Time‐Lapsing Evaluation of the Retardation Behaviour of Polypropylene Homo‐ and Copolymers using the Stepped Isothermal Method based on Depth‐Sensing Macroindentation

Abstract

SummaryThe Stepped Isothermal Method (SIM) is a relatively new method for accelerated determination of the creep behaviour of polymers. The need for such a new method arises from the fact that for modern plastic components such as pipe systems minimum lifetimes of 50 years and more are achieved. The analysis of creep applying conventional methods of testing over such long periods of time is not reasonable from an economic point of view. This forms the basis for the development of accelerated procedures such as SIM. Plastic components can exhibit creep characteristics to be a function of the position due to processing. Such position‐dependent creep behaviour cannot be imaged by volume‐sensitive creep tests such as SIM under uniaxial tensile load. Therefore, SIM was implemented by means of recording macroindentation to characterize the local long‐time creep behaviour and the expressiveness of this method for different polypropylene materials was shown in this study.