Study of heat shrinkability of crosslinked low‐density polyethylene/poly(ethylene vinyl acetate) blends

Abstract

ABSTRACT:In this study, the heat-shrinkage property in polymer was induced by first compounding low-density polyethylene/poly(ethylene vinyl acetate) (LDPE/EVA) blends with various amounts of peroxide in a twin-screw extruder at about 130°C. The resulting granules were molded to shape and chemically crosslinked by compression molding. A process of heating-stretching-cooling was then performed on the samples while on a tensile machine. Shrinkability and effective parameters were also investigated using thermal mechanical analysis. The results showed that the gel fraction was higher for the sample of higher EVA content with the same amount of dicumyl peroxide (DCP). A decrease in the melting point and heat of fusion (⌬H f ), as determined from DSC, was observed with an increase in the DCP content. Studies on the heat shrinkability of the samples showed that samples stretched above the melting point had a higher shrinkage temperature than those stretched around the crystal transition temperature. The results showed that by increasing the peroxide content, the shrinkage temperature was decreased. These could be attributed to the formation of new spherulites as well as changes in the amount and the size of crystals. Furthermore, in samples elongated at 120°C (above the melting point), the rate of stretching had no effect on the shrinkage temperature. The results showed that the extent of strain had no effect on the temperature of shrinkage, but rather on the ultimate shrinkage value.

Thermal and mechanical properties of uncrosslinked and chemically crosslinked polyethylene/ethylene vinyl acetate copolymer blends

“…That is why the gel content increases with an increasing amount of EVA in the blend and gel affected blend properties are altered in the way as expected. 28 This effect on the mechanical behavior of PE/EVA blends is shown in Table V. At a given temperature and peroxide content, with increased EVA from 20 to 40 wt %, the elongation at the break decreases.…”

Dynamic mechanical analysis and thermal properties of LLDPE/EVA/modified silica nanocomposites

“…Multicomponent nanocomposite systems have attracted attention in recent years because the mechanical, physical, optical, and rheological properties of blends can often be modified with incorporating low content of inorganic nanofillers. One of the methods for improving the properties of PE/EVA blend is the addition of nanoparticles containing hydroyxyl groups on their surfaces, which results in surface of particles and formation of hydrogen bonds between the primary particles and high aspect ratio of nanoparticles [1][2][3][4][5]. As it is clear, distribution and dispersion of nanoparticles in the blend matrix is a rather complicated process.…”

Effect of rubber content on mechanical properties and heat shrinkage of ethylene vinyl acetate copolymer blended with epoxidized natural rubber

“…5,6 EVA was crosslinked by irradiation 2,3,7,8 or dicumyl peroxide (DCP). 4,5,[9][10][11][12] Polyethylene has been used for blending with EVA. [7][8][9] There were many blends between EVA and synthetic rubbers for heat shrinkability purpose, including polyacrylic rubber, 10 polyurethane, 11,12 epichlorohydrin, 13 chlorosulfonated polyethylene, [14][15][16] and carboxylated nitrile rubber.…”

“…4,5,[9][10][11][12] Polyethylene has been used for blending with EVA. [7][8][9] There were many blends between EVA and synthetic rubbers for heat shrinkability purpose, including polyacrylic rubber, 10 polyurethane, 11,12 epichlorohydrin, 13 chlorosulfonated polyethylene, [14][15][16] and carboxylated nitrile rubber. 5,6 Although there are a few articles reporting on EVA/epoxidized natural rubber (ENR) blend [17][18][19][20] ; however, based on our knowledge, there is no publication of heat shrinkability of EVA/ENR blend.…”