Role of blend phase ratio in controlling morphology, compressive, and recovery behavior of low‐density polyethylene/ethylene‐vinyl acetate foams

Abstract

This work presents a detailed study on the influence of blend phase ratio upon the morphology, crystallinity, mechanical and viscoelastic properties of crosslinked foams based on blends of low-density polyethylene (LDPE) and ethylenevinyl acetate copolymer (EVA). Non-isothermal foaming is carried out via melt compression molding using dicumyl peroxide and azodicarbonamide as crosslinking and foaming agents, respectively. Rheo-mechanical spectrometer characterization reveals faster crosslinking for EVA, leading to higher rate of melt viscosity increase for EVA-rich blends during heating. This results in the formation of foams with higher cell density and gel content than LDPE-rich foams. Compressive stress-strain behavior and viscoelastic hysteresis of the LDPE-rich foams are governed by the degree of crystallinity and cell density, whereas for the EVA-rich foams cell density and gel content are dominant.Increasing the crosslink density results in enhanced compressive behavior with excellent recovery of stress to 60% strain during four compression cycles.

Dynamic Cross-linked Poly(butylene adipate-co-terephthalate) for High-Performance Green Foam

“…The curves of compressive stress over strain during the loading period for all foams follow the typical nonlinear behavior always shown by soft elastomers. 52,53 From the unloading curve, the foams of PBAT vitrimers show a lower residual strain than that of neat PBAT after the recovering process, and the residual strain reduces with the increased cross-linked degree of PBAT vitrimers. 54,55 The improved elasticity for foams of PBAT vitrimer can be ascribed to the elasticity and cell structure contributed by the dynamic cross-linked network.…”

Extrusion foaming of multiphasic polyethylene/ethylene-vinyl acetate copolymer/carbon nanotube mixtures: Tailoring foam properties by selective localization of nanoparticles

“…10,11 Accordingly, LDPE is typically blended with other polymers with more elastomeric behavior like poly(ethylene-co-vinyl acetate) (EVA). 12,13 The PE/EVA blend foams demonstrate better flexibility, higher toughness, more significant impact resistance, and lower thermal conductivity than LDPE foams. It is also worth noting that the PE/EVA blend foams improve resistance to electrical discharge and solvents, stress cracking resistance, weather-ability, creep behavior, and service temperature.…”

“…It is also worth noting that the PE/EVA blend foams improve resistance to electrical discharge and solvents, stress cracking resistance, weather-ability, creep behavior, and service temperature. [11][12][13] Li et al in 2021 14 prepared microcellular LDPE/EVA foams by using a physical foaming agent, supercritical CO 2 , via a low-temperature solid-state batch foaming process. By using a crosslinking reaction and the presence of micron-size phase-separated domains and crystalline structures, their prepared elastomeric polyolefin foams showed considerable higher tensile and compression strength comparing with other elastomeric polyolefin foams.…”