Sustainable Plastics

A topical collection in Polymers (ISSN 2073-4360). This collection belongs to the section "Polymer Chemistry".

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Editors

Polymers and Advanced Materials Group (PIMA), School of Technology and Experimental Sciences, Universitat Jaume I (UJI), Avenida de Vicent Sos Baynat s/n, 12071 Castellón, Spain
Interests: biodegradable polymers; biopolyesters; food packaging; nanocomposites; polymer processing
Special Issues, Collections and Topics in MDPI journals
Food Engineering Research Institute (FoodUPV), Universitat Politècnica de València (UPV), Camino de Vera s/n, 46022 Valencia, Spain
Interests: bio-based and biodegradable polymers; green composites; polymerization of biopolymers; processing of bioplastics; nanofibers obtained by electrospinning; sustainable polymer technologies for food preservation; controlled release of active compounds in plastic formulations; biopolymers for food packaging; bioeconomy; circular economy
Special Issues, Collections and Topics in MDPI journals

Topical Collection Information

Dear Colleagues,

Sustainable plastics comprise a whole family of biopolymers and additives. Biopolymers are materials that are either partly or fully derived from biomass, are biodegradable, or feature both properties. Bioplastics offer advantages compared to conventional petrochemical plastics in that they save fossil resources by using natural resources that regenerate annually and provide the unique potential of carbon neutrality. Furthermore, biodegradability is an add-on property of certain types of bioplastics that offers a sustainable means of recovery at the end of a product’s life. Moreover, the use of natural additives has been currently envisioned as a safe and environmentally friendly alternative to replace synthetic ones. As a result, by now, a large number of different sustainable plastics have been developed and have entered different markets, particularly in food packaging and disposable applications. Nevertheless, market shares of these bioplastics are in most areas still negligible since high production costs impair price competitiveness in relation to their fossil-derived counterparts. Therefore, to compensate for current disadvantages in pricing, it is essential that bio-based materials are superior with respect to sustainability considerations. This requires detailed and deep environmental analyses, from polymerization to end-of-life options, that also include the whole value chains.

Under the prevailing technologies, feedstock cultivation is one of the critical factors due to its various and potentially significant ecological impacts. Based on their development status, bioplastics feedstocks have generally been divided into first, second, and third generations according to their development stage. First-generation feedstocks are usually carbohydrate-rich plants that are also suitable as food or animal feed, e.g., corn and sugarcane. Although these feedstocks currently offer the highest yields, their cultivation is a critical factor due to intensive agriculture and the resulting negative competitiveness with human feeding. Against this background, second- and third-generation feedstocks have been proposed in recent years. The second generation includes feedstocks that are not suitable for food or animal feed, which can be either nonfood crops (e.g., cellulose) or by-products from first-generation feedstocks (e.g., corn stover or sugarcane bagasse). The third generation includes the currently most innovative feedstocks, which are still at an early stage of development. It comprises the most novel forms of feedstock extractions from a range of substrates like whey, industrial and municipal waste, or algae. However, all these feedstocks thus require specific forms of treatment and imply highly heterogeneous production chains. As a consequence, one cannot instantly classify them as more or less sustainable than the currently dominating first generation. Instead, an evaluation of their environmental performances requires careful analysis.

This collection covers all topics related to the science and technology of bioplastics, including the novel feedstocks, polymerization processes, characterization, and final applications, as well as life cycle analysis. Research articles and reviews on biopolymers and natural additives will be considered for this collection with the main aim of sharing a collection of cutting-edge technology research related to sustainable plastics.

Dr. Luis Cabedo Mas
Prof. Dr. Sergio Torres-Giner
Collection Editors

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Keywords

  • Biopolymers
  • Natural additives
  • Polymer feedstock cultivation
  • Compostable plastics
  • Life cycle analysis
  • Sustainable food packaging
  • Biodegradable disposables

Published Papers (7 papers)

