Test MethodSqueeze flow induced crystallization monitoring in polymers

A rheo-optic set-up originally designed for applying a shear strain to the material (CSS450 from Linkam) was used to generate a squeeze flow and follow the subsequent crystallization of the polymer. A polypropylene was used as the test material. The squeeze was achieved using the gap control motor of a hot stage conventionally used for shear measurements. The lubricated squeeze flow ensured a biaxial elongational strain in the sample. The crystallization kinetics is largely enhanced by the squeeze flow which, similarly to shear effects, leads to increase the nucleation. Moreover, x-ray measurements revealed that for our study squeeze flow promotes the formation of β crystalline phase. However, no specific crystalline orientation was obtained.