Enzymatic and chemical hydrolysis of polyethylene terephthalate fabrics

Abstract

Alkaline and enzymatic hydrolyzes of poly(ethylene terephthalate) fabrics (PET) were mechanistically compared based on released degradation products (HPLC-UV-RI) and changes in surface properties [hydrophilicity, cationic dyeing, X-ray photoelectron spectroscopy (XPS)]. Enzymatic hydrolysis led to an increase in the amount of hydroxyl and carboxyl groups on the surface resulting in an enhanced water absorption and dyeability. Enzymes partially adsorbed to PET fabrics during hydrolysis were completely removed by subsequent extraction according to XPS analysis. In contrast to the enzyme treatment, alkaline hydrolysis did not lead to an increase of hydroxyl and acid groups according to XPS while both treatments caused a substantial increase in hydrophilicity and were more effective on amorphous fibers. Alkaline hydrolysis led to a greater increase in the K/S value after cationic dyeing due to enlarged surface area. Consequently, ESEM-images demonstrated that alkaline treatment drastically affected the surface morphology of the polymer resulting in crater-like structures of the fibers, whereas after enzymatic treatment the morphology of the fibers remained unchanged. To reach similar benefits in hydrophilicity, drastically higher amounts of degradation products were released during alkaline hydrolysis as also indicated by >6% weight loss compared to <1% after enzyme treatment. © 2008 Wiley Periodicals, Inc.