Study On Electrical Transport,Thermal And Mechanical Properties Of Graphene Composites

With the rapid development of flexible wearable electronic devices,higher requirements are placed on the sensing materials,which is required to have high sensitivity,flexibility,and the ability to detect full-range human activities.In addition,with the development of microelectronic devices toward high-performance,lightweight,and miniaturization,the development of lightweight,high thermal conductivity materials has become a key issue for researchers.Graphene has excellent electrical properties and thermal properties.It can be used as electric or thermally conductive fillers to greatly improve the overall performance of the composites.Graphene has broad application prospects in the field of flexible conductive and lightweight thermal management.In this paper,a flexible and conductive graphene oxide/polymer sponge was prepared by self-assembly.The composite sponge can be easily processed into sensors with different dimensions and different shapes to meet the requirement of detecting multiple forms of strain with high sensitivity.Three-dimensional graphene/polyurethane sponges exhibit excellent mechanical properties and cycle stability to compression;two-dimensional planes are very suitable for electronic skin to detect bending,stretching and impact;one-dimensional linear composite sponges exhibit torsional and With its ultra-high-sensitivity response,the resolution can reach to 0.01N.As a wearable device,it has successfully detected human activities such as finger bending and vibration.The excellent comprehensive properties of the composite sponge make it very suitable for flexible electronic stress sensors.In addition,according to its unique response curve to the compression strain,we proposed a corresponding equivalent circuit model to analyze its mechanism of resistance change.In order to prepare lightweight thermal conductive materials,the thermal properties of graphene/epoxy and graphene/epoxy/carbon fiber composites were studied in this paper.The results show that compared with pure epoxy resin,graphene/epoxy composites Shows an increase of 8.5 times the normal thermal conductivity with a lower filler content of 12wt%,and the the density is only 0.078 g/cm3.The thermal conductivity of the ternary composites has also been improved by a factor of four.In addition,we proposed a self-assembly-impregnation two-step composite method which successfully solved the problem of the difficulty of preparation using the impregnation method at higher graphene content,and prepared a ternary composite material with higher graphene content and improved thermal conductivity.This method also provides a reference for the preparation of other nanomaterials and polymers.