Tuning the rheological and mechanical properties of biodegradable PHBH/PLA/PVAc ternary blends via PVAc content control

Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH) is a biodegradable and sustainable copolymer that has garnered attention as a suitable alternative to certain types of single-use plastics. Herein, PHBH/poly(lactic acid) (PLA)/poly(vinyl acetate) (PVAc) ternary blends were initially melt compounded in an effort to obtain novel biodegradable materials with balanced properties. The effect of PVAc content on the miscibility, phase morphology, crystallization, rheological and mechanical properties was investigated. The results showed that PVAc component was selectively dispersed in the PLA dispersed phase at low content and migrated into the PHBH matrix when its content increased to 20 wt%. With the increase in PVAc content, the blends melts showed the improved viscosity and elasticity. The interesting aspect was that the mechanical properties of the ternary blends were enhanced by the introduction of PVAc. The increases of 33%, 38%, 54% were achieved in the elongation at break, tensile strength and Young's modulus of ternary blend containing 20 wt% PVAc compared with neat PHBH. Such combination of increased rheological and mechanical properties would contribute to expanding the practical applications of the biodegradable and sustainable PHBH materials.