Study On Preparation And Properties Of Self-Catalyzed Phthalonitrile Resin

The rapid development of modern science and technology puts forward higher requirements for material properties,so that materials can be used in harsh working environment.As the leader of high temperature resistant thermosetting resin,phthalonitrile resin has attracted great interest of many researchers due to its excellent thermomechanical properties,corrosion resistance,flame retardancy,high glass transition temperature and thermal decomposition temperature.It is expected to be widely used in aerospace,shipbuilding,microelectronics and military fields.However,the resin also has some obvious shortcomings,such as high melting point of monomer,poor processing performance,high post curing temperature,volatile catalyst,brittleness and lack of functionality.This paper focuses on the structural modification of phthalonitrile monomer and the preparation of resin thermal conductive composite.In view of the problems of high melting point,poor processing performance and volatile catalyst of phthalonitrile resin,this paper firstly studies the phthalonitrile resin monomer.Based on the molecular structure design,the second generation phthalonitrile monomer(ACPP)with autocatalytic performance was designed by introducing flexible aromatic ether bond and amino pyrimidine structure into phthalonitrile monomer through one pot and two-step method.This monomer has low melting point(84?)and low viscosity(<2 Pa·s),which shows good processability and suits for many kinds of processing methods.Moreover,ACPP polymer has good thermal stability,high storage modulus(4288 Mpa)and glass transition temperature(T_g>400?).These excellent properties provide a good foundation for the preparation of composite materials.In this paper,the silanized multi-walled carbon nanotubes(MWCNTs)were added to the ACPP polymer to give the resin thermal conductivity.The results show that the surface of MWCNTs was successfully modified with KH-560,and the grafting rate was 1.3%.The thermal conductivity and thermal properties of the composite increase with the increase of MWCNTs content.When the addition amount is 3 wt.%,the thermal conductivity of the composite reaches 0.32 W·m^-1·K^-1,which is 33%higher than that of the pure resin;in the atmosphere of air and N₂,the temperature of the composite at 5%thermal weight loss is479.4?and 485.1?,respectively;the initial storage modulus of the composite reaches4408 MPa,which is 8.7%higher than that of the pure resin,and T_g is greater than 400?and tends to increase.These results show that the addition of MWCNTs can effectively improve the thermal properties and thermal conductivity of the polymer.The results of three-point bending analysis show that the bending strength and modulus of composites with MWCNTs content of 1 wt.%are 23.8%and 20%higher than those of the original resin,respectively,reaching the maximum value.