Study On Structure And Properties Of Polymer Based Damping Materials

Polymer based damping materials have attracted considerable attention in the field of functional materials due to their outstanding properties for reducing vibration and noise.In this dissertation,the viscoelastic properties of chlorinated butyl rubber（CIIR）/ethylene-vinyl acetate copolymer（EVA）,CIIR/acrylic resin elastomer（AR） and CIIR/ Butadiene Styrene Block Copolymer（SBC） blends are studied by dynamic mechanical analysis（DMA）,respectively.Based on the three polymer blends,effects of carbon black,calcium carbonate,mica,organic additive A （polymeric sterically hindered phenol） and B（2,2’-methylene -bis（4-methyl-6-tert-butylphenol）） on the dynamic mechanical properties of the composites are investigated systematically.For CIIR/EVA and CIIR/AR compatible systems,the maximum of loss factor（tanδ） decreases when the concentrations of carbon black（CB）, calcium carbonate（Ca） and mica（M） increase.However,loss modulus（E″） increases remarkably by the addition of mica,which is not observed in the case of carbon black and calcium carbonate.When 100phr mica is added, the maximum of E″increases from 5.2×10⁸ Pa to 7.8×10⁸ Pa for CIIR/EVA system,while from 4.7×10⁸ Pa to 7.8×10⁸ Pa for CIIR/AR system.It can be attributed to to the fact that the polymeric matrix inserts into the interlaminar space of lamellar mica and forms a microconstrained layer damping structure,which can induce the shear effect when the applied stress acts on the composites.For CIIR/SBC incompatible system, it is found that the compatibility is improved due to the addition of carbon black or mica.For the carbon black filled system,either interaction between functional groups like hydroxyl groups on the surface of carbon black and polar groups of CIIR,or physical adsorption between non-polar part of carbon black and non-polar polymer SBC,leads to the improvement of compatibility between CIIR and SBC phase.For the mica filled system, the improvement of compatibility can be attributed to the formation of the microconstrained layer damping structure.For additive A filled CIIR/EVA compatible system,a new damping peak is observed above the liquid-liquid transition temperature(T_ll) of the matrix,implying the phase separation,which is not observed in the case of additive B.However,for CIIR/AR compatible system,phase separation is observed by the addition of either A or 13.In addition,the hybrids with A are found to show better damping stability than those with B.On the other hand,the increase in glass transition temperature（T_g） and the maximum of tanδis observed at a higher frequency.From 1Hz to 31.4Hz,the maximum of tanδincreases from 0.47 to 0.49,while T_g increases by 10℃.Furthermore,T_g increases by 2℃whereas the maximum of tanδdecreases slightly from 0.85 to 0.83 when the CIIR/AR/A/B/CB/Ca/M/80/20/20/20/20/100/100 composites is tested under relative humidity 50%.Furthermore,either the prepared damping materials consisting of CIIR, AR,organic additive and fillers or the damping materials with a laminated gradient structure can achieve high damping（tanδ＞0.3） within the temperature range more than 100℃,which is broad enough to meet the application requirement.