Structure development and biodegradability of uniaxially stretched poly(L-lactide)

The effects of uniaxial drawing conditions on the orientation of various po ly(L-lactide) (PLLA) samples were investigated using Fourier transform infr ared dichroism and thermal analysis, The results showed that the orientatio n in uniaxially stretched PLLA was determined by the drawing rate, drawing temperature, and draw ratio. For the amorphous sample, a higher orientation was obtained at a lower drawing temperature due to the slower chain relaxa tion. On the other hand, a higher orientation was achieved for the precryst allized samples at a higher drawing temperature due to the larger deformati on of spherulites. The hydrolysis tests of PLLA films showed that the rate of hydrolysis was dependent on the degree of orientation as well as the per cent crystallinity, After preferential hydrolysis of the amorphous regions, the surface of oriented PLLA samples might be covered by a layer of relati vely inactive crystal lamellae, causing a reduction in the rate of hydrolys is, (C) 2001 Elsevier Science Ltd. All rights reserved.