Damping And Mechanical Properties Of Ni Foam/Epoxy Resin Composites Modified With CNTs

Metal foam/ polymer composites are a new type of structural and functional damping composites developed in recent years,which can realize multiple damping mechanisms such as complex damping,structural damping and interface damping to make them become one of the most promising damping composites.To further expand their application field,the researchers have focused on the improvement of damping performance by the method of changing the structure of metal foam(porosity and pore size),injecting the polymer with high damping performance and so on.However,there was less study on the interface damping.Based on the hybrid law of damping composites,Ni foam and epoxy resin were selected as elements of damping composites in this paper,and carbon nanotubes(CNTs)were directly synthesized on Ni foam to improve the damping and mechanical properties of Ni foam /epoxy resin composites by modifying the interface between Ni foam and epoxy resin.The main research works and achievements were as follows:1)A new simple chemical vapor deposition(CVD)process was proposed to grow CNTs on nickel foam directly without any catalysts and hydrogen.The coverage,morphology,structure and graphitization of CNTs were characterized by field emission scanning electron microscopy(FE-SEM),transmission electron microscopy(TEM),Raman spectroscopy and thermogravimetric analysis(TG)at different reaction temperatures.Meanwhile,the effect of reaction time on the yield of CNTs was studied.Finally the optimum reaction temperature and reaction time were determined as 680 and 30 min.The growth mechanism of CNTs on nickel foam was ?proposed through a series of tests.The CVD method was convenient and inexpensive,which could simplify the process,it was favorable for the mass production of uniform CNTs on nickel foam.2)The molding of Ni foam/ epoxy resin composites modified with CNTs was studied.Firstly,in order to meet the requirements of the vacuum infusion molding process(VIMP)and product performance,the resin system was selected and matched,and then a visualized double-sided rigid mold was designed to ensure the quality and performance of product.According to the characteristics of the resin system,the injection temperature was set as 25?.The vacuum pressure was set to 0.04 MPa and then increased to 0.08 MPa.Finally,the resin system was measured by differential scanning calorimetry(DSC),and the final curing process was determined by the method of T-? extrapolation and spinning as follows: 60?/2h+80?/2h+120?/1h,and the VIMP was well used to prepare high-quality Ni foam/epoxy resin composites modified with CNTs.3)The effect of CNTs on the damping property of Ni foam/epoxy resin composites was studied.The dynamic mechanical property of pure epoxy resin,Ni foam/epoxy resin composites and Ni foam/epoxy resin composites modified with CNTs were tested by dynamic mechanical analyzer(DMA).The variation laws of loss factor,storage modulus and loss modulus with temperature and frequency were analyzed,and the comparative study was also carried out.The results showed that the loss factor and loss modulus of pure epoxy resin,Ni foam/epoxy resin composites and Ni foam/epoxy resin composites modified with CNTs decreased with the increasing of frequency in the frequency spectrum,but the storage modulus increased with the frequency,and the loss factor,storage modulus and loss modulus of Ni foam /epoxy resin composites modified with CNTs were still larger than those of two other materials.In the temperature spectrum,the loss factor and loss modulus increased firstly and then decreased when the temperature was increased,but the storage modulus decreased with the temperature.Compared with Ni foam/epoxy resin composites,the maximum loss factor of Ni foam/epoxy resin composites modified with CNTs increased from 0.69 to 0.78,the glass transition temperature shifted from 60?to 68?,the effective damping temperature range widened from 39?to 44?,and the peak area of Ni foam/epoxy resin composites modified with CNTs increased by 18.9%.It could be concluded that the interface modified with CNTs was able to improve the damping property of Ni foam/epoxy resin composites greatly.4)The mechanical property of Ni foam/epoxy resin composites modified with CNTs was studied.The compression and tensile property of Ni foam,pure epoxy resin,Ni foam/epoxy resin composites and Ni foam/epoxy resin composites modified with CNTs were analyzed and compared by the method of experiment,and the corresponding compression and tensile deformation characteristics were obtained.Compared with Ni foam and pure epoxy resin,the compression and tensile of Ni foam/epoxy resin composites modified without and with CNTs were improved.When CNTs were deposited on Ni foam,the compression elastic modulus and strength increased by 15.3% and 19.4%,the tensile elastic modulus and strength increased by 15.2% and 10.2%,by comparison with Ni foam/epoxy resin composites.It was further demonstrated that the interface modified with CNTs could effectively improve the mechanical properties of Ni foam/epoxy resin composites.