Development Of Dyeable Fine/Ultrafine Polypropylene Fiber

Due to the excellent performance,fine denier polypropylene fiber can be widely applied in industrial and apparel fields such as air purification and sportswear,etc.However,the poor dyeability has been recognized as the main obstacle for its further application.And reported investigations related to overcoming this problem are not suitable for large-scale application,such as high cost,poor spinnability,high dtex of monofilament,decreased mechanical performance and bad brightness.Based on the preliminary researches of our group,in this study,polystyrene(PS),hyperbranched polyesteramide(HBPY)and montmorillonite(MMT)were blended to prepare fine/ultrafine polypropylene fiber with good dyeing performance,excellent mechanical properties,well spinnability and controllable cost.Firstly,the PP/PS/HBPY ternary blending system was prepared with synthesized PS/HBPY composite granules by in-situ suspension polymerization technique.By addition with PS,less HBPY was needed,and the softening point could be raised,which solved the feeding problem.The influence of HBPY was investigated,the results showed PS was well dispersed in the matrix,the addition of HBPY could dramatically increase the interphase boundary,so the heterogeneous nucleation of PP was improved as well as the crystallization temperature was increased.Meanwhile,the crystal growth rate of PP tested by DSC was decreased with the increasing amount of HBPY.So the total crystallization velocity was enhanced by introducing HBPY but decreased with the increasing additive amount,and the maximum degree of crystallinity occurred at lwt.%HBPY in the system.Rheological behavior indicated the incorporation of HBPY had little negative influence on the spinnability of PP.As in spun fiber,HBPY could also increase the crystallinity,meanwhile the content of a-form phase and the crystallite size,which indicated its bad drawing performance.But the dyeing performance was significantly enhanced with the addition of HBPY,further investigation was successively proceeded.Then,PP/PS/HBPY/MMT quaternary blending system was prepared with PP,PS and PP/HBPY/MMT modified masterbatch.Based on its three-dimensional spherical dendritic molecular structure and abundant functional groups,the HBPY component was served as a modifier of MMT to overcome the adverse effects of MMT on the mechanical properties of PP fiber.The HBPY and MMT components were used to increase the dyeing performance stemming from their large number of polar groups and the ability for heterogeneous nucleation.The results showed the interlamellar spacing of MMT could be significantly increased by adding HBPY,indicating the HBPY macromolecule could be intercalated into the layer structure of MMT.Meanwhile,the interphase boundary of blending system was increased,the distance between PP macromolecular chain and crystal surface was reduced by calculating the reducing of the crystallization activation energy.Further research indicated the nucleation of this quaternary blending system was mainly controlled by HBPY component.With the increasing amount of MMT,the total crystallization velocity increased slightly,while the crystallinity decreased.Rheological behavior indicated that the incorporation of HBPY could decrease the negative influence of MMT on PP spinnability.The results of fiber performance tests showed the hybrid of HBPY and MMT was good for the formation of β-form crystal,decreased the β crystallite size and reduced the content of α-form phase,which indicated a good trend of drawing performance of as-spun fiber.The increase of interlamellar spacing of MMT could not only improved the dyeing performance,but also enhanced the mechanical properties of PP fiber.As discussed above,the building of PP/PS/HBPY/MMT quaternary blending system for preparing dyeable fine denier polypropylene fiber showed a good application prospect considering the excellent spinnability,outstanding mechanical performance,well dyeability and relatively low cost.