2023

Jump to: 2022, 2021

26 pages, 3211 KiB  
Review
Understanding the Impact of Biodegradable Microplastics on Living Organisms Entering the Food Chain: A Review
by Konstantin V. Malafeev, Annalisa Apicella, Loredana Incarnato and Paola Scarfato
Polymers 2023, 15(18), 3680; https://doi.org/10.3390/polym15183680 - 06 Sep 2023
Cited by 6 | Viewed by 2127
Abstract
Microplastics (MPs) pollution has emerged as one of the world’s most serious environmental issues, with harmful consequences for ecosystems and human health. One proposed solution to their accumulation in the environment is the replacement of nondegradable plastics with biodegradable ones. However, due to [...] Read more.
Microplastics (MPs) pollution has emerged as one of the world’s most serious environmental issues, with harmful consequences for ecosystems and human health. One proposed solution to their accumulation in the environment is the replacement of nondegradable plastics with biodegradable ones. However, due to the lack of true biodegradability in some ecosystems, they also give rise to biodegradable microplastics (BioMPs) that negatively impact different ecosystems and living organisms. This review summarizes the current literature on the impact of BioMPs on some organisms—higher plants and fish—relevant to the food chain. Concerning the higher plants, the adverse effects of BioMPs on seed germination, plant biomass growth, penetration of nutrients through roots, oxidative stress, and changes in soil properties, all leading to reduced agricultural yield, have been critically discussed. Concerning fish, it emerged that BioMPs are more likely to be ingested than nonbiodegradable ones and accumulate in the animal’s body, leading to impaired skeletal development, oxidative stress, and behavioral changes. Therefore, based on the reviewed pioneering literature, biodegradable plastics seem to be a new threat to environmental health rather than an effective solution to counteract MP pollution, even if serious knowledge gaps in this field highlight the need for additional rigorous investigations to understand the potential risks associated to BioMPs. Full article
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20 pages, 9743 KiB  
Article
Incorporation of Argan Shell Flour in a Biobased Polypropylene Matrix for the Development of High Environmentally Friendly Composites by Injection Molding
by María Jordà-Reolid, Virginia Moreno, Asunción Martínez-Garcia, José A. Covas, Jaume Gomez-Caturla, Juan Ivorra-Martinez and Luis Quiles-Carrillo
Polymers 2023, 15(12), 2743; https://doi.org/10.3390/polym15122743 - 20 Jun 2023
Cited by 1 | Viewed by 1159
Abstract
In this study, a new composite material is developed using a semi bio-based polypropylene (bioPP) and micronized argan shell (MAS) byproducts. To improve the interaction between the filler and the polymer matrix, a compatibilizer, PP-g-MA, is used. The samples are prepared using a [...] Read more.
In this study, a new composite material is developed using a semi bio-based polypropylene (bioPP) and micronized argan shell (MAS) byproducts. To improve the interaction between the filler and the polymer matrix, a compatibilizer, PP-g-MA, is used. The samples are prepared using a co-rotating twin extruder followed by an injection molding process. The addition of the MAS filler improves the mechanical properties of the bioPP, as evidenced by an increase in tensile strength from 18.2 MPa to 20.8 MPa. The reinforcement is also observed in the thermomechanical properties, with an increased storage modulus. The thermal characterization and X-ray diffraction indicate that the addition of the filler leads to the formation of α structure crystals in the polymer matrix. However, the addition of a lignocellulosic filler also leads to an increased affinity for water. As a result, the water uptake of the composites increases, although it remains relatively low even after 14 weeks. The water contact angle is also reduced. The color of the composites changes to a color similar to wood. Overall, this study demonstrates the potential of using MAS byproducts to improve their mechanical properties. However, the increased affinity with water should be taken into account in potential applications. Full article
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2022

