Synthesis Of Polyurethane Elastomer And Its Temperature Sensitivity

Temperature-sensitive polyurethane is a new functional polymer material with deformation and temperature-sensitive function and can make a reversible response to changes in external temperature.It is a new branch point of research,development and application in recent years.It has large formulation controllability and performance.The wide selection range and excellent deformation recovery function can meet the application requirements of many special occasions.It has broad application prospects in the fields of electrical and electronics,aerospace,medical correction,petroleum engineering and daily life.Its research is increasingly favored by materials scientists and has become the fastest growing class of smart materials in recent years.Therefore,it is imperative to study temperature-sensitive polyurethane elastomers with excellent comprehensive properties.This topic uses the semi-prepolymer method to prepare temperature-sensitive polyurethane elastomers,and explores the types,molecular weight and combined use of soft segment polyols,hard segment content,chain extension coefficient,combined use of chain extenders,free isocyanate content and other factors.The relevance of the performance of temperature-sensitive polyurethane;then the influence of the micro-crosslinking network on the deformation and temperature-sensitive performance of the temperature-sensitive polyurethane is studied.We examine the influence of deformation temperatures,external forces,number of cycles and heating rates during recovery on temperature-sensitive polyurethane through the bending qualitative method,the compression qualitative method and the DMA tensile quantitative method.The study found that:(1)We found that the mechanical properties,thermal stability,glass transition temperature,and deformation temperature sensitivity of polyester polyurethane are better than those of polyether type by changing the types of soft segment polyols,especially PCDL type.The deformation fixation rate and deformation recovery rate of polyester type are higher than that of polyether type.PCDL1000 polyurethane has the highest deformation fixation rate and deformation recovery rate,and the recovery rate can reach 93.56%.The mechanical properties of polyols show a decreasing trend as the molecular weight of the soft segment increases,the glass transition temperature decreases,the thermal oxidative aging performance decreases,the long chain index decreases,and the deformation fixation rate and deformation recovery rate decrease.PCDL1000 is the highest.When the polycarbonate polyol is used in combination,the physical and mechanical properties are the best.When the soft segment is used in a ratio of PCDL10/PCDL20=60/40,and the LCB index is the largest.With the increase in the ratio of PCDL20,the temperature range corresponding to the loss peak,good dynamic performance,thermal oxidative aging performance first increases and then decreases,the degree of decrease in tensile strength first increases and then decreases,when the soft segment is used in combination with a ratio of PCDL10/PCDL20=60/40,the deformation fixation rate is the highest.(2)As the hard segment content increases,the mechanical properties increase,the glass transition temperature increases,the relaxation time decreases,and the crosslink density increases.The better the heat-resistant oxygen aging performance,the LCB index increases.When the hard segment content is 55%,the LCB index is the largest.When the hard segment content is 50%,the deformation fixation rate and the deformation recovery rate are both the highest,and at the same external force,the strain when the hard segment content is relatively low.With the increase of the chain extension coefficient large,the mechanical properties increase first and then decrease,the glass transition temperature gradually increases,the internal friction increases,and the better the heat-resistant oxygen aging performance.When the chain extension coefficient is 1.15,the deformation recovery rate is the highest.When chain extenders BDO,DEOA,and chain extender B are used in combination,the mechanical properties will increase with the increase in the proportion of chain extender B.The glass transition temperature increases,the sample residue rate increases,the thermal stability increases,the better the heat-resistant oxygen aging performance,the LCB index gradually increases.When the chain extender is used in combination with a ratio of 6:1:3,the LCB index is the largest and the recovery rate is the highest.With the increase of the free isocyanate content,the better the mechanical properties,the higher the glass transition temperature,the higher the residual rate of the sample,the higher the thermal stability,and the loss factor value first increases and then decreases,the LCB index increases,and the LCB index is the largest when the free isocyanate content is 10%.(3)According to the bending method and compression qualitative method,the temperature-sensitive polyurethane has two-dimensional and three-dimensional shape memory properties.The deformation recovery rate first increases and then decreases with the increase of the deformation temperature.When the deformation temperature is 80 °C,The deformation recovery rate is the largest at 92.56%,and the faster the recovery speed,the overall deformation fixation rate does not change much as the external force increases,and the deformation recovery rate shows a downward trend.The recovery rate is optimal when the external force is 0.5 MPa.The deformation recovery rate first increases and decreases with the change of the heating rate,and it is optimal when the recovery heating rate is 10 ?/min.The shape recovery rate decreases with the increase of the number of cycles,but the overall change is not large.