Fracture behaviour of biodegradable polymer/polyolefin-natural fibers ternary composites systems

In this work, blends of MaterBi K (MBK), a starch based biodegradable polymer with polypropylene (PP), high density polyethylene (HDPE) and polystyrene (PS) were prepared in an intensive mixer PP-g-MA; HDPE-g-MA and SEBS-g-MA were incorporated at 2 wt.% to corresponding matrix respectively in order to analyze the effect of compatibilizer amount on the morphology and final properties. The composites, with 20 wt.% of alkaline treated hemp fibers, were prepared by injection molding. Fracture and water absorption of matrices and composites were studied and the effect of each component was established. Blending of the MB matrix with PP and HDPE did not raise the Jc, with the exception of the MB-S3 blend which has a slight improvement in fracture energy. On the other hand, the fiber incorporation to blends improves significantly the Jc values for all samples compared with their respective matrices. The best result was obtained for the B8-S2 blend and the B8-P2 compatibilized blend. The water absorption of equilibrium was also studied, resulting from 0.3 % to 0.9 % for the polymer blends and raises from 5 % to 7 % for the fiber reinforced blends.