Research On The Relationship Between Different Chemical Structure And Vibration Response Characteristics Of Polyurethane Elastomer

With the development of science and technology,the artificial process of production has been gradually replaced by mechanical processing.However,the vibration is always generated along with the mechanical processing from the used machines,which has dramaticlly affected our normal life.As a kind of material that can convert mechanical vibration into thermal energy,damping material has good vibration reduction ability,so as to achieve the purpose of protecting instruments and operators.Due to its special structure of soft and hard segments,polyurethane elastomers as a kind of good damping material have the very broad applications.Thisthesis,will apply polyurethane to the field of damping materials.Three relationships between the damping performance of polyurethane elastomer and the different vibration forms,the change of the polyol structure,and the change of isocyanate index would be discussed:First,through the same polyurethane sample,using the damping factor as the evaluation standard,the relationship between different vibration response methods and the damping performance of the polyurethane elastomer was discussedin three aspects: the vibration mode of dynamic thermomechanical analyzer,the preload pressure,and the loading frequency in different vibration modes.The study found that the damping performance in compression mode was better than that in stretch mode;the greater the preload pressure,the narrower the effective damping temperature range,and the peak value of the damping factor increased first and then decrease;the greater the loading frequency,the wider the effective damping temperature range,the peak of the damping factor gradually increased in the stretch mode,and gradually decreases in the compression mode.Second,the relationship between the change of polyol structure and the damping performance of the polyurethane elastomer was discussed in three aspects: the type of polyol,the molecular weight of the polyol,and the compounding of different polyol molecular weights.The study found that the presence of branch chains in the soft segment or the greater interaction between the hard and soft segments would improve the damping performance;the larger the molecular weight and the larger the peak damping factor generated the worse mechanical properties;adding a small molecular weight system to a system with a large molecular weight would increase the glass transition temperature and mechanical properties,whilethe oppositewould increase the peak damping factor and effective damping temperature range.Finally,the content of isocyanate was changed to discuss the effect of isocyanate content on the damping performance of polyurethane elastomer.The study found that the more isocyanate content would hold the narrower effective damping temperature range,the smaller peak damping factor,the higher glass transition temperature and the better mechanical properties.