Study On Preparation And Properties Of Shape Memory Polyurethane And Its Composites

A leading candidate among the field of potential materials applied in space inflatable structure is shape memory composite material. The matrix resin component provides the shape memory behavior to the composite. Polyurethane (PU) with shape memory property was synthesized in this dissertation. And organic montmorillonite (MMT) was added to prepare the PU/MMT nano-composite. The properties of the PU with and without MMT were investigated in details. Composite was prepared with aramid fabric as reinforced material.Shape memory polyurethane (SMPU) were synthesized by choosing poly 1,4-butylene glycol adipate (PBAG) as soft segment, 4,4'-diphenylmethane diisocyanate (MDI) and two different diols (1,4-butanediol (BDO) or Hydroquinone di(b-hydroxy-ethyl) ether (HQEE)) as hard segment with solution polymerization method. Structures of the products were characterized. Glass transition temperature (Tg) and viscosity average molecular weight were tested respectively. Shape memory property and tensile property were studied simultaneously. The results showed that polyurethane with shape memory property was synthesized successfully. The glass transition temperature were all above 45℃. And the shape recovery rate could reach 100% through the bending-recovery test.The system with MDI, PBAG, BDO as reactants and the molar ratio 4/1/3 was chosen to prepare polyurethane/montmorillonite (PU/MMT) nano-composite with monomer intercalation polymerization method. Structures of the products were performed by Infrared Spectroscopy (IR) test. Wide Angle X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM) and Molau test were used to investigate the lamellar structure of the PU/MMT composites. Properties of the products before and after modification were compared. The results showed that the intercalated nano-composites were prepared. Thermal stability, shape memory property and mechanical property of polyurethane were improved after modification with MMT.The aramid fabric reinforced polyurethane composites were prepared with solution immersion method. The shape memory property of the composites was studied. And a composite tube was prepared and it was verified that the tube had good folding-deploying ability. The tensile strength of the composites was all above 300 MPa which showed that it can satisfy the requirement applying in space inflatable structure.