Bio-based Plastic Materials Research Articles

Thermal Decomposition of Bio-Based Plastic Materials.

This research delves into a detailed exploration of the thermal decomposition behavior of bio-based polymers, specifically thermoplastic starch (TPS) and polylactic acid (PLA), under varying heating rates in a nitrogen atmosphere. This study employs thermogravimetry (TG) to investigate, providing comprehensive insights into the thermal stability of these eco-friendly polymers. In particular, the TPS kinetic model is examined, encompassing the decomposition of three distinct fractions. In contrast, PLA exhibits a simplified kinetic behavior requiring only a fraction described by a zero-order model. The kinetic study involves a systematic investigation into the individual contributions of key components within TPS, including starch, glycerin, and polyvinyl alcohol (PVA). This detailed analysis contributes to a comprehensive understanding of the thermal degradation process of TPS and PLA, enabling the optimization of processing conditions and the prediction of material behavior across varying thermal environments. Furthermore, the incorporation of different starch sources and calcium carbonate additives in TPS enhances our understanding of the polymer's thermal stability, offering insights into potential applications in diverse industries.

Processing and characterization of antimicrobial bioplastic films based on green microalgae Scenedesmus obliquus extract-loaded polyurethane

The green microalga Scenedesmus obliquus, isolated from the Egyptian environment, was used for the synthesis of bio-based plastic materials. Polyurethane (PU) was blended with different proportions (0%, 10%, 20%, and 40%) of chloroform extract to form bioplastic films. The bioplastic films were characterized using water vapor transmission rate measurements and scanning electron microscopy (SEM). The WVTR of pure PU was 193.37 g/m2. day, while the values of algae/PU films were 129.74, 122.56, and 99.75 g/m2.day. S. obliquus reported having Palmitic, which possesses antimicrobial activity and acts as an effective antimicrobial agent in the synthesized bioplastic films. Antimicrobial activity of the algal extract and the synthesized bioplastic films were tested against two Gram-positive bacteria; Staphylococcus aureus, Enterococcus faecalis, two Gram-negative bacteria; Escherichia coli, Pseudomonas aeruginosa, and Candida albicans as a model for fungi. The results indicated that S. obliquus extract exhibited a clear antimicrobial activity against all tested microbes. The antimicrobial rate of bioplastic films containing 40% of the extract reached 100% after 2 h of contact with E. coli and E. faecalis. In conclusion, this study offers a promising future for the use of biodegradable antimicrobial bioplastic films as an affordable and environmentally friendly alternative to plastics in many applications.

Aerobic aquatic biodegradation of bio-based and biodegradable polymers: Kinetic modeling and key factors for biodegradability

With the increasing concern about plastic waste, numerous efforts have been made to find substitutes for existing non-biodegradable synthetic polymers. Bio-based and/or purported petroleum-based biodegradable polymers are considered probable plastic replacement candidates. However, the durability of non-biodegradable plastic is a key feature of plastics. Thus, a balance must be achieved between biodegradation and environmental material stability. The objective of this study is to determine the impact of crystallinity, molecular chemistry, and hydrophilicity on the rate of aquatic biodegradation of biobased plastic materials. In the present study, twelve bio-based/purported biodegradable materials were investigated under aerobic aquatic biodegradation conditions for 56 days by tracking oxygen consumption. Crystallinity, hydrophobicity, chemistry, and chemical structure were varied to understand potential means for controlling the rate of biodegradation. The biodegradation kinetics were analyzed and discussed, relating to the characteristics of polymers. Polyvinyl alcohol (PVA), Chitosan, Rayon, Polyhydroxy-butyrate-co-valerate (PHBV), PHBH, and Polybutylene succinate (PBS) showed the biodegradation extents over 70% at 56 days. Cellulose acetates (CAs) and Polylactic acid (PLA) showed biodegradation extent lower than 20%. The chemistry of the polymer backbone chain, substituent structure, and degree of substitution were the dominant factors affecting biodegradation. The crystallinity of the polyesters had a negative correlation with the initial biodegradation rate and the ultimate biodegradation of polyesters, and the hydrophobicity of the polymers delayed the initiation of biodegradation. The aerobic aquatic biodegradation results related to the polymer characteristics are useful for product designers and environmental scientists to understand the fate of these polymeric materials in the environment.

