Preparation Of Polymer Damping Materials And Designation Of Constrained Damping Structure

Damping refers to the capacity of energy depletion,which is used as an important means of vibration and noise control.The current study is focused on the preparation of damping materials and the designation of damping structure.The aims of this paper were to prepare polymer damping materials with wide temperature range and the designation of constrained damping structure.The damping properties of acrylonitrile-butadiene rubber/polyvinyl chloride(NBR/ PVC)system were investigated from polymerization degree of PVC,curing systems, carbon black types,dioctyl phthalate(DOP)content,respectively.NBR/PVC(70/30) showed the widest temperature range(-16～34℃)of tanδ≥0.5 after researching the different ratios of NBR/PVC,which was suitable for using at room temperature.Based on these,AO-80 was added in the NBR/PVC system to obtain a higher tanδpeak at higher temperature.It was found that two phases,NBR/AO-80 and CIIR phase,were formed in chlorinated butyl rubber(CIIR),NBR and AO-80 ternary system.The damping properties of CIIR/NBR/AO-80 system changed greatly with the increase of NBR content.When the content of CIIR and AO-80 were 100 phr and 50 phr,respectively,and the content of NBR changed from 20 phr to 30 phr even to 100 phr,NBR/AO-80 phase was firstly dispersed,then part continuous,even to continuous phase with better damping properties. However,the liquid-liquid transition(T₁₁)of CIIR was restricted with the increase of NBR content.T₁₁of CIIR was fully restricted at 100 phr NBR.Damping properties of two phases,NBR/AO-80 and CIIR/PSY phase,could be improved by Adding PSY in CIIR/NBR/AO-80 system.The tanδpeak position of CIIR shifted to high temperature with high tanδ.The position of NBR/AO-80 phase's tanδpeak was not shifted,but the value of tanδpeak was increased.The tanδbetween the two peaks was also improved. The temperature range of tanδ≥0.5 could extent to 98℃(-23℃～75℃)and 105℃ (-11℃～94℃)for CIIR/NBR/AO-80/PSY(100/20/50/35)and CIIR/NBR/AO-80/PSY (100/30/50/50),respectively.Both of them were excellent damping materials.The modal strain energy method was used to calculate the natural frequencies and modal loss factors by finite element analyse software,Ansys.The calculating result was analyzed and compared with the analytical solution of literatures.The result indicated that based on suitable model and units,the predicting errors of the natural frequencies and modal loss factors of the constrained damping structure were very small.The method was suitable for calculating the natural frequencies and modal loss factors of the constrained damping structure.Based on this method,it could predict the effect of polymer damping material parameters(including the thickness,modulus and Poisson's ratio)and constrained layer's thickness on damping properties of the constrained damping structure.It could also provide optimization for the designation of constrained damping structure and selection of polymer damping material.Modal loss factor was mainly decided by the storage modulus and loss factor of damping materials in the damping structure.In the designed constrained damping structure with aluminum as the base layer and constrained layer,seven damping materials were selected as the damping layer,respectively.High modal loss factors(more than 0.2)were found for CIIR/NBR/AO-80(100/20/50)system in the temperature range (10～50℃).With steel as the base layer and constrained layer,and three typical damping materials were selected as the damping layer,respectively.High modal loss factors(more than 0.3)were also found for CIIR/NBR/AO-80/PSY(100/20/50/35)system in the temperature range(10～50℃).