Alkaline Hydrolysis of Titanium Dioxide Delustered Poly(ethylene Terephthalate) Yarns 1

Polyester yams containing four levels of TiO 2 delusterant were hydrolyzed with NaOH and examined for physical and morphological changes. All four yarn types showed progressive weight loss with increasing time of hydrolysis. There was a loss in tenacity after six hours, but there were no changes in crystallinity. Surface morphology differed between the yams with and without delusterant after NaOH treatment. Hy drolyzed, delustered yams developed large, axially oriented pits along the fiber surfaces, while such pitting was absent on hydrolyzed yams containing no delusterant. The pitting originated where delusterant particles were embedded in the polymer matrix. Pits may develop in this location by preferential degradation of the less ordered polymer around the particles. With longer treatment time, the pits enlarged in size and, on fibers with high delusterant concentration, merged with adjacent pits, radically altering the surface topology of the fibers.