Degradation of bio-based film plastics in soil under natural conditions

The degradation of bio-based plastic materials in field soil under natural conditions was investigated in this study. Three bio-based plastics materials, which contained polylactide (PLA) with polybutylene adipate terephthalate and additives (PLA_1), PLA-based polyester blend with mineral filler (PLA_2), and polybutylene succinate with mineral filler (PBS_1) in the form of the film, were subjected to soil burial biodegradation processes. The experiments were carried out in a climate with an average annual temperature of 9.4 °C, in winter and summer periods for one year. The degradation of the materials was evaluated by macro- and microscopic observations, weight loss, thermogravimetric analysis, and tensile test. Macroscopic observation indicated that changes in the color of film surface were visible for samples PBS_1 after 12 months of degradation. Using microscopic inspection the erosion of surface samples PLA_1 and PBS_1 after 12 months was observed. Mass loss of samples PLA_1 and PLA_2 after one year of degradation were below 0.6 %. Moreover, for PBS_1 sample, mass loss was equal to 4.3 %. Based on the obtained results of the mass loss, a description of the degradation kinetics was proposed, showing the changes in the thickness of the tested polymer over time. The thermal stability of the samples PLA_1 and PLA_2 decreased during the degradation process by 16.1 and 2.6 °C, respectively, and for PBS_1 increased by 1.7 °C. Tensile strength at break after 12 months of degradation decreased for sample PLA_1 and PLA_2 by 27.3 and 5.8 %, respectively, and increased for sample PBS_1 by 28.2 % compare to unexposed sample.

Carbon Footprint of Single-Use Plastic Items and Their Substitution

Single-use plastic is having a significant environmental impact and its reduction is a mandatory step to reduce plastic pollution worldwide. Indeed, the time that a plastic item can persist in the environment is very long and it is well known that it can produce devastating effects in particular in seas and oceans. Moreover, production, use and disposal of plastic items have a significant impact also on the greenhouse effect; this can be estimated in a life cycle approach, by evaluating their carbon footprint. In this work, a review of the carbon footprint evaluation of different single-use plastic categories has been carried out, developing a methodology to immediately evaluate the benefits related to their substitution with compostable and bio-plastic and/or multiple-use items and materials. The result of the novel methodology developed is a certain number of matrixes, which can categorize impact values in order to compare them with replacement with bio-based plastic materials or multi-use things. Finally, the methodology was tested and validated through a case study, where a plastic reduction plan was proposed and implemented and the CO2 equivalent reduction was assessed, demonstrating a reduction potential related to a replacement by bioplastic or other materials equal, respectively, to 73% and 90%.

Smart Material Choice: The Importance of Circular Design Strategy Applications for Bio-Based Food Packaging Preproduction and End-of-Life Life Cycle Stages

This article provides a systematic literature review on the integrated approach of bio-based plastic food packaging in a circular economy. It focuses on the following key areas: (1) the role of bio-based plastic food packaging in a circular product design strategy and material choice in the preproduction life cycle stage; (2) the role of bio-based plastic food packaging in circular resource management systems and the product disposal life cycle stage; and (3) an optimal bio-based plastic food packaging application in regard to prioritising end-of-life treatment. While there are dedicated publications on the role of packaging in a circular economy, circular packaging design, packaging waste management, and bio-origin plastic applications in food packaging, this article aims to provide an integrated review and recommendations on the best bio-based plastic food packaging material selection, applications based on a circular economy, and scenarios on waste/resource management that prioritise end-of-life treatment. Three of the current most popular bio-based plastic materials in the flexible and rigid food packaging categories were selected: starch blends, bio-PE, and PLA for flexible food packaging and PLA, bio-PET, and bio-PE for rigid packaging. This article highlights the fact that a smart material choice in the circular design strategy is a key factor that has a direct impact on the last packaging life cycle stage (disposal), and concludes that bio-based plastic materials are a way to close the food packaging loop, either by re-use or recycling. This article also provides recommendations on the best bio-based plastic food packaging material selection, and applications based on the circular economy and waste management that prioritise end-of-life treatment. The research results indicate a research niche for the application of re-usable biodegradable materials in food packaging. The findings of this research allow product designers and packaging companies to advance the understanding of the most efficient bio-based plastic food packaging integration into the circular economy via decision making of product material choice and end-of-life treatment. Based on the results of this article, scholars can develop new themes for further research.

Processing and Characterization of Bioplastics from the Invasive Seaweed Rugulopteryx okamurae.

