Study On Morphology And Properties Of LDPE/PA6 In-situ Fibrillation Composites

LDPE/PA6 in-situ fibrillation composite fibers were prepared via different drawing rate. The effect of drawing rate on crystalline behavior and morphology of the fibers was investigated. The rheological behavior and tensile properties of the fibers and the composites that were made of the fibers via hot press or injection were investigated and the effect of the processing on them was discussed.The results of DSC, WAXD and IR showed that the PA6 phases were amorphous. The crystallinity of LDPE increased firstly and decreased later and the crystal defects might increase as drawing rate increased. The fibril diameter decreased from 0.80-8.30μm to 0.40-1.00μm and the skin-core structure was aggravated showed by the SEM. The shear field, which was derived from the drawing field and the temperature grade of the section, was a key that control the dimension of PA6 phases before fibrillation while the drawing field controlled their fibrillation extent.The rheological behavior was studied using capillary rheometer. The melt of composite fiber showed non-Newtonian behavior. The fluid viscosity was affected by the dimension and amount of fibrils. The rate of viscosity decrease was the most from 170 to 210℃. The bigger the fibril diameter was, the higher the fluid viscosity was at 150℃. The viscosity of hot press 60 was the highest at 150℃and that of hot press 2 was the highest at 190℃and 230℃. The difference of the viscosity among injection composites was disappeared at each temperature.Tensile modulus, tensile strength and yield strength of single fiber increased linearly and the slope of the second even tensile phase increased exponentially as drawing rate increased exponentially while breaking elongation began to decrease when drawing rate was larger than 50m/min and yield elongation was invariable. The tensile properties of hot press 60 were better than those of other hot press composites. The tensile properties of injection composites were almost the same and were the worst in the three composites.