HYDRAZINOLYSIS OF POLY (ETHYLENE TEREPHTHALATE)

Abstract

Hydrazinolysis of poly (ethylene terephthalate) (PET) fibers was studied using hydrazine hydrate aqueous solution. Hydrazinolysis took place slowly at the early stage of degradation at low temperature. At this stage percent of degradation was lower than 25% and outlook of the degraded fiber surfaces was same as that of the undegraded. Then drastic degradation proceeded from the surfaces of the fibers. It is observed in the scanning electron microscopic photographs that the fibers became thin and were etched to form patterns of bricks on the surfaces of the fibers.
Changes of the crystallinity caused by hydrazinolysis and behavior of phenol adsorption suggested that the degradation took place at the amorphous regions at the early stage of hydrazinolysis.
In order to confirm that hydrazinolysis proceeded at the amorphous regions at early stage, alkaline hydrolysis was utilized. The alkaline hydrolysis rate of hydrazinolyzed fibers was faster than that of undegraded fibers. The alkaline hydrolysis proceeded in two steps accompanied by increase of the crystallinity of the fibers and decrease of hydrazide group content.
By the two step degradation of hydrazinolysis and subsequent alkaline hydrolysis PET powder which has high molecular weight ([η]=0.45) and high crystallinity of 92% (calculated from the density) was obtained.