Storage Of Shape Memory Polyurethane Synthesis And Characterization,

Shape memory polyurethanes (SMPU) have attracted more and more attentions recently due to their unique properties. Energy storage materials are also a hot topic as the increasing shortage of energy, which can store and release large amount of latent heats over a defined temperature range. In our research, SMPUs which consist of a crystallized soft segment of polyethylene glycol (PEG) and a hard segment of toluene diisocyanate (TDI) and different chain extenders are synthesized. Shape memory property and energy storage property of polyurethanes are investigated. The thermal conduct properties of polyurethane are also modified by adding talc.The structures and properties of these unmodified and modified polyurethanes have been investigated by using Scanning Electronic Microscopy (SEM), Differential Scanning Calorimetry (DSC), X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopic Analysis (FTIR) and Thermo gravimetric Analyzer (TG) etc.There is a critical molecular weight of PEG to form crystal in the polyurethane, which is 2000. The degree of crystallinity of soft segments and melt temperature increase as the molecular and content of PEG increases. The average efficiency of enthalpy also increases as the molecular weight and content of PEG increase, it reaches 44% when the molecular of PEG is 4 000 and the content is 80wt%, which is the highest. Adding appropriate content of talc in the polyurethane can improve the efficiency of enthalpy of crystallization. When the content of talc is 5wt%, the enthalpy of crystallization increases from 21 J/g to 57 J/g, which is equivalent to the value of melting enthalpy. These polyurethanes are cast into films. The films can be used as a separating layer in thermo-regulated non woven. The shape of SMPU are held below 30℃, and the original shape will be recovered again within 20 seconds at 40℃.