Research On The Movement Of Polymer Mesoscopic Conformation In Injection Molding By Dissipative Particle Dynamics Simulation

Polymer melt flow molding process is one of the important processes of polymerinjection molding which directly affects the mechanical properties, appearance andother important features of molding products. There are lots of researchers in thisfield who come from whole world have been studying the movement process by theaspects of theory, experiment and computer simulation. So far, the polymer injectionmolding computer simulation is mainly focused on the macro simulation which isbased on continuum theory, but the quality of products always depends on themicroscopic and mesoscopic structure of molding materials, so the movement andevolution of the polymer chains and the conformation of mesoscopic structure in theprocess of flow is very important. This paper try to use the dissipative particledynamics method(DPD) method to study the structural change regularity in polymerfluid flow from mesoscopic scale simulation.Analyzing the theoretical basis of DPD method and simulation implementationmethod, including the establishment of the model, the selection of potential functionform, the measure to determine initial conditions and boundary conditions, theselection of simulation parameters, dimensionless processing, simulation calculationprocess and so on.The nonequilibrium Poiseuille flow is simulated by using DPD method.Poiseuille flow is a kind of viscous laminar flow, and the flow characteristics ofPoiseuille flow are analyzed by the simulation data, such as fluid velocity distribution,density distribution, pressure distribution, etc.. Then the DPD simulation results arecompared with the classical theory of fluid mechanics calculation value andconfirming the correctness of the simulation algorithm and the parameter file settings.Besides, this simulation plays an important role in polymer melt flow simulation.Establishing polymer melt coarse particle model and coarsening chain model,and determining the motion equation of coarse particles and the conformationevolution equation of coarsening chain. The flow of polymer melt filling process is simulated by DPDmacs. Through processing the simulation data, the flow regularityof the melt filling mold flow is obtained: the regional fluid particle velocitydistribution; the relationship between the driving force and flow velocity; coarseningchain in the migration behavior of pressure flow field; coarsening chain conformationchange rule. Then the results are compared with other literature in the relevantconclusions, and the causes of flow regularities are analyzed.