Impacts Of The NP-interaction On The Mechanical Properties And Electrical Percolation Of AuNP-polyethylene Composite

In recent years,considerable attention is paid to flexible elastic materials because of their superior mechiancal and electromechanical properties.The emergence and research of this new material play a very important role in the development of high elasticity(stretchability)and excellent electrical conducting materials.Indeed,the emergence of new materials represented by flexible and elastic conductive composites as an example has greatly promoted the technological innovation in developing flexibale,stretchable and bendable electronics and the intelligent development of above-mentioned functional nanocomposites.Different from the traditional composite materials,the van der Waals force between the nano-scale particles of the nano-composite materials has substantial influence on the mechanical and electrical properties of materials at the nanoscale and macroscopic scales.Therefore,it is essential to study the impacts of the interaction between nano-particles under the nanoscale condition for the mechanical and electrical properties of nanocomposites.At present,there are very few experimental studies on the electromechanical properties of the gold nano-particle(AuNPs)-polyethylene composite(metal rubber)and the molecular dynamics simulations on the mechanics of the nanocomposite.More efforts are therefore required to carry out analysis on AuNP-PE nanocomposite,a newly developed flexible conductive material.In nanocomposites,the van der Waals interaction between AuNPs is greatly enhanced,which may significantly change the overall mechanical and electrical properties.This thesis uses multiscale simulations techniques to examine this fundamental issue in the mechanics of nano-composites,where the tensile test was performed on the nanocomposite based on molecular dynamics simulation,and its pezoresistive responsences were studied and analyzed by combining the molecular simulations,Montel Carlo method and a resistor model.Finally,the dynamics of AuNPs in the deformation of the material was studied in the simulations.The main conclusions are summarized as follows:(1)molecular dynamics simulation,it was found that the attraction of the gold nanoparticles bond the gold nanoparticles together.The effect is significant even when the volume fraction of the gold nanoparticles was 5-10%.,which increases the young's modulus,yield and fracture stress of the material.(2)The attraction between the nanoparticles has a significant influence on the dynamic behavior of the nano-gold particles and its trajectory in the deformation of the matrix,thus improving the sensitivity of the conductivity of the tunneling conductive phase,ie the piezoresistive sensitivity of the material has Significantly increased.(3)Unlike the monotonically increasing trend of resistance in the contact conduction phase,the resistance value decreases with strain when the tunneling conduction phase is corrected.When the maximum value is reached,the resistance will reverse and the resistance will increase with strain.(ie,the increase in particle spacing)and monotonously rise.This finding is different from the experiments of intuition and contact conduction phases,perfecting the perception of the piezoresistive properties of material nanoparticle composites.(4)Constitutive relationship of high elastic materials is found to be bale to well fit the molecular dynamics data of “gold nano-particles-polyethylene” composites,in in the low strain and high dstrain range.The material parameters were then extracted for the nanocomposite.In particular,the first three parameter for low order terms are found to be sensitive to the volume fraction of the gold particles while the other three for higher order terms are found to be nearly independent of the volume fraction of the nano-particles.