Non-degradable Plastics Research Articles

End-of-Life Management Options for Agricultural Mulch Films in the United States—A Review

Polyethylene plastic mulches are widely used in specialty cropping systems in the United States due to the horticultural benefits they provide. However, polyethylene mulch is reapplied seasonally, generating large volumes of plastic waste that contribute to plastic pollution concerns. This review synthesizes scientific and industry findings to provide a state of current end-of-life options of polyethylene mulch in the United States and identifies opportunities that can improve plastic waste management with a special emphasis on soil-biodegradable plastic mulches. Major points discussed are: (1) polyethylene mulch use in specialty cropping systems, (2) economic, environmental and waste management impacts of polyethylene mulch use, (3) current common end-of-life pathways of used polyethylene mulch, (4) use of soil-biodegradable plastic mulch as an alternative to reduce the amount of plastic waste in the environment and offset the negative impacts associated with residual non-degradable plastics, (5) socioeconomic factors that reduce the adoption of soil-biodegradable plastic mulch, and (6) limitations of soil-biodegradable mulch. The results of this review conclude that recycling and upcycling of used polyethylene mulch can be a more sustainable disposal option, however cleaning and decontaminating used polyethylene mulch is costly and commercial technology is often not accessible nor economically viable in many regions in the current economic and political situation. To make recycling a viable pathway in the future, research and policy developments are necessary to refine and encourage recycling. Soil-biodegradable plastic mulches can offer an additional opportunity to help address these limitations, but they are not permitted in organic agriculture in the United States. Further studies are necessary to address the current knowledge gaps and gain a better understanding of the factors influencing the degradation of soil-biodegradable mulches under diverse field conditions. Improved end-of-life strategies should continue to be pursued that balance sustainable use of plastic mulch while minimizing environmental risks.

ACTIVE FOOD PACKAGING: A BRIEF REVIEW OF BIODEGRADABLE FILMS, EDIBLE COATINGS, AND SACHETS

Food packaging generally consists of low-cost and non-degradable plastic materials that contribute to environmental pollution. For this reason, new food-packaging systems with good mechanical and barrier properties have been developed as an alternative to replace synthetic polymers used in food packaging. In this sense, this article briefly reviews the active packaging concept and the development of biodegradable films, edible coatings, and sachets used in food preservation. These technological innovations gained increasing importance in the food industry over the years, constituting a new paradigm in the industry, as they interact desirably with food, promoting various solutions such as: extending or maintaining the shelf life, monitoring or improving the quality and safety of food products. In addition, these innovative systems have aroused the interest of researchers for their ability to prevent deterioration and maintain the fresh aspect, firmness, and brightness of foods, making them more attractive to consumers. Several studies have shown that active packaging is an efficient system for preserving fruits and vegetables. The application of biodegradable films, edible coatings, and sachets was discussed in this work, showing the benefits of their use in various food products.

Starch-Based Rehealable and Degradable Bioplastic Enabled by Dynamic Imine Chemistry

The increasingly serious environmental pollution caused by petroleum-based nondegradable plastics has evoked intense research interest in the development of sustainable and degradable bioplastics. Starch is one of the most promising biopolymers for the preparation of bioplastic. However, it is still a great challenge to develop starch bioplastics with high strength, low water sensitivity, and excellent water resistance. Herein, we reported a facile chemical modification method for the synthesis of a novel starch bioplastic. In this process, an easily available starch derivate, dialdehyde starch (DAS), is cross-linked using diamine based on dynamic imine chemistry to prepare DAS-based polyimine (DAS-PI). This DAS-PI exhibits excellent thermal malleability, and it can be easily thermoformed into novel starch bioplastic without using any plasticizer. The resulting starch bioplastic shows high mechanical strength (40.6 MPa), high thermal stability, and excellent water/chemical resistance, as well as heat-induced self-healing ability. Moreover, it can be easily chemically degraded and recycled. This work provides a novel method of producing high-performance starch bioplastics without using plasticizers.