The seaweed Rugulopteryx okamurae, from the Pacific Ocean, is considered an invasive species in the Mediterranean Sea. In this work, the use of this seaweed is proposed for the development of bio-based plastic materials (bioplastics) as a possible solution to the pollution produced by the plastic industry. The raw seaweed Rugulopteryx okamurae was firstly blended with glycerol (ratios: 50/50, 60/40 and 70/30), and subsequently, they were processed by injection molding at a mold temperature of 90, 120 and 150 °C. The rheological properties (frequency sweep tests and temperature ramp tests) were obtained for blends before and after processing by injection molding. The functional properties of the bioplastics were determined by the water uptake capacity (WUC) values and further scanning electron microscopy (SEM). The results obtained indicated that E’ was always greater than E”, which implies a predominantly elastic behavior. The 70/30 ratio presents higher values for both the viscoelastic moduli and tensile properties than the rest of the systems (186.53 ± 22.80 MPa and 2.61 ± 0.51 MPa, respectively). The WUC decreased with the increase in seaweed in the mixture, ranging from 262% for the 50/50 ratio to 181% for the 70/30 ratio. When carrying out the study on molded bioplastic 70/30 at different temperatures, the seaweed content did not exert a remarkable influence on the final properties of the bioplastics obtained. Thus, this invasive species could be used as raw material for the manufacture of environmentally friendly materials processed by injection molding, with several applications such as food packaging, control–release, etc.

Attached and planktonic bacterial communities on bio-based plastic granules and micro-debris in seawater and freshwater

Bio-based plastics, produced from renewable biomass sources, may contribute to lowering greenhouse gases and the demand for fossil resources. However, their environmental fate is not well understood. Here, we compared the impacts of industrially produced granules (G) and micro-debris (MD) from three pristine bio-based plastics: high-density polyethylene (HDPE), polylactic acid (PLA) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) on natural bacterial communities in seawater and freshwater using metagenomics. After one month, we found a dissimilarity between the microbial communities forming a biofilm on the plastics and planktonic bacteria. Further, different bacterial groups became dominant on different bio-based plastics, i.e. Burkholderiaceae, Solimonadaceae, Oleiphilaceae, and Sneathiellaceae on HDPE and Alteromonadaceae on PLA and Rhodobacteraceae on PHBV in seawater, and Beijerinckiaceae and Chitinophagaceae on HDPE, Microtrichaceae on PLA and Caulobacteraceae and Sphingomonadaceae on PHBV in freshwater. Variovorax, Albimonas and Sphingomonas genera were recorded on bio-based plastics in both seawater and freshwater. This study describes how different bio-based plastic materials and granule sizes influence the development of natural bacterial communities.

Separation and Purification of Biogenic 1,3-Propanediol from Fermented Glycerol through Flocculation and Strong Acidic Ion-Exchange Resin.

In the present work, was investigated the separation and purification procedure of the biogenic 1,3-propanediol (1,3-PD), which is a well-known valuable compound in terms of bio-based plastic materials development. The biogenic 1,3-PD was obtained as a major metabolite through the glycerol fermentation by Klebsiella pneumoniae DSMZ 2026 and was subjected to separation and purification processes. A strong acidic ion exchange resin in H+ form was used for 1,3-PD purification from the aqueous solution previously obtained by broth flocculation. The eluent volume was investigated considering the removal of the secondary metabolites such as organic acids (acetic, citric, lactic, and succinic acids) and 2,3-butanediol (2,3-BD), and unconsumed glycerol. It was observed that a volume of 84 mL of ethanol 75% loaded with a flow rate of 7 mL/min completely remove the secondary metabolites from 10 mL of concentrated fermented broth, and pure biogenic 1,3-PD was recovered in 128 mL of the eluent.

Environmental Sustainability of Plastic in Agriculture

This article investigates the environmental sustainability of plastic nets in agricultural environments based on published experimental data. This article focuses on biodegradable and synthetic plastics used in farms as mulching materials and shade materials/greenhouse covering materials (shade nets and plastic films) to protect plants from pests and extreme weather. The sustainability was determined by three factors, carbon footprint from cradle to the end of life (LCA), durability (resistance to photo-oxidation and high tensile strength), and affordability. The LCA analyses showed that the production of polyethylene (PE) requires less energy and generates low quantities of greenhouse gas equivalents. Beyond the LCA data, biodegradable polymers are sustainable based on biodegradability and compostability, ability to suppress weeds, control soil temperatures, and moisture, and augment fertigation and drip irrigation. However, existing technologies are a limiting factor because lab-based innovations have not been commercialized. In addition, industrial production of shade nets, plastic greenhouse covers, and mulching materials are limited to synthetic plastics. The bio-based plastic materials are sustainable based on biodegradability, and resistant to photo-oxidation. The resistance to UV degradation is an essential property because solar radiation cleaves C-C bonds, which in turn impact the mechanical strength of the materials. In brief, the sustainability of plastics in farms is influenced by LCA data, mechanical and optical properties, and performance relative to other materials.

