Production Of Bio-based Plastics Research Articles

Green Synthesis of Bioplastics from Microalgae: A State-of-the-Art Review.

The synthesis of conventional plastics has increased tremendously in the last decades due to rapid industrialization, population growth, and advancement in the use of modern technologies. However, overuse of these fossil fuel-based plastics has resulted in serious environmental and health hazards by causing pollution, global warming, etc. Therefore, the use of microalgae as a feedstock is a promising, green, and sustainable approach for the production of biobased plastics. Various biopolymers, such as polyhydroxybutyrate, polyurethane, polylactic acid, cellulose-based polymers, starch-based polymers, and protein-based polymers, can be produced from different strains of microalgae under varying culture conditions. Different techniques, including genetic engineering, metabolic engineering, the use of photobioreactors, response surface methodology, and artificial intelligence, are used to alter and improve microalgae stocks for the commercial synthesis of bioplastics at lower costs. In comparison to conventional plastics, these biobased plastics are biodegradable, biocompatible, recyclable, non-toxic, eco-friendly, and sustainable, with robust mechanical and thermoplastic properties. In addition, the bioplastics are suitable for a plethora of applications in the agriculture, construction, healthcare, electrical and electronics, and packaging industries. Thus, this review focuses on techniques for the production of biopolymers and bioplastics from microalgae. In addition, it discusses innovative and efficient strategies for large-scale bioplastic production while also providing insights into the life cycle assessment, end-of-life, and applications of bioplastics. Furthermore, some challenges affecting industrial scale bioplastics production and recommendations for future research are provided.

Reactive extraction of pyridinedicarboxylic acid (PDCA) with tri-n-octylamine and Aliquat 336 in 1-octanol – A promising approach to access microbially produced PDCA

Pyridinedicarboxylic acids (PDCA) are analogues to terephthalic acid and promising molecules for the production of bio-based plastics. Previous work achieved the microbial production of PDCAs from the renewable resource lignin but an efficient and low cost method to recover PDCA from fermentation broth is still missing. Reactive extraction is commonly applied for the extraction of carboxylic acids from aqueous phase. In this study, we investigate reactive extraction of PDCA with the two extractants tri-n-octylamine (TOA) and Aliquat 336 in the diluent 1-octanol. The extraction and re-extraction were optimized with 2,5-PDCA in an aqueous solution leading to up to 98 % extraction for both extractants. Re-extraction by pH swing resulted in > 95 % re-extracted 2,5-PDCA. A scale-up in liquid–liquid centrifuges enabled continuous extraction and re-extraction in liter scale with a yield of 95 %. A concentration factor of 3.6 was achieved and the organic phase was recycled. The approach also showed transferability to the processing of complex fermentation solution. 2,4-PDCA, microbially produced in a bioprocess, could be recovered by 65 % in one single extraction and re-extraction step from biomass-free fermentation broth.

Laboratory and field scale biodegradability assessment of biocomposite cellphone cases for end-of-life management.

The increase in production of biobased plastics as a replacement for fossil fuel-based plastics has created the need for studies to assess their degradation under various conditions. However, developing reliable laboratory and field-testing protocols for biobased materials and products still requires extensive research. In this study, the biodegradability of a biocomposite consumer product, smart cellphone case, was determined under laboratory scale anaerobic (38°C) and composting assays (58°C) as well as under field scale (60-67°C) composting conditions. The laboratory scale composting assay was conducted for 46days using cellphone cases with dimensions of 7×3.5×0.2 and 4.6×3.5×0.2cm, which achieved approximately 20% biodegradation. The field scale composting conditions achieved 55% weight loss of cellphone cases in 80days. The subsequent anaerobic biodegradation assays contained three different sized (grinded, cut into 2×2×0.2 and 4×4×0.2cm pieces) biocomposite cellphone cases conducted under mesophilic conditions for 169days. Among the conditions tested, the size of cellphone cases did not cause a significant difference in biodegradation under anaerobic conditions. Anaerobic digestion conditions yielded only 6-8% biodegradation, which was significantly lower than that of composting. The results agree with literature on conventional waste streams stating that aerobic microbial processes are more effective to break down complex substrates, similar to biocomposite cellphone cases tested, than their anaerobic counterparts.

