A Literature Review on Sustainability of Bio-Based and Biodegradable Plastics:Challenges and Opportunities

This study examines the literature on bio-based and biodegradable plastics published between 2000 and 2021 and provides insights and research suggestions for the future.The study gathers data from the Scopus and ISI Web of Science databases,then picks 1042 publications objectively and analyses their metadata.Furthermore,144 papers from the Web of Science are analysed to present insights and classifications of the literature based on content analyses,including assessment/evaluation of the sustainability of bio-based and biodegradable Plastics,sustainability of biodegradable Plastics,and factors driving the uptake of biodegradable plastics.The study finds that most research on bio-based and biodegradable plastic film evaluations considered only one dimension of sustainability,few considered two dimensions,and very few considered three dimensions.Though,in recent years,academic and industrial interest has grown dramatically in biodegradable plastics towards sustainability.The triple bottom line method in this report(economic benefit,social responsibility,and environmental protection)was employed to assess the biodegradable plastics towards sustainability.Top journals,Influential authors,top contributing institutions,top contributing nations,and contributions by fields are all identified in this study.This research gives a detailed but straightforward theoretical design of bio-based and biodegradable polymers.The study’s results and future research initiatives provide a new path for further investigation and contribution to the field.

Gastric carboxylesterases of the edible crab Cancer pagurus (Crustacea, Decapoda) can hydrolyze biodegradable plastics

A promising strategy to counteract the progressing plastic pollution of the environment can involve the replacement of persistent plastics with biodegradable materials.Biodegradable polymers are enzymatically degradable by various hydrolytic enzymes.However,these materials can reach the environment in the same way as conventional plastics.Therefore,they are accessible to terrestrial,freshwater,and marine biota.Once ingested by marine organisms,highly active enzymes in their digestive tracts may break down biodegradable compounds.We incubated microparticles of five different biodegradable plastics,based on polylactictic acid(PLA),polybutylene succinate(PBS),polybutylene adipate terephthalate(PBAT)and polyhydroxybutyrate-co-valerate(PHBV),in-vitro with the gastric fluid of the edible crab Cancer pagurus and evaluated the hydrolysis rates by pH Stat titration.A plastic blend of PLA with PBAT showed the highest hydrolysis rate.The enzymes in the gastric fluid of crabs were separated by anion exchange chromatography.Fractions with carboxylesterase activity were identified using fluorescent methylumbelliferyl(MUF)-derivatives.Pooled fractions with high carboxylesterase activity also hydrolyzed a PLA/PBAT plastic blend.Carboxylesterases showed molecular masses of 40–45 kDa as determined by native gel electrophoresis(SDS-PAGE).Our study demonstrated that digestive carboxylesterases in the gastric fluid of C.pagurus exhibit a high potential for hydrolyzing certain biodegradable plastics.Since esterases are common in the digestive tract of organisms,it seems likely that other invertebrates possess the ability to hydrolyze biodegradable plastics.

Life Cycle Assessment of Biodegradable Plastics

Many industrial products made from fossil fuels cause the problems of global warming,depletion of fossil fuel resources and decrease of the land by landfill.In this report,the amounts of CO2 emissions as the environmental load and the specific energy consumptions as the depletion of fossil fuel resources of biodegradable plastics and conventional plastic as food trays are compared using life cycle assessment methodology.The amount of CO2 emission of PHB(poly(3-hydroxybutyrate-co-4-hydroxybutyrate)) tray was the smallest among those of trays of other plastics.The specific energy consumption of SPCL(starch/polycaprolactone) was the smallest among those of trays of other plastics.It clearly reveals that the utilization of the biodegradable plastics is an effective way of alternatives of the conventional plastics.

