Melt Fracture of Polystyrene

Abstract

<p> A high-pressure nitrogen-driven viscometer has been used to study the melt fracture of polystyrene. The polystyrene samples used differed in molecular weight and molecular weight distribution. The weight average molecular weight (Mw) ranged from 97,200 to 1.8 x 10^6 and the distribution breadth (Mw/Mn) from 1.06 to 9.21. Results obtained indicate that the critical shear stress varies linearly with 1/Mw, increases slightly with temperature and is independent of the polydispersity of polymers. This type of behaviour is satisfactorily explained in terms of Graessley's entanglement theory.</p>