Modification of PVC/ENR blend by electron beam irradiation: effect of crosslinking agents

Abstract

In order to improve the mechanical properties of PVC/ENR blends, they were irradiated by using a 3.0 MeV electron beam machine with doses ranging from 20 to 200 kGy. Changes in mechanical properties of the blends with increasing irradiation dose were investigated. In an attempt to maximize the beneficial effect of irradiation, the influence of multifunctional acrylates (MFA) such as TMPTA, HDDA and EHA on the 70/30 PVC/ENR blend was investigated. The properties studied include hardness, gel fraction, tensile strength, elongation at break and glass transition temperature. The results revealed that all mechanical properties increased with increasing irradiation dose with exception of elongation at break. The enhancement in blend properties was further improved by addition of MFA. This is attributed to the increase in crosslink density. The steady increase in gel fraction with irradiation dose and the shifting of the irradiation those towards a lower value to achieve 70% gel fraction upon addition of MFA has provided evidence for significant increase in crosslink density. Among the MFA employed in this studies, TMPTA was found to render highest mechanical properties to the blend with irradiation. Thus, TMPTA can be useful as an efficient crosslink enhancer to PVC/ENR blends. Results from Fourier transform infrared spectroscopy (FTIR) indicated radiation-induced crosslinks formed in PVC/ENR blends sensitized by TMPTA. The single glass transition temperature obtained confirms that the blend remains miscible upon irradiation with the presence of TMPTA. The changes in blend properties upon irradiation with the addition of acrylated polyurethene (PU) oligomer are also presented in this paper.