Extensional flow-induced crystallization of isotactic poly-1-butene using a filament stretching rheometer

TLDR: In this paper, a filament stretching rheometer is used to investigate the extensional flow-induced crystallization of two commercial grade isotactic poly-1-butene samples, and the degree of crystallinity of the stretched fibers is quantified using differential scanning calorimetry measurements as a function of extension rate and accumulated Hencky strains.

Abstract: A filament stretching rheometer is used to investigate the extensional flow-induced crystallization of two commercial grade isotactic poly-1-butene samples. The degree of crystallinity of the stretched fibers is quantified using differential scanning calorimetry measurements as a function of extension rate and accumulated Hencky strains. All the measurements are performed using the Janeschitz-Kriegel protocol. The samples are first melted to erase their thermal and mechanical history. They are then quickly quenched to T=98°C after which the stretch is imposed. The deformed filament is then allowed to crystallize fully at T=98°C. The extensional rheology of both the samples shows only minimal strain hardening. For the case of the lower molecular weight sample, the percent crystallinity increases from 46% under quiescent conditions to a maximum of 63% at an extension rate of e=0.05 s−1. This corresponds to an increase of nearly 50% above the quiescent case. The high molecular weight sample shows similar tr...