可生物降解塑料取代传统塑料--对碳排放的影响

In recent years,a great deal of attention has been focused on the environmental impact of plastics,includ-ing the carbon emissions related to plastics,which has promoted the application of biodegradable plas-tics.Countries worldwide have shown high interest in replacing traditional plastics with biodegradable plastics.However,no systematic comparison has been conducted on the carbon emissions of biodegrad-able versus traditional plastic products.This study evaluates the carbon emissions of traditional and biodegradable plastic products(BPPs)over four stages and briefly discusses environmental and economic perspectives.Four scenarios-namely,the traditional method,chemical recycling,industrial composting,and anaerobic digestion-are considered for the disposal of waste BPPs(WBPPs).The analysis takes China as a case study.The results show that the carbon emissions of 1000traditional plastic products(plastic bags,lunch boxes,cups,etc.)were52.09-150.36 carbon emissions equivalent of per kilogram(kg CO_(2)eq),with the stage of plastic production contributing 50.71%-50.77%.In comparison,1000 similar BPPs topped out at 21.06-56.86 kg CO_(2)eq,approximately 13.53%-62.19%lower than traditional plastic prod-ucts.The difference was mainly at the stages of plastic production and waste disposal,and the BPPs showed significant carbon reduction potential at the raw material acquisition stage.Waste disposal plays an important role in environmental impact,and composting and anaerobic digestion are considered to be preferable disposal methods for WBPPs.However,the high cost of biodegradable plastics is a challenge for their widespread use.This study has important reference significance for the sustainable development of the biodegradableplastics industry.

Effects of biodegradable mulch on soil water and heat conditions,yield and quality of processing tomatoes by drip irrigation

To combat the problem of residual film pollution and ensure the sustainable development of agriculture in oasis areas,a field experiment was carried out in 2019 at the Wuyi Farm Corps Irrigation Center Test Station in Urumqi,Northwest China.Four types of biodegradable mulches,traditional plastic mulchs and a control group(bare land;referred to as CK)were compared,including a total of six different treatments.Effects of mulching on soil water and heat conditions as well as the yield and quality of processing tomatoes under drip irrigation were examined.In addition,a comparative analysis of economic benefits of biodegradable mulches was performed.Principal component analysis and gray correlation analysis were used to evaluate suitable mulching varieties for planting processing tomatoes under drip irrigation.Our results show that,compared with CK,biodegradable mulches and traditional plastic mulch have a similar effect on retaining soil moisture at the seedling stage but significantly increase soil moisture by 0.5%-1.5%and 1.5%-3.0%in the middle and late growth periods(P<0.050),respectively.The difference in the thermal insulation effect between biodegradable mulch and plastic mulch gradually reduces as the crop grows.Compared with plastic mulch,the average soil temperature at 5-20 cm depth under biodegradable mulches is significantly lowered by 2.04°C-3.52°C and 0.52°C-0.88°C(P<0.050)at the seedling stage and the full growth period,respectively,and the water use efficiency,average fruit yield,and production-investment ratio under biodegradable mulches were reduced by 0.89%-6.63%,3.39%-8.69%,and 0.51%-6.33%(P<0.050),respectively.The comprehensive evaluation analysis suggests that the black oxidized biological double-degradation ecological mulch made from eco-benign plastic is the optimal film type under the study condition.Therefore,from the perspective of sustainable development,biodegradable mulch is a competitive alternative to plastic mulch for large-scale tomato production under drip irrigation in the oasis.

Evaluation of Mechanical Properties of Highly Filled Jute Fiber Reinforced Composites

This study aims for development of highly filled jute fiber reinforced composites that contains jute fiber over fiber weight fraction 60%,and jute fiber reinforced composite was fabricated by the hot-pressing method.The molding temperature was changed from 175°C to 230°C,to investigate the effect of molding temperature on the mechanical properties of jute fiber reinforced composites.The effect of surface treatment of jute fiber on the mechanical properties of jute fiber reinforced composites was also investigated.As a result,the jute fiber reinforced composites using surface treated fiber has low porosity,and the jute fiber reinforced composite having low porosity has high flexural strength and modulus.The jute fiber reinforced composite using acetone treated fiber molded at 200°C has the maximum flexural strength and modulus.

