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 p oly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) in a compost was investi gated using simulated and natural environments. These include exposure in s terile 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 i mmersion in sterile water at 60 degrees C was studied in detail. The result s show that during a period of 50 days, water and air have little or no eff ect on the degradation of PHBV in a garden waste compost. The degradation i s due to microbial action only. According to the literature, the degradatio n 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 i mmersion times (200 days), the degradation process no longer obeyed first o rder kinetics and a decrease in mol% HV in the copolymer was observed. (C) 1999 Elsevier Science Ltd. All rights reserved.