Jump to: 2023, 2021

24 pages, 4857 KiB  
Article
Development and Characterization of Fully Renewable and Biodegradable Polyhydroxyalkanoate Blends with Improved Thermoformability
by Patricia Feijoo, Kerly Samaniego-Aguilar, Estefanía Sánchez-Safont, Sergio Torres-Giner, Jose M. Lagaron, Jose Gamez-Perez and Luis Cabedo
Polymers 2022, 14(13), 2527; https://doi.org/10.3390/polym14132527 - 21 Jun 2022
Cited by 15 | Viewed by 2989
Abstract
Poly(3-hydroxybutyrate-co-3-valerate) (PHBV), being one of the most studied and commercially available polyhydroxyalkanoates (PHAs), presents an intrinsic brittleness and narrow processing window that currently hinders its use in several plastic applications. The aim of this study was to develop a biodegradable PHA-based [...] Read more.
Poly(3-hydroxybutyrate-co-3-valerate) (PHBV), being one of the most studied and commercially available polyhydroxyalkanoates (PHAs), presents an intrinsic brittleness and narrow processing window that currently hinders its use in several plastic applications. The aim of this study was to develop a biodegradable PHA-based blend by combining PHBV with poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH), another copolyester of the PHA family that shows a more ductile behavior. Blends of PHBV with 20% wt., 30% wt., and 40% wt. of PHBH were obtained by melt mixing, processed by cast extrusion in the form of films, and characterized in terms of their morphology, crystallization behavior, thermal stability, mechanical properties, and thermoformability. Full miscibility of both biopolymers was observed in the amorphous phase due to the presence of a single delta peak, ranging from 4.5 °C to 13.7 °C. Moreover, the incorporation of PHBH hindered the crystallization process of PHBV by decreasing the spherulite growth rate from 1.0 µm/min to 0.3 µm/min. However, for the entire composition range studied, the high brittleness of the resulting materials remained since the presence of PHBH did not prevent the PHBV crystalline phase from governing the mechanical behavior of the blend. Interestingly, the addition of PHBH greatly improved the thermoformability by widening the processing window of PHBV by 7 s, as a result of the increase in the melt strength of the blends even for the lowest PHBH content. Full article
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15 pages, 2157 KiB  
Article
Developing Microbial Co-Culture System for Enhanced Polyhydroxyalkanoates (PHA) Production Using Acid Pretreated Lignocellulosic Biomass
by Rijuta Ganesh Saratale, Si-Kyung Cho, Avinash Ashok Kadam, Gajanan Sampatrao Ghodake, Manu Kumar, Ram Naresh Bharagava, Sunita Varjani, Supriya Nair, Dong-Su Kim, Han-Seung Shin and Ganesh Dattatraya Saratale
Polymers 2022, 14(4), 726; https://doi.org/10.3390/polym14040726 - 14 Feb 2022
Cited by 11 | Viewed by 3281
Abstract
In the growing polymer industry, the interest of researchers is captivated by bioplastics production with biodegradable and biocompatible properties. This study examines the polyhydroxyalkanoates (PHA) production performance of individual Lysinibacillus sp. RGS and Ralstonia eutropha ATCC 17699 and their co-culture by utilizing sugarcane [...] Read more.
In the growing polymer industry, the interest of researchers is captivated by bioplastics production with biodegradable and biocompatible properties. This study examines the polyhydroxyalkanoates (PHA) production performance of individual Lysinibacillus sp. RGS and Ralstonia eutropha ATCC 17699 and their co-culture by utilizing sugarcane bagasse (SCB) hydrolysates. Initially, acidic (H2SO4) and acidified sodium chlorite pretreatment was employed for the hydrolysis of SCB. The effects of chemical pretreatment on the SCB biomass assembly and its chemical constituents were studied by employing numerous analytical methods. Acidic pretreatment under optimal conditions showed effective delignification (60%) of the SCB biomass, leading to a maximum hydrolysis yield of 74.9 ± 1.65% and a saccharification yield of 569.0 ± 5.65 mg/g of SCB after enzymatic hydrolysis. The resulting SCB enzymatic hydrolysates were harnessed for PHA synthesis using individual microbial culture and their defined co-culture. Co-culture strategy was found to be effective in sugar assimilation, bacterial growth, and PHA production kinetic parameters relative to the individual strains. Furthermore, the effects of increasing acid pretreated SCB hydrolysates (20, 30, and 40 g/L) on cell density and PHA synthesis were studied. The effects of different cost-effective nutrient supplements and volatile fatty acids (VFAs) with acid pretreated SCB hydrolysates on cell growth and PHA production were studied. By employing optimal conditions and supplementation of corn steep liquor (CSL) and spent coffee waste extracted oil (SCGO), the co-culture produced maximum cell growth (DCW: 11.68 and 11.0 g/L), PHA accumulation (76% and 76%), and PHA titer (8.87 and 8.36 g/L), respectively. The findings collectively suggest that the development of a microbial co-culture strategy is a promising route for the efficient production of high-value bioplastics using different agricultural waste biomass. Full article
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2021

