Preparation And Study Of High Damping Elastomer With Broad Temperature And Frequency Ranges Based On Epoxidized Natural Rubber

The vibration and noise comes with the rapid development of industrial society whichseriously harms the production and living of people in most situations, polymers have beenwidely used as the damping materials to control the vibration and reduce the noise efficiently,which attributes to the mechanical relaxation of the segments of the long chains, during therelaxation process, part of the vibration energy can be dissipated as heat due to the friction ofpolymer chains. The loss factor （tanδ）, defined by the ratio E″/E′of loss （E″） and storagemodulus （E′）, can be used as a measure of the vibration energy dissipation. To meet therequirements of practical damping applications, good damping materials should exhibit a highloss factor （tanδ>0.3） over a temperature range of at least60–80°C. The vibration frequencyis another important factor, which is needed to be considered in the application of dampingmaterials. As we know, the damping properties of polymers in the low vibration frequency areweak, therefore, the damping materials with broad frequency range are also demanded toreduce the harmfulness caused by low or changed frequency vibration. The effectivefrequency ranges of damping materials are obtained from the plots of tanδ versus frequencywhich are deduced according to the time temperature superposition principle and WLFequation. In this paper, two broad effective damping temperature and frequency rangeselastomers based on ENR are prepared and studied.The single component elastomers with broad effective damping temperature andfrequency range are prepared which the rubber body is ENR and the vulcanization agent isphenolic resin. On the one hand, the chemical crosslinking will be formed between ENRmolecular chains and phenolic resins, on the other hand, some intermolecular hydrogen bondsmay be formed between the phenolic hydroxyl group of phenolic resin and epoxy ring ofENR, which restrict the motion of segments chains of ENR and broaden the effectivedamping temperature and frequency range of ENR. The cured ENR with phenolic resin ascuring agent shows much broader effective damping temperature and frequency range thanthat of using the other two curing agents, sulfur and peroxide curing systems, its effectivedamping temperature range is from-47.6to100°C and effective damping frequency rangecovers the range from10^-5to109Hz. The existence of hydrogen bonds is conformed by theFTIR analysis. The smaller the substituent on the Benzene ring and the steric hinderanceeffect of phenolic resin, the stronger the hydrogen bond will be. The ENR cured by2402PFhas much broader effective damping temperature and frequency range than that of other fourkinds phenolic resin as curing agents. With the increase of2402PF’s content, the glass transition temperature （Tg） of cured ENR shift to higher temperature due to the increase of theactivation energy which is needed during the glass transition. When using5phr2402PF ascuring agents, the cured ENR achieves the broadest effective damping temperature andfrequency ranges and the lowest activation energy,126.2kJ/mol. With the increase of theaddition content and the decrease of the particle size of carbon black, the damping peaktemperature will shift to higher temperature, the height of damping peak will decrease, but thedamping properties of cured ENR at higher temperature and lower frequency will beimproved.The broad effective damping temperature and frequency range damping elastomer basedon the blends of chlorinated butyl rubber（CIIR） and ENR are prepared. As the existence ofintensive side methyl of CIIR and strong polar epoxy ring of ENR, to take advantage ofstrong steric hindrance effect and polarity differences between CIIR and ENR, the CIIR/ENRblends show a marco-homogeneous but micro-phase separation structure, the Tg of ENR shiftto higher temperature dramatically. The Tg of ENR-50（the extent of the epoxidation is50%）is5.1°C, while blended with CIIR at the blend ratio80to20, the Tg of ENR phase in blendshift to75.6°C. With the increase of the epoxidation extent of ENR, the Tg of ENR phase inblend will shift to higher temperature, thus the CIIR/ENR-50/ENR-40ternary blend isprepared, and its effective damping temperature range is-92.3to76.8°C and effectivedamping frequency range is10^-4to10¹³Hz when the blend ratio is70/17/13, the broadest ofall the ternary blends.