Effect of the high‐density polyethylene melt index on the microcellular foaming of high‐density polyethylene/polypropylene blends

Abstract

ABSTRACT:The effect of high-density polyethylene (HDPE)/polypropylene (PP) blending on the crystallinity as a function of the HDPE melt index was studied. The melting temperature and total amount of crystallinity in the HDPE/PP blends were lower than those of the pure polymers, regardless of the blend composition and melt index. The effects of the melt index, blending, and foaming conditions (foaming temperature and foaming time) on the void fractions of HDPEs of various melt indices and HDPE/PP blends were also investigated. The void fraction was strongly dependent on the foaming time, foaming temperature, and blend composition as well as the melt index of HDPE. The void fraction of the foamed 30:70 HDPE/PP blend was always higher than that of the foamed 50:50 HDPE/PP blend, regardless of the melt index. The microcellular structure could be greatly improved with a suitable ratio of HDPE to PP and with foaming above the melting temperature for long enough; however, using high-meltindex HDPE in the HDPE/PP blends had a deleterious effect on both the void fraction and cell morphology of the blends.

Investigation into Failure in Mining Wire Ropes—Effect of Crystallinity

“…In this manner, and because of its higher crystallinity and its role in reducing spherulite sizes, PE functions as a stiffener for the PP matrix. It is reported that a higher PP content in a blend leads to a higher void fraction compared to samples with a lower PP content [24,25].…”

Lightweight Plastic Materials

“…The foam morphology is related to a structure of polymers -the most important are branchings in the polymer chain and crystallinity (Huang et al, 2008;Rachtanpun et al, 2004;Su & Huang, 2010;Li et al, 2007). It is well established that foaming is easier with amorphous polymers like PS than with crystalline ones like polyolefines.…”

Preparation and characterization of microcellular thin polycarbonate sheets

“…Until now, the research on microcellular foams has been mainly directed at polystyrene, 10 -18 polypropylene, 19 poly(methyl methacrylate), 20 polyamide, 21 polysulfone, 9,22,23 poly(ether sulfone), 23,24 poly(ether imide), 24 or their blends. [25][26][27][28][29][30][31] Only a few studies have been conducted on the preparation of microcellular polycarbonate (PC) foam, 5,32,33 one of the most important engineering plastics. Because of weak melt strength and melt elasticity, its foaming is more difficult than other plastics.…”