An attempt has been done to impregnate chitin/chitosan with molecular weigh between 3,000 and 5,000 into poly(ethylene terephthalate)(PET) fabric using supercritical carbon dioxide, which is non-toxic, non-flammable, cheap and easily recyclable. The final purpose of this investigation is to give high anti-bacteria property having extremely high washing durability onto PET fabric. Chitosan-lactic acid salt with a molecular weight of around 5,000 was successfully impregnated into PET fiber using supercritical carbon dioxide and the salt was impregnated in the largest amount among the materials tested, whereas no chitin could be impregnated. The fact that 70% of the chitosan impregnated into PET remained and continued to show anti-bacterial properties after the fabric was subjected to 50 cycles of home laundry washing suggests that the chitosan molecules were partially impregnated into and onto the PET surface.
