Preparation And Properties Of Heat Resistant Polyurethane And Its Fiber

Polyurethane(PU)fiber is more and more widely used in textile industry because of the feature of high resiliency and low modulus due to the soft-hard segment structure.However,the development of high temperature dry-spun PU fiber is currently required in the process of dye and hot finalization.In this paper,high temparture PU was sucessfully synthesized,by means of which some chain extenders were used to improve the thermal stability of the hard segment.What's more,the research and preparation of high temperature resistant dry-spun PU fiber and the relationship between the structure and the heat resistant performance was studied.The main research work was as follow:(1)PU was synthesized through preploymer-chain extension methond,in which preploymer included Poly-(tetramethyleneetherglycol)(PTMG)and 4,4-diphenylmethane diisocyanate(MDI),and chain extenders included trans-1,4-cyclohexane diamine(CHDA),1,2-ethylene diamine(EDA),1,6-hexamethylene diamine(HMDA).Fourier infrared spectrum(FTIR)indicated that PU had been successfully synthesized,with viscosity range of 243-595 Pa·s.EDA5.0 had the best thermal stability,with initial decomposition temperature and T_5%276?and 323?.Besides HMDA5.0,the tensile strength retention of PU increased,with dry and wet tensile strength retention of EDA5.0 110%and 114%.(2)PU fiber was sucessfully prepared by dry spinning,of which chain extenders were CHDA/1,2-propylene amide(PDA)and EDA,with M_n range of 5.1-7.5×10⁴ DA and viscosity range of 243-595 Pa·s,indicating the good spinnabilit.Compared with PU film,high temparture forming process raised the orientation and crystallinity of fiber.EDA fiber had higher T_g,lower T_ms and?H_ms than CHDA/PDA.EDA6.0 had the highest thermal stability,with initial decomposition temperature and T_5%274?and 305?.The strength retention after heat treatment was outstanding,which was also a little higher than PU film,with dry and wet tensile strength retention of EDA6.0 113%and 181%.The breaking strength of as-spun fiber of CHDA/PDA was poorest,but after wet-heat treatment the breaking strength and elongation at break were greatly increased,because after heat treatment,the movement of molecular chain becomes more easily,which improves the micro phase separation degree and the conformation of neat chain structure.Strength retention of all fiber were higher than commercially common product,and were close to commercial high-temperature resistant product,which indicated that all prepared PU fiber was satisfied with the requirements of high temperature treatment.However,due to the different chain extender system,the spinning process should be adjusted to improve the strength of as-spun fiber.