新型聚酰胺酰亚胺纤维的制备及其力学性能增强OA

In order to effectively enhance the mechanical properties of polyamide-imide(PAI)fibers and promote their ap-plication in the field of flame retardant protection,PAI fibers were prepared via wet-spinning.Firstly,the influ-ences of PAI mass fraction and needle specification on the mechanical properties of PAI as-spun fibers were in-vestigated.Secondly,by modifying the heat treatment process and adopting a"cyclic wet-spinning method",significant improvements were achieved in the mechanical properties of PAI as-spun fibers.The results demon-strated that when the PAI mass fraction was 24%and needle gauge was 26G,PAI as-spun fibers exhibited opti-mal mechanical properties with a breaking strength of 21.20 MPa and a breaking elongation of 20.62%.Further-more,high-temperature treatment was employed to induce thermal imidization reaction in PAI as-spun fibers.It was found that with the increase of temperature,the intensity of thermal imidization reaction was enhanced lead-ing to superior mechanical properties of PAI fibers.The optimum temperature for thermal imidization reaction was determined to be 340℃,resulting in a breaking strength of 86.16 MPa and breaking elongation values of 19.12%for PAI-340 fibers at this condition.The PAI as-spun fibers were subsequently subjected to high-tem-perature treatment through stepwise heating,with a termination temperature of 340℃.It was observed that in-creasing the number of temperature stages resulted in reduced heat input during the process,leading to a lower degree of thermal imidization reaction and consequently less improvement in the mechanical properties of the PAI fibers.Finally,"cyclic wet-spinning method"in which raw materials comprised of PAI-220 fibers were utilized followed by subsequent wet-spinning and heat treatment processes to produce high-strength PAI fibers.The resulting breaking strength and breaking elongation values for these newly developed fiber samples(PAI@220-340)were measured as 92.15 MPa and 20.76%,respectively.These high-strength PAI fibers were self-extinguishable after removal away from the flame and exhibited great application potential in the field of flame-retardant protection.