Simultaneous biaxial drawing of poly (epsilon-caprolactone) films

The objective in our study was to investigate the biaxial drawing of Poly ( epsilon-caprolactone) (PCL), a bioerodable polyester that is flexible and e lastomeric. PCL films were fabricated using solution casting and melt-press ing methods, and biaxially drawn to draw ratio of 3 x 3. The morphology, me chanical properties and gas permeability changes of the undrawn and drawn f ilms were studied. Results showed that even at the low draw ratio used, a f ibrillar morphology developed in the films, interspersed with undrawn mater ial. The tensile strengths of the drawn films were also improved by 50-160% . The solution-cast films have higher gas permeabilities (20-fold), with Kn udsen flow character, than melt pressed films. This higher gas permeability was attributed to the presence of microvoids and drawing defects. Permeabi lity was reduced in the melt-pressed films and oxygen was found to permeate three times faster than nitrogen. Biaxial drawing increased the gas permea bility slightly but selectivity remained unchanged. (C) 2000 Elsevier Scien ce Ltd. All rights reserved.