Non-isothermal crystallization kinetics of polypropylene/polytetrafluoroethylene fibrillated composites

摘要

Non-isothermal crystallization kinetics of polypropylene (PP)/polytetrafluoroethylene (PTFE) fibrillated composites is presented. In-situ fibrillated PP/PTFE-composites containing 1 and 3 wt% PTFE were prepared by melt compounding using a twin-screw extruder. The morphology and non-isothermal crystallization behavior of the composites were examined using scanning electron microscopy and differential scanning calorimetry, respectively. The Mo equation was used to analyze the kinetics of non-isothermal crystallization behavior. The PTFE created a three-dimensional (3-D) network. A low PTFE content promoted crystallization through fast nucleation, whereas a high PTFE content decreased the crystallization kinetics through hindering the crystal growth. These findings are all based on the Mo equation analysis. The activation energy and nucleation activity were also evaluated, and the way in which the PTFE nanofibers affected the crystallization was discussed in detail. Polarized optical microscopy images revealed that the size of PP spherulites decreased with the increase of PTFE content. Finally, the effect of PTFE on the crystalline phase of PP was investigated by wide angle X-ray diffraction. Graphic abstract