Characterization of 3D Printed Poly(3-Hydroxybutyric-Co-3-Hydroxyvalerate) by Fused Granular Fabrication through Thermal and Mechanical Analyses

Poly[R-3-hydroxybutyrate-co-(R-3-hydroxyvalerate)] (PHBVs) copolymers are promising biopolymers, which could substitute petroleum-based plastics for various applications. PHB and PHBV pellets were processed on a customized 3D printer via Fused Granular Manufacturing (FGM) approach modified with a Mahor screw extruder. To anticipate the behaviour of PHBVs when transformed using conventional thermo-mechanical shaping processes, thermal and mechanical analyses were carried out in order to better understand the effect of annealing temperature on their crystallization behaviour and mechanical properties of PHB polymer and PHBV copolymer. The objectives of the present work were to propose an experimental strategy to study the melting and crystallization events, crystalline structure changes, and mechanical performances of both PHB homopolymer and PHBV copolymer according to identical thermal annealing treatments. A monitoring of 3D printed PHB and PHBV structures was achieved by coupling Differential Scanning Calorimetry (DSC) and tensile tests. .

Influence of temperature on production of lactic acid from kitchen garbage

The production of lactic acid from kitchen garbage, the precursor for production of biodegradable plastics is described in detail. The influence of temperature on the lactic acid concentration, sugar concentration, and decrement of garbage were evaluated through experiments. Fermentation were carried out in an incubator at 5, 25, 37 and 50 ℃. The latic acid produced was maximum at initial pH 6.0 and 37 ℃, i.e. 38 g/L with a yield of 0.23 g/gVS. It is concluded from the experimental results that temperature has quite a considerable effect on the production of lactic acid; lactic acid concentration increases with temperature until 37 ℃, and production rate of lactic acid drops at 50 ℃; the optimal fermentation is 37 ℃. This study shows that production of lactic acid from kitchen garbage is feasible and reduction of garbage can be realized.

Knowledge and Opportunities from the Plastisphere:A Prelude for the Search of Plastic Degrading Bacteria on Coastal Environments

Plastic pollution has become an urgent issue,since its invasion to everyecosystem has led to multiple impacts on the environment and human pop-ulations.Certain microbial strains and genera had shown the ability to bio-degrade plastic sources under laboratory conditions.In this minireview,wecallect and analyze scientific papers and reports of this microbial activity aswe contextualize this information on the global plastic pollution problem,toprovide an updated state of the art of plastiq/biodegradation with microbialagents.Along with a broad understanding of the general process of plasticbiadegraclation hosted by micrnarganisms.The contributions of this mini-revicw came from the identification of rescarch gaps,as well as proposalsfor new approaches.One of the main proposals focuses on coastal environ-nents and in particular coastal wetlands as a great microbiome source withpatential for plastic biodegradation,whether reported or undiscovered.Ourfinal proposal consists of the application of this knowledge into technologictools and strategies that have a remarkable impact on the battle against theplastic pollution problem.

Towards greener polymers:Trends in the German chemical industry

Global plastics production is expected to exceed 400 million tons and reach 600 million tons by 2060.Their synthesis currently accounts for approximately 3%of global greenhouse gas emissions.Approximately 60%of all polymers are produced for single-use.Examples include shopping bags,packaging materials,mulch films,and soluble polymers for cosmetics and other purposes.Currently,only a portion of single-use plastic is recycled or disposed of in incinerators or landfills.An estimated 20%is not disposed of properly and pollutes the global environment,especially the oceans.In response to these challenges,the United Nations,European Union,and many nation-states are developing regulatory frameworks that encourage the chemical industry to produce plastics with a smaller environmental footprint and often support this through research funding.Possible solutions include:(1)the use of green energy,green hydrogen,bio-based feedstocks,or CO_(2) in synthesis;(2)the reuse or recycling of plastics through conversion or pyrolysis;and(3)the production of biodegradable polymers.The German chemical industry contributes approximately one-third of polymer production in the EU.It is embedded in the EU regulatory and research landscape and anchored in the European Green Deal,which aims for carbon neutrality by 2050.In this paper,we describe how BASF and Evonik,two leading German chemical companies with strong but different polymer portfolios,respond to the call for greener polymers and how technologies are being developed to make polyurethanes,a particularly important and difficult-to-recycle family of elastomers and duromers,renewable and circular.Reducing the environmental footprint of plastics requires not only innovative materials but also proper governance,regulatory and collection systems,and public willingness to cooperate.In an international comparison of these competencies,expressed by the"polymer management index"(PMI),Germany achieved a top position.

