Effects Of Spinning Conditions On Structure Of Thermal Regulating PAN Fibers

Thermal regulating fibers with the function of heat absorption, storage, redistribution and release, is a typical application in the textile field of renewable energy technologies. To prepared thermal regulating fibers with the wet spinning, the presence of microencapsulated phase change materials (MEPCM) influenced the polymer phase separation behavior and gel phenomenon, which also affected the fiber structure. Fiber structure quality affected fiber properties. This paper researched the factors affected fiber structure in the process of thermal regulating fiber preparation, which would lay the theoretical and practical basis to improve the properties of fiber.This paper first discussed the influences of preparation process conditions (emulsion temperature, emulsion time, oil phase monomer concentration, additive types added) on the polyamide paraffin MEPCM performance, and studied thermal stability of the MEPCM using differential scanning calorimetry (DSC) and thermo gravimetric (TG). Then it was made thermal regulating PAN fibers with MEPCM made in the optimal process as functional additive, polyacrylonitrile as carriers, and researched the effects of the spinning solvent type, spinning dope composition and spinning process on the structure of the thermal regulating fibers.Then the scanning electron microscope (SEM), Fourier transform infrared spectrum (IR), X-ray diffraction (XRD), optical microscope, polarizing thermal microscope, single fiber tensile strength tester and dyeing method were used to study fiber structure.The results showed that, the optimum conditions of the preparation of polyamide paraffin MEPCM was the water phase emulsification temperature of37℃, emulsifying time for60s, trimesoyl chloride (TMC) concentration of10%and using OP-15as emulsifier. The MEPCM particle size was smaller, heat enthalpy value was bigger, wall materials thermal decomposition put the highest heat and after drying microcapsule wall material thermal stability increased significantly; Polyamide paraffin MEPCM were processed by dimethyl sulfoxide (DMSO), sodium thiocyanate (NaSCN) and concentrated sulfuric acid etc., due to heat storage capacity and heat stability changing little showed that wall materials could tolerate the solvent; The fibers made of DMSO and NaSCN as solvent separately were both appeared uneven size of crack in longitudinal section. The fibrillated level of the fiber made of DMSO as solvent was less than the fiber made of NaSCN as solvent, but the degree of crystallinity and crystal size were bigger; The thermal regulating polyacrylonitrile (PAN) fibers made of DMSO as solvent in the gel spinning, with the increased amount of containing solid, the mechanical properties and the ratio of volume density increased, but the dyeing percentage decreased; With the increase of the content of MEPCM, fiber fracture stress and volume ratio density decreased; Added additive calcium chloride to the spinning solution, the fiber draft ratio, mechanical properties, volume density and degree of orientation improved, but the dyeing rate decreased. Calcium chloride content was3%that the fiber structure was the best; In the spinning solution to add non-ionic surfactant OP-10and cationic surfactants all could improve fiber spinnability, and improved fiber mechanical properties; Spinning pressure and draft ratio increased, fiber fracture stress and volume ratio density increased, oppositely strength coefficient of variation was down; SEM observation results showed that the fiber fibrillated phenomenon was emerged in the process of primary fiber drawn. The fibers heat treatment could reduce the residual internal stress in the fiber, and made fiber produce contraction, then the structure became dense. The heat treatment temperature is advisable at110℃or so.