Melt-spun Of PP/EVA Blending Modification Sheath-core Composite Hollow Fibers And Properties

A series of composite hollow fibers were fabricated by melt-spinning process using PP as sheath and polypropylene (PP)/ethylene-vinyl acetate (EVA) blended chips as core, in which contains 5-20wt% of EVA and 95-80wt% of PP. The effects of the selected material, sheath-core ratios, EVA contents, melt spinning temperature and extruding speed/winding velocity on melt-spinning stability were studied; and the best spinning conditions were determined. The mechanical performance of matrix fiber was also studied.1. Blended chips are prepared when the content of EVA is in the range of 0-20wt%. The blend is thermodynamically incompatible system. Its density is linear to composition, and the crystalline zones of PP and EVA remain in their original crystal phase and don't form mixed crystal.2. Under strictly controlled spinning process conditions, PP/EVA blends are spun into a definite diameter and well-distributed sheath-core composite hollow fiber. The optimal spinning parameters are determined as, EVA content is 10wt% in blended chips, the sheath-core ratio is 6/4, melt spinning temperature is 230℃, extruding speed is 39.69g/min and the winding velocity is 500m/min.3. With the increase of EVA contents and drawing ratio, the tensile strength and extension at break drop. The titer, tensile strength and extension at break of the fiber containing 10wt% EVA are 9dtex, 3.0cN/dtex and 39% respectively.4. The polar group of EVA in the inner sheath-core composite hollow fiber adsorbs small organic molecular. The adsorptive capacity depends on the content of EVA.5. The adsorptive capacity depends on the discrepancy of solubility parameter between ethylene-vinyl acetate and small organic molecular. The sheath-core composite hollow fiber has better adsorptive capacity to methyl acrylate than styrene, ethyl acetate and cedar wood oil.6. As the drawing ratio increases, the adsorption capacity of the fiber to small organic molecular decreases. With the rise of temperature, the adsorption capacity of the matrix fiber will reach a maximum at 50℃.