Disintegration behaviour of bio-based plastics in coastal zone marine environments: A field experiment under natural conditions

The accumulation of plastic wastes in the marine environment represents a steadily increasing global environmental threat. The replacement of conventional plastics with bio-based biodegradable materials may contribute to alleviating the problem in the long run. This work studies the disintegration behaviour of three bio-based plastic materials, namely Polyhydroxybutyrate (PHB), Polybutylene sebacate (PBSe), Polybutylene sebacate-co-terephthalate (PBSeT), in three different coastal zone marine environments under natural conditions. The three studied environments were: 1) the seashore zone which is periodically covered by the seawater due to waves or tide, called eulittoral or intertidal zone; 2) the water column zone of small depth (about 10 m), called pelagic zone; and 3) the interface zone between the water column and the seabed sediment at small depth (about 20 m), called sublittoral or benthic zone. The experiments took place in the Aegean Sea at the SW coast of Salamis Island. The results showed that disintegration, as an indicative measure of biodegradation, occurs in all three tested environments, even though the rate depends on the material, the habitat, and the prevailing during the testing period environmental conditions. The degrees of disintegration of all materials in the three environments exhibited significant differences: Benthic > Intertidal > Pelagic. The observed disintegration can be attributed to biodegradation since the negative reference Low-density Polyethylene (LLDPE) material did not disintegrate.

Biobased conductive plastic materials for manufacturing capacitive lamps

Electrical conductive compounds based on biobased plastic materials partially from renewable resources and graphite were developed. This innovative material has demonstrated capacitive properties to be used for the base of lamps manufactured by 3D Printing. A high surface electrical conductivity has been achieved (10−2S/cm). The material is suitable to be processed by the filament extrusion technology and further by additive manufacturing technology such as fused deposition modelling (FDM). 3D printed lamps reduced the environmental impact in comparison to commercial lamps based on glass and metallic materials. The 3D printed lamp is fully functional, as the base of the lamp is sensitive and turns on touching with hand.

Factors influencing the market diffusion of bio-based plastics: Results of four comparative scenario analyses

The emerging bio-based economy is initiating a shift from fossil-based resources towards renewable resources. The use of biopolymers is seen as being a key component in sustainable product development. Research on biopolymers for bioplastics production mainly focuses on product development, environmental performance and cost-related aspects, and neglects the issue of bioplastic market diffusion. This paper aims at identifying the factors influencing the market diffusion of bioplastic by considering the four biopolymers: polylactic acid (PLA), polyhydroxyalkanoate (PHA), lignin and cashew nut shell liquid (CNSL). Scenario techniques employing effects analysis and cross impact analysis are applied in the assessment. The effects analysis shows that the price of PLA and PHA is influenced by the process costs, whereas the prices of CNSL and lignin based novel bio-based plastic materials, are influenced by further technological innovations. The sales volume of all four biopolymers largely depends on the price as well as on marketing activities. The cross impact analysis identifies a range of possible outcomes. While a further price reduction and an increasing sales volume can be assumed likely in the case of PHA and lignin, the scenarios for PLA and CNSL are rather uncertain. The results provide insight into the possible impact of further price and sales volume developments in the bio-based plastic market.

Characterization of pea protein-based bioplastics processed by injection moulding

This study assesses the behaviour of pea protein isolate (PPI) as a potential candidate for the development of biobased plastic materials processed by injection moulding. Around 30–40% of glycerol as plasticizer was required to obtain good processability of PPI/GL blends to produce bioplastics. A mixing rheometer that allows recording of torque and temperature during mixing and a small-scale-plunger-type injection moulding machine were used to obtain PPI/GL blends and PPI-based bioplastics, respectively. Rheological and differential scanning calorimetry measurements were made to guide the selection of suitable conditions for injection and moulding. For injection, we selected a temperature relatively close to the maximum of the loss tangent, but moderate enough to avoid crosslinking effects (50°C), and for moulding, a high temperature (130°C) to favour crosslinking in the mould. An increase in the PPI/GL ratio leads to an enhancement of elastic bending and tensile properties of bioplastic specimens, as well as an increase in their ability to absorb mechanical energy before rupturing. On the other hand, the PPI/GL specimens become less transparent. In addition, water uptake of these bioplastics has been found to be very high and fast.