In Vitro and Ex Situ Biodegradation of Low-Density Polyethylene by a Rhizopus sp. Strain Isolated from a Local Dumpsite in North-East Algeria

Low density polyethylene (LDPE) is the most abundant non-degradable plastic waste. Widely used in packaging material, it represents a serious threat to all ecosystems. In the present study, a Rhizopus sp. fungal strain was isolated from soil of a landfill located in north-east Algeria and cultured on potato dextrose agar. The in vitro biodegradability of pieces of the same plastic bag (0.2, 0.4, and 0.6 g) was estimated in minimal liquid medium and on minimal solid medium. Furthermore, biodegradation of plastic bag pieces was examined in seawater, tap water and soil. The isolated Rhizopus sp. strain could degrade the plastic bag waste. The highest in vitro rate occurred in the minimal liquid medium for both the 0.4-g and 0.6-g pieces (a 20% decrease in weight). In natural media, the highest weight decrease was different depending on the substrate: 5% in seawater for the 0.2-g piece, 10% in tap water for the 0.4-g piece and 8% in soil for the 0.4-g piece. This strain could also form a biofilm in Malt Extract Broth (MEB). These results revealed that the isolated Rhizopus sp. strain has considerable biodegradative ability based on different measures.

Utilisation of natural wastes: Water-resistant semi-transparent paper for food packaging

Use of non-degradable plastics in food packaging is alarming for the environment as they are often thrown away after short consumption. Though papers are replacing plastics in different sectors, their low water resistance limits their use in food packaging. in the past, water-resistant papers have been fabricated, but the natural degradability of the paper has been compensated. This study proposes water-resistant yet biodegradable papers from naturally abundant wastes, such as banana plant (BP) and water hyacinth (WH) and validates their properties for practical packaging uses. The resources were completely used, avoiding generation of any in-process biomass residue. This study for the first time reports the impact of ethyl cellulose (EC) coating (∼10 μm) on paper surfaces. The morphology and chemical analysis of the coated papers confirmed the consistent formation of EC layer on paper surfaces. The presence of EC significantly reduced the vapour transmission (22–30%) and moisture content (6–11%) of the papers. Water drops were stable on the coated surfaces at least for 20 min and then were wiped off leaving a dry surface. EC coating considerably increased the tensile index, i.e., 13–17% for BP and 20–35% for WH, though elongation and modulus properties remained almost unchanged. All the papers showed ultraviolet (UV)-resistance, while the coated papers were more transparent in the visible light region. Overall results confirmed the potential of the proposed EC-coated papers as a promising alternative to single-use plastics in food packaging.

The Utilization of E-Waste in Asphalt Pavement: A Review

E-waste generation has increased due to the rapid rate of modernization and technology development. The total amount of E-waste is estimated to be 65.3 million metric tonnes by 2025 globally. This rapid growth is making E-waste management a global issue. Electronic waste includes electronic devices, which reached their end-of-life such as computers, screens, televisions, smartphones, tablets, radios, air conditioners and refrigerators. The disposal of electronic waste is difficult because of highly toxic and non-degradable plastic contents and metals such as lead, lithium, copper and chromium, which can result in adverse effects on the environment. To deal with this issue, several studies have confirmed that electronic waste can be used in experimental works related to asphalt pavements, bitumen and bituminous mixes can be modified in order to improve the performance of bituminous concrete mixtures. According to the obtained results from previous and ongoing research efforts, the use of E-waste plastics in asphalt pavement materials have enhanced the asphalt pavement properties such as resistance to permanent deformation, high-temperature properties and asphalt stability. This paper affords an overview of the studies that have been conducted using E-waste in flexible pavement. This review transacts through the applications of electronic-waste plastics within the asphalt modification in an environmentally friendly manner. Furthermore, the impact of E-waste on the durability, stability, viscosity, penetration, softening point and low and high-temperature performance are discussed.

Influence of UV degradation of bioplastics on the amplification of mercury bioavailability in aquatic environments

Bioplastics have emerged to minimize the ecological footprint of non-degradable plastics. However, the effect of their degradation in aquatic systems, including the interaction with toxic metals, is still unexplored. In this work, the influence of UV-aging on structure, chemistry, wettability, rigidity, and Hg-sorption of commercially available bioplastic (BIO)- and polyethylene (PE)-based films was studied. To mimetize the materials disposal in fresh-/saltwaters, non-saline/saline aqueous solutions were used in Hg-sorption studies. ATR-FTIR spectra revealed that the BIO film was a coblended starch/polyester-based material, whose microstructure, physicochemical, and mechanical properties changed after UV-aging to a higher extent than in PE film. AFM and kinetic modelling pointed out electrostatic interactions/complexation as the mechanisms involved in the increased Hg-sorption by the UV-aged BIO film. An increased salinity did not impair its Hg-sorption. Therefore, when disposed in aquatic systems, starch/polyester-based bioplastics can play a potential vector for amplifying Hg along the food chain.

