Thermal Expansion Property Study Of Graphene/Polymer-based Nanocomposites

In recent years,graphene,as a representative of new materials,has been widely applied in composites due to its excellent mechanical,electrical and thermal properties.There are also some reported studies on thermal expansion property of graphene composites.However,because of the different research methods and emphasis,there is a lack of a comprehensive research regarding the combination of theory,numerical simulation and experiment.In this context,the main contents of this thesis are summarized as follows:Firstly,therepresentativevolumeelement(RVE)modelof grapheme/polymer-based nanocomposites was built by finite element software,the macroscopic thermal expansion properties of the materials was analyzed by the software,the changing regularity of thermal expansion coefficient under the conditions of different dispersity and loading of graphene was investigated.The results indicated that,by adding graphene,the thermal expansion coefficient of the polymer can be effectively decreased.Moreover,a larger decreasin g degree of the thermal expansion coefficient could be achieved by adding a larger content of graphene,and the thermal expansion rate linear changes with the temperature change.Moreover,techniques including ultrasonic dispersion,mixing and stirring,and isothermal curing,etc.,were used to fabricate graphene/epoxy nanocomposites.In the experiment,the content of graphene in the composites is1.0~5.0wt%,through the continuous improvement of the preparation process,a relatively perfect preparation process was finally developed.Thereafter,the thermal expansion property was measured and analyzed by using the static thermal mechanical analyzer(TMA)within the temperature range of 30~110~oC.Finally,thethermalexpansioncoefficientofgraphene/epoxy nanocomposites was calculated by the mechanical model based on the Eshelby-Mori-Tanaka method.Comparing the theoretical predictions with the experimental results and the finite element simulations,and verificating their correctness and effectiveness,mutually.The present work provides possibility for future fabrication of conductive polymer composites with zero thermal expansion,and also provids some simple and efficient methods to acquire the thermal expansion coefficients of new types of nanocomposites.