A new look at the modification of polyethylene terephthalate by sodium hydroxide

Abstract

Weight reduction is an alkali treatment of polyethylene terephthalate (PET) fabric with the aim of improving drape, handle and touch. The reaction of aqueous alkaline such as sodium hydroxide on PET is reported to be of the topochemical type meaning that the chemical reaction, hydrolysis, is limited to the fibre surface, and alkali does not affect the PET fibre core. Moreover, it is also reported that roughening of the fibre surface is a result of excess PET oligomers on the fibre surface after hydrolysis. New evidence obtained from small and wide angle X-ray scattering, wide angle X-ray scattering and atomic force microscopy reported in this article reveals that the bulk microstructure of PET is indeed affected by the weight reduction process and the roughening of the surface is a result of the new topology formed after weight reduction. A wide range of mechanical properties are measured. The wetting time is reduced from an average of 30 seconds to less than 1 second as a result of weight reduction. It was also found that dimensions of the PET fabrics were not affected by the weight reduction process.