Crystal morphology and tensile properties of LLDPE containing PP fibers as obtained via dynamic packing injection molding

The fibrillated linear low-density polyethylene (LLDPE)/isotactic polypropylene (iPP) fiber blends were subjected to dynamic packing injection molding (DPIM), in which the prolonged shear was exerted on the melt during solidification stage. Transcrystallization of LLDPE on PP fibers, with stacked lamellae parallel to each other and aligned approximately perpendicular to the long axial of the fibers, has been achieved for the first time in DPIM due to the prolonged shear. PP fibers were found to align parallel to the flow direction along thickness up to the oriented zone of sample prepared by DPIM. The presence of oriented PP fibers enhanced the orientation of LLDPE that developed row-nucleated type morphology. The molding temperatures were changed between 160 °C and 200 °C to investigate the effect of molding temperature on the crystalline microstructure of the blends. As increasing the molding temperature from 160 °C to 200 °C, the partial melting of PP fiber was changed to complete melting, resulting in a dramatic change of the crystal morphology and the mechanical properties as well.