Dynamic and Static Mechanical Properties of Crosslinked Polymer Matrices: Multiscale Simulations and Experiments

Abstract

We studied the static and dynamic mechanical properties of crosslinked polymer matrices using multiscale simulations and experiments. We continued to develop the multiscale methodology for generating atomistic polymer networks, and applied it to the case of phthalonitrile resin. The mechanical properties of the resulting networks were analyzed using atomistic molecular dynamics (MD) and dissipative particle dynamics (DPD). The Young’s and storage moduli increased with conversion, due both to the appearance of a network of covalent bonds, and to freezing of degrees of freedom and lowering of the glass transition temperature during crosslinking. The simulations’ data showed good quantitative agreement with experimental dynamic mechanical analysis measurements at temperatures below the glass transition. The data obtained in MD and DPD simulations at elevated temperatures were conformable. This makes it possible to use the suggested approach for the prediction of mechanical properties of a broad range of polymer matrices, including ones with high structural heterogeneity.

Multiscale Simulations Approach: Crosslinked Polymer Matrices

“…The first stage of our methodology involves the concept of the so-called "mesoscale chemistry" [1,3,6], which is used to study the complex polymerization process of appropriate monomers and to construct and equilibrate polymer networks at the mesoscale level. We introduce all molecular structures in terms of the simplified bead-and-spring model.…”

“…On the third stage, the mechanical properties of constructed CG matrices are analyzed by DPD simulations. A uniaxial deformation of the simulation box along one of the axes is applied keeping the volume of the box constant (NVT ensemble), and stress-strain response curves are measured [6]. The dimensionless units in DPD are rescaled to GPa by the simple linear scaling procedure, the scaling factor depends on CG representation of molecular species.…”

“…The mechanical properties of these samples are investigated by applying uniaxial deformation of small amplitude (either with constant strain rate or cyclic) and measuring its mechanical response. The details on equilibration procedure and the methodology of calculation of T g and mechanical properties are given in works [5,6]. The hybrid computational scheme described above was tested for different polymer matrices.…”

“…During the last decade, we developed a multiscale simulation methodology that makes it possible to predict various physical properties of highly crosslinked polymer materials [2][3][4][5][6]. In this work, we summarize our simulations methodology combining coarse-grained MSC technique with full atomistic modelling.…”

Molecular Insights into Sequence Distributions and Conformation-Dependent Properties of High-Phenyl Polysiloxanes

“…Molecular dynamics (MD) simulation provides a powerful and intuitive method to probe the structure-property relationships of polymer systems, which not only provide a reasonable interpretation of the experimental results, but also predict the properties of the material to some extent [15][16][17][18][19][20][21]. A great deal of effort has been made with MD simulations combining theoretical calculations to investigate the distribution of isomeric conformations, unperturbed dimensions, blend compatibility, and interfacial dynamics [22][23][24][25][26][27].…”