Structure memory effects of polyethylene blends in temperature window

Abstract

Temperature window effect has been used to extrude polyethylene blends 5000s/TR-571 and bimodal polyethylene GC100s with low extrusion temperatures and pressures. Rheological results indicate that the temperature window effect occurs during the extrusions of the GC100s and blends 5000s/TR-571. For the blends 5000s/TR-571, both the temperature window and the minimum extrusion pressure dramatically decreases with increasing content of 5000s. For bimodal polyethylene GC100s, successive self-nucleation and annealing (SSA) fractionation results suggest that the pick at high temperature on the SSA curve of the extrudates obtained inside the temperature window is remarkably lower than those of the extrudates obtained outside the temperature window. This indicates that the lamellae of the extrudates obtained in the window are thinner than those obtained outside the window, which is attributed to the fact that the well-aligned chains as the result of structure memory effect can act as nucleating agent in the crystallization process. POLYM. ENG. SCI., 54:303–309, 2014. © 2013 Society of Plastics Engineers