Preparation And Property Of Shape Memory Polyurethane

Poly-1,4-butylene adipate glycol (PBAG) is an excellent crystalline polyols. It can be used as a shape memory unit for the polyurethane with excellent mechanical property and shape memory property. In this paper, shape memory polyurethane with different molecular weights PBAG as soft segment was prepared (SMPU). The effects of isocyanides, chain extender and mole ratio on the properties of shape memory polyurethane materials were investigated. Polyurethane was modified by polyether-modified silicone oil, terminal hydroxyl silicone oil, silane coupling agent and amino silicone oil. In addition, the shape memory polyurethane-silicone were reinforced by carbon fiber (CF) and modified by nano-BaSO4.The results showed that PBAG-4000 was the optimal soft segment for polyurethane shape memory system. The results showed that the MBPU4-4 system had a better performance in the mechanical properties and shape memory properties, which tensile strength and elongation at break were 29.1 MPa and 655 percent, respectively, when the molar ratio of PBAG/MDI/BDO was 4:1:3. At the same time, the shape fixed rate was 100%, shape recovery rate was 98.3% and the final recovery.time was 430s.The characterization of FTIR spectra indicated that the silicone resin have embedded into the polyurethane molecule chain of the MBPU4-4 system. The results showed that the tensile strength and elongation at break of the composites increased firstly then decreased with increasing of the silicone content.The tensile strength and elongation at break of the composites with 6phr polyether-modified silicone oil (PUJ5-6) reached to 33.0MPa and 719%, respectively. The tensile strength was 34.5MPa and elongation at break was 739% when the content of the terminal hydroxyl silicone oil is 2phr (PUH8-2). The polyurethane systems modified by other two silicone oils showed good mechanical properties compared with the MBPU4-4 system. When the composites were modified by lphr silane coupling agent (PUK5-1), the tensile strength reached to 30.6MPa and elongation at break reached to 748%. When the composites were modified by 0.5phr amino silicone oil (PUN5-0.5), the tensile strength reached to 30.3MPa and elongation at break reached to 707%.After adding the silicone, the Crystallization of the soft segment material of polyurethane were dropped, phase compatibility of the hard segments between the soft segments were promoted. The size of crystals was reduced and the thermal response time was reduced, so that the shape memory properties of the material had been greatly promoted. The final recovery time of PUJ5-6, PUH8-2, PUK5-1 and PUN5-0.5 systems were 183s,220s,328s and 175s, respectively. The shape recovery rate of polyurethane modified with silicone all reached to 100%, and the initial decomposition temperature and the maximum decomposition temperature increased by adding the silicone.The composites were reinforced by carbon fiber (CF) and Nano-modified BaSO4. The tensile strength and elongation at break of PUJ5-6 and PUH8-2 system increased gradually with the addition of CF content, and reached to the maximum value at 5phr. But the mechanical properties of two systems were decreased after the first increase with addition of BaSO4 content, and achieved the best performance at 2phr. The shape memory tests showed that both the residual deformation and shape recovery time increased with the addition of nanoparticle, while the shape memory properties decreased.