Investigation on the solid–liquid (S–L) phase separation of the PE/LP blend with different molecular weight polyethylene

The solid–liquid (S–L) phase separation occurs in the polyethylene (PE)/liquid paraffin (LP) blend, which exhibits different characteristics for the molecular weight of PE. Herein, we have studied the S–L phase separation process of PE-500 (molecular weight of 5,000,000)/PE-60 (molecular weight of 600,000)/LP melts by the hot-stage-optical device. It is found that the clarification temperature and cloud temperature of PE-500/PE-60/LP blend decreased with the addition of PE-60. The isothermal crystallization behavior of these ternary blends is explored further using differential scanning calorimetry (DSC). According to the analysis results of Avrami equation and Arrhenius equation, the exponent n increases from 1.23 to 2.42 at higher temperature, indicating that the melt with high PE-60 content have a growth pattern between two and three dimensions, which could lead to larger pore. The activation energy at high temperature increases from 738.568 to 1321.259 $$ {\text{kJ}}/{\text{mol}} $$ with enhancing PE-60 content, while the activation energy decreases from 209.689 to 36.608 $$ {\text{kJ}}/{\text{mol}} $$ at lower temperature. It demonstrates that PE-60 content is not conducive to nucleation at high temperatures, but in favor of growth at low temperature. We believe the pore structure of PE microporous membrane may be controlled by different ratios of PE-500/PE-60 and crystallization temperature.