| Modified polyurethane viscoelastic damping material（viscoelastic dampingmaterial for short） is videly applied in the damping viberation and noise reductionfield because of their excellent viscoelastic property, and can combine with thesubstract to form the constrained damping structure. However, as polymers, it can’tavoied the aging problem during the application. This work has charaterized thecommen performance of viscoelastic damping material, the aging behavior of theviscoelastic damping material and the constrained damping structure were analyzedstressly. The weather resistanc performance and corrosive resistance of theviscoelastic damping material and the constrained damping structure were studied bythe accelerating aging test, Fourier Transtorm Infrared Spectroscopy (FTIR) andmetallurgical microscope were applied, the main research contents and conclutionsare as follows.Firstly, the commen performance of viscoelastic damping material and itsconstrained damping structure were charactorazed. The mechanical property ofviscoelastic damping material increased fast in the early stage and then increasedslowly in the late stage, tensile strength of viscoelastic damping material of10dayshad increased by428.57%, and its tensile strength of65days had increased by99.55%.Solidification study showed that, the gel time of viscoelastic damping material was190~228s, and the tack free time was35~45min. Solid content study indicated that,the solid content of viscoelastic damping material was high to92.68%, which showedthat viscoelastic damping material was a high solid content enverioment-friendlymaterial with no VOC. Water absorption test showed that, the water absorption ofviscoelastic damping material in7days respectively were no more than2.3%, whichillustrated good water resistans. The damping analysis showed that, the viscoelasticdamping material had excellent damping effect, the loss fator of the constainedstructure at25Hz was0.98436, coMPared the loss fator of moter plate withoutdamping material was0.4636.Secondly, the weathering resistance test illustrated that, high temperature and the humidity had much effect on the viscoelastic damping material, the surfacemorogragh showed that, after thermal oxidative aging, thermocycling test, freeze andthawing cycling test and hygrothermal aging, the content of air bubble in viscoelasticdamping material was decreased, the material was more dense, so that the dampingperformance was increased from different degree, air bubble decrease was the maincause of decline of the damping performance. Mechanical property test showed that,the tensile strength of viscoelastic damping material increased by2.7%after56daysof thermal oxidative aging, after56times of thermocycling tests, the tensile strengthof viscoelastic damping material increased by16.93%, after56days of hydrothermalaging, the tensile strength of viscoelastic damping material decreased by79.23%.FTIR study inllustrated that the chemical structrure of surface of the material wasdestroyed, moculer chain of such as N-H, C=O, C-N and C-H were broken indifferent degree. Damping performance test showed that, the fisr order loss factordecreased by13.88%after56days of thermal oxidative aging, and it decreased by32.02%after56days of hygrothermal aging. Hygrothermal aging influenced a lot onviscoelastic damping material; this environment condition should be avoided duringthe application.Thirdly, corrosion resistance study of viscoelastic damping material showed that,viscoelastic damping material had good acid resistance, alkal resistance and sea waterresistance, but the engine oil had influence on the material. FTIR spectual illuctratedthat, chemical structure of the surface of the viscoelastic damping material changedafter immersion in10%sulfuric acid,15%sodium hydroxide and the sea water,molecule chain of the hard and soft section were destroyed. However, surfacemorograph showed that the inside of the material remined well. Tensil strengthdecreased by12.87%after120days of sulfuric acid immersion, and the first orderloss fater of the constrained structure increased by31%; Tensil strength increased by16.0%after120days of sodium hydroxide immersion, the first order loss fater of theconstrained structure was decreased by20.69%; Tensil strength decreased by1.6%after120days of sea water immersion, the first order loss fater of the constrainedstructure was increased by52.48%; Tensil strength increased by62.75%after120 days of engine oil immersion, the first order loss fater of the constrained structure wasincreased by64.83%; engine oil should be avoided during the application.These experiments and studies provided data to the application of viscoelasticdamping material in the damping viberation and noise reduction field, showingtheoretical support to enhance the safety and durability, which has important guidancesignificant. |
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