Additively manufactured macroporous chambers facilitate large volume soft tissue regeneration from adipose-derived extracellular matrix

Breast tissue engineering is a promising alternative intervention for breast reconstruction. Due to their low immunogenicity and well-preserved adipogenic microenvironment, decellularized adipose tissue (DAT) can potentially regenerate adipose tissue in vivo. However, the volume of adipose tissue regenerated from DAT can hardly satisfy the demand for breast reconstruction. Tissue engineering chamber (TEC) is an effective technique for generation of large adipose tissue volumes. However, TEC applications necessitate reoperation to remove non-degradable plastic chambers and harvest autologous tissue flaps, which prolongs the operation time and causes potential damage to donor sites. We improved the TEC strategy by combining bioresorbable polycaprolactone (PCL) chambers and decellularized adipose tissues (DAT). A miniaturized porous PCL chamber was fabricated based on scaling differences between human and rabbit chests, and basic fibroblast growth factor (bFGF)-loaded DAT successfully prepared. In rabbit models, a highly vascularized adipose tissue that nearly filled up the PCL chamber (5 mL) was generated de novo from 0.5 mL bFGF-loaded DAT. The newly formed tissue had significantly high expressions of adipogenic genes, compared to the endogenous adipose tissue. The concept described here can be exploited for breast tissue engineering. Statement of significanceDecellularized adipose tissue (DAT), which provides infiltrated cells adipogenic microenvironment, can potentially regenerate adipose tissue in vivo. Nevertheless, the volume of regenerated adipose tissue is insufficient to repair large sized tissue defect. Tissue engineering chamber (TEC) could provide a protective space for in situ regeneration of large volume tissue. Herein, a new strategy by combining biodegradable polycaprolactone chambers and basic fibroblast growth factor-loaded decellularized adipose tissue is proposed. In rabbit model, newly formed adipose tissue regenerated from DAT successfully filled the dome shaped chamber with ten folds higher volume than DAT, which is proportionally similar to women breast. This work highlighted the importance of adipogenic microenvironment and protective space for adipose tissue regeneration.

Consumer Perceptions of the Use of Nondegradable Plastic Packaging and Environmental Pollution: A Review of Theories and Empirical Literature

Studying people’s perceptions of their attitudes and behaviour toward the use and inappropriate disposal of plastics is necessary because it helps explain the meaning of sustainable environmental behaviour in the context of African countries. Formulating appropriate behavioural change interventions may lead to a shift in people’s behaviour in terms of plastic consumption if they become aware of the environmental risk of plastics. Using a qualitative review of literature, relevant materials for this paper were identified using a search strategy that involved keywords and databases. Previous empirical studies employed several theoretical frameworks. However, inconsistences in the use and definition of variables, make comparing the results of these studies difficult. Although the literature is growing, more empirical evidence is still needed to understand the drivers of people’s perceptions toward unsustainable environmental behaviour in the context of African countries and to formulate appropriate behavioural change interventions. A review of the literature determined four broad drivers of people’s perceptions toward unsustainable environmental behaviour. These include policy or institutional variables, product and market attributes, community variables, and individual characteristics. Additionally, we offer a consolidated conceptual framework for analysing consumer perception in relation to the use of nondegradable plastics and environmental pollution and identify the drivers of people’s perceptions. Policy implications for developing countries as well as future research directions are flagged.

Biodegradable Microplastics: A Review on the Interaction with Pollutants and Influence to Organisms.

Biodegradable plastics attract public attention as promising substitutes for traditional nondegradable plastics which have caused the serious white pollution problem due to their persistence. However, even for biodegradable plastics, natual conditions for the rapid and complete degradation are rare. Even more serious is that biodegradable plastics might be disintegrated into microplastics more rapidly than tranditional plastics, emerging as another threat to the environment. Similar to traditional microplastics, biodegradable microplastics could adsorb many pollutants by various physicochemical effects and release additives. Biodegradable microplastics have been confirmed to be toxic to the organisms as particle matter and the vector as pollutants. Under some conditions, biodegradable microplastics may pose more severe negative impacts on the organisms. With the fierely increasing trend to replace the nondegradable plastic commodities with biodegradable ones, it is necessary to evaluate whether biodegradable plastics and the generated microplastics would alleviate plastic pollution or induce greater ecological impacts.

