Preparetion And Properties Research Of Thermally Induced Shape Memory Polyester Waterbrone Polyurethane

Thermally stimulated shape memory polymer has received great attentions because of its excellent properties and enormous application prospect recently. In this paper, shape memory waterborne polyurethane were synthesized from isophorone diisocyanate (IPDI), polyester polyol (PBA),dimethylol propionic acid (DMPA), and ethylenediamine(EDA) by self-emulsified method. The structure of this shape memory polyurethane was characterized by Fourier transform infrared spectroscope (FTIR). The effects of PBA molecular weight, the molar ratio of NCO group to OH group, the amount of DMPA, the amount of EDA on the basic properties and shape memory effect of shape memory waterborne polyurethane were discussed.In the study of the basic properties of the polyurethane, the following research results were obtained. The particle size of the polyurethane emulsion, the tensile strength and the elongation to break of the polyurethane films, the crystal enthalpy, melting temperature, melting enthalpy of soft segment of the polyurethane films enlarged, but the viscosity, the crystallization temperature of soft segment of the polyurethane films and the water absorption decreased as the increase of PBA molecular weight. The soft segment of the polyurethane films does not crystallize when PBA molecular weight is 2000. With the increase of the molar ratio of NCO group to OH group, the particle size of the polyurethane emulsion, the tensile strength of the polyurethane films, melting temperature enlarged, but the viscosity, the water absorption, the crystallization temperature, crystal enthalpy, melting enthalpy of soft segment of the polyurethane films and the elongation at break decreased. With the increase of the amount of DMPA, the viscosity, the water absorption, crystallization temperature of soft segment of the polyurethane films and the tensile strength of the polyurethane films went up, but the particle size, the crystal enthalpy, melting temperature, melting enthalpy of soft segment of the polyurethane films and the elongation at break declined. With the increase of the amount of EDA, the particle size, the crystallization temperature, crystal enthalpy, melting temperature, melting enthalpy of soft segment of the polyurethane films and the tensile strength of the polyurethane films went up, but the viscosity, the water absorption declined. The elongation at break increased and decreased when the amount of EDA increased.In the study of shape memory effect of the polyurethane, the following results were obtained. The shape fixed ratio went up with the increase of PBA molecular weight and the amount of EDA. The shape fix ratio of TSMWPU decreased as the molar ratio of NCO group to OH group and the amount of DMPA increased. The increase of PBA molecular weight and the amount of DMPA gave better shape recovery ratio while the ratio declined with the increase in the molar ratio of NCO group to OH group and the amount of EDA. The polyurethane films exhibited the best shape memory effect at stretch ratio of 100%, stretch rate of 50mm/min, stretch temperature of 60℃ and recovery temperature of 120℃.From the above, the mechanical properties and shape memory properties of the polyurethane films is better when the molecular weight of PBA is 4000, the molar ratio of NCO group to OH group is 2.7, the amount of DMPA is 4.9% and the amount of EDA is 80%.