Exploring perceptions of environmental professionals, plastic processors, students and consumers of bio-based plastics: Informing the development of the sector

Bio-based plastics are produced from bio-based raw materials such as sugar cane, potatoes, corn, and agricultural and slaughterhouse waste. The evolution of the bio-based plastics market is affected by the stakeholders involved owing to their role in production processes, environmental guidelines and purchasing decisions. It is therefore imperative to understand the perceptions of stakeholders in order to inform the development of the bio-based plastics sector. This novel exploratory study investigates the perceptions and opinions of three stakeholder groups: environmental professionals and plastic processors; university students; and consumers in Belfast, Northern Ireland. During the focus groups (25 participants in total), samples of bio-based plastics, including starch-based monolayer and multilayer, and polyethylene terephthalate (PET), were presented. A qualitative analysis using the framework method revealed that environmental professionals and plastic processors were aware of both the benefits of bio-based plastics, such as a reduction in use of fossil fuels; and the challenges, which include the utilisation of agricultural land for biomass substrates and possible contamination of current conventional plastic recycling streams. Although there was a general lack of knowledge among students and consumers about bio-based plastics, they conveyed their beliefs that the use of agricultural waste will lead to closed-loop systems, resulting in a balanced approach to production and waste management. Some students and consumers, raised concerns about contamination of food by bio-based packaging prepared from slaughterhouse waste. However, these participants supported the use of slaughterhouse waste in the production of bio-based plastics for non-food contact items. The students and consumers and some of the environmental professionals and plastic processors were reluctant to pay more for bio-based plastics. The results indicate that manufacturers of bio-based plastics could benefit from informing consumers about the environmental impacts of beginning-of-life parameters, such as production processes and feedstocks, by using life cycle assessment parameters. This should be incorporated into information provided on labelling using standards from neutral organisations. This research could inform future communication strategies around bio-based plastics with both the public and industry.

The Sustainability of Plastic Nets in Agriculture

This review article contributes new knowledge relating to the sustainability of antihail, anti-insect, and windbreak plastic nets in agriculture. Based on the review, biobased plastic nets made from polyamino acids, polysaccharide derivatives (DS), polyhydroxybutyrate (PHB), polycaprolactone (PCL), polyhydroxylalkanoate (PHA), and polylactic acid (PLA) are shown to be highly biodegradable compared to conventional plastics such as high-density polyethylene (HDPE), polyethylene (PE), and polyvinyl chloride. The biodegradability of these materials is due to the use of natural precursors. However, nonbiodegradable plastics are the materials of choice in agricultural applications for the following reasons. Global commercial production of biobased plastics is low (~1%) due to the absence of facile and scalable production methods. Even though biobased materials are ecologically benign, they are limited in agricultural settings, given the low tensile strength and disruption of the activities of natural insect predators such as spiders. The enhancement of the material properties of biobased plastics involves a trade-off with sustainability. Chemical additives such as heavy metals and volatile compounds enhance the mechanical properties of biobased plastics but limit their sustainability. The current constraints on the production of biobased plastic nets can be resolved through electrospinning techniques that facilitate the development of plastic nets with controllable composition, porosity, and surface areas.

Applying an attitude network approach to consumer behaviour towards plastic

In a time of rapid climate change, understanding what may encourage sustainable consumer behaviour is a vital but difficult challenge. Using an attitude network approach, we investigated which associations people have towards conventional and bio-based plastic in order to develop an empirically-based approach to initiate attitude- and behaviour change. With a qualitative study (N = 97), we distilled 25 evaluative reactions (i.e. beliefs, emotions, and behaviours) that encompass people's attitudes towards using (bio-based) plastic. These reactions were used to create a new scale, which was subsequently tested among 508 online participants. The resulting data was then used to build a network displaying relationships between participants' evaluative reactions regarding plastic use. Analyses of this network indicated that guilt was most strongly connected to people's willingness to pay more for bio-based plastic products. Based on this, we conducted another study (N = 285) in which we experimentally manipulated guilt (general guilt, personal guilt, and control condition) to determine its effects on people's willingness to pay for a sustainable cause. Results indicate that manipulating guilt can lead participants to donate more to a sustainable cause. This effect was fully mediated by self-reported guilt. Determining which factors influence consumers to change their buying behaviour towards sustainability is the first step in creating a demand for more sustainable products amongst the public and investors.

