The effect of using the two-step extrusion method on the oxidation induction time value of recycled high density polyethylene

Abstract

The two-step extrusion method was used to manufacture pipe-grade high density polyethylene (HDPE) material from recycled HDPE. With the two-step extrusion method, dicumyl peroxide (DCP) can completely react after reactive extrusion without adding antioxidants in the first step, which increased the degree of cross-linking and the molecular weight of the recycled HDPE. Then, adding the antioxidant in the second extrusion step can avoid the conflict between the two additives. As a result, this method improved the oxidation induction time (OIT) and the environmental stress cracking resistance (ESCR) value of HDPE compared with the traditional one-step extrusion method. For both Irganox 1035 and Irganox 300, the OIT using the two-step extrusion method is much higher than that using the one-step method. In addition, introducing carbon black (CB) into the black masterbatch affected the OIT. When the CB content was 0.8%, the OIT was at its maximum value. © 2012 The Society of Polymer Science, Japan (SPSJ) All rights reserved.