Study On Fine And Dyeable Blend Polypropylene Fiber

Polypropylene (PP) fiber is an ideal material for high-class sportswear and fashion, because of its low specific gravity, lower thermal conductivity, resistance to abrasion, and good chemical resistance. With special performance of wet permeability, good hydrophobic property, fast dry and soft hand, fine PP fiber is one of the most heated topics in the field of fiber. However, being lack of dyeability, fine PP fiber didn't find a broad spectrum of use in apparel field. Blending modification has played positive roles in improving the dyeability of PP fiber with advantages, such as simple operation, better efficacy. But it is difficult to make PP fiber fine and dyeable at the same time. Modified PP fiber with large fiber fineness and low depth of shade is the common phenomena. How to obtain dark shades of fine PP fiber has been an urgent problem to be solved for its application. The paper covers the study of dyeable modification of PP by blending with Polystyrene-Bentonite (PS-Bentonite), polymer nano-particles, and HBP (Hyperbranched polymers) resulting in fine fibers with looser morphology and polar functional groups which benefit the dyeability. The main achievement and efforts are described below.(1) PS-Bentonite composite particles prepared by in-situ suspension polymerization were used as modifier to improving the dyeability of fine PP fiber. The process of suspension polymerization was affected by adding bentonite. With increasing the Bentonite content, the conversion of monomer became lower, and the shape of composite particles was changed to be irregular. The structure and properties of the PP/PS-Bentonite blends were also investigated. The result showed that bentonite has a good dispersion in the blends, and its crystal structure were not affected by PP and PS. The study of crystallization behavior of PP in PP/PS-Bentonite blends showed that bentonite act as nucleating agents. Although there is no difference among the crystal forms in PP and its blends, the blends have lower degree of crystal and different crystal morphology and a higher crystallization temperature. Additions of the composite increased complex viscosities of blends(2) HBP was used for improving the dyeability of fine PP fiber. The crystallization behavior of PP in PP/HBP blends showed that HBP acted as nucleating agent and the non-isothermal crystallization kinetics of PP/HBP blends can be successfully described by Avrami and Mo theories. With increasing the HBP content, the crystallization activation energy decreased and crystallization rate increased. Polarized light microscope (PLM) tests confirmed that HBP acted as a nucleation agent. The results of WXRD analysis showed that the introduction of HBP didn't change the crystal forms of PP in the blends. DSC tests showed that PP/HBP blends have the melting temperature of 160?, which is the characteristic melting point of the a-phase of PP. DMA and DSC data showed PP and HBP was partial miscibility. Additions of HBP improve the melt liquidity of PP, and only a little HBP can make the melt viscosity decrease very much. The thermal stability of PP increased with increasing the HBP content.(3)It was the first time to use the designed polymer nano-particles prepared by seed emulsion polymerization as modifier to improve the dyeability of fine PP fiber. It was found that increasing reaction temperature can improve the reaction rate and monomer conversion. Reaction temperature had little effect on particle size distribution, but it can largely affect the particle size. The experimental results of PP/polymer nano-particles blends showed that the polymer nano-particles obtained by freeze-dried method had a good dispersion in the blends and were beneficial to complex viscosities. Complex viscosities?* increased with polymer nano-particles contents increasing. The crystallization behavior of PP/Polymer nano-particles blends showed that the crystal forms of PP in the blends didn't change. However, the introduction of polymer nano-particles decreased the degree of crystallinity and changed crystal morphology.(4)Fine and dyeable PP fibers were successfully obtained by referring to melt-spinning of PP, comparing with the rheological properties between PP and the blends. WXRD analysis showed that modified fiber had lower degree of crystal than that of pure PP fiber. The sonic orientation is almost the same because of the same draw ratio. Mechanical tensile tests showed that the order of strength at break for prepared fine PP fiber was PP/PS-Bentonite<PP/Polymer nano-particles< PP< PP/HBP. But the strength of all fibers could satisfy the requirement of textiles.(5)It was the first time to obtain fine blend PP fibers which can be dyed to dark shade. Fine PP fiber modified with 5% HBP (H5) was dyed with CI Disperse Red 202, and exhibited the deepest and brightest shade. K/S values of H5 were 4594% of that of pure PP fiber, and its wash fastness reached class 5. Fine PP fiber modified with 5% polymer nano-particles (CS-1) could be dyed with three primary colors, and it also can be dyed to dark shade. K/S values of CS-1 were 2345-3870% of that of pure PP fiber, and its wash fastness reached class 4-5. Fine PP fiber modified by PS-Bentonite can be dyed to deeper middle shade.(6) A reasonable mechanism of improved dyeability of fine PP/HBP blend fiber was investigated. In the case of pure fine PP fiber, dye uptake can be contributed to free volume available within the unmodified fiber, while dye uptake of fine PP/HBP blend fiber can be contributed to the polar groups incorporated by HBP. FTIR data showed that there was H-bond interaction between dyes and HBP molecules. So the depth of shade of fine PP/HBP fiber increased with increasing HBP content.