Study On The Preparation Of CNT/EP Composite And Its Force-electrical Behavior

Since they were discovered,carbon nanotubes(CNTs)have attracted much attention in academic research because of their excellent mechanical,electrical and thermal properties.Meanwhile,epoxy resins(EP)are common materials with stable physical and chemical properties and they are often used as the matrix to make composites.This research focuses on the fabrication process of the CNT/EP composites and their force-electrical characteristics.The research contents are as follows.First,the method to the preparation of CNT/EP composite films was optimized based on the mixing-dispersion-forming process.By the proposed process,copper meshes are embedded in composite films to make electrodes so that the connection quality between the electrodes and the composite matrix can be improved.Using the present method,composite films with various CNT contents were fabricated for ensuing testing.Second,the effects of CNT load on the mechanical properties and the conductivity of the CNT/EP composites were investigated experimentally.The results show that the Young’s modulus,the tensile strength and the limit strain of the composites all grow at the beginning and then turn to a descending phase as the CNT content increases,while the conductivity of the composites increases monotonically with the CNT content.Third,the force-electrical characteristics of CNT/EP composites were studied.The conductivities of the composite films were measured when they were subjected to stretching.Experimental results indicate that the conductivity of the composites is sensitive to the CNT content.Generally,the greater the tensile strain is,the larger is the resistivity of the CNT/EP material.However,the sensitivity of the composite specimens is also dependent on the CNT content.Basically,at higher level of CNT content,the sensitivity coefficient of the specimen is relatively lower.On the other hand,lower CNT load results in larger sensitivity coefficient,but the dispersion of the test results also increases,which means the piezoresistive behavior of the CNT/EP film is less stable.Based in the force-electrical characteristics of the CNT/EP composite,a pressure sensor was designed and tested.The results show that this kind of pressure sensor has a great potential to be applied in practical engineering.Last,a highly efficient numerical approach was proposed based on the three-dimensional statistical resistor network model to calculate the conductivity of CNT/EP composites.Numerical results prove that the present approach can reduce the computational cost tremendously without loss of accuracy.