Fibres & textiles in eastern europe vol:16 issue:6 pages:73-76
In this work, it is shown that optical techniques, more specifically birefringence and transmitted intensity measurements, provide an excellent tool to characterize the transition to highly anisotropic structures in polymer crystallization for shear rates close to industrial processing conditions. This is illustrated for the flow-induced crystallization of isotactic poly-l-butene (PB-1). A characteristic upturn in the flow birefringence and a sharp increase in crystallization kinetics both indicate the onset of the formation of shish-kebab structures with an increased level of molecular orientation. Moreover, the results indicate that this transition is strongly molecular weight (M-w) dependent.