Molecular Dynamics Studies Of The Mechanical Behaviors And Thermal Conductivity Of The DGEBA/MTHPA/CNB Composites

The application range of pure epoxy resins is very limited.Epoxy resins need to be cross-linked with the curing agent to be widely used in various fields of production and life.The commonly used curing agents are polyamine curing agents and acid anhydride curing agents(PA).With the large-scale use of high-voltage switchgear in the power industry,the number of years of operation continues to increase,and problems such as aging and breakage of equipment often occur,and it is particularly important to ensure safe and stable operation of equipment.Basin insulators are key components in high-voltage equipment,and their performance directly determines the reliability of the operation of the switchgear.The performance of the basin insulator is mainly determined by the epoxy casting material.Therefore,starting from the substrate formulation of the material,the thermal properties and mechanical properties of the epoxy resin material are studied to improve the performance of the epoxy resin material.The simulation and experimental research on epoxy resin system with polyamine as curing agent has been extensive,and the simulation research of epoxy resin system using acid anhydride as curing agent is relatively limited.The acid anhydride-based curing agent has low toxicity,low shrinkage,and excellent dielectric properties.The simulation and experimental research on epoxy resin system with polyamine as curing agent has been extensive,and the simulation study of epoxy resin system using anhydride as curing agent is relatively limited.Therefore,this study studied the epoxy resin system of bisphenol A epoxy resin(DGEBA)and methyltetrahydrophthalic anhydride(MTHPA),and explored the addition of carbon nanotube tree bud(CNB)to DGEBA / The influence of thermal conductivity and mechanical properties of MTHPA epoxy resin.First,a program of automatic cross-linking reaction of DGEBA and MTHPA molecules and annealing was performed using perl language to obtain a series of epoxy resin models with different cross-linking degrees.The energy,free volume,mean square displacement and radial distribution function of different cross-linking models are analyzed to prove the rationality of the model.Secondly,molecular dynamics simulation was used to calculate the mechanical and thermal properties of epoxy resin models with different cross-linking degrees.The cross-linking degree was analyzed for the glass transition temperature,linear thermal expansion coefficient,thermal conductivity,Young's modulus and shear of epoxy resin.The effect of cutting modulus.It is concluded that when the degree of crosslinking is 60%,the glass transition temperature,Young's modulus,thermal conductivity and the like are the closest to the experimental data.The model of 60% cross-linking degree can be used to simulate the actual production of epoxy resin.Various performances.Finally,molecular dynamics simulations were used to study the effects of carbon nanobuds(CNB)on the mechanical properties and thermal conductivity of crosslinked epoxy resins based on DGEBA and MTHPA.Four different models were constructed using the same method,including carbon nanotubes(CNTs),carbon nanotubes(CNB),functionalized nanotube buds(FCNB)with one fullerene,and four An epoxy nanocomposite of functionalized nanotube buds(FCNBs)of fullerene,and calculated the glass transition temperature,linear thermal expansion coefficient,thermal conductivity,Young's modulus and shear modulus of the four models.And compared with the pure DGEBA / MTHPA system.Among them,the performance improvement of DGEBA / MTHPA / FCNBs model was the most significant,and the Tg value increased significantly by 34.3%.The improvement in Young's modulus and shear modulus was also more pronounced,increasing by 44.5% and 51.8%,respectively.Because of the size effect of CNT in thermal conductivity,the SWCNT introduced into the epoxy matrix only has a length of 2.2 nm,and there is an interface thermal resistance between the SWCNT/CNB and the matrix,so the thermal conductivity is increased but not Very significant.