Thermal, Physico-Mechanical and Degradation Characteristics of Compatibilized Biodegradable Biopolymers and Composites

Due to negative effects of petroleum-based plastic waste on environment, a significant consideration is given to biopolymers as sustainable alternatives. However, incompetence in technology and cost prevent the applications of biopolymers. This study evaluated the effect of compatibilizer and wood fiber filler on five types of biopolymers. To assess weathering characteristics, biocomposites were subjected to 2000 h of accelerated weathering. Biocomposites were soil buried at temperatures of 30°C and 60°C for quantifying biodegradation. Compatibilization improved thermal and physico-mechanical properties. All properties deteriorated upon weathering, but no considerable differences were observed between compatibilized and uncompatibilized composites. After soil biodegradation, weight loss and increased water absorption were observed. Biodegradation was significant after soil burial at 60°C. Compatibilized composites after 30°C soil burial showed lower biodegradation than uncompatibilized composites, but at 60°C, it was reversed. Results confirm improved properties with compatibilization without affecting UV weathering characteristics, and achieving higher biodegradation at elevated temperatures.North Dakota Agricultural Experiment Station; North Dakota NSF EPSCo

Study of the matrix-filler interface in PLA/Mg composites manufactured by Material Extrusion using a colloidal feedstock

The aim of this paper is to investigate the evolution of a matrix-filler interface during the processing of novel composites formed by a matrix of polylactic acid (PLA) and Mg particles, when they are manufactured by Materials Extrusion. The particles addition to the PLA was carried out through the preparation of a Magnesium stable suspension in the polymer solution. To improve the Mg dispersion, the surfaces of the particles were previously modified by the adsorption of dispersants, namely Polyethylenimine (PEI) and Cetyltrimethylammonium bromide (CTAB) in aqueous suspension. The physical and mechanical characterization of PLA/Mg composites show that the Mg surface modification is the key to its successful dispersion due to the formation of ionic interactions between the dispersants and the matrix. This is favoured by the seeding effect of the PEI-modified Mg particles over the PLA re-precipitation during the composite shaping. Moreover, a PEI-PLA covalent bond appeared in the printed scaffolds as a consequence of the temperature applied (165¿°C) during extrusion and printing. Consequently, the matrix-filler strengthened interface improved the extrusion process and permits the printing of 3D customized pieces. At the same time, particle agglomeration and the nozzle blocking is prevented