The fracture of poly(hydroxybutyrate) - Part II - Fracture mechanics studyafter annealing

The fracture behaviour of poly(hydroxybutyrate) (PHB) after high-temperatur e annealing has been studied using linear elastic fracture mechanics techni ques. The effect of the annealing temperature on the polymers' fracture tou ghness both initially and after re-ageing is examined. Annealing at tempera tures of 120 degrees C or above is found to result in an improvement in bot h the critical stress intensity factor and the strain energy release rate m easurements of fracture toughness which is largely maintained on re-ageing. A more detailed study of the re-ageing behaviour after annealing at 130 de grees C finds G(c) to remain approximately constant but K-c to increase sli ghtly with age. (C) 1998 Chapman & Hall.