Jump to: 2023, 2022

16 pages, 3817 KiB  
Article
Manufacturing and Characterization of Environmentally Friendly Wood Plastic Composites Using Pinecone as a Filler into a Bio-Based High-Density Polyethylene Matrix
by Maria del Carmen Morcillo, Ramón Tejada, Diego Lascano, Daniel Garcia-Garcia and David Garcia-Sanoguera
Polymers 2021, 13(24), 4462; https://doi.org/10.3390/polym13244462 - 20 Dec 2021
Cited by 3 | Viewed by 3784
Abstract
The use of wood plastic composites (WPC) is growing very rapidly in recent years, in addition, the use of plastics of renewable origin is increasingly implemented because it allows to reduce the carbon footprint. In this context, this work reports on the development [...] Read more.
The use of wood plastic composites (WPC) is growing very rapidly in recent years, in addition, the use of plastics of renewable origin is increasingly implemented because it allows to reduce the carbon footprint. In this context, this work reports on the development of composites of bio-based high density polyethylene (BioHDPE) with different contents of pinecone (5, 10, and 30 wt.%). The blends were produced by extrusion and injection-molded processes. With the objective of improving the properties of the materials, a compatibilizer has been used, namely polyethylene grafted with maleic anhydride (PE-g-MA 2 phr). The effect of the compatibilizer in the blend with 5 wt.% has been compared with the same blend without compatibilization. Mechanical, thermal, morphological, colorimetric, and wettability properties have been analyzed for each blend. The results showed that the compatibilizer improved the filler–matrix interaction, increasing the ductile mechanical properties in terms of elongation and tensile strength. Regarding thermal properties, the compatibilizer increased thermal stability and improved the behavior of the materials against moisture. In general, the pinecone materials obtained exhibited reddish-brown colors, allowing their use as wood plastic composites with a wide range of properties depending on the filler content in the blend. Full article
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20 pages, 4384 KiB  
Review
An Overview of Recent Advancements in Microbial Polyhydroxyalkanoates (PHA) Production from Dark Fermentation Acidogenic Effluents: A Path to an Integrated Bio-Refinery
by Rijuta Ganesh Saratale, Si-Kyung Cho, Ganesh Dattatraya Saratale, Manu Kumar, Ram Naresh Bharagava, Sunita Varjani, Avinash A. Kadam, Gajanan S. Ghodake, Ramasubba Reddy Palem, Sikandar I. Mulla, Dong-Su Kim and Han-Seung Shin
Polymers 2021, 13(24), 4297; https://doi.org/10.3390/polym13244297 - 08 Dec 2021
Cited by 8 | Viewed by 3723
Abstract
Global energy consumption has been increasing in tandem with economic growth motivating researchers to focus on renewable energy sources. Dark fermentative hydrogen synthesis utilizing various biomass resources is a promising, less costly, and less energy-intensive bioprocess relative to other biohydrogen production routes. The [...] Read more.
Global energy consumption has been increasing in tandem with economic growth motivating researchers to focus on renewable energy sources. Dark fermentative hydrogen synthesis utilizing various biomass resources is a promising, less costly, and less energy-intensive bioprocess relative to other biohydrogen production routes. The generated acidogenic dark fermentative effluent [e.g., volatile fatty acids (VFAs)] has potential as a reliable and sustainable carbon substrate for polyhydroxyalkanoate (PHA) synthesis. PHA, an important alternative to petrochemical based polymers has attracted interest recently, owing to its biodegradability and biocompatibility. This review illustrates methods for the conversion of acidogenic effluents (VFAs), such as acetate, butyrate, propionate, lactate, valerate, and mixtures of VFAs, into the value-added compound PHA. In addition, the review provides a comprehensive update on research progress of VFAs to PHA conversion and related enhancement techniques including optimization of operational parameters, fermentation strategies, and genetic engineering approaches. Finally, potential bottlenecks and future directions for the conversion of VFAs to PHA are outlined. This review offers insights to researchers on an integrated biorefinery route for sustainable and cost-effective bioplastics production. Full article
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12 pages, 872 KiB  
Article
Effect of Organic Modifier Types on the Physical–Mechanical Properties and Overall Migration of Post-Consumer Polypropylene/Clay Nanocomposites for Food Packaging
by Eliezer Velásquez, Sebastián Espinoza, Ximena Valenzuela, Luan Garrido, María José Galotto, Abel Guarda and Carol López de Dicastillo
Polymers 2021, 13(9), 1502; https://doi.org/10.3390/polym13091502 - 07 May 2021
Cited by 14 | Viewed by 2386
Abstract
The deterioration of the physical–mechanical properties and loss of the chemical safety of plastics after consumption are topics of concern for food packaging applications. Incorporating nanoclays is an alternative to improve the performance of recycled plastics. However, properties and overall migration from polymer/clay [...] Read more.
The deterioration of the physical–mechanical properties and loss of the chemical safety of plastics after consumption are topics of concern for food packaging applications. Incorporating nanoclays is an alternative to improve the performance of recycled plastics. However, properties and overall migration from polymer/clay nanocomposites to food require to be evaluated case-by-case. This work aimed to investigate the effect of organic modifier types of clays on the structural, thermal and mechanical properties and the overall migration of nanocomposites based on 50/50 virgin and recycled post-consumer polypropylene blend (VPP/RPP) and organoclays for food packaging applications. The clay with the most hydrophobic organic modifier caused higher thermal stability of the nanocomposites and greater intercalation of polypropylene between clay mineral layers but increased the overall migration to a fatty food simulant. This migration value was higher from the 50/50 VPP/RPP film than from VPP. Nonetheless, clays reduced the migration and even more when the clay had greater hydrophilicity because of lower interactions between the nanocomposite and the fatty simulant. Conversely, nanocomposites and VPP/RPP control films exhibited low migration values in the acid and non-acid food simulants. Regarding tensile parameters, elongation at break values of PP film significantly increased with RPP addition, but the incorporation of organoclays reduced its ductility to values closer to the VPP. Full article
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