Dynamic and capillary rheology of LDPE‐EVA–based thermoplastic elastomer: Effect of silica nanofiller

Abstract

The effect of pristine silica nanoparticles on the dynamic and capillary rheology of a model LDPE‐EVA thermoplastic elastomeric system is explored in this paper. The pristine silica nanoparticles were melt‐blended with the LDPE‐EVA system at 1.5, 3, and 5 wt% loadings, respectively, by varying the sequence of addition. In one of the compositions, coupling agent bis‐[3‐(triethoxysilyl)propyl] tetrasulphide (Si‐69) was used to improve the interaction of hydrophilic silica particles with polymer matrix. Results obtained reveal that the viscoelastic behavior of such composites is influenced remarkably by loadings of silica, variation of sequence, and addition of Si‐69. Upon addition of coupling agent, G′ value increases especially at higher strain levels due to increased polymer‐filler interactions. All systems with various loading of nanosilica represent an increase in elastic response with increasing frequency. Both the unfilled and filled blends exhibit rheological behavior of non‐Newtonian fluids. But interestingly, the viscoelastic response varies markedly with the temperature. The dynamic and steady shear rheological properties register a good correlation in regard to the viscous vs. elastic response of such systems. Finally, the rheological behavior is correlated with morphology of the present system processed at various shear rates. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers

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

“…The detailed rheological behavior of filled unirradiated samples has been presented in one of our earlier publications. 12 In addition, the melt viscosity increases with increase in the radiation dose [ Fig. 1(d)] because of the radiation-induced crosslinking effect.…”

“…8 The melt viscosity decreases with the increase in the rate of shear, showing the pseudoplastic or shear thinning nature of the samples. 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.…”

“…The details of the instrument were discussed in our recent publication. 12 The TPE films were cut into small pieces and fed into the hot barrel after compaction. The capillary die used was 30-mm long, 1-mm in diameter, having L/D ratio of 30 : 1, with a conical entry having multiple cones of 45 and 60 , which are known to minimize the pressure drop at the entrance.…”

“…The details of the instrument were given in our earlier publication. 12 The linear viscoelastic (LVE) region of the blends was initially determined by strain sweep at a test frequency of 0.5 Hz. In the strain sweep test, the strain amplitude was programmed to change in steps from 1.40% to 697.50% at a constant temperature (50 C) and at a constant frequency of 0.5 Hz, respectively.…”

“…10,11 In one of our recent publications, we have reported a comparative study of dynamic and capillary rheology of pristine nanosilica-filled LDPE-EVA-based TPE system with variations in sequence of silica addition, their loading, and with the use of coupling agent. 12 We have also demonstrated the details of the dynamic rheological properties and capillary rheology of such system and have derived the correlation between them. The rheological behaviors have also been correlated with the resultant morphology of such system at various shear rates.…”