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

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 degrees C, in air at 60 degrees C and in a garden waste compost. In addition, the chain scission degradation mechanism of PHBV on immersion in sterile water at 60 degrees 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 degrees 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. (C) 1999 Elsevier Science Ltd. All rights reserved.