Development of rice protein bio-based plastic materials processed by injection molding

Rice protein concentrate (RPC) has been evaluated as a potential candidate for the development of bio-based plastic materials processed by injection molding. Around 30% of glycerol (GL) as plasticizer and other additives (sodium bisulfite as a reducing agent as well as glyoxal and L-cysteine as cross-linking agents) were required to obtain good processability of RPC/GL blends to produce bioplastics. A mixing rheometer that allows recording of torque and temperature during mixing and a small-scale-plunger-type injection molding machine were used to obtain RPC/GL blends and RPC-based bioplastics, respectively. Rheological measurements were taken to guide the selection of suitable conditions for injection and molding. For injection, we selected a temperature relatively close to the glass transition temperature, but moderate enough to avoid crosslinking effects (87°C), while for molding, we selected a higher temperature (130°C) to favor crosslinking in the mold. However, other processing parameters (e.g., injection pressure) also need to be optimized. Final products (bioplastics) are plastic materials from renewable polymers (rice proteins) with both adequate properties for important industrial applications such as packaging, agriculture, etc. and high biodegradability when subjected to composting conditions. Adding each of the aforementioned additives leads to final specimens with different mechanical properties, as shown by dynamic mechanical temperature analysis and tensile strength measurements.

Heat resistance of new biobased polymeric materials, focusing on starch, cellulose, PLA, and PHA

ABSTRACTThis review provides state of the art information on the heat resistance of biobased thermoplastic materials. It gives an overview of the parameters used to indicate heat resistance, strategies to improve the heat resistance of (biobased) plastic materials and some current “heat resistant” commercially available biobased plastics materials. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42305.

Bringingd-limonene to the scene of bio-based thermoset coatings via free-radical thiol–ene chemistry: macromonomer synthesis, UV-curing and thermo-mechanical characterization

The increasing pursuit for bio-based plastic materials led us to investigate the potential use of the monoterpene limonene in thermoset synthesis using the free-radical mediated thiol–ene reaction. The high efficiency of this reaction to prepare multifunctional ene-terminated resins, as intermediary macromolecular precursors, for thermosets synthesis was demonstrated under thermal and photoinitiated conditions. Although an excess of terpene favors formation of well-defined macromonomers in organic solution, the characteristic low-vapor pressure of limonene hinders its simple removal (or recycling) via evaporation after synthesis. Alteration to an initial thiol–ene stoichiometry of 1 : 0.5 enables production of high molecular weight resins in the form of ‘hyperbranched oligomeric-like’ structures having moderate polydispersity. UV-curing of these polyfunctional resins combined with equal mole compositions of multifunctional alkyl ester 3-mercapto propionates yields highly sticky, amorphous and flexible elastomers with different thermo-mechanical properties. These can be further modulated by varying the amount of unreacted thiol occluded within the networks working as a plasticizer. Introduction of a renewable cycloaliphatic structure into the materials offers a convenient way to enhance the glass-transition temperature and stiffness of traditional thiol–ene networks. The materials synthesized may be considered potentially useful as sealants and adhesives in a wide variety of applications including organic coatings. The versatility of UV-irradiation over thermal initiation makes this method particularly suitable for green industrial synthesis processes via thiol–ene chemistry using limonene and multifunctional thiols. The thiol–ene system evaluated herein serves as a model example for the sustainable incorporation of natural diolefinic monomers into semi-synthetic thiol–ene networks exhibiting a range of thermo-mechanical properties.

Development of albumen/soy biobased plastic materials processed by injection molding

Biobased plastics from renewable polymers constitute a highly interesting field for relevant industrial applications such as packaging, agriculture, etc., in which thermomechanical techniques (i.e. extrusion, compression molding, etc.) are increasingly being used. In spite of the potentials of injection molding in the manufacture of shaped products it is still scarcely used with biopolymers. This study evaluates injection molding as an alternative to produce biobased materials from blends prepared in a mixing rheometer, using different albumen/soy ratios and glycerol as the plasticizer. Viscoelastic measurements and DSC of protein/glycerol blends were used to select suitable processing conditions. Physicochemical properties of injection-molded probes were characterized through dynamic mechanical thermal analysis, tensile strength, water uptake and transmittance tests. Occurrence of shear-induced effects over mixing was confirmed by extractability analysis of protein concentrates and blends, particularly for soy-based systems. Both proteins and their mixtures yield injection-molded bioplastics, although showing lower mechanical properties than LDPE standards.