Melt spinning of high-strength fiber from low-molecular-weight polypropylene

Polypropylene (PP) with high melt flow index (MFI) or low molecular weight, although desired in melt spinning for enhanced productivity, is difficult to be spun into high-strength fiber using the standard process where extensive jet stretching is applied. In this work, a processing route involving minimal jet stretch has been explored. A two-stage hot drawing procedure in the solid state was found to be suitable for producing high-strength fiber from low-molecular-weight PP with an ultrahigh MFI of 115 g/10 min. Fibers produced achieve a maximum tensile strength and Young's modulus of approximately 600 MPa and 12 GPa, respectively. The melt temperature of the fiber reached 170.8°C, approximately 5°C higher than that of the original resin. Wide-angle X-ray diffraction (WAXD) study shows that the stable α-monoclinic crystalline structure is developed during the drawing process. A well-oriented crystalline structure along the fiber axis is generated, having a crystalline orientation factor as high as 0.84. POLYM. ENG. SCI., 56:233-239, 2016. [C] 2015 Society of Plastics Engineers
INTRODUCTION Melt spinning is a common process to produce high-tenacity polypropylene (PP) fiber, one of the leading commercial fibers in the field of industrial textiles. Efforts to make strong PP [...]