The environmental attributes of wood fiber composites with bio-based or petroleum-based plastics

While bio-based composites (bio-based plastics reinforced with natural fibers) have been discussed as potential sustainable alternatives to petroleum-based plastic composites, there are few quantitative environmental impact assessments of these materials. This work presents comparisons of petroleum-based and bio-based plastics as well as their composites to (1) assess environmental impacts from plastics and composite production and (2) determine which environmental impacts can be mitigated through production of bio-based composites, based on current manufacturing methods. Environmental impact assessments were performed to determine the burdens associated with cradle-to-gate production of bio-based and petroleum-based plastics and their composites with wood flour (i.e., sawdust) filler. The scope of this work incorporated emissions from thermoplastic and wood flour production as well as pelletization, molding, and transportation processes. Environmental impacts were assessed for several impact categories using the US Environmental Protection Agency’s TRACI method. Using impacts quantified, as well as material property data from 36 sources in the literature, comparisons were drawn between composite types. Multiple functional units were used including a constant mass of material produced and two comparison methods normalizing environmental impacts by material properties. Uncertainty assessments were performed to determine environmental impact distributions for each plastic and wood fiber composite type. The production of bio-based plastics and their composites led to lower environmental impacts than petroleum-based plastics and composites in several impact categories: global warming potential, fossil fuel depletion, and certain human health impacts. However, the production of bio-based plastics and their composites also resulted in some higher environmental impacts, such as eutrophication. Bio-based composites are capable of possessing similar or improved mechanical properties to their petroleum-based counterparts. As such, normalized environmental impacts to material properties indicated that bio-based composites could lead to desirable combined mechanical and environmental attributes for certain applications. Considering the differences between environmental impact categories and uncertainties in environmental impact assessments, selection of constituents cannot be based solely on material feedstock to mitigate environmental impacts in wood fiber composites. Findings indicate that both environmental impact assessments and mechanical properties should be considered concurrently to effectively distinguish the benefits of selecting petroleum-based or bio-based plastics. This work shows that depending on the intended application, the selection of a bio-based feedstock could either be beneficial for mitigating certain environmental impacts, have little effect on impacts, or increase environmental impacts. These findings reveal the importance of considering property alteration and multiple effects of utilizing these resources.

Selecting for lactic acid producing and utilising bacteria in anaerobic enrichment cultures.

Lactic acid‐producing bacteria are important in many fermentations, such as the production of biobased plastics. Insight in the competitive advantage of lactic acid bacteria over other fermentative bacteria in a mixed culture enables ecology‐based process design and can aid the development of sustainable and energy‐efficient bioprocesses. Here we demonstrate the enrichment of lactic acid bacteria in a controlled sequencing batch bioreactor environment using a glucose‐based medium supplemented with peptides and B vitamins. A mineral medium enrichment operated in parallel was dominated by Ethanoligenens species and fermented glucose to acetate, butyrate and hydrogen. The complex medium enrichment was populated by Lactococcus, Lactobacillus and Megasphaera species and showed a product spectrum of acetate, ethanol, propionate, butyrate and valerate. An intermediate peak of lactate was observed, showing the simultaneous production and consumption of lactate, which is of concern for lactic acid production purposes. This study underlines that the competitive advantage for lactic acid‐producing bacteria primarily lies in their ability to attain a high biomass specific uptake rate of glucose, which was two times higher for the complex medium enrichment when compared to the mineral medium enrichment. The competitive advantage of lactic acid production in rich media can be explained using a resource allocation theory for microbial growth processes.

