Antimicrobial finishing of polypropylene nonwoven fabric by treatment with chitosan oligomer

Water-soluble chitosan oligomer was prepared for finishing polypropylene nonwoven fabrics to impart antimicrobial activity. The weight average molecular weight was 1814 and its degree of deacetylation was 84%. Polypropylene nonwoven fabrics were treated with chitosan oligomer solution by the pad-dry method. Antimicrobial activity was measured by the shake flask method. The chitosan oligomer showed high antimicrobial activities against Proteus vulgaris, Staphylococcus aureus, and Escherichia coli at 0.01% and 0.05% level, respectively, showing above 90% of reduction rate. Chitosan oligomer was the most effective against Proteus vulgaris. However, it was not effective against Klebsiella pneumoniae and Pseudomonas aeruginosa below the treatment concentration of 1.0%. Fabrics became stiffer and less air permeable with the increase of treatment concentration. Tensile strength of the treated samples was lower than that of the untreated one. Liquid strike-through time of the sample treated with 0.5% chitosan oligomer solution (3.0 s) was comparable with that of a hydrophilic finished sample available commercially (2.6 s). (C) 1999 John Wiley & Sons, Inc.