Structures and properties of wet spun thermo-regulated polyacrylonitrite-vinylidene chloride fibers

Thermo-regulated polyacrylonitrilevinylidene chloride (PAN/VDC) fibers containing 4-40 wt.% of micro phase-change materials (microPCMs) were wet-spun. In this study, fibers containing less than 30 wt.% of microencapsulated n-octadecane were spun smoothly. The structures and properties of the fibers were investigated by using Fourier transform infrared, scanning electron microscopy, differential scanning calorimetry, wide-angle X-ray diffraction, dynamic mechanical analysis and thermogravimetric analysis, etc. The microcapsules were intact and evenly distributed inside the polymer matrix. The tensile strengths of the fibers with titers in the range of 1.9 to 10.9 dtex were 0.7 to 2.0 cN/dtex. The elongation of the fibers was approximately 7%. The heat-absorbing, and heat-evolving temperatures of the fibers increased slightly with the increase of the content of microPCMs. The enthalpy of melting or enthalpy of crystallization of the fiber containing 30 wt.% of microPCMs was approximately 30 J/g, and the enthalpy of melting or enthalpy of crystallization increased steadily as the content of microPCMs increased. The modulus of the fiber decreased with the increase in the amount of microPCMs in the fiber. The glass transition temperature of the fiber was 89-108 degrees C which decreased with the increase of the content of microPCMs, and the melting and decomposing temperatures of the fiber were approximately 190 and 220 degrees C, respectively. The fibers had a limited oxygen index value that was higher than 25% and were permanently in flame retardation.