Recycling and Reutilizing Polymer Waste via Electrospun Micro/Nanofibers: A Review.

The accumulation of plastic waste resulting from the increasing demand for non-degradable plastics has led to a global environmental crisis. The severe environmental and economic drawbacks of inefficient, expensive, and impractical traditional waste disposal methods, such as landfills, incineration, plastic recycling, and energy production, limit the expansion of their applications to solving the plastic waste problem. Finding novel ways to manage the large amount of disposed plastic waste is urgent. Until now, one of the most valuable strategies for the handling of plastic waste has been to reutilize the waste as raw material for the preparation of functional and high-value products. Electrospun micro/nanofibers have drawn much attention in recent years due to their advantages of small diameter, large specific area, and excellent physicochemical features. Thus, electrospinning recycled plastic waste into micro/nanofibers creates diverse opportunities to deal with the environmental issue caused by the growing accumulation of plastic waste. This paper presents a review of recycling and reutilizing polymer waste via electrospinning. Firstly, the advantages of the electrospinning approach to recycling plastic waste are summarized. Then, the studies of electrospun recycled plastic waste are concluded. Finally, the challenges and future perspectives of electrospun recycled plastic waste are provided. In conclusion, this paper aims to provide a comprehensive overview of electrospun recycled plastic waste for researchers to develop further studies.

Durability of Reinforced Concrete Containing Biochar and Recycled Polymers

In the field of sustainable construction materials, the production of eco-friendly concretes, obtained by the addition of waste products such as biochar and recycled polymer particles, offers interesting alternatives to traditional materials. Biochar is a carbonaceous solid by-product obtained from the thermo-chemical conversion of biomass and its addition into concrete admixtures can offer an eco-friendly carbon sequestration solution, capable to slightly improve concrete properties. Recycled polymer materials can be used to partially replace conventional aggregates with the aim of obtaining lighter concretes that help to face the disposal challenge presented by this non-degradable plastic waste. However, the influence of these waste additions on the corrosion behavior of steel rebars embedded in these “eco-concretes” is still unexplored. Within this context, this work presents some results of an extensive study dealing with the concrete mechanical and physical properties and the rebar corrosion resistance during cyclic exposures to chloride-containing solutions.

Self-healable hydrophobic films fabricated by incorporating natural wax into cellulose matrix

Biodegradable cellulose films have high mechanical strength, excellent flexibility, and good transparency, which are potential candidate materials to replace petroleum-based packaging materials and disposable products. However, the poor hydrophobicity of cellulose films seriously limits their practical application. Herein, self-healing hydrophobic films were fabricated by incorporating natural wax into cellulose matrix. The effects of types of natural waxes, wax content, and annealing temperature on the performances of films were systematically investigated. The resultant films exhibited good hydrophobicity (water contact angle: ∼120°), and high tensile strength (>120 MPa), which could be completely biodegraded in natural soil (within 81 days). Importantly, the self-healing of hydrophobic films could be achieved by releasing wax from inside to surface of cellulose matrix during the annealing process. This work demonstrated a facile strategy for designing and developing hydrophobic and self-healable cellulose-based materials for packaging materials to replace petrochemical plastics, which is conducive to alleviate environmental problems caused by nondegradable plastic pollution.

