Shape memory property of poly(l-lactide-co-ɛ-caprolactone) copolymers

Poly(l-lactide-co-ɛ-caprolactone) (PCLA) copolymers were prepared by ring-opening polymerization using stannous octaoate as catalyst. Their thermal properties and crystallinity were determined by using differential scanning calorimetry and X-ray diffraction. The mechanical properties are significantly affected by the copolymer composition. With increasing ɛ-caprolactone (ɛ-CL) content, the tensile strength of copolymers decreases and the maximum strain increases gradually. The shape memory property of PCLA copolymers was investigated by tensile test and its dependence on the composition and the deformation strain was also revealed. The crystallinity poly(l-lactide) (PLLA) or the entanglement of molecular chains is considered as physical cross-links, while the amorphous fraction acts as reversible phase and is responsible for the shape memory property of PCLA copolymers.