Radiation effects on poly(propylene) (PP)/ethylene–vinyl acetate copolymer (EVA) blends

Abstract

Radiation effects on poly(propylene)/ethylene-vinyl acetate copolymer (PP/EVA) blends are discussed. Increasing the EVA content enhanced the crosslinking effect of radiation in PP/EVA blends. This effect was significant when the EVA content was Ն50% in PP/EVA blends that were exposed to ␥-ray irradiation in air. This phenomenon is discussed in relation to the compatibility, morphology, and thermal properties of PP/EVA blends. The results indicate that the effect is dependent on the compatibility, the increase in the amorphous region content, and the EVA content in PP/EVA blends. The possible mechanism of radiation crosslinking or degradation in irradiated PP/EVA blends was studied quantitatively by a novel method, a "step analysis" process, and thermal gravimetric analysis.

Morphology and chain mobility of reactive blend nanocomposites of PP‐EVA/Clay

“…Nevertheless, the nanocomposites obtained using the masterbatch clay introduction strategy presented different morphologies as a function of the PP/EVA concentration ratio. Figure (b) presents the irregularly joined droplet morphology of the EVA phase dispersed into the continuous PP phase for the PPEVA2MB sample, previously observed in Figure (a) . The reaction of PP and EVA using DCP and the previous introduction of nanoclay into the EVA matrix (masterbatch) caused the joined anisotropic morphology for this nanocomposite.…”

Reactive compatibilization of polymer blends by γ‐irradiation: Influence of the order of processing steps

“…Other parameters can modify the efficiency of irradiation, such as the compatibility of polymers,12 the atmosphere,13 the radiation rate and the total dose. For example, Miguez Suarez et al10 have shown that LDPE undergoes crosslinking reactions at low doses but chain scissions at high doses.…”

Formation of Vinylidene in Polypropylene/Ethylene Vinyl Acetate (PP/EVA) Blends During Degradation

“…The higher mobile methyl radicals in PVA chains combined with alkyl radicals in PP chains can enhance cross-linking in PP=EVA blend. So that the cross-linking in PP=EVA blend was enhanced by alkyl radicals in PP chains and methyl radicals in EVA chains [9] . Along with alkyl radicals, the possibility of formation of vinylidene in PP segments also enhances the cross-linking [21] .…”

“…However, the radiation cross-linking efficiency of PP is lowered because of its tendency to undergo chain-scission and easy oxidation by irradiation in air. But both alkyl radicals in PE chains and methyl radicals in PVA chains participate in the radiation cross-linking of EVA (EVA is a block copolymer consists of the chains in PE and PVA) [9] .…”

“…Effects of EVA content on photo-oxidation of polymer blends, such as PVC=EVA [7] , LDPE=EVA [8] and HDPE= EVA [9] have been reported, in which EVA acted mostly as a modifier. Influences from UV irradiation on EVA composites containing inorganic fillers like EVA=carbon black [10] and EVA=carbon nanotube [11] systems were also attempted.…”