Preparation And Properties Of Pressure-resistant Sound Absorbing Polyurethane Elastomer

With the development of sonar detection technology,in order to improve the survivability,"deep dive" has become an important development trend of underwater navigation bodies,which puts higher requirements on pressure and sound absorption for underwater acoustic absorption materials.In this paper,the preparation and performance of pressure-resistant sound-absorbing polyurethane elastomers are studied.The purpose is to develop a hydroacoustic sound absorbing material that can be used in a "deep dive" environment and maintain good sound absorption performance under high hydrostatic pressure.The contents include the preparation of intrinsic polyurethane elastomers,the use of particle reinforced modified polyurethane elastomers,and testing and characterizing properties.According to the molecular design principle,the polyurethane elastomer formulation system(diisocyanate,polypropylene glycol 2000 and triethanolamine)was designed and screened,and the intrinsic polyurethane elastomer was synthesized by one-step method to investigate its mechanical and acoustic properties.The results show that when the hard segment content is 30 wt%(35.78 phr of diisocyanate,100 phr of polypropylene glycol 2000,0.72 phr of triethanolamine),the polyurethane elastomer has the best tensile and compressive properties,and the tensile strength,compression modulus are 4.18 MPa and 18.06 MPa,respectively.The sound absorption performance reaches its peak when the hard segment content is 20 wt%,and the absorption coefficient of the polyurethane elastomer can reach 0.7 in the frequency ranges from 2 to 25 kHz.The optimized polyurethane elastomer formulation that have both pressure and sound absorption properties is: 22.43 phr of diisocyanate,100 phr of polypropylene glycol,and 2.57 phr of triethanolamine.Hollow glass microspheres were used to reinforce the polyurethane elastomer,and the effect of hollow glass microspheres on the performance of elastomer was investigated.The results show that when the content of unmodified hollow glass microspheres is 0.5 phr and 3 phr respectively,the tensile properties and compressive properties of the composites are optimized.Compared with the unreinforced samples,the tensile strength and compressive modulus increase by 9% and 19%,respectively.When the modified hollow glass microspheres is 2 phr and 3 phr,the tensile properties and compressive properties of the composites is best,respectively.Compared with the unreinforced samples,the tensile strength and compressive modulus increase by 40% and 21%,respectively.The polyurethane elastomer's sound absorption performance decreases with the hollow glass microspheres were reinforcedCarbon nanotube reinforced polyurethane elastomer was used to investigate the effect of carbon nanotube reinforcement on the performance of the elastomer.The results show that the tensile and compressive properties of the composites are optimized respectively when the content of carbon nanotubes is 0.05 wt% and 0.2 wt%,respectively.The tensile strength and compressive modulus increase by 8 % and 28 % compared with the unreinforced samples.The sound absorption coefficient of the polyurethane elastomer is reduced to less than 0.2,after reinforced with carbon nanotubes.