Influence Of Introducing Suspension Chain And Constructing Gradient Structure On Damping Performance Of Castor Oil-based Polyurethane

As a viscoelastic material,polyurethane has good vibration and noise reduction effect,but its application is limited due to its narrow effective damping temperature range（TR）and low loss factor（tanδ）.In this project,castor oil was used as polyol to synthesize bio-based polyurethane,and castor oil-based polyurethane was modified by introducing pendant chains and constructing gradient structure.The effect of two modification methods on the structure and properties of castor oil-based polyurethane were researched,the comprehensive damping performance was investigated in depth.The main contents are as follows:1.Through molecular structure design,pendant chains were used into the hard segment of castor oil-based polyurethane.the DMTA results showed that with the increase of the content and length of pendant chains in the hard segment,both TR and tanδ_maxof polyurethane increased effectively,and the content of pendant chains was 40%,the polyurethane tanδ_maxincreased from0.9 to 1.5,the TR widened from 29.7℃（35.2～64.9℃）to 56.4℃（-10.0～46.4℃）,and moved to the low temperature direction to 45.2℃,covering a wide range from low temperature to high temperature.range,so that the comprehensive damping performance of polyurethane can be greatly improved.2.The n-dodecanethiol is grafted into the main chain of castor oil through thiol-ene click reaction,and then castor oil is used as the soft segment to synthesize polyurethane,so as to achieve the purpose of introducing pendant chains into the soft segment of polyurethane.the DMTA characterization results showed that with the increase of the content of n-dodecanethiol pendant chain in the polyurethane,the TR is obviously broadened.When the ratio of double bond and thiol group is 3:3,the TR of the polyurethane reaches74.0 from 34.3℃（17.1～51.4℃）℃（-8.3～65.7℃）,TR obviously moves25.4℃ to the low temperature direction,so that the polyurethane damping performance can effectively cover a wide temperature range from low temperature to high temperature.At the same time,the polyurethane tanδ_maxdecreased slightly,but still maintained a high damping performance greater than 1.3.The castor oil-based polyurethane gradient material with gradually changing pendant chain content was successfully prepared by double-channel microinjection method.the study found that the TR of the polyurethane gradient material reached 70.5℃（3.4-73.9℃）compared with 53.5℃ and35.2℃ of the pure components A and B,and the tanδ_maxwas 1.4,indicating that the construction of the gradient structure can maintain a high level of tanδ_maxin the polyurethane.at the same time,the TR has been significantly broadened,so that its damping performance has been comprehensively improved.