Improvement of Hydrophilicity of Polylactic Acid (PLA) Fabrics by Means of a Proteolytic Enzyme from Bacillus licheniformis

Abstract

Polylactic acid (PLA) has received considerable attention as a biomass material for the textile industry. To use a PLA fabric in the textile industry, suitable postprocessing that can promote hydrophilicity of such fabrics is required. Here, hydrolytic action of a proteolytic enzyme (alcalase from Bacillus licheniformis) on PLA fibers was evaluated. In addition, the effects of an additive on the enzymatic hydrolysis were analyzed. The results revealed that the optimal enzymatic-hydrolysis conditions for this alcalase are pH 9.5, temperature 60 degrees C, enzyme concentration 50 % on weight of fabric (owf), and L-cysteine concentration of 3 mM. PLA fabrics were hydrolyzed effectively, however; there was no damage to these fabrics judging by tensile strength and surface observations. X-ray diffractometry identified a new peak (at 2 theta=18.5 degrees), implying a morphological change caused by the treatment. Moreover, hydrophilic properties such as moisture regain and dyeing properties were enhanced by this proteolytic enzymatic hydrolysis. Therefore, according to this study, enzymatic hydrolysis is a suitable finishing method for improvement of hydrophilicity of PLA fabrics.