Simultaneous biaxial drawing of poly (ε-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 elastomeric. PCL films were fabricated using solution casting and melt-pressing methods, and biaxially drawn to draw ratio of 3 x 3. The morphology, mechanical properties and gas permeability changes of the undrawn and drawn films were studied. Results showed that even at the low draw ratio used, a fibrillar morphology developed in the films, interspersed with undrawn material. The tensile strengths of the drawn films were also improved by 50-160%. The solution-cast films have higher gas permeabilities (20-fold), with Knudsen flow character, than melt pressed films. This higher gas permeability was attributed to the presence of microvoids and drawing defects. Permeability was reduced in the melt-pressed films and oxygen was found to permeate three times faster than nitrogen. Biaxial drawing increased the gas permeability slightly but selectivity remained unchanged. (C) 2000 Elsevier Science Ltd. All rights reserved.