Improvement of mechanical properties of cashmere fibers during microwave vacuum drying

Abstract

To study the mechanical property changes of cashmere fibers during the microwave vacuum drying (MVD) process, as well as the mechanism and key factors for the improvement of the mechanical properties, cashmere fibers were dried under different conditions. The mechanical and friction properties of cashmere fibers with different drying end points were tracked, and the structure−property relationship of cashmere was also analyzed at multiple scales. The amide I band infrared spectrum of the cashmere fiber was peak-fitted, and thermal analysis of the cashmere was carried out by differential scanning calorimetry. The results showed that there was a certain critical point of optimum fiber mechanics in the MVD process, and when the fibers were dried to the official regain of cashmere (15%), the fibers had the optimal value of the mechanical properties. MVD relieved the accumulated stress in the fibers, so that their strength and elongation were restored and the hydrogen bonds in the amide I band of cashmere fibers were not changed. The transformation of the secondary structure of cashmere and the denaturation of the ortho- and para-cortical cells were the fundamental reasons for the improvement of the mechanical properties of cashmere during the MVD.