Sustainability of Bio-based Plastics and Composites

Plastics undoubtedly are indispensable and widespread commodities of the modern world, commonly found in a vast range of applications. Nonetheless, the awareness and concerns about the environmental impacts associated with the fossil-based plastics - that is, climate change, depletion of fossil resources, and plastic debris - are continuously on the rise. To efficaciously abate these impacts, different disciplines and approaches are needed to be used in a complementary manner, with contributions derived from the development of novel, bio-based materials as well as analytical and legal tools. To this end, in the present doctoral dissertation, approaches of material synthesis, multi-criteria decision-making (MCDM) analysis, life cycle assessment (LCA), and instruments of private law were combined in an interdisciplinary manner to analyze the selected set of bio-based plastics and composites. Accordingly, the MCDM analysis techniques of Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) and Simple Additive Weighting (SAW) were applied to identify the most suitable and interesting raw materials to produce bio-based plastics, which results were further utilized to synthesize a set of selected biocomposites in the laboratory conditions. A widely used methodology of LCA was, subsequently, employed to explore the environmental impacts derived from the developed biocomposites, with a focus on the impact categories of carbon footprint as well as agricultural-related indicators of acidification, eutrophication, and land use. Finally, the potential of a range of private law instruments - ecolabels, certification marks, and European certification marks (EUCM) - was explored as vessels to convey the sustainability information derived from the results of LCA. MCDM analysis revealed that the cultivation of castor beans and extraction of subsequent castor oil possessed the highest environmental impacts in comparison with other alternatives, despite the popularity of castor oil as a building block for commercial, bio-based polyamides (PAs). Consequently, varying concentrations of biofillers of starch and biochar were blended with the selected, neat PA- and polylactic acid (PLA) -matrices, which substantially reduced the carbon footprint and agricultural-related impacts of the plain plastics. Lastly, integration of LCA-results with different private law instruments were found not only to strengthen the sustainability information they convey, but also to possess potential to shape the behaviour of the targeted stakeholders. Overall, despite the need to enhance certainty, credibility, and comprehensivity of the applied data and methodologies, the present doctoral dissertation offers valuable information about the sustainability of the selected bio-based plastics and composites.