Effect of hygrothermal aging on the essential work of fracture response of amorphous poly(ethylene terephthalate) sheets

The toughness of amorphous poly(ethylene terephthalate) (PET) sheets before and after hygrothermal aging was determined by the essential work of fracture (EWF) concept. Hygrothermal aging at 60 degreesC for 100 h of the specimens was performed in hot water and soft drink (Coca-Cola), respectively. The EWF parameters were determined using the energy partitioning method of Karger-Kocsis et al., at various testing temperatures (T = -20 degreesC, + 23 degreesC, + 60 degreesC, respectively) at constant deformation rate (v = 2 mm/ min). It was found that the specific essential work of fracture terms are more sensitive for the test conditions than the plastic ones. Changes in the former terms were assigned to an alteration in the viscoelasticity of PET owing to temperature and the plasticising effect of water. (C) 2003 Elsevier Ltd. All rights reserved.