High Damping Polyurethane Elastomer With Controllable Wide Temperature Range Based On Dynamic Covalent Bond And Dangling Chain Synergy

The main problem facing rubber-based elastomer damping materials at this stage is their poor controllability and predictability of damping temperature range,that is,the material can only exhibit high damping in a certain temperature range within its use temperature range.When the ambient temperature changes greatly,the damping failure often occurs,resulting in huge economic losses in production and life.At the same time,the damping material also faces the drawback that it is difficult to balance the damping performance and the mechanical performance.The existing modification methods to obtain materials with excellent damping performance in a wide temperature range generally sacrifice the mechanical performance as a cost,which also leads to its narrow application.Therefore,how to improve the controllability of the damping performance of the elastomer damping material while taking into account its mechanical properties is the focus and difficulty of the current damping material research.The overall performance of polyurethane elastomer materials is excellent.Generally,the T_gof polyurethane is below room temperature,and it has good damping performance in the glass transition region,but the damping performance in the temperature range above T_gis poor and it is difficult to meet the actual needs.The special micro-phase separation structure of polyurethane and the high designability of the structure are very suitable as research objects to explore the controllability of the damping performance of rubber-like elastomers.At the same time,polyurethane has good mechanical properties.Based on the molecular structure design of polyurethane,a small amount of dangling chains and dynamic covalent bonds-disulfide bonds are introduced into the polyurethane network structure.A small number of dangling chains are used to improve the damping performance of polyurethane from T_gto room temperature and the dynamic exchange of disulfide bonds improves the damping performance of polyurethane above room temperature.Based on the synergy between the two,the controllability of the damping temperature range of polyurethane in its using temperature range is finally achieved.At the same time,a small number of hanging chains can ensure certain mechanical properties of the material.Considering the shortcomings of poor heat resistance of polyurethane,polysiloxane with good thermal stability is selected as the suspension chain to improve the high temperature resistance of polyurethane while improving the damping performance of polyurethane.We first introduced dynamic disulfide bonds into the polyurethane system.From the perspective of increasing the friction loss of molecular chains,the dissociation and reorganization of intermolecular forces,and the breakage and reorganization of disulfide dynamic covalent bonds,we explored the influence of different chain extension coefficient,the structure of different disulfide bond-containing small chain extenders,different disulfide exchange catalysts and catalyst content on the degree of microphase separation,damping performance,molecular chain segment motion ability and mechanical properties of polyurethane.When the chain extension coefficient of the polyurethane material is 1.4,with the chain extender is 2,2'-diaminodiphenyl disulfide,and the disulfide exchange catalyst is Cu Cl₂,and the addition amount is 1/30 of the molar amount of disulfide bonds,the effective damping temperature range?tan??0.3?of polyurethane can reach 148??-48??100??,while tensile strength and elongation at break of materials is 16.8MPa and 926%respectively.Based on the introduction of dynamic disulfide bonds,further introduction of siloxane pendant chains was conducted to investigate the degree of micro-phase separation,damping performance and mechanical properties of polyurethanes with different siloxane pendant chain contents,different hard segment structures,different soft segment structures and soft segment molecular weight.And we also explored the impact of siloxane suspension chain on the high temperature resistance of polyurethane materials.When the suspension chain content reaches 20%,the effective damping temperature range of polyurethane can reach 182??-62??120??,while tensile strength and elongation at break of materials is 6.8MPa and695%respectively,and the polyurethane can be in long-term use at temperature of100?120?.