Study On Hollow Porous Polypropylene Fiber With The Separability

Polypropylene hollow fibers have the properties of light weight and keeping warm. Withthe continuous development of science technology and people’s demand for life quality,people have focused on the problem of biomedical and environment pollution. Usingpolypropylene fibers as clothing materials can’t meet the people’s demand, polypropylenehollow porous fibers which have the separation property have arised people’s attention, and italso has been the hot topic of polypropylene fiber research. Polypropylene hollow porousfibers are playing a leading role in the ocean resources development, high efficient ofchemical separation process, artificial hearts application and comprehensive utilization ofindustrial waste etc.Polypropylene is modified based on the method of melting spinning-stretch, and it isblended with β nucleating agent. The dual blend is spinned into hollow fibers through thehollow spinneret. Through the stretch treatment, polypropylene fibers’ lamella crystalstructure which is parallel and perpendicular to the extrusion direction can be stretched intomicropore structure. Polypropylene hollow porous fibers with separation property areprepared by this method, and it can have the new morphology an structure. Polypropylenefibers can have new morphology an structure through this method.The methods and the results of research are as follows:(1) The blend materials of PP and β nucleating agent are prepared by using direct moltenblending method, and its crystallization process is charactered.(2) The composite materials of PP and β nucleating agent are treated by melting, castingand cutting, and its rheology is characterd to determine the spinning process parameters.(3) The preparation of PP and β nucleating agent blending fibers: PP is blended with βnucleating agent in different proportion, and the blend is spinned into hollow fibers by usinghollow spinneret. The process conditions and formula of fibers preparation is researched(4) The blending hollow fibers are stretched, and the stretch process conditions are alsoanalyzed. (5) The hollowness and microstructure of polypropylene hollow porous fibers areobserved and characrtered, and its mechanical properties are also analyzed.(6) The blending fibers are tested and analyzed by using DMA in certain frequencies, andits dynamic mechanical properties are also analyzed.(7) The blending fibers are tested and analyzed by using TGA, and its thermalgravimetryproperties are also analyzed.(8) The hollow porous fibers separate dye and test the light transmittance of filtrate.The research results show that: β nucleating agent can increase the crystallization rateand make the crystal grain more fine. The toughness and ductility of polypropylene areimproved because of the crystallinity increasing which results from the β nucleating agent.Because the crystallinity increases, the polypropylene spherulites are destroyed and thespherulite density becomes lower. The amorphous area can form the micropore structureeasily after the hollow fibers are stretched. The micropore structure not only have the effect offiltration and separation, but also can improve the toughness of blending fibers further. But itsmechanical property will decrease. β nucleating agent results in the blend appears the shearthinning phenomenon, the non-newtonian index n is less than1,and the blend is thepseudoplastic fluid. The blend viscosity decreases and its fluidity become more fine with theincrease of the content of β nucleating agent.