Morphological Analysis of Polyethylene Foams with Post-use Material Incorporated

Abstract

This study investigated the morphology of low-density polyethylene (LDPE) foams with post-use polyethylene (p-PE) incorporated. Samples manufactured using compression molding were analyzed through scanning electron microscopy. Micrographs were treated using the software Image Tool for Windows, version 3.00. This allowed the determination of cell size (0–2500 μm) and cell area (0–1500 .103 μm2) distributions. The research found that all compositions with p-PE material incorporated (15, 30, 40, 50 and 70% w/w) had similar morphologies, except the composition with 70% of p-PE, which gave a more significant increase in the amount of smaller cells. In comparison to samples with virgin LDPE only, all samples with p-PE showed an increase in cells with smaller areas (< 60 μm) and smaller diameters (< 850 μm2), especially those with 70% p-PE. This finding may be explained by the smaller melt flow index of the p-PE (0.60 g.min-1) in relation to LDPE (l.74 g.min-1), which hinders cell growth. The addition up to 70%, of p-PE in formulations which contain 5% of azodicarbonamide leads to PE foams with ideal density ranges for use as packaging (30 to 70 kg.m3).