Mechanical properties and morphology of high‐density polyethylene/linear low‐density polyethylene blend

Abstract

Abstract The binary blend of high‐density polyethylene (HDPE) and linear low‐density polyethylene (LLDPE) in the range of composition from 100% HDPE to 100% LLDPE has been investigated for tensile and flexural properties and the morphology in the deformed state on tensile fracture. Tensile properties (initial modulus, yield stress, and elongation‐at‐yield, ultimate tensile strength and elongation‐at‐break, and work of yield and work of rupture) and flexural properties (flexural modulus and flexural yield stress) are studied as a function of blend composition. Behavior, in terms of these properties, is distinguishable in three zones of blend composition, viz. (i) HDPE‐rich blend, (ii) LLDPE‐rich blend, and (iii) the middle zone. In zones (i) and (ii), the variations of these properties are more or less linear, whereas in the middle region [i.e., zone (iii)], there is a reversal of trends in variation or sometimes a behavior opposite to the expected one. The results are explained on the basis of the effects of cocrystallization and the presence of octene‐containing segments in the amorphous phase. Scanning electron micrographs of the tensile fracture surfaces are presented to illustrate the occurrence of transverse bands interconnecting the fibrils.