Hydrolytic Degradation of Poly(3-hydroxybutyrate), Polylactide and their Derivatives: Kinetics, Crystallinity, and Surface Morphology

Abstract

Hydrolytic degradations of biodegradable poly(3-hydroxybutyrate) (PHB), polylactide (PLA) and their derivatives were explored by kinetic and structure methods at 37 and 70°C in phosphate buffer. It was revealed the kinetic profiles for copolymer PHBV (20% of 3-hydroxyvalerate) and the blend PHB-PLA (1:1 wt. ratio). The intensity of biopolymer hydrolysis depending on temperature is characterized by total weight loss and the viscosity-averaged molecular weight decrement (ΔMW) as well as by WAXS and AMF techniques. Characterization of PHB and PHBV includes both ΔMW and crystallinity evolution (x-ray diffraction) as well as the AFM analysis of PHB film surfaces before and after aggressive medium exposition. The degradation is enhanced in the series PHBV < PHB < PHB-PLA blend < PLA. The impact of MW on the biopolymer hydrolysis is shown.

Keywords:

• AMF
• bacterial poly(3-hydroxybutyrate)
• copolymer PHBV
• crystallinity
• PHB-PLA blend non-enzymatic hydrolysis
• polylactide
• role of molecular weight
• total weight loss
• WAXS