The Preparation Of Core-Shell Fiber And Its Application On Polypropylene Modification

For its excellent mechanical properties, good heat resistance, good environmental stress cracking performance and excellent rigidity, and easy processing molding, polypropylene(PP) is widely used in modern industry, but its toughness is very poor, especially weak impact property at low temperature. Consequently, much research work focuses on the modification of PP. Electrospinning is a kind of novel method to produce polymer nanofibers or microfibers continuously at present. In this paper, different kinds of coaxial fibers are prepared by coaxial electrospinning, the main work is shown as follows:1. The plastic/ rubber coaxial fibers are prepared through coaxial electrospinning technology. We investigated the influence of electrospinning parameters on morphology and structure of core-shell fiber. PC/EPDM coaxial fibers of diameter 600-800nm, PVP/EPDM coaxial fibers of diameter 100-200nm,PA6/CR coaxial fibers of diameter 200-400nm are prepared separately. In this paper, our work and experimental results provide the theoretical basis on preparing the excellent core-shell fiber.2. Various amounts of coaxial fibers are mixed with polypropylene (PP) in the single-screw. SEM observation showed that adding the capacity agent during the processing was necessary to improve the compatibility between core-shell fibers and the matrix. DSC,XRD and PLM results demonstrated that the crystallization rate was increased with the increasing content of fibers, as well as promoted beta crystal growth and decreased crystal size of composites. Especially after adding the capacity agent, fine microcrystal was founded in the composites. The mechanical properties showed that the notched impact strength of composites was improved greatly. Specifically, for cured PC/EPDM coaxial fiber about 33.8% higher than that of neat PP, and for PA6/CR, PVP/EPDM and uncured PC/EPDM coaxial fibers were 32.82%,23.27% and 17.56% respectively. To be noticed, with the improved notched impact strength, the rigidity of the PVP/EPDM coaxial fibers filled composites was decreased correspondingly, while PA6/CR and PC/EPDM coaxial fibers could improve the notched impact strength and keep the rigidity as well.