Change in stiffness and effect of orientation in degrading polylactide films

The degradation pattern of the synthetic absorbable polyester is thought to occur from the center of the material outward, and the bulk degradation is therefore attributed largely to the chemical composition of the material. It was hypothesized that this pattern might be altered by changing the morphology of the material, i.e., by introducing molecular orientation into the system. A new solid state uniaxial orientation (SS-UO) process was used to orient two types of lactide polymer films. The films were exposed to a phosphate buffered solution, then chemically, mechanically, and visually analyzed after predetermined times. This paper explores the results of flexural testing which will be later correlated with microscopic degradation events, as part of the larger degradation study. The results show that, while orientation does not have an overall significant effect on the flexural modulus, there is a significant material/orientation interaction. (C) 1998 Elsevier Science Ltd. All rights reserved.