Highly smooth, robust, degradable and cost-effective modified lignin-nanocellulose green composite substrates for flexible and green electronics

Cellulose-based substrates have emerged as strong candidates for flexible and green electronics to impede e-waste generation and fulfill device functions. However, current cellulose-related substrates are incapable to ensure both high performance and low-cost requirements. Here, we developed high-performance, low-cost, and eco-friendly green composite substrates for flexible and green electronics. The green composite substrates were constructed by two natural components of lignin and nanocellulose derived from wood. Through pretreatments of dialysis fraction and epoxidation modification, lignin's heterogeneous structure and moderate surface activity were remarkably improved. The two components exhibit excellent compatibility, and the regenerated substrates demonstrate plastic-like high performance and paper-like degradability, showing low surface roughness (4.68 nm), high ultimate tensile stress (146 MPa) and elastic modulus (16.16 GPa), high transmittance (59.57%@750 nm), and prominent thermal, electrical stability and flame retardancy. After lignin pretreatments, the ultimate tensile stress was vastly increased by 554%. And modified lignin can be added with an ultra-high loading amount (up to 50 wt%), which significantly reduces substrate cost. Consequently, RFID antennas were fabricated on these substrates, which demonstrate distinctive degradability. This study provides a sustainable approach to utilize lignin and cellulose to produce value-added green composites. This work presents a promising route for traditional electronics to replace non-degradable plastics to head towards flexible and green electronics to reduce e-waste generation.

Novel strategy to interpret the degradation behaviors and mechanisms of bio- and non-degradable plastics

China government has implemented regulations to completely ban the use of disposable plastics with about 54 million kt, resulting in tremendous controversies about non-degradable and biodegradable plastics. However, there is still a lack of direct evidence to elucidate the difference of degradation mechanisms among them, which limits the development of applications for biodegradable materials. In this work, we provide direct evidence to clarify the degradation mechanisms between bio- and non-degradable materials. Cellulose, polybutylene adipate terephthalate (PBAT), and polyethylene (PE) film were subjected to phosphate-buffered solution (PBS) degradation, ultraviolet (UV) aging, and soil degradation, and the possible degradation mechanism analysis was carried out. The results exhibited that the cellulose film possessed the shortest degradation cycles whether in PBS degradation, UV aging, or soil degradation, moreover, the cellulose film showed a much higher weight loss of 99.1% after 98 days of soil degradation compared with PBAT film (2.1%) and PE film (1.7%). Additionally, we proposed possible degradation mechanisms to pave the way for the fabrication of green and degradable packaging plastics.

Efficient preparation of all cellulose composite films using a plasticizing-rolling method

Efficient manufacturing cellulose is a promising solution to solve severe environmental problems resulted from non-degradable plastics. Herein, we propose a plasticizing-rolling technique to manufacture cellulose featuring high cellulose ratios (50 wt%) and low temperature (65 °C). Plasticization effect from plasticizers (BmimCl and LiCl) uniformly plasticizes cellulose while shear effect from rolling destroys the crystal area of cellulose, both increasing the mobility of cellulosic molecular chains. SEM images and XRD analysis reveal prepared films are all cellulose composite (ACC), cellulose I in the core area and cellulose II in the surface area. ACC films have high transparency (81 %), tensile strength (73.6 ± 4.8 MPa), and thermal stability. The relationship of structure and properties of ACC films was also discussed and a particle–matrix composite model was proposed to analyze high transparency of ACC films. In conclusion, the proposed method presents a potential to efficiently produce high-performance cellulose materials at large scale.

Mechanically Strong, Hydrostable, and Biodegradable Starch–Cellulose Composite Materials for Tableware

AbstractThe extensive use of nondegradable plastic tableware has brought serious environmental problems. Starch‐based materials are good alternatives to plastics, but poor mechanical properties and intrinsic hydrophilicity limit their utilizations. In order to address this issue, naturally abundant bagasse pulp fiber is used as the reinforcing agent to improve the mechanical properties of starch and polydimethylsiloxane coating (CSB35‐PDMS50) to improve their hydrophobicity and hydrostability. CSB35‐PDMS50 reaches the tensile strength of 21.2 MPa and contact angle of 121°. The enhancement of the mechanical strength can be explained by strong hydrogen bonding between starch and cellulose, as indicated by noncovalent interaction‐reduced density gradient (NCI‐RDG) analysis. CSB35‐PDMS50 retains the low water adsorption rate within 60 h, remains stable in water for 24 h without morphology change, and maintains initial hydrophobicity after continuous abrasion in sandpaper and high‐pressure water spraying due to the formation of Si─O–C bonds. The water absorption capacity of CSB35‐PDMS50 is less than 10% when used as the cap materials for Eppendorf tube for 30 days. Furthermore, CSB35‐PDMS50 demonstrates good biodegradability in the soil with 74% in 100 days. The tableware prepared from ther composites demonstrates good potentials as the competitive substitute for plastics with easy production, high strength, and biodegradability.

