Study on the Melt-Spinnability of Poly(L-lactic acid)

In this work, three kinds of different poly(L-lactic acid) (PLLA) materials for melt-spinning were investigated with respect to the molecular weight (MW) and molecular weight distribution (MWD), racemization, optical purity, thermal properties, and melt-spinnability. It was found that the high MW was not the only factor to affect the melt spinnability of PLLA, the racemization and the amount of residual monomer would also affect the thermal properties and melt-spinnability of PLLA. The results showed that it could be melt-spun and hot-drawn by using the general melt-spinning device for PLLA pellet with good stereoregularity and comparatively high MW. For PLLA pellet with high MW and moderate stereoregularity, it must be treated at an appropriate temperature to increase the crystallinity before dry and extrusion, which could make the pellet be spun without agglomeration, whereas the draw ability of such as-spun fiber was still poor. However, if the stereoregularity of PLLA pellet was poor, it could not be spun even it had very high MW. Only when MW, racemization, and the amount of residual monomer of the PLLA pellets all meet the requirements, PLLA fibers could be prepared by melt-spinning. POLYM. ENG. SCI., 49:2315-2319, 2009. (C) 2009 Society of Plastics Engineers