The effects of melt grafted maleated polybutylene succinate on the properties of poly(hydroxybutyrate-co-hydroxyhexanoate)/polybutylene succinate blends

Abstract

Poly(hydroxybutyrate-co-hydroxyhexanoate) (PHBHH)/poly(butylene succinate) (PBS) blends were prepared using a melt blending technique. A compatibilizer of maleated PBS (PBSgMA) was produced using reactive melt grafting by varying the maleic anhydride (MA) monomer concentration ranging from 3 to 10 parts per hundred resin (phr). Fourier-transform infrared (FTIR) spectroscopy and nuclear magnetic resonance (NMR) spectroscopy analyses confirmed the grafting reaction of the PBSgMA. The PBSgMA was incorporated in the 80PHBHH/20PBS and 50PHBHH/50PBS blends to investigate the effect of maleated compatibilizer on the tensile, flexural, drop weight impact, and water absorption properties of the blends with droplets dispersed and co-continuous morphology. The incorporation of PBSgMA increased the tensile and flexural strength of both the 80PHBHH/20PBS and 50PHBHH/50PBS blends, where the optimum properties achieved at 5 phr concentration of MA. The drop weight impact test results showed that uncompatibilized and compatibilized 50PHBHH/50PBS blends had higher critical strain energy release rate (Gc) than the neat PHBHH. However, blending and compatibilizing did not have a positive effect on the critical stress intensity factor (Kc) of the neat PHBHH. Scanning electron microscopy (SEM) confirmed the improvement of interfacial adhesion and PBS polymer dispersion in PHBHH/PBS blends when incorporated with 5PBSgMA. The water absorption test results demonstrated that compatibilized blends absorbed slightly more water than uncompatibilized blends due to the presence of hygroscopic carboxyl groups of the PBSgMA. However, water absorption effects were reversible and did not result in severe permanent damage to the blends.