The influence of resin characteristics on the high speed melt spinning of isotactic polypropylene. I. Effect of molecular weight and its distribution on structure and mechanical properties of as‐spun filaments

Abstract

Abstract The fine structures and tensile mechanical properties were characterized for high speed melt spun filaments prepared from three polypropylenes with melt flow indices in the range 12–300. It was found that spinnability and the resulting structure and properties are affected by both the weight average molecular weight and the polydispersity of the polymer. Higher tenacities, with consequent lower percent elongation to break, could be achieved by spinning the narrow molecular weight distribution polymers at high spinning speeds. This effect was associated with the development of higher birefringence in these samples. Modulus did not correlate with birefringence in the present study, but it was found to be controlled by the nature and level of crystalline order developed in the filaments.