Effect of molecular orientation on the biodegradability of aliphatic polyester

The effect of morphological microstructure on the biodegradability of aliph atic polyester, poly(epsilon-caprolactone) (PCL) was studied in terms of cr ystallite size, crystallinity and amorphous and crystalline orientation fac tors. Microstructural changes during hydrolysis/biodegradation of the drawn PCL films were investigated by the conventional small and wide angle X-ray scattering methods. The lower was the draw ratio, the higher the hydrolyti c degradability or biodegradability. With the increase of the hydrolysis ti me, the long period, at earlier stage, decreased; then slightly recovered a nd the crystallinity increased while the lamellar thickness remained unchan ged. The amorphous orientation factors start to decrease at earlier stage a nd gradually go down to zero before the end of hydrolysis. In the case of c rystalline orientation factor, although the values decrease with increasing hydrolysis time, they do not reach zero point. After the biodegradation fo r 60 days, crystallinity, crystal lateral size and lamellar thickness in al l drawn PCL films decreased, and then it was confirmed that even crystallin e regions were degraded for long term biodegradation test.