Warpage and Shrinkage Optimization of Injection-Molded Plastic Spoon Parts for Biodegradable Polymers Using Taguchi, ANOVA and Artificial Neural Network Methods

In this study, it is attempted to give an insight into the injection processability of three self-prepared polymers from A to Z. This work presents material analysis, injection molding simulation, design of ex- periments alongside considering all interaction effects of controlling parameters carefully for green biodegradable polymeric systems, including polylactic acid （PLA）, polylactic acid-thermoplastic poly- urethane （PLA-TPU） and polylactic acid-thermoplastic starch （PLA-TPS）. The experiments were carried out using injection molding simulation software Autodesk Moldflov~~ in order to minimize warpage and volumetric shrinkage for each of the mentioned systems. The analysis was conducted by changing five significant processing parameters, including coolant temperature, packing time, packing pressure, mold temperature and melt temperature. Taguchi＇s [.27 （35） orthogonal array was selected as an efficient method for design of simulations in order to consider the interaction effects of the parameters and reduce spu- rious simulations. Meanwhile, artificial neural network （ANN） was also used for pattern recognition and optimization through modifying the processing conditions. The Taguchi coupled analysis of variance （ANOVA） and ANN analysis resulted in definition of optimum levels for each factor by two completely different methods. According to the results, melting temperature, coolant temperature and packing time had significant influence on the shrinkage and warpage. The ANN optimal level selection for minimiza- tion of shrinkage and/or warpage is in good agreement with ANOVA optimal level selection results. This investigation indicates that PLA-TPU compound exhibits the highest resistance to warpage and shrink- age defects compared to the other studied compounds.

Degradability of biodegradable plastic films and its mulching effects on soil temperature and maize yield in northeastern China

Plastic film is an important resource in agricultural production,but it takes hundreds of years to degrade completely in natural environment.The large-scale use of plastic film will inevitably lead to serious environmental pollution.One way to solve the problem is to develop a substitutable mulching film,such as a biodegradable film that can ultimately be decomposed to water,carbon dioxide,and soil organic matter by micro-organisms.In this study,a 2-year experiment was conducted to determine the degradation properties of a biodegradable plastic film,including degradation rate,surface microstructure,tensile strength and elongation at break,and the effects of different mulching treatments on soil temperature and maize yield.The mulching experiment was conducted with three different biodegradable plastic films with different degradation rates,using a common plastic film and a non-mulched treatment as control.With the addition of the additives for degradation in the biodegradable plastic films,the degradation rates increased significantly,which were 7.2%-17.8%in 2017 and 18.1%-35.2%in 2018 after maize harvesting.However,the degradation occurred mainly on the ridge side.The decrease in tensile strength and elongation was proportional to the degradation rate of the degradable film.The SEM results indicated that the surface microstructures of the biodegradable films were loose and heterogeneous after maize harvesting.Biodegradable plastic film mulching increased the soil temperature at soil depths of 5 cm,15 cm,and 25 cm,over the maize’s entire growth period,by 3.1℃-3.2℃ in 2017 and 1.2℃-2.1℃ in 2018 compared with the non-mulched treatment.The biodegradable plastic film increased the maize yield by 10.4%-14.3%in 2017 and 11.6%-24.7%in 2018.The soil temperature and maize yield increases were statistically significant;however,with respect to maize qualities,there were no statistically significant increases among the five treatments.This study shows that biodegradable plastic film can be used as a substitute for common plastic film.However,the ingredients in biodegradable plastic films should be improved further to ensure that they can be degraded completely after crop harvest.

