Model prediction of the ESCR of semicrystalline polyethylene: Effects of melt cooling rate

Abstract

The effects of melt cooling rate on the morphology and environmental stress cracking resistance (ESCR) of a commercial-grade high-density polyethylene (HDPE) were investigated by DSC, WAXS, Raman spectroscopy, DMTA, microhardness, and standard Bell test. The results showed exclusion of short chain branches from the crystallites leading to their perfection by decrease in the melt cooling rate. Accordingly, samples' ESCR increased because of the aforementioned crystal thickening. In addition, quantitative evaluation of crystal strength was performed for the first time by microhardness technique. Crystal strength or the required energy for plastic deformation of unit area of the crystals, DhÁ' c , complemented crystal thickening hypothesis. The product of Dh and average crystal thickness, ' c , was also proportional with storage modulus of the samples at ESCR test temperature. The evaluation of the results using the recently proposed model based on the analogy of crack growth through amorphous phase of semicrystalline polymers in harsh environments with crack growth at adhesive polymer-substrate interfaces showed reasonably good correlation. Finally, the comparison of literature and current research data based on the new model delineated new directions for phenomenon generalization.

Creep–Fatigue Relationship in Polymer: Molecular Dynamics Simulations Approach

“…Runt and Jacq showed an effect of the degree of crystallinity on the fatigue crack propagation in PE, the increasing of crystallinity improves fatigue resistance. Sharif et al found an increase in storage modulus with degree of crystallinity. Boiko et al presented the increasing of dynamic storage modulus with the draw ratio.…”

Fabrication of a novel polyethylene/starch blend through mediation of a high‐energy ball milling process: Mechanical properties and formation mechanism

“…The HDPE powder, with density of 0.95 (g/cm 3 ) and melt flow index of 0.35 (g/10 min) at 190°C, was supplied by Bandar Imam Petrochemical Company, Bandar Imam, Iran (Poliran HB0035). The weight‐average molecular weight and Poly Dispersity Index (PDI) were obtained by gel permeation chromatography as 225,000 (g/mol) and 20.5, respectively 19. The maize starch (C*GEL 03401, 26% amylose), with density of 0.54 (g/cm 3 ), was purchased from Cargill Deutschland GmbH, Krefeld, Germany.…”

A study on environmental stress cracking in nano-SiO2-filled polycarbonate

“…In this case, the stress to failure is significant lower than the expected limit without the attack of a stress cracking agent [1][2][3][4]. The mechanisms of ESC failure in polymeric materials have been extensively investigated during the last 50 years, the formation of ESC in plastics can be considered more a physical than a chemical process, the cracking agent does not cause a chemical degradation of the polymer, instead, it diffuses slowly into the polymer matrices under tension and causes hydrostatic pressure, which accelerates the cracking propagation and results in a catastrophic brittle failure of the plastic components [5][6][7]. Previous researches have shown that ESC has been identified as being responsible for *25 % of plastic component failures in service [1,8].…”