WATER FUGACITY IN ABSORBING POLYMERS

Absorbable biomaterials, as dynamic systems, require special handling, processing, and characterization techniques beyond those of the tradi tional nonabsorbable materials. As the material degrades or absorbs, i n vitro or in vivo, it undergoes structural, physical, and chemical ch anges. These changes in the base material may significantly impact the performance of a particular biomedical device; hence, it is important that the investigator consider the full range of properties that cons titute the lifetime of a given absorbable material. The long term degr adation study presented here sought to identify. one such property, th e change in water retention of a degrading oriented polylactide film. The investigation found through differential scanning calorimetry that later stages of degradation are often characterized by a stronger ret ention of water, potentially due to a higher number of polar carboxyl groups within the relatively hydrophobic polymer matrix. (C) 1997 John Wiley & Sons, Inc.