Optimization of dye incorporation into modified poly(ethylene terephthalate) knitted fabrics by response surface methodology

Poly(ethylene terephthalate) can be modified by UV light and/or N,N-dimethylacrylamide to better incorporate disperse dyes. In this work, PET knitted fabrics were modified by DMAAm and UV light and then dyed with azo and anthraquinone disperse dyes. Factorial designs were performed at two levels using the following factors: DMAAm treatment time, dyeing time, and UV light exposure time. The best dyeing conditions were obtained with anthraquinone dye in the dyeing of UV light → DMAAm-modified PET knitted fabrics. In this case, the highest amount of incorporated dye was 6.3 mg/g under the following conditions: 77 min UV light exposure time; 15 min and 85 °C DMAAm treatment time and temperature, and 164 min and 85 °C dyeing time and temperature. The diffusion coefficients obtained were in the order of 10−5 cm2/min. The results showed that the azo dye diffuses faster into modified PET than the anthraquinone dye does.