New extensional rheometer for creep flow at high tensile stress. Part II. Flow induced nucleation for the crystallization of iPP

摘要

A novel extensional rheometer for creep experiments has been presented in part I. The device can be used also for an investigation of the influence of short term elongational flow on the structure development in crystalline polymers. It enables the application of defined portions of mechanical work to the polymer sample in its state of undercooled melt. For the purpose short-term elongational creep is used. With increasing mechanical work the number density of nuclei in iPP increases by decades. Results, as previously obtained with shear flow, are introduced for comparison. Prospects of a theoretical description are discussed.