BIODEGRADABLE FIBERS .1. POLY-L-LACTIC ACID FIBERS PRODUCED BY SOLUTION SPINNING

Fibres of about 620 000 viscometric molecular weight, M(v), were obtained by a spinning/drawing process using a poly-L-lactic acid/chloroform solution. Mechanical properties of fibres increased with draw ratio (DR) up to tensile modulus and strength of 10 GPa and 1.1 GPa, respectively. Moreover, draw ratio appeared to affect fibre structure and morphology, producing different amounts and types of crystallinity (characterized by two close but well distinct melting peaks, as revealed by DSC) or causing different failure modes in the stressed-up-to-break fibres. As demonstrated by scanning electron microscopy, a microfibrilar structure is developed for draw ratios higher than about 8.