The effect of trimethylol propane tetraacrylate (TMPTA) and organoclay loading on the properties of electron beam irradiated ethylene vinyl acetate (EVA)/natural rubber (SMR L)/organoclay nanocomposites

Abstract

Ethylene vinyl acetate (EVA)/natural rubber (SMR L)/organoclay nanocomposites were prepared by melt blending technique with 0-10 phr organoclay loading and 3 phr TMPTA. Electron beam initiated crosslinking on these samples was carried out using a 3.0 MeV electron beam machine with doses ranging from 50 to 200 kGy. XRD results proved that dispersion of organoclay in the nanocomposites was slightly improved by irradiation with TMPTA. This was further supported by transmission electron microscopy images, where the nanoscale dispersion of organoclay was more homogenous throughout the irradiated polymer matrix compared to nonirradiated samples. TMPTA also increased the gel fraction yield, tensile properties and thermal stability of the irradiated neat EVA/SMR L and its nanocomposites. TMPTA was found to act as a crosslink initiator, which promotes crosslink bridges via free radical mechanism in EVA/SMR L matrix. SEM observation shows that the fracture behavior of the irradiated neat EVA/SMR L and its nanocomposites with TMPTA is significantly different compared to the fracture behavior of the nonirradiated neat EVA/SMR L. The distinct failure surface structure formed in the irradiated samples with TMPTA explains the overall higher value of tensile properties.

Effects of ageing on the fire behaviour of flame-retarded polymers: a review

“…Chain scission can lead to small molecules with resulting decrease in thermal stability. Moreover, irradiation may modify the fillers or their dispersion into the matrix . Interactions between crosslinking agent and FR have also been postulated .…”

Influence of radiation-crosslinking on flame retarded polymer materials—How crosslinking disrupts the barrier effect

“…Dripping is prevented when the material is crosslinked and this can be detrimental in some tests (Balabanovich and Schnabel, 2002). Irradiation may modify the fillers (Shafiq and Yasin, 2012;Ahmad et al, 2013) and their dispersion into the matrix (Lu et al, 2005;Ismail et al, 2010;Ahmad et al, 2013;Zaidi et al, 2013) while dispersion is a key parameter controlling the flame retardancy. Crosslinking would prevent the expansion of intumescent systems and therefore their efficiency as flame retardants (Shukri et al, 2008).…”

Effect of organoclay loading on the crosslinking and degradation of irradiated ethylene(vinyl acetate) copolymer/natural rubber nanocomposites

“…Incorporation of a crosslink promoter to the nanocomposites was found to further promote the homogenous dispersion of organoclay as evidenced from transmission electron (TEM) micrographs and x-ray diffraction (XRD) results. 17 However, in both of the previous work the influence of organoclay dispersion on the crosslinking and degradation of irradiated EVA/SMR L nanocomposites was not studied in depth.…”