Preparation And Properties Of High Dielectric Low Modulus Polysilicone Dielectric Elastomer Composite

Dielectric elastomer is an electroactive polymer that can be mechanically moved under an applied electric field electric field.It can deform under an applied electric field and convert electrical energy into mechanical energy;it can also convert deformed mechanical energy into electrical energy.Therefore,dielectric elastomers have been used in the fields of sensor,biomedicine,driver,microelectronics,etc.Due to the fast response,high energy density,good flexibility,biocompatibility,electrical insulation and widely applicable temperature,silicone rubber has been considered as a typical matrix for dielectric elastomers.However,the low dielectric constant limited its application fields.Carbon nanotubes(CNT)have excellent electrical properties and can improve the interface polarization ability of the polymer matrix.Therefore,the preparation of carbon nanotube/silicone rubber composite materials can effectively increase the dielectric constant of the material.However,the addition of conductive inorganic filler may also improve the modulus and strength of the material,thus reducing the softness of the material.In this paper,CNTs are designed to be hanged on the network of silicone rubber through molecular chain entanglement,then the carbon nanotube/silicon rubber dielectric elastomer with high dielectric and low modulus were obtained.The main research content and results are as follows:1.The effects of the ratio of hydroxy silicone oils with different viscosities and the amount of crosslinking agent on the mechanical properties and heat aging properties of the silicone rubber matrix were studied,and the formula and process for preparing the silicone rubber dielectric elastomer matrix were determined.2.The crosslinking agent Tetraethyl orthosilicate(TEOS)was modified with n-octanol(C8)firstly,and then added into the silicone rubber.The silicone rubber modified with Cs was obtained.The mechanical property,dielectric property and thermal aging performance of the modified silicone rubber were tested.It was found that the addition of fatty chain would reduce the Young's modulus of silicone rubber and increase the dielectric constant,and the preparation process of modified silicone rubber matrix was determined.3.CNT-ODA/SR-C8 composites were prepared by introducing the octadecylamine(ODA)modified carboxyl carbon nanotubes(CNT-ODA)into SR-C8.The surface modification of CNT was characterized using Raman spectroscopy,XPS and TEM,it was confirmed that octadecylamine was successfully wrapped on the surface of carbon nanotubes.The effect of the addition of CNT-ODA on the mechanical properties,dielectric properties,energy loss and thermal aging properties of CNT-ODA/SR-C8 composites was studied.The results show that due to the mutual entanglement between the C8 structure in the silicone rubber and the octadecylamine on the surface of the carbon nanotubes,the modified carbon nanotubes can be well dispersed in the SR-C8 matrix.After adding CNT-ODA,the Young's modulus and dielectric constant of the composite material increase.When the amount of CNT-ODA is 2.0%,the dielectric constant reaches 19.5 at 50 Hz,which is nearly 5 times higher than that of pure silicone rubber,Young's modulus is only 0.62 MPa.At the same time,the composite material has lower hysteresis loss and better heat aging performance.