A Novel Elongational Rheology Control of PS by SBS and Dicumyl Peroxide

Abstract

A novel polystyrene(PS) with an incorporation of a small mass fraction of styrene-butadine-styrene(SBS) and dicumyl peroxide(DCP) has been developed to enhance strain-hardening significantly under elongational flow. Here, strain-hardening is defined as steep increase of elongational viscosity at large strain which deviates from linear viscoelastic curve. The content of SBS was in a range from 1wt% to 10wt%, and the content of DCP was in a range from 0.01wt% to 0.1wt%. Pure PS at 180 °C did not exhibit any strain-hardening. Whereas, significant enhancement of strain-hardening was observed for PS blended only 1wt% SBS and 0.1wt% DCP. The magnitude of strain-hardening (SH) was over 10 up to Hencky strain of 3. Note that the parameter, SH, is defined as elongational viscosity at large strain to linear viscoelastic envelope at the same time. Enhancement of strain-hardening was in the order of SBS content and DCP content. The magnitude of strain-hardening(SH) for PS/SBS/DCP(SH~70 at the maximum) was much more remarkable than that of any other PS such as PS/UHMW-PS and branched PS reported before(SH<10). This is a new method to control elongational rheology of PS and has advantages over conventional ways in terms of its easier process than other methods such as introducing long-chain branching and high molecular weight in postreactor.