Effect of abiotic factors on the degradation of poly(3-hydroxybutyrate- co-3-hydroxyvalerate) in simulated and natural composting environments

Abstract

The effect of abiotic factors such as water and air on the degradation of poly(3-hydroxybutyrate- co-3-hydroxyvalerate) (PHBV) in a compost was investigated using simulated and natural environments. These include exposure in sterile water at 60°C, in air at 60°C and in a garden waste compost. In addition, the chain scission degradation mechanism of PHBV on immersion in sterile water at 60°C was studied in detail. The results show that during a period of 50 days, water and air have little or no effect on the degradation of PHBV in a garden waste compost. The degradation is due to microbial action only. According to the literature, the degradation of PHBV in sterile water follows a random chain scission process. We have found that degradation follows random chain scission kinetics only in the beginning of the immersion in sterile water at 60°C. After longer immersion times (200 days), the degradation process no longer obeyed first order kinetics and a decrease in mol% HV in the copolymer was observed.