Poly (ε-caprolactone)s (PCLs) with different molecular weight were cross-linked by γ-radiation．The radiation crosslinking feature was examined by Soxhlet extractor with toluene and analyzed by using the Charlesby-Pinner equation．The crosslinking degree is related to molecular weight and radiation dose

and the relation between the sol fraction and the radiation dose follows the Charlesby-Pinner equation．Radiation may cause a drop of tensile strength and elongation for all the samples d．The DSC diagrams demonstrated that radiation caused an increase of crystallinity and a decrease of melting temperature of PCL crystals．The DMA analysis indicated that radiation crosslinking raised heat deformation temperature of PCL and caused a rubbery state after the melting of PCL crystals．The shape memory results indicated that only those specimens that had a sufficiently high cross-linking degree (gelcontent is higher than about 15％) were able to show the typical shape memory effect

a large recoverable strain and a high final recovery rate．The response temperature of the recovery effect (about 55℃) was related to the melting point of the samples．The PCL shape memory polymer was characterized by its low recovery temperature and large recovery deformation．