PLA. The differential scanning calorimetry (DSC) analysis revealed the low miscibility between these two polymers and the improving effect of PBSA in PLA crystallization. The bending test carried out on the sheets of PLA/PBSA blends showed the direct influence that the PBSA has on the reduction of the shape memory that is intrinsically offered by neat PLA. Full article
(This article belongs to the Special Issue Environmentally Friendly Polymers and Polymer Composites)
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Open AccessArticle
The Effect of Varying Almond Shell Flour (ASF) Loading in Composites with Poly(Butylene Succinate (PBS) Matrix Compatibilized with Maleinized Linseed Oil (MLO)
Materials 2018, 11(11), 2179; https://doi.org/10.3390/ma11112179 - 03 Nov 2018
Cited by 3
Abstract
In this work poly(butylene succinate) (PBS) composites with varying loads of almond shell flour (ASF) in the 10–50 wt % were manufactured by extrusion and subsequent injection molding thus showing the feasibility of these combined manufacturing processes for composites up to 50 wt [...] Read more.
In this work poly(butylene succinate) (PBS) composites with varying loads of almond shell flour (ASF) in the 10–50 wt % were manufactured by extrusion and subsequent injection molding thus showing the feasibility of these combined manufacturing processes for composites up to 50 wt % ASF. A vegetable oil-derived compatibilizer, maleinized linseed oil (MLO), was used in PBS/ASF composites with a constant ASF to MLO (wt/wt) ratio of 10.0:1.5. Mechanical properties of PBS/ASF/MLO composites were obtained by standard tensile, hardness, and impact tests. The morphology of these composites was studied by field emission scanning electron microscopy—FESEM) and the main thermal properties were obtained by differential scanning calorimetry (DSC), dynamical mechanical-thermal analysis (DMTA), thermomechanical analysis (TMA), and thermogravimetry (TGA). As the ASF loading increased, a decrease in maximum tensile strength could be detected due to the presence of ASF filler and a plasticization effect provided by MLO which also provided a compatibilization effect due to the interaction of succinic anhydride polar groups contained in MLO with hydroxyl groups in both PBS (hydroxyl terminal groups) and ASF (hydroxyl groups in cellulose). FESEM study reveals a positive contribution of MLO to embed ASF particles into the PBS matrix, thus leading to balanced mechanical properties. Varying ASF loading on PBS composites represents an environmentally-friendly solution to broaden PBS uses at the industrial level while the use of MLO contributes to overcome or minimize the lack of interaction between the hydrophobic PBS matrix and the highly hydrophilic ASF filler. Full article
(This article belongs to the Special Issue Environmentally Friendly Polymers and Polymer Composites)
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Open AccessArticle
Ductility and Toughness Improvement of Injection-Molded Compostable Pieces of Polylactide by Melt Blending with Poly(ε-caprolactone) and Thermoplastic Starch
Materials 2018, 11(11), 2138; https://doi.org/10.3390/ma11112138 - 30 Oct 2018
Cited by 7
Abstract
The present study describes the preparation and characterization of binary and ternary blends based on polylactide (PLA) with poly(ε-caprolactone) (PCL) and thermoplastic starch (TPS) to develop fully compostable plastics with improved ductility and toughness. To this end, PLA was first melt-mixed in a [...] Read more.
The present study describes the preparation and characterization of binary and ternary blends based on polylactide (PLA) with poly(ε-caprolactone) (PCL) and thermoplastic starch (TPS) to develop fully compostable plastics with improved ductility and toughness. To this end, PLA was first melt-mixed in a co-rotating twin-screw extruder with up to 40 wt % of different PCL and TPS combinations and then shaped into pieces by injection molding. The mechanical, thermal, and thermomechanical properties of the resultant binary and ternary blend pieces were analyzed and related to their composition. Although the biopolymer blends were immiscible, the addition of both PCL and TPS remarkably increased the flexibility and impact strength of PLA while it slightly reduced its mechanical strength. The most balanced mechanical performance was achieved for the ternary blend pieces that combined high PCL contents with low amounts of TPS, suggesting a main phase change from PLA/TPS (comparatively rigid) to PLA/PCL (comparatively flexible). The PLA-based blends presented an “island-and-sea” morphology in which the TPS phase contributed to the fine dispersion of PCL as micro-sized spherical domains that acted as a rubber-like phase with the capacity to improve toughness. In addition, the here-prepared ternary blend pieces presented slightly higher thermal stability and lower thermomechanical stiffness than the neat PLA pieces. Finally, all biopolymer pieces fully disintegrated in a controlled compost soil after 28 days. Therefore, the inherently low ductility and toughness of PLA can be successfully improved by melt blending with PCL and TPS, resulting in compostable plastic materials with a great potential in, for instance, rigid packaging applications. Full article
(This article belongs to the Special Issue Environmentally Friendly Polymers and Polymer Composites)
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Review

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Open AccessReview
Recent Trends in the Use of Pectin from Agro-Waste Residues as a Natural-Based Biopolymer for Food Packaging Applications
Materials 2020, 13(3), 673; https://doi.org/10.3390/ma13030673 - 03 Feb 2020
Abstract
Regardless of the considerable progress in properties and versatility of synthetic polymers, their low biodegradability and lack of environmentally-friendly character remains a critical issue. Pectin is a natural-based polysaccharide contained in the cell walls of many plants allowing their growth and cell extension. [...] Read more.
Regardless of the considerable progress in properties and versatility of synthetic polymers, their low biodegradability and lack of environmentally-friendly character remains a critical issue. Pectin is a natural-based polysaccharide contained in the cell walls of many plants allowing their growth and cell extension. This biopolymer can be extracted from plants and isolated as a bioplastic material with different applications, including food packaging. This review aims to present the latest research results regarding pectin, including the structure, different types, natural sources and potential use in several sectors, particularly in food packaging materials. Many researchers are currently working on a multitude of food and beverage industry applications related to pectin as well as combinations with other biopolymers to improve some key properties, such as antioxidant/antimicrobial performance and flexibility to obtain films. All these advances are covered in this review. Full article
(This article belongs to the Special Issue Environmentally Friendly Polymers and Polymer Composites)
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