Functionalization Of Filler And Its Investigation On Thermal Conductivity Of Epoxy Natural Rubber Composites

With the continuous development of electronic devices,the integration and miniaturization of these devices are increasing.However,it leads to a rapid increase in power consumption and the generation of more heat.To ensure the stability and lifespan of electronic devices,the development of high-performance thermal interface materials has become an important strategy for addressing their heat dissipation.Epoxy natural rubber（ENR）is widely used in the field of heat dissipation materials due to its excellent dielectric properties,good insulativity,and easy processing.However,its thermal conductivity（λ）is relatively low,which limits its widespread use in the field of thermal interface materials.A simple and effective method for improvingλof ENR is incorporating high thermally conductive ceramic filler.However,the poor interface compatibility between ceramic filler and ENR results in high interface thermal resistance（R_c^*）,which limits the significant improvement ofλ.In this work,functionalized thermally conductive ceramic filler was dispersed in ENR to prepare high thermally conductive elastomer composites.In Chapter 3 of this work,micron-sized boron nitride（BN）was covalently modified by polyrodanine（PRd）（denoted as BN-PRd）,and then was filled into the ENR matrix using a mechanical mixing method to prepare high thermally conductive ENR elastomer composites.The N-C=S functional groups in PRd participated in the vulcanization reaction of ENR,allowing formation of stable covalent bonds between BN and ENR chains.Therefore,the interfacial interaction between filler and matrix is significantly enhanced.When 30 vol%of BN-PRd was filled,theλof the as-prepared ENR composite reached 0.4270 W/（m K）,which was 3.05 times that of pure ENR（λ=0.1400 W/（m K））.In Chapter 4 of this work,micro-sized alumina（Al₂O₃）and BN were covalently modified using PRd（denoted as Al₂O₃-PRd and BN-PRd,respectively）,and the two modified filler with different dimensions were filled into the ENR matrix to prepare high thermally conductive ENR elastomer composites.During the cross-linking process,PRd provided covalent bond interactions between the thermally conductive filler and ENR,reducing the R_c^*of composites.In addition,the two-dimensional BN-PRd sheets also acted as bridges between zero-dimensional Al₂O₃-PRd particles,which constructing a three-dimensional thermally conductive network in the ENR composites.As a result,theλof the ENR composites reached 0.5147 W/（m K）,which was 3.70 times that of pure ENR.In Chapter 5 of this work,poly（catechol-polyamine）（PCPA）was used for non-covalent modification of Al₂O₃ nanoparticles,followed by covalent modification using bis-[γ-（triethoxysilyl）propyl]tetrasulfide（Si69）,to prepare core-shell structured thermally conductive nanoparticles（denoted as Al₂O₃-PCPA-Si69）.They were then dispersed into the ENR matrix to produce high thermally conductive ENR elastomer composites.The non-covalent PCPA modification protected the inherentλof Al₂O₃ nanoparticles,while the Si69 participated in the vulcanization reaction of ENR,providing strong covalent bond interactions between Al₂O₃ nanoparticles and ENR chains,thereby reducing the R_c^*of the composites.In addition,the formation of thermal channels within the composites leaded theλof the ENR composites reached 0.3773 W/（m K）at 30 vol%Al₂O₃-PCPA-Si69 nanoparticles,which was 2.70 times that of pure ENR.