Effect of Enzymatic Hydrolysis of Polyamide 6,6 with Mixtures of Proteolytic and Lipolytic Enzymes on Dyeability

Enzymes are biological catalysts which are well known in textile wet processing to enhance the handling and appearance, desizing, bleaching, softening, shrink-proofing, dyeability and pilling behavior of various textile products. The aim of this work was to investigate the changes induced on nylon 6,6 fiber by enzymatic system using mixture of proteolytic and lipolytic enzymes. Technical measurements were studied including Fourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA), weight loss (WL), bending lengths (BL), scanning electron microscopy, moisture absorbency (MA), and reflectance spectroscopy (RS). For this purpose, nylon 6,6 fabrics were first treated separately with different concentrations of protease and lipase mixtures in solution. The dyeing process was then carried out on the treated fabrics with two reactive and acid dyes. The intensity of major peaks in FTIR spectra of the protease treated samples are in favor of chemical changes of the polypeptide functional groups in fabric. Thermal studies also show significant decrease in thermal degradation temperature of the treated polymer at higher temperatures of 400°C. Protease and lipase mixtures decreased the weight of samples while lipase intensified the weight loss comparing with protease. The results of color measurements showed that the more concentration of lipase enzyme used in mixture, the darker the color of dyed sample is.