Study On Preparation And Sound Absorption Properties Of High-damping Foam Butyl Rubber

To solve the vibration noise hazards caused from industrial production,transportation and society,rubber is selected as matrix to investigate the damping property due to its characteristic viscoelasticity.However,some holes will be produced in the after-foamed rubber,which in existence change the sonic straight line and make it become a multi-hole material with sound-absorption capacity.Butyl rubber is a damping sound-absorption material with excellent comprehensive performance,which has unique molecular chain structure,small numbers of carbon-carbon double bond and large amounts of side-methyl.Rare earth is an element with unique electronic layer structure and has a special photo-electromagnetic effect.Nowadays,rare earth/macromolecule composites has been developed and applied based on its excellent comprehensive performance.Owing to that large numbers of foamed holes exist inside the after-foamed butyl rubber,the reinforcing reagent needs to be added for improving the weak mechanical properties.Butyl rubber compound was firstly prepared using mechanical mixing,and then the foaming agent azodicarbonamide was added into the blending.After uniformed mixing and vulcanization molding,the foamed butyl rubber can be obtained.The effect of vulcanization process and foaming agent content on the damping sound-absorption properties of foamed butyl rubber was investigated.The results showed that the damping properties of foamed butyl rubber exhibited the optimum value at the vulcanization temperature of 165?for 30 min,and the maximum loss tangent reached 1.44 at-25?;when the vulcanization process finished under the vulcanization temperature of 160?for 50min and pressure-maintaining and cooling process continued until to the room temperature,the sound-absorption property of foamed butyl rubber reached the optimum,and the maximum sound-absorption coefficient was 0.32 at 400Hz.After foaming,the damping and sound-absorption properties of butyl rubber have obvious improvement.When the foaming agent was 6phr,the comprehensive performance reached the optimum.The effect of carbon black content and filler type and content on the damping sound-absorption properties of foamed butyl rubber was discussed.The results showed that small numbers of carbon black can increase the damping property but decrease the sound-absorption property,and the damping sound-absorption properties decreased as the increasing content of carbon black.Carbon black reinforced foamed butyl rubber loaded with Gd₂O₃ had the optimum damping sound-absorption properties,the maximum loss tangent reached 1.5 at-20?and the maximum sound-absorption coefficient was 0.39 at 400Hz.The general law regarding the influence of the filler content on the damping sound-absorption properties of foamed butyl rubber is low-amount filler can clearly improve the sound-absorption property of foamed butyl rubber,and the weak sound-absorption effect will appear as rising filler content.SEM images showed that the best foam-hole morphology presented in carbon black reinforced foamed butyl rubber loaded with CeO₂.The effect of white carbon black content and filler type and content on the damping sound-absorption properties of foamed butyl rubber was investigated.The results showed that only small numbers of white carbon black can increase the damping property.White carbon black reinforced foamed butyl rubber loaded with Y₂O₃ had the optimum damping sound-absorption properties,the maximum loss tangent reached 1.625 at-25?and the maximum sound-absorption coefficient was0.48 at 400Hz.Finally,the effect of the material thickness on carbon black or white carbon black reinforced foamed butyl rubber loaded with rare earth oxides was analyzed.The results showed that the low-frequency sound-absorption property increased with the increasing material thickness,which exhibited the optimum at the thickness of 60mm.The maximum sound-absorption coefficient was 0.73 at 400Hz and the effective sound-absorption frequency band was 200²000Hz.