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 ( f m ) on the structure and mechanical properties of polylactide fibers are studied. With the increase of f m 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 ( T g ) are found, whereas for a sample aged for 30 days, only a single T g appears. With the increase of f m , the crystallinity and crystalline orientation of polylactide fibers increase, which can restrict the physical aging. Therefore, polylactide fibers are relatively brittle when the f m is below 20 Hz. However, when f m reaches 30 Hz, elongation at break ( ɛ b ) of polylactide fiber increases rapidly to 1122%. With the further increase of f m , ɛ b decreases and break stress ( σ b ) increases. In addition, physical aging can make ɛ b decrease and σ b increase.