Preparation And Properties Of Insulating And Thermally Conductive Composites Based On Polyarylene Ether Nitriles

The development trend of miniaturization,centralization and portability of electronic devices and equipment has put forward higher requirements for heat dissipation materials.Functional polymer polyarylene ether nitrile(PEN)not only has heat resistance and high insulation,but also has excellent mechanical properties and excellent processing properties,which makes it widely used.However,the application of PEN in thermally conductive materials has been limited due to the low thermal conductivity of the PEN.Therefore,in the thesis,graphene oxide(GO),hexagonal boron nitride(hBN)and multi-walled carbon nanotubes(MWCNTs)are selected as thermal conductive particles to prepare filled thermally conductive composite materials,extending the application of PEN in terms of insulation and thermal conductivity.GO,hBN,and MWCNTs are all excellent thermally conductive materials,and these three have similar cyclic molecular structures,which make?-?interactions between them and easy to combine.The main research contents of the thesis are as follows:Firstly,polyarylene ether nitrile with different chemical structures was designed and synthesized in thesis.By exploring and comparing the mechanical property,electrical property,thermology property,thermal conductivity and other properties of PEN films,combined with the difficulty of preparation and processability,the type of hydroquinone-resorcinol polyarylene ether nitrile(HQ/RS-PEN)was choosed to be the most suitable polymer matrix.Secondly,the filler hBN/GO was prepared by ultrasonic dispersion and mechanical blending because of the?-?interaction between hBN and GO,and then it was added to the HQ/RS-PEN to prepare hBN/GO/PEN composite materials.The electrical property test confirmed that the hBN/GO/PEN composites had good insulating property.When the filler content reached 50 wt%,the volume resistivity remained at 4.2×10^-10S/cm.The addition of fillers effectively increases the thermal conductivity of the composites.When the hBN/GO content is 50 wt%,the thermal conductivity of the hBN/GO/PEN composites reaches 0.622 W/(m·K),which is 2.2 times that of the polymer film.Finally,MWCNTs were introduced to construct a three-dimensional thermal network structure together with two-dimensional hBN and GO.It is found that the combination between the three filler particles is the best through the SEM when the content of MWCNTs is 0.5 wt%.hBN is distributed along MWCNTs,and MWCNTs are connected to GO,realizing the encapsulation of GO by hBN.Meanwhile,MWCNTs connect scattered hBN together to improve the thermal conduction pathway.The electrical property test confirmed that the MWCNTs/hBN/GO/PEN composite films have good insulating property.When the MWCNTs content is 0.5 wt%,the volume resistivity remains at 6.5×10^-10S/cm.Through the thermal conductivity test,it was found that the addition of MWCNTs effectively increased the thermal conductivity of the composite materials.When the content of MWCNTs was 0.5 wt%,the thermal conductivity of the composite films reached 0.4556 W/(m·K).The thermal conductivity of the MWCNTs/hBN/GO/PEN composite film was increased by 33%compared with the hBN/GO/PEN composites and was increased by 56%compared with the pure PEN film.