Instrumented dart impact evaluation of linear low density polyethylene at controlled impact energy

Abstract

AbstractInstrumented impact testing of linear low density polyethylene (LLDPE I) (ethylene and 1‐octene copolymer) was carried out using a Rheometrics Drop‐Weight Tester (RDT‐5000). A method of partial penetration at controlled impact energy was used and developed. The set impact speed was raised step by step in small intervals of 0.25 m/s over a range of 0.76 m/s to 9.14 m/s. The impact deformation profiles of LLDPE I were obtained for a series of specimens impacted at different speeds. The stress states of the LLDPE I during the corresponding impact events were obtained with the instrumented impact tup. By comparing the observed impact profile with the force‐displacement trace, the yield point and the initial failure point of LLDPE I were assessed. The point of 100 percent of the maximum load on the force‐displacement trace of a total penetration impact was shown to be the yield point. On the basis of the determination of the yield point, a parameter, ductile ratio (D.R.), was redefined to characterize the ductility of polymers. The initial break point of LLDPE I was determined. The effect of specimen thickness and test temperature on the impact properties was investigated.