Alkali Resistance of the Silk/PLA Mixture

As a new textile material, silk/PLA mixture combines the outstanding characteristics of silk and PLA fibers, but this mixture is subjected to some problems owing to the poor alkali resistance of PLA fiber during the pretreatment and reactive dyeing processes. In the present work, the alkali resistance of silk/PLA mixture was tested with three alkalis, namely sodium hydroxide, sodium carbonate and sodium bicarbonate. It was found that silk component was less influenced by sodium carbonate and sodium bicarbonate, whereas PLA component was more or less influenced by three alkalis. Silk/PLA mixture showed low weight loss after sodium carbonate and sodium bicarbonate treatment, but had very high weight loss after sodium hydroxide treatment. 10 g/L sodium carbonate and 3 g/L sodium hydroxide resulted in the obvious changes in the morphological structure of PLA. After the alkaline treatment, the IR spectra of PLA treated with 3 g/L alkali displayed great variations, and the intensity of the peak at 3429.3 cm-1 increased with the strength of alkalis, showing that the partially hydrolysis of PLA occurred.