INFLUENCE OF DRAWING AND BEAT TREATMENT ON SURFACE FREE-ENERGIES OF POLYETHYLENE TEREPHTHALATE FIBERS

The surface free energies of polyethylene terepthalate fibers with dif ferent draw ratios were experimentally determined by contact angle mea surements in n-alkane/water systems. The dispersive component of the s urface free energy increased with increasing draw ratio, whereas the n ondispersive one remained almost constant. After heat treatment, the d ispersive surface free energy increased, but was reduced above 140 deg rees C. The nondispersive component increased by heat treatment at 190 degrees C. The increases in the density and birefringence of the fibr es due to the drawing and heat treatment suggested that the increase i n the dispersive surface free energy was caused by the increase in the atomic density at the fiber surface due to drawing and heat treatment . ESCA results indicated that the increment in the nondispersive surfa ce free energy due to heat treatment was caused by the addition of fun ctional groups to the fiber surface due to heat treatment.