Molecular Dynamics Simulation Of Energy Dissipation Of Polymer Blends Under Shearing Action

It is occurred dynamic stress relaxation when the polymer is subjected to periodic alternating stress.Due to the friction between the polymer monomers,the energy dissipation is produced by the relative motion of the polymer segments during the dynamics stress relaxation process.Reducing the energy consumption can improve viscoelasticity of polymer materials in a certain time scale.Mixing two polymers promotes the release of molecular chain configuration,reduces energy consumption in the process of polymer dynamic stress relaxation and thus improves the viscoelasticity of polymer.Therefore,this paper simulated and calculated the modulus parameters of the polymer blend with oligomer under shearing using the molecular dynamics simulation method,to analyze the changes in the molecular chain configuration and reveal the mechanism of the viscoelastic properties of the polymer blend.Based on the Green-Kubo function,a novel molecular dynamics simulation scheme was developed to quantitatively calculate the dynamical relaxation of polymer melt or polymer blends at equilibrium.The blending rule for the dynamical configuration relaxation of polymer and oligomer chains in the blends was proposed in order to clarify the role of oligomers on the viscoelastic property of polymers.The results of the modulus parameters in a certain time scale show that the relaxation time of the oligomers with low chain stiffness is smaller than the relaxation time of the polymer with large molecular chain stiffness.Adding oligomers with low stiffness into polymer melt can modify significantly the viscoelastic properties of polymer-oligomer composites.In addition,reducing the molecular chain length and molecular chain stiffness or increasing the volume fraction of oligomer can reduce the loss modulus and the energy dissipation of the polymer blend,thereby improve the viscoelasticity of polymer blend.In conclusion,the addition of oligomer can promote the release(unentanglement)process of the polymer chain configuration of polymer blend,reduce the energy dissipation and improve the viscoelasticity of polymer blend.