Exploring the simultaneous effect of nano‐silica reinforcement and electron‐beam irradiation on a model LDPE/EVA‐based TPE system

Abstract

BACKGROUND: The technical properties of polyolefinic thermoplastic elastomer (TPE) systems can be modified significantly using fillers like nano-silica. Controlled irradiation can potentially be an effective way of tailoring the technical properties of such nano-silica-filled TPE systems. RESULTS: The effect of controlled electron-beam irradiation on the properties of a pristine silica nanoparticle-filled model low-density polyethylene/ethylene-(vinyl acetate) (LDPE/EVA) TPE system is explored in this paper. The morphology of such a filled system was investigated using scanning electron microscopy (SEM) and field-emission SEM. The dispersion of silica particles was analysed using transmission electron microscopy which clearly indicates that at low loading a fine dispersion of silica occurs in the polymer matrix. Swelling studies and Fourier transform infrared analyses indicate the occurrence of a favourable EVA-silica interaction. On the whole, it is observed that electron-beam irradiation induces a high degree ofreinforcement in all the silica-filled samples through interfacial crosslinking as well as controlled crosslinking in the two polymer phases. In a few samples the processing characteristics are remarkably preserved following concurrent nano-silica reinforcement and irradiation, while the technical properties of TPE systems, including set, solvent swelling and mechanical properties, are improved. However, the improvement in properties is a strong function of sequence of addition of filler in the LDPE/EVA blends. CONCLUSION:The green technique studied can be potentially extended for the improvement of the technical properties of conventional TPE systems.

Effect of controlled electron beam irradiation on the rheological properties of nanosilica‐filled LDPE‐EVA based thermoplastic elastomer

“…Because of the higher atomic number of silica particles, radiation crosslinked interfacial area (also to some extent to the continuous matrix) is accordingly more. 15 Thus, initially viscosity is high. But after a certain shear rate, structural breakdown of EVA domains with aggregated silica particles occurs.…”

“…4,7 In our system, silica particles play dual functions, namely, as reinforcing filler 12 and as radiation sensitizer. 15 In all the compositions, EVA domains have been found to exist as dispersed phase in the continuous matrix. 17 However, it has been found that in CS/3-1, in the continuous phase, due to intermixing of EVA and LDPE silica particles remained associated in both phases as well as in the interface.…”

“…Silica was also found to be well diffused in the continuous matrix and in the interface because of the significant reduction of filler-filler interaction. 15,18 Upon irradiation (at 20 kGy dose), crosslinking occurs, leading to improved interfacial bonding. The improvement in interfacial bonding upon irradiation has been evident by swelling-deswelling kinetic analysis of such system in one of our recent publications.…”

“…This intermixing phenomenon has been proven by extensive FTIR and TEM analysis in one of our recent publications. 15 Because of intermixing, crystallinity of LDPE matrix was reduced. 17 On the contrary, for CS/3-2 no such intermixing was found as the silica-EVA masterbatch was prepared previously before mixing them with LDPE.…”

“…In one of our earlier publications, we have reported the simultaneous effect of nanosilica reinforcement and electron beam irradiation on this system highlighting the structureproperty correlation of such TPE systems. 15 In this work, our aim is to explore the effect of controlled dose of electron beam irradiation on the rheological (oscillatory and steady state) characteristics of this particular filled TPE system and to correlate this property with the resultant morphology at different shear rates.…”