Structure And Dynamic Property Of Linear Polymer Blends

The structure and dynamic properties of binary blends linear polymer chain at equilibrium and nonequilibrium in this paper.These properties include the mean-square end-to-end distance,mean-square radius of gyration and it’s tensor component,diffusion coefficient,relaxation time,viscosity,first normal stress difference and second normal stress difference.We adopted molecular dynamics simulation method used tothe statistical average of particles that satisfying the classical dynamical equations and at different coordinates of the various moments toobtain the dynamics properties. We adoptedhigh-performance parallel programing technology-MPI(Message Passing Interface)in order to save time,The method for controlling temperature used the dissipative particle dynamics thermostat.The simulation result included:In the equilibrium state(there is no external force field), the effect of the volume fraction or weight-averaged molecular weight(polydispersity) of binary blends of linear polymer chain to the mean-square end-to-end distance and mean-square radius of gyration is very small, Binary blends of linear polymer chain close ideal chain.Binary blends of linear polymer in the equilibrium state, short chain show a slow diffusion than polymer chain in the monodisperse system, long chain show a quick diffusion than polymer chain in the monodisperse system;short chain show a long relax time than polymer chain in the monodisperse system, long chain show a short relax time than polymer chain in the monodisperse system.Binary blends of linear polymer(the following is called blends polymer) in the nonequilibrium state(add shear field), on the viscosity-shear rate curve, at first, there is flat table then a turning and finally a marked drop in the viscosity, display a shear thinning behavior of the polymer. The corresponding viscosity of the flat region is called zero shearing viscosity. The height of the platform increasealong with the increase of weight-averaged molecular weight. There is a simple linear relationship between zero shearing viscosity and volume fraction is η=Фηa+(1-Ф)ηbin the equilibrium. Ф is volume fraction of short chain.The blends polymer in the nonequilibrium state(add shear field), as the increase of the shear rate, long and short chains are stretched,the mean-square end-to-end distance and the mean-square radius of gyration will increase.The blends polymer in the nonequilibrium state(add shear field), as the increase of the shear rate, scaled the flow component of the average gyration tensor increase, and scaled the gradient component and scaled the vorticity component decrease. The influence of volume fraction on the every component of the average gyration tensor is very small.The blends polymer in the nonequilibrium state(add shear field), along with the increase of the shear rate, the firs normal stress difference and negative second normal stress difference increase. At lower shear rate, along with the increase of the short chain’s volume fractions, the first normal stress difference and negative second normal stress difference decrease.The blends polymer in the nonequilibrium state(add shear field), along with the increase of the shear rate, orientation resistance parameter tends to be consistent. At lower shear rate, along with the increase of the volume fraction of short chain, the orientation resistance parameter increase and along with the increase of the volume fraction of long chain, the orientation resistance parameter decrease.