Effect of processing on the environmental stress cracking resistance of high-impact polystyrene

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• 作者：Luca Andena^a ; ^{luca.andena@polimi.it" class="auth_mail" title="E-mail the corresponding author} ; Marta Rink^a ; Claudia Marano^a ; Francesco Briatico-Vangosa^a ; Leonardo Castellani^b
• 关键词：Polystyrene ; Environmental stress cracking ; Processing ; Fracture
• 刊名：Polymer Testing
• 出版年：2016
• 出版时间：September 2016
• 年：2016
• 卷：54
• 期：Complete
• 页码：40-47
• 全文大小：2073 K

文摘

Processing conditions have a strong effect on the final mechanical properties of products made of polymeric materials. Relevant phenomena most commonly include thermal stresses, physical ageing, frozen-in strains and molecular orientation. In this work, two different high-impact polystyrenes, processed by thermoforming, were considered: a “standard” one and a grade specifically resistant to Environmental Stress Cracking (ESC). The main effect induced by thermoforming was molecular orientation. The local degree of orientation was measured on a thermoformed product and its effect on the material ESC behavior in sunflower oil was studied. A Fracture Mechanics approach was applied to evaluate the fracture resistance of the two materials. Results show that a higher degree of orientation increases the fracture resistance in air but has no effect on the (expectedly lower) resistance in the active oil environment.