Bio-based composite from poly(butylene succinate) and peanut shell waste adding maleinized linseed oil

Nowadays, the biobased plastic products have become one of the worldwide topics that people give the attention. Applications of bio-based poly (butylene succinate) (PBS) is interesting since it is fully biodegradable. However, the resin cost is expensive compared to olefins so that it is not widely used. This research attempted to produce cost-effective composite sheets from PBS and peanut shell powder (PSP) with particle size of 100 mesh in the weight ratio of 70/30, 60/40, and 50/50 wt% using a twin-screw extruder and then a compression molding. In addition, maleinized linseed oil (MLO) of 3 phr was used as a compatibilizer for the composites. It was found that the obtained composites had higher Young’s modulus and Shore D hardness with respect to the PSP content, but elongation at break was reduced. The impact resistance by means of the falling dart impact test also reduced with the higher PSP content. Adding MLO into the PBS/PSP composites increased elongation at break and impact resistance, but reduced the rigidity due to plasticizing effect. Due to lignocellulosic nature of PSP, the thermal stability of the composites was decreased and MLO did not have significant influence on it. After the weathering testing for 60 h, mechanical properties and thermal stability of the composites were reduced significantly implying that these bio-based composites could degrade faster compared to pure PBS sample.

Consumer preferences for outdoor sporting equipment made of bio-based plastics: Results of a choice-based-conjoint experiment in Germany

Within sports industry a lot of plastic is used. A rapid diffusion of new products causes a lot of plastic waste and substantial environmental problems, which could be reduced in part through the use of bio-based plastics produced from renewable biomass raw materials. Consumer interest in bio-based plastics is currently limited by the small range of bio-based plastic products, a lack of experience with bio-based plastics and high prices. In this study the preferred attributes of a bio-based plastic drink bottle for bicycles and a running shoe with a bio-based sole were identified using a choice-based-conjoint analysis (CBC). Members of a German online panel were surveyed in November 2014. The analysis of seven attributes for both of the products revealed that origin of the raw materials was the most important factor, with respondents having a clear preference for the use of raw materials cultivated in Germany. Respondents also preferred products containing a high percentage of bio-based plastic, products associated with a large reduction of CO2-emissions and products not involving the use of plastic softeners. A general interest in the bio-based sample products could be identified, but the respondents rejected a high price premium. The importance of domestically cultivated raw materials is consistent with findings of previous studies investigating primarily foodstuff. The insights of this study could form the basis of a promising strategy to promote consumer products made of bio-based plastic.

Characterization of bio-based plastic made from a mixture of Momordica charantia bioactive polysaccharide and choline chloride/glycerol based deep eutectic solvent

Momordica charantia bioactive polysaccharide (MCBP) was used as an alternative source for the production of bio-based plastics (BPs) with choline chloride/glycerol-based deep eutectic solvent (DES) as a plasticizer. In this study, MCBP was initially extracted using 0.1 M citric acid at temperature 80 °C for 2 h, precipitated using ethanol, and then lyophilized. Subsequently, seven BPs were prepared: MCBP without plasticizer (MCBP), with 1% (w/w) of glycerol (MCBP-G), or with 1% (w/w) of DES at different choline chloride/glycerol molar ratios (i.e. 1.5:1, 1:1, 1:1.5, 1:2, and 1:3). The properties of these BPs were then investigated. Results showed that the tensile strains, stresses and moduli were in the range of 1.3–13.3%, 4.8–19.1 MPa and 132–2487 MPa, respectively. The melting temperatures were found in the range of 92.6–111.4 °C whereas the moisture absorptions and water vapour transmission rates (WVTR) of BPs were 1.4–6.5% and 3.6–5.4 mg/m2·s, respectively. The results also showed that these BPs exhibited bioactivities, such as microbial inhibitory activity (19.5–32.3 mm), free radical scavenging activity (10.3–18.3%) and ferric reducing antioxidant power (FRAP, 16.1–20.0 mM). In addition, it was observed that using DES as a plasticizer had improved the properties of BP, such as tensile strain (354.7–937.5%), melting temperature (4.6–20.3%), radical scavenging activity (0.6–88.6%), FRAP (0.9–18.7%) and antimicrobial activity (12.3–33.6%) compared to MCBP, due to the fact DES has caused different degrees of plasticization via hydrogen bonds and ionic bonds with the polymer chains, and induced a lower pH condition. Therefore, it was suggested that these BPs with DES could contribute to food preservation properties.

