Design And Preparation Of Polyurethane Damping Elastomer With Hydroxyl-terminated Styrene Butadiene Rubber As Soft Segment

Vibration and noise are ubiquitous in social production and life,and their harm to machinery and equipment and the human body makes the design and development of damping materials with high loss performance of great significance.The loss effect of damping material on vibration mechanical energy and sound energy is mainly accomplished through the viscous internal friction effect of the material and the elastic relaxation process.Damping materials can absorb vibrational mechanical energy and acoustic energy through viscous internal friction and elastic relaxation processes.The benzene ring structure in styrene-butadiene rubber can generate more internal friction during the movement of the molecular chain to show good damping performance,so it is often used in rubber damping materials and products.Polyurethane materials have the advantages of strong designability,adjustable damping performance,and easy forming and processing,and are widely used in the field of damping,vibration reduction and noise reduction.This paper combined the advantages of styrene butadiene rubber and polyurethane,hydroxyl terminated styrene butadiene rubber(HTSSBR)were synthesized by anionic reactive polymerization,a series of hydroxyl terminated styrene butadiene rubber polyurethane elastomers(HTSSBR-PU)were synthesized by using HTSSBR as soft segment,the influencing factors of polyurethane damping properties were studied,which provided technical support for the design of polyurethane damping materials with high loss properties.The first part of this paper(chapter 3)explored the influence of the structure of HTSSBR on its glass transition temperature(Tg).The result show that the molecular weight and structure of HTSSBR can be precisely controlled by anionic living polymerization.Its molecular weight distribution was narrow,and PDI was below 1.35.When the styrene content increased from 24.9%to 49.8%,its Tg increased from-18.0? to-0.1?.When the styrene content was basically unchanged at 34.1%and the 1,2-butadiene structure content increased from 44.3%to 50.9%,its Tg increased from-13.7? to-7.7?.The Tg of HTSSBR can be adjusted within a certain range by changing the content of styrene and the content of 1,2-butadiene structure.The second part of this paper(chapter 4),a series of HTSSBR-PU were synthesized with diphenylmethane diisocyanate(MDI),1,4-butanediol(BDO)and trimethylolpropane(TMP)as hard segments,and the effect of HTSSBR structure on the properties of HTSSBR-PU was explored.The results show that when the styrene content in HTSSBR increases from 24.9%to 49.8%,the Tg of HTSSBR-PU increases from-12.1? to 7.8?,the maximum loss factor(tan?max)increased from 1.51 to 1.70,and the effective damping temperature range(?T)above 50?,the tensile strength increased from 3.97MPa to 10.29MPa.When the styrene content in HTSSBR remains unchanged,the 1,2-butadiene structure content increased from 44.3%to 50.9%,the Tg of HTSSBR-PU increased from-7.9? to-0.4?,tan?max was above 1.50,?T was around 60?,and the tensile strength was about 5MPa.When the molecular weight in HTSSBR increased from 2400 to 15,700,the Tg of HTSSBR-PU decreased from-6.8? to-15.8?,tan?max increased from 1.50 to 1.71,?T was above 29.8?,and the tensile strength decreased from 7.35MPa to 5.43MPa.The Tg of these three series of HTSSBR-PU was adjustable within a certain range,and the tan?max wsa above 1.50,which had a good application prospect in the field of damping,vibration reduction and noise reduction.The third part of this paper(chapter 5),the effects of hard segment content,isocyanate type and PTMG content on the properties of polyurethane were studied.The results show that the mechanical properties of HTSSBR-PU can be effectively improved by adjusting the hard segment or introducing PTMG as the blended soft segment.When the hard segment content increased from 25%to 45%,the microscopic phase separation of MDI-PU was more obvious,the average particle size of the hard segment gradually increased,and the Tg of HTSSBR-PU decreased from-7.9? to-9.5?.The tan?max decreased from 1.60 to 1.33,and the ?T was above 30?,the tensile strength first increased and then decreased,reaching the maximum value of 11.65MPa when the hard segment content was 35%.When p-phenylenediisocyanate(PPDI)and 4,4'dicyclohexylmethane diisocyanate(hmdi)were used as raw materials,by comparing the performance of MDI-PU,PPDI-PU and HMDI-PU,we found that the structure of different isocyanates had little effect on the loss peak position of polyurethane.Compared with PPDI-PU,MDI-PU had a higher tan?max;compared with HMDI-PU,MDI-PU had excellent mechanical properties and damping properties.When PTMG was used as the soft segment of blending,the PTMG content increased from 0%to 75%,the Tg of polyurethane decreased from-7.9? to-37.0?,the tan?max of polyurethane decreased from 1.59 to 0.59,the ?T decreased from 61.9? to 28.9?,and the tensile strength increased from 5.90MPa to 23.73MPa.