Effects of residual wax content on the thermal, rheological, and mechanical properties of high‐density polyethylene

Abstract

The influence of residual wax content on the thermal, rheological, and mechanical behavior of two high‐density polyethylene (HDPE) samples from different lots of the same supplier was characterized. HDPE with a low wax content presented a higher melting temperature and a wider melting endotherm. A decrease in the degree of crystallinity and thermal stability of HDPE with a higher wax content was observed. Thermograms obtained by DSC indicated a small additional exothermic transition associated with the exclusion of residual wax. A higher wax content in HDPE produces a decrease in its viscosity due to a lubricating effect, which allows the sliding of HDPE chains of high molecular weight. In contrast, HDPE with lower wax content achieves greater elongational viscosity and melt strength. The mechanical testing results show that HDPE with higher wax content presented lower Young's modulus, tensile strength, elongation at break, and Izod impact strength than HDPE with lower wax content. The results obtained show that a relatively slight difference in wax content significantly affects HDPE properties.

Experimental study on the effect of molecular weight and chemical composition distribution on the mechanical response of high‐density polyethylene

“…Furthermore, the low MW fraction (oligomer, waxy molecules) in the HDPE resin has the lubricating function and slides the high MW chains, effectively reducing the melt's viscosity. [ 60,61 ] Therefore, the simultaneous influence of molecular parameters can influence the friction between small molecules and entanglements friction factor, consequently zero‐shear viscosity, particularly when comparing resins with almost similar average MW.…”