PHASE SEGREGATION AND IMPACT TOUGHNESS IN LINEAR LOW-DENSITY POLYETHYLENE

The impact behaviour of three linear low density polyethylenes (LLDPE) has been studied using the energy partitioning methodology recently d eveloped in this laboratory. The aim was to elucidate the origin of th e high toughness of this class of polymers and to establish whether a rubber toughening mechanism is involved. It has been found that LLDPEs have an unexpectedly high intrinsic toughness, and that there is a si gnificant ductile contribution to the total fracture energy from shear lip energy absorption. No evidence of a conventional rubber toughenin g mechanism has been found. However, the shear lip area (and hence thi s specific component of the total fracture energy) increases with the concentration of the segregated 'rubbery' phase.