Study On The Relationship Between High Frequency Dynamic Mechanical Properties And Damping Properties In Shock Environment Of Polymethylvinylphenylsiloxane Rubber

Weapons,electronic systems and other equipment are subjected to high-speed shock load during accidental impact,drop and other process,which are likely to cause the malfunction,failure or damage of the key components and precision components inside the system.It is an important protective measure to use the excellent rubber damping materials for impact isolation.PVMQ has excellent resistance to high and low temperature,aging and radiation resistance.It also has superior electrical insulation property,good chemical stability and biocompatibility,showing excellent comprehensive properties.It is widely used in electronics,transportation,aerospace and other fields,so it is expected to be used as a high-performance damping material in high-impact environments.Dynamic mechanical properties are important basis for the design and application of damping materials.High shocks will produce high-frequency and high-overload vibrations,but the current related researches mainly focus on the study of the dynamic mechanical properties of PVMQ under low frequency conditions,so it is not sufficient to provide sufficient evidence for the application of PVMQ as a high impact damping material.Therefore,this paper is based on the time-temperature equivalence principle and the impact damping performance test device,focusing on the PVMQ in the high-frequency,high-impact conditions of the dynamic mechanical properties to carry out related research work.The main conclusions have been obtained as follows:(1)PVMQ with different phenyl contents were prepared.Based on thermomechanical dynamic mechanical properties analysis and time temperature equivalent principle,the influence of phenyl contents on the dynamic mechanical properties of PVMQ were studied.The results showed that with the increase of phenyl contents,the glass transition temperature(Tg)of PVMQ moves to high temperature,and the maximum damping factor increases.Under the condition of low frequency at room temperature,the damping factor of PVMQ is less than 0.3,which is difficult to use as an excellent damping material.However,PVMQ has good damping performance under high frequency conditions.With the increase of phenyl contents,the frequency corresponding to the maximum damping factor decreases,and the effective damping frequency domain shifts to the low frequency direction.When the phenyl content is about 30 mol%,silicone rubber has good damping performance in the frequency range of 9.0×10~3Hz~2.2×10~6Hz and temperature range of-15 ~oC~25 ~oC.(2)Diphenyl peroxide(BPO)and dicumyl peroxide(DCP)were used to obtain PVMQ with different cross-linking network structures.The effect of crosslinked network structure on the dynamic mechanical properties of PVMQ were studied.The results showed that the influence of the crosslinked network structure on the dynamic mechanical properties-frequency spectrum of PVMQ is significantly greater than that of the dynamic mechanical properties-temperature spectrum.When the crosslink density increases,the effective damping frequency domain narrows and moves to the high frequency.When the density is too large,some molecular segments lose their ability to move and the damping factor decreases significantly.At the same time,when the cross-linking densities are close,the effective damping frequency domain of the PVMQ obtained by DCP vulcanization and the effective damping frequency domain of the phenyl silicone rubber obtained by BPO have significant differences due to the different construction methods of the cross-linked network structure.(3)Two kinds of fumed silica with different surface characteristics were used as reinforcing fillers.The effects of the surface characteristics and the amount of silica on the dynamic mechanical properties of PVMQ were studied.The results show that the higher the amount of silica filler,the stronger the interaction between the filler and the PVMQ,the more effective the inhibitory effect on the movement of molecular segments,and the lower the damping factor.The surface characteristics and amount of silica have no obvious effect on the glass transition temperature and effective damping temperature range of PVMQ,but it has a significant impact on the effective damping frequency domain.When the amount of silica increases,the effective damping frequency domain becomes narrower.When there is a strong interaction between silica and PVMQ,the effect of silica on the effective damping frequency domain is even more pronounced.(4)The accelerometer sensor can be used to sense the characteristic parameters of the shock environment,so a composite damping structure composed of PVMQ sample and an acceleration sensor were designed.The influence of the phenyl contents,the sample thickness and the sample compressibility on the shock-damping properties of PVMQ were studied by means of a drop hammer impact loading device and a data acquisition system.The results showed that the higher the phenyl contents,the better the impact damping performance of PVMQ,which can effectively filter or attenuate the high-frequency vibration signals generated in high-impact environment.At the same time,it showed that the thicker the sample,the lower the compression rate,and the better the impact damping effect of phenyl silicone rubber.