Segmentation of interested and less interested consumers in sports equipment made of bio-based plastic

Currently only few products are made of bio-based plastic instead of conventional plastic, whose production and use is causing many environmental problems. Bio-based product alternatives could have a positive impact in consumer sectors relating to nature, such as the outdoor sporting equipment sector. For this reason, consumers’ interest in bio-based sports equipment, their product preferences and the factors which influence their interest were analyzed. Using choice-based-conjoint experiments and latent class analysis, consumer groups who are interested in these products could be differentiated from those who are less or not interested. Respondents with interest in bio-based sports equipment prefer a high bio-based plastic content, a large reduction in potential CO2-emissions and the use of regionally grown raw materials. Respondents with less interest in bio-based plastic products prefer low-priced products made of conventional plastic. To enable a more precise differentiation between these consumer groups, a discriminant analysis was also conducted. Above all, personal attitudes such as environmental awareness and nature relatedness differentiated the interest groups. With regard to Short-Schwartz-Values, only universalism and benevolence sufficiently differentiated between the interested and less interested respondents. Considering environmentally friendly behavior in other areas, interest in bio-based plastic seems to correlate with preference for organic food. Socio-demographic data did not explain the differences between the two interest groups. Finally, respondents who were interested in bio-based products had more positive expectations and stricter requirements regarding the cultivation of raw materials.

Replacing fossil based plastic performance products by bio-based plastic products—Technical feasibility

Larger scale market introduction of new bio-based products requires a clear advantage regarding sustainability, as well as an adequate techno-economic positioning relative to fossil based products. In a previous paper [Broeren et al., 2016], LCA results per kg and per functionality equivalent of bio-based plastics were presented, together with economic considerations. The present paper discusses the mechanical and thermal properties of a range of commercially available bio-based plastics based on polylactic acid (PLA), cellulose esters, starch and polyamides, and the feasibility of replacing fossil-based counterparts based on performance. The evaluation is approached from an end user perspective. First, potentially suitable bio-based plastics are selected based on manufacturers’ specifications in technical data sheets, then a first experimental evaluation is performed on injection moulded ISO specimens, and finally a further selection of plastics is tested on large 50×70cm panels. This technical feasibility study indicates that so far bio-based plastics do not completely match the properties of high performance materials like flame retardant V-0 PC/ABS blends used in electronic devices. The performance gap is being decreased by the development of stereocomplex PLA and hybrid PLA blends with polycarbonate, which offer clearly improved properties with respect to maximum usage temperature and toughness. In addition, several materials meet the V-0 flammability requirements needed in specific durable applications. On the other hand, improving these properties so far has negative consequences for the bio-based content. This study also shows that replacement of bulk polymers like PS is feasible using PLA compounds with a bio-based content as high as 85%.

Transgene autoexcision in switchgrass pollen mediated by the Bxb1 recombinase.

