Keywords: biopolyester, Izod impact tests, fracture morphology, fracture micromechanisms, biopolymers, dynamic fracture, crack initiation, crack propagation, shear yielding, crack branching, striations
Micromechanisms of dynamic fracture in biopolyester
A biopolymer is a naturally occurring polymeric substance formed from individual molecules in a biological system. Biopolymers can also be synthetic by manipulation of the individual molecules once obtained outside the biological system. In the present investigation, attempts are made to investigate the basic mechanisms of dynamic fracture in a polyester biopolymer. Izod impact tests of polyester were carried out per ASTM-D256 standard and at different temperatures to establish the basic mechanisms; crack initiation, crack propagation, and final fracture. Scanning electron microscopes (SEM-JEOL 5910 LV and LEO 1430 VP) were used to investigate the fracture morphologies in polyester. SEM studies revealed that crack initiation in polyester was by shear yielding mechanism, and the crack propagation region was characterised by crack branching mechanism and the presence of striations.