Molecular Simulation Studies On Micro-Structure And Thermal Conductivity Of Polymer Materials

Polymer material,welled with wood,metal,and silicate,is called as the world first four popular materials.And polymer has many characteristics of high toughness,high temperature resistant,corrosion resistant,resistant to extreme conditions etc,and have special optics,electricity and magnetism performance,which enable polymer to be an ideal replacement of metal materials.To improve the performance of polymer thermal conductivity mechanism and realization way of research,for both can effective thermal conductivity and corrosion resistance of the development of special polymer(plastic),has important theoretical significance and engineering application value.Molecular Dynamics Simulation("MID Simulation" for short)is an important tool to observe physical and chemical process mechanism which in the experiment are difficult to measure the micro structure and characteristics.In this paper,a seires of MD simulations were performed and a force field as well as model which is fit for polymer was built to study conducting polymer mechanical properties and its heat transfer performance,which can elaborate the nature of the stress and deformation and heat transfer in the polymer,and provides a basis for the prediction of the change process.In this paper,firstly,using of molecular dynamics simulation method,this paper established a coarse-grained(CG)model potential field parameters and polymers polyethylene.Basing on this CG model,force performace and structure properties were researched while their parameters,such as bond lengths distribution,angular distribution and so on,were analyzed to prepare with results of all-atomic simulations.As a result,accuracy and reliability of the CG force field was verified.Secondly,we studied the mechanical properties and thermal properties of single-chain polyethylene using CG force field and calculated physical parameters of single-chain polyethylene,such as young's modulas,tensile limit,thermal conductivity and so on.Results indicate a young's modulas of 0.053 GPa as well as thermal conductivity of 1914.055 W·m-I·K-1 which is affected by the length of chain and temperature of system By analyzing the phonon transport spectrum,a debye temperature of 257.930 K was achieved.Finally,we studied the mechanical properties and thermal properties of polyethylene module,it discussed the influence of CG parameter for physical properties of materials.Based on the obtained CG Field,when polyethylene module stretching were simulated,through the stress-strain curve,we obtained Young's modulus polyethylene is about 0.01 GPa,consistent with the actual value;CG potential parameters of Lennard-Jones potential ? is the main parameters affecting the physical properties of polymer block,the larger s the greater the value of force between the carbon chain,the greater the magnitude of calculated Young's modulus,the phase transition temperature increases.we use Muller-Plathe method simulation module disorderly polyethylene thermal conductivity of 0.09365 W·m-1 ·K-1,and the actual physical parameter values(0.1?0.5W m-1 ·K-1)approximation.We further study the effects of tensile strain on the polyethylene heat transfer performance,studies have shown that the thermal conductivity increases with increasing material strain,strain at 8.00,its thermal conductivity is increased by about 6.6 times,it has been significantly improved.