Thermal, mechanical, and rheological properties of micro-fibrillated cellulose-reinforced starch foams crosslinked with polysiloxane-based cross-linking agents.

The disposal of non-degradable plastic packaging and plastic pollution are widespread environmental problems. The development of a fully biodegradable alternative foam packaging with excellent water barrier properties from polysaccharides is quite challenging. In this work, micro-fibrillated cellulose fiber-reinforced starch foams (MFC-SFs) were developed by crosslinking with two poly(siloxane)-based crosslinking agents that enhanced their strength and water barrier properties. The polysiloxane crosslinking agents studied were a cationic trimethylsiloxy-terminated poly(aminoethyl aminopropyl methyl siloxane)-co-poly(dimethylsiloxane) or PAEAPS-co-PDMS, and a non-ionic siloxy-terminated poly(dimethylsiloxane) or TMS-t-PDMS. The applied dosage of polysiloxane crosslinking agents was varied from 1.33 to 5.32% to achieve the optimum strength and moisture barrier properties. The results show that the tensile strength increased from 1.78MPa for the control to 2.76MPa for the MFC-SF crosslinked with 5.32% PAEAPS-co-PDMS. The corresponding tensile strength for the MFC-SF crosslinked with TMS-t-PDMS was 2.53MPa, which is still considerably higher than the control MFC-SF. The water absorption also decreased from 326.8% for the control to 102.5% and 79.8% for the MFC-SFs crosslinked with 5.32% PAEAPS-co-PDMS and TMS-t-PDMS respectively. The crosslinking of MFC-SFs with TMS-t-PDMS provided better hydrophobicity compared to the crosslinking with PAEAPS-co-PDMS. The developed packaging could be a promising alternative to non-degradable foam packaging.

Characterization of Polyhydroxybutyrate Producing Bacterium Isolated from Sewage Sample

The increasing importance of the non-degradable plastics has emerged as one of the major concerns. For this, research is being ventured from the existing reserve to produce bioplastics on the basis of biodegradability properties. Polyhydroxybutyrate, a thermoplastic that is biodegradable as well as environmental friendly, is one such example. Present study identifies potential bacteria strains producing Polyhydroxybutyrate from sewage soil sample collected from Tenali, Guntur District. AR15, one of the derivatives from the ten bacterial isolates recognized through Sudan Black staining, was perceived to be a potential PHB producer. A preliminary identification of the isolate was achieved through biochemical characterization and was found to be Bacillus sp. Biopolymer obtained from the isolate was characterized by FTIR and TGA. Further the biopolymer compared with standard and was seen to be Polyhydroxybutyrate.

Preparation and Characterization of Low Density Polyethylene-Chitosan Nanoparticles Biocomposite as a Source of Biodegradable Plastics

Proper incorporation of natural polymers such as chitosan, starch, or cellulose in the matrix of non-degradable polymers has been proposed to bring about a possible lasting solution to the menace caused by non-degradable plastics in the environment. Biodegradable composite films of low-density polyethylene-chitosan nanoparticles (LDPE/CHNP) has been prepared by solvent casting method. The physiochemical, thermal, biodegradability and microbial inhibition test of the biocomposite have also been investigated to optimize the prepared composite. Physiochemical, thermal, and microbial inhibition rate has been found to increase with increase in chitosan nanoparticles (CHNP) loading in the prepared matrix. The mechanical studies showed that the tensile strength and elastic modulus increased with increasing loading of chitosan nanoparticles. The improvement in the mechanical properties have been attributed to the compatibility of the composite. The prepared LDPE/CHNP biocomposite film with 15% chitosan nanoparticles showed maximum elastic modulus of 23.10 and tensile strength of 3.52, as well as the best dispersion of particles as revealed by the morphological studies of the composite films. The result of the biodegradation study showed that the degradation efficiency and rate increased in CHNP loading with 20% CHNP loading having the maximum degradation efficiency of 50% and rate 0.12 g/d after 21days. The biocomposite film prepared has proved to be degradable, having antimicrobial properties, thereby it could act as an eco-friendly alternative to conventional non-degradable plastics and could be applied in food packaging, fuel cell and wastewater treatment.