Melt miscibility and solid-state properties of metallocene LLDPE blends with HDPE: Influence of MM of LLDPE

Abstract

The influence of relative molecular mass (MM) of LLDPE on the rheological, thermal and mechanical properties of two sets of m-LLDPE/HDPE blends of low and high branch content (BC) was studied. Blends of m-LLDPE with linear HDPE reveal no influence of MM (60–100 kg/mol) on melt miscibility at low BC (about 20 branches/1 000 C). However, at high BC levels (about 40 branches/1 000 C), MM affects the melt miscibility of m-LLDPE/HDPE blends. The DSC results suggest that compatibility in the solid state is independent of MM and BC. For all blends studied, the HDPE-rich blends are found to contain single crystal populations, suggesting high degree of cocrystallization, whereas, m-LLDPE rich phase shows separate crystallization. Mechanical properties of these blends are found to be a strong function of blend compatibility and the specific properties of the blend components. In general, the high BC pairs show poor mechanical properties.

Keywords

molecular mass / metallocene LLDPE / miscibility / rheological property