Efficient synthesis of hydroxyl functioned polyesters from natural polyols and sebacic acid

Amphiphilic hydroxyl functioned polyester（HFP） can be used as compatibilizers for blends of starch and resins.We developed a synthetic method for effective preparation of HFPs.Water was removed by high flow rate N_2 rather than high vacuum during polycondensation of sebacic acid with xylitol,sorbitol,or mannitol in the presence of dehydrative condensation catalyst and the product is with[η]of 27.2 mL/g,M_n of 1903,M_w of 167,693,T_g of -30.5℃,T_m of 44.0℃.Weight loss is 1.73%under 200℃. The integral distributions of molecular weight are 43.6 wt%and 63.8 wt%over 10,000 and 3000,respectively.The results indicated that higher molecular weight HFP was economically synthesized.

Biological conversion of methane to polyhydroxyalkanoates:Current advances,challenges,and perspectives

Methane emissions and plastic pollution are critical global challenges.The biological conversion of methane to poly-b-hydroxybutyrate(PHB)not only mitigates methane emissions but also provides biodegradable polymer substitutes for petroleum-based materials used in plastics production.This work provides an early overview of the methane-based PHB advances and discusses challenges and related strategies.Recent advances of PHB,including PHB biosynthetic pathways,methanotrophs,bioreactors,and the performances of PHB materials are introduced.Major challenges of methane-based PHB production are discussed in detail;these include low efficiency of methanotrophs,low gas-liquid mass transfer efficiency,and poor material properties.To overcome these limitations,various approaches are also explored,such as feast-famine regimes,engineered microorganisms,gas-permeable membrane bioreactors,two-phase partitioning bioreactors,poly-b-hydroxybutyrate-co-hydroxyvalerate synthesis,and molecular weight manipulation.

Optimizing a nitrogen-supplemented, condensed corn soluble medium for growth of the Polyhydroxyalkanoate producer Pseudomonas putida KT217

Pseudomonas putida KT217 produces medium-chain-length polyhydroxyalkanoate(mcl-PHA)that is of commercial interest as a biodegradable plastic.To reduce PHA production costs,a less expensive medium to grow P.putida KT217 to a high cell dry weight(CDW)was developed.P.putida KT217 was grown in aerated shake flasks on a condensed corn solubles(CCS)based medium that provided several organic acids and carbohydrates that were utilized for growth.The medium was prepared by adding various amounts of fresh CCS(100-600 g/L,or 34.9-209.4 g/L dry basis)to water and then centrifuging and filtering.The CCS permeate media contained dry matter levels of 28.8-164.9 g/L.The CCS permeate medium containing 108.4 g/L solids produced approximately 6 g CDW/L,at a growth rate of 1.03 per hour,and maximum cell population of 4×109 CFU/mL.Because CCS is low in nitrogen,ammonium hydroxide was added at a level of 1.73 g/L,and this significantly increased the CDW(>20 g/L)produced in an aerated bioreactor.Therefore,a nitrogen supplemented CCS medium could provide a cheap source of nutrients for production of P.putida KT217 and PHA.

Valorization of poly-β-hydroxybutyrate(PHB)-based bioplastic waste in anaerobic digesters of food waste for bioenergy generation:reactor performance,microbial community analysis,and bioplastic biodegradation

This study aims to investigate the significance and biodegradation pathways of PHB-based bioplastic in anaerobic digesters treating food waste,where the reactor performance of changed methane generation,bioplastic biodegradation efficiency,and bioinformatic analysis of functional microbes were emphasized.The results showed that PHB-based plastic film could be partially biodegraded in the food waste digester,and a bioaugmentation use of Alcaligenes Faecalis(AF)and Bacillus Megaterium(BM)was beneficial to largely accelerate the degradation process through a beneficial shift of both the functional bacterial and archaeal species.Microbial community analysis indicated that the major bacterial species belonged to genera Candidatus_Cloacimonas,Rikenellaceae,and Defluviitoga,while the dominant methanogenic archaeal species belonged to genera Methanomassiliicoccus,Methanosarcina,and Methanosaeta.Bioplastic biodegradation analysis suggested that the optimal fractions of AF and BM for PHB-based plastic degradation were 50% AF and 75% BM,respectively,which deserves further optimization and scale-up validation.The finding of this study would contribute to the combined management of PHB-based bioplastic with food waste for clean energy recovery and a greener environment.