Influence of steady shear flow on dynamic viscoelastic properties of un-reinforced and Kevlar, glass fibre reinforced LLDPE

[摘要] An experimental study was conducted to observe the effects of parallel-superposed flow condition on viscoelastic properties of LLDPE, Kevlar fibre reinforced LLDPE and hybrid of short glass fibre and Kevlar fibre reinforced LLDPE. Parallel-plate rheometer was employed for these tests. Rheological parameters such as loss modulus (𝐺â€�?) and dynamic viscosity (𝜂′) do not vary significantly on superposing steady state shear with oscillatory shear in the studied range of experiment at 185°C in un-reinforced LLDPE. Kevlar fibre reinforced LLDPE and Kevlar/glass fibre reinforced LLDPE showed significant changes in the flow behaviour under various sets of superposed conditions. Storage modulus (𝐺â€�?), and 𝐺â€�? become highly sensitive to low oscillatory angular frequencies (ðœ�?) under superposed conditions. These curves show two different regions with increased ðœ�? value. At low ðœ�? values, parameters 𝐺â€�? and 𝐺â€�? change sharply reaching a certain value, thereafter, changes are moderate with increased ðœ�?. In case of 𝜂′ a maxima is observed, position of which, depends upon the value of steady shear rate. Maxima shifts towards higher frequencies with the increased steady shear rate.

[学科分类] 材料工程

[关键词] Kevlar fibre;glass fibre;LLDPE;rheological properties;hybrid composites.