Rheo-optical characterization of the shear-induced non-isothermal crystallization of polyamide 6

The use of rheo-optical techniques to evaluate crystallization in polymer processing has many advantages; however, it is still little seen.Shear-induced crystallization of polyamide 6 (PA6) was here proposed and studied with these techniques.Mixtures of PA6 in a polypropylene (PP) matrix were also studied.A polarized light optical microscope, with an AxioVision system attached to its top allowing the acquisition of photos at any time during the measurement and a Linkam hot stage device to control shear and temperature, was modified to receive a specially built quantitative rheo-optical detector.Temperature was variable, characterizing non-isothermal analysis.The experiments consisted of varying the shear rate on the polymer system while collecting the respective cross-polarized transmitted light intensity response by LabVIEW software.Shear rates of 1, 10, 100 and 180 s -1 were applied to all samples.Differential scanning calorimetry (DSC) analysis was also performed to predict crystallization behavior.PA6's crystallization increased with the increase of shear rate; however, for the PP/PA6 mixtures under the highest rates, crystallization intensity falls from a specific temperature in which the polymer's viscosity is not enough to maintain the structural integrity.Data related to PP/PA6 mixtures showed that shear increases crystallization if the polymer has time to organize itself.