Advanced Ecocomposites Materials

The thesis is divided into five chapters: the first four chapters cover the state of the art review on wood plastic composites, lignin and the recycling of bioplastics. The fifth chapter cover the experimental work of the thesis. In chapter fifth the materials and methods used are firstly presented followed by the discussion on the results obtained. The research work performed during the PhD was focused on the development of novel eco-compatible thermoplastic composites. The experimental work was based on the use of two polymer matrices: polypropylene and poly(lactid acid). Polypropilene is not biodegradable but by the addition of a lignin based polymer the carbon biocontent was increased obtaining a formulation readily available and suitable for applications. The results presented on these blends outlined an increased thermal stability and mechanical resistance due to the addition of the lignin based system. This result is promising for the application of this blend in the automotive field. Many automotive parts, such as for example the under hood parts, require improved thermal performances that can be fulfilled by the proposed approach. To overcome the problem of the use of petroleum based plastic the use of PLA was investigated in the research. PLA can be synthetized starting from sugar resulting in a ecofriendly matrix. PLA can be composted so it is a viable option to improve the ecocompability of polymers. However, PLA has an high cost of production which, since now, limited its acceptance in mass production. Therefore, to reduce PLA cost and, at the same time, improve the mechanical and thermal properties the addition of lignin was studied. The results obtained showed that, as for PP, lignin is a potentially good additive. However, the results showed some processing issues due to the thermal stability of PLA which was negatively affected by the reactive moiety of lignin. The results obtained confirmed that combining natural fillers (i.e. lignin) with polymers synthetized by natural sources (i.e. PLA) promising blends can be obtained. However, processing should be optimized to minimize the degradation. To achieve such goal, a feasible process could be to chemical modify the lignin structure or the PLA matrix. Lignin is a multifunctional polymers thus, the approach could be oriented to link moiety which can reduce the interaction with the ester group of PLA. In addition to the improvement of the thermal stability of PLA/Lignin blends future work will be oriented to the use of such blends as matrix for natural fiber composites. This further development will be pursued to obtain sytems suitable for structural applications.