An investigation of the relationship between thermal relaxations and the impact performance of rotationally moulded linear low density polyethylenes

• Published in: Proceedings of the Institution of Mechanical Engineers. Part L, Journal of materials, design and applications Journal of materials, design and applications, 2005-02, Vol.219 (1), p.1-10
• Main Authors: Pick, L T, Harkin-Jones, E
• Format: Article
• Language: English
• ISSN: 1464-4207; 2041-3076
• DOI: 10.1243/146442005X10210

Abstract The objective of this paper is to provide a better understanding of how thermal relaxations in linear low density polyethylenes are related to the crack initiation energy of rotomoulded parts. Trials were carried out on two Ziegler-Natta catalysed linear low density polyethylenes (LIDPE) and two metallocene catalysed linear low-density polyethylenes (mLLDPE). Instrumented impact tests and dynamic mechanical thermal analysis (DMTA) were carried out on each material at a wide range of temperatures. The frequency of impact at each test temperature was determined, and the DMTA results were shifted to a corresponding frequency. A correlation can be seen between changes in loss modulus and crack initiation energy with temperature. When comparing the crack initiation energy of the samples and the tan Δ values, it can be seen that the β transition affects the way in which the polymer behaves under impact. A method for predicting impact performance over a wide temperature range is proposed.