Effect of chain structure on ductile-brittle transition in some polyestercarbonates

The relation between chain structure and ductile-brittle transition (DBT) i n polyestercarbonates (PEC) was investigated by measuring the fracture ener gy and observing the fracture surfaces of a homologous series of PEC contai ning phthalate units. DBTs were determined in terms of various test conditi ons including specimen thickness, test speed, and notch-tip radius. With an increase in the phthalate content, transition was found to shift to a thin ner specimen, a lower test speed, and a higher notch-tip radius. It was con cluded that the DBT is directly affected by the extent of entanglement in t hese copolymers. (C) 2001 Elsevier Science Ltd. All rights reserved.