BackgroundSwitchgrass (Panicum virgatum L.) has a great potential as a platform for the production of biobased plastics, chemicals and energy mainly because of its high biomass yield on marginal land and low agricultural inputs. During the last decade, there has been increased interest in the genetic improvement of this crop through transgenic approaches. Since switchgrass, like most perennial grasses, is exclusively cross pollinating and poorly domesticated, preventing the dispersal of transgenic pollen into the environment is a critical requisite for the commercial deployment of this important biomass crop. In this study, the feasibility of controlling pollen-mediated gene flow in transgenic switchgrass using the large serine site-specific recombinase Bxb1 has been investigated.ResultsA novel approach utilizing co-transformation of two separate vectors was used to test the functionality of the Bxb1/att recombination system in switchgrass. In addition, two promoters with high pollen-specific activity were identified and thoroughly characterized prior to their introduction into a test vector explicitly designed for both autoexcision and quantitative analyses of recombination events. Our strategy for developmentally programmed precise excision of the recombinase and marker genes in switchgrass pollen resulted in the generation of transgene-excised progeny. The autoexcision efficiencies were in the range of 22-42% depending on the transformation event and assay used.ConclusionThe results presented here mark an important milestone towards the establishment of a reliable biocontainment system for switchgrass which will facilitate the development of this crop as a biorefinery feedstock through advanced biotechnological approaches.

Manufacture of natural fiber-reinforced polyurethane composites using the long fiber injection process

This paper gives an overview of recent activities in the production of natural fiber- -reinforced polyurethane (PUR) composites. Extensive research is being conducted to develop marketable solutions for the production of bio-based plastics. In composite applications, natural fibers can be used as a substitute for synthetic fibers and help to make a significant contribution towards ecological and efficient lightweight components. In addition, an outlook on current developments in Long Fiber Injection (LFI) processing for the application of natural fiber-reinforced polyurethane composites, specifically in electric vehicles is given.

Evolution of D-lactate dehydrogenase activity from glycerol dehydrogenase and its utility for D-lactate production from lignocellulose.

Lactic acid, an attractive, renewable chemical for production of biobased plastics (polylactic acid, PLA), is currently commercially produced from food-based sources of sugar. Pure optical isomers of lactate needed for PLA are typically produced by microbial fermentation of sugars at temperatures below 40 °C. Bacillus coagulans produces L(+)-lactate as a primary fermentation product and grows optimally at 50 °C and pH5, conditions that are optimal for activity of commercial fungal cellulases. This strain was engineered to produce D(-)-lactate by deleting the native ldh (L-lactate dehydrogenase) and alsS (acetolactate synthase) genes to impede anaerobic growth, followed by growth-based selection to isolate suppressor mutants that restored growth. One of these, strain QZ19, produced about 90gL(-1) of optically pure D(-)-lactic acid from glucose in <48h. The new source of D-lactate dehydrogenase (D-LDH) activity was identified as a mutated form of glycerol dehydrogenase (GlyDH; D121N and F245S) that was produced at high levels as a result of a third mutation (insertion sequence). Although the native GlyDH had no detectable activity with pyruvate, the mutated GlyDH had a D-LDH specific activity of 0.8μmolesmin(-1) (mgprotein)(-1). By using QZ19 for simultaneous saccharification and fermentation of cellulose to D-lactate (50 °C and pH5.0), the cellulase usage could be reduced to 1/3 that required for equivalent fermentations by mesophilic lactic acid bacteria. Together, the native B. coagulans and the QZ19 derivative can be used to produce either L(+) or D(-) optical isomers of lactic acid (respectively) at high titers and yields from nonfood carbohydrates.

Considerations for Manufacturing Bio-Based Plastic Products

One engine that drives the United States’ economic growth is an ever-increasing demand for manufactured products, both at home and abroad. This increase has created a major concern for the environment in terms of disposing used goods and ensuring that these products are safe. As environmental concerns grow, however, renewable resources are gaining increasing attention, especially as industrial ecology and product biodegradability gain importance. Added to this, biological materials are increasingly being utilized to replace traditional materials in manufacturing. To aid both educators as well as researchers, this paper examines several considerations that are essential for manufacturing plastic products that contain biomaterials. These include the selection of materials, the selection of manufacturing processes, manufacturing costs, and the quality of final products. Additionally, several standard methods that are commonly used for the determination of mechanical and physical properties are compiled; thus this paper should be a useful resource for both educators and researchers. The trends discussed here and their implications are critical for those involved in manufacturing, because contrary to conventional wisdom, simultaneously meeting the material production needs of our society, as well as that of the environment are not mutually-exclusive.