Structure and mechanical property of polylactide fibers manufactured by air drawing

Polylactide fibers were prepared by air drawing. The effects of mass throughput (Q) and frequencies of electric machinery of drawing air (fm) on the structure and mechanical properties of polylactide fibers are studied. With the increase of fm and the decrease of Q, the diameter of polylactide fiber decreases gradually. For a sample aged for less than 3 days, two glass transition temperatures (Tg) are found, whereas for a sample aged for 30 days, only a single Tg appears. With the increase of fm, the crystallinity and crystalline orientation of polylactide fibers increase, which can restrict the physical aging. Therefore, polylactide fibers are relatively brittle when the fm is below 20 Hz. However, when fm reaches 30 Hz, elongation at break (ɛb) of polylactide fiber increases rapidly to 1122%. With the further increase of fm, ɛb decreases and break stress (σb) increases. In addition, physical aging can make ɛb decrease and σb increase.