Case Studies

Cross-linked Structure of Thermosetting Resin

It may be possible to use a simplified chemical reaction model to create a complex three dimensional network structure when using molecular dynamics to study cross linked structure of thermoset plastics. However, the molecular weight required for such a reaction process would be so large that it would require a long calculation time to relax the entire system structure.

It is therefore recommended to use coarse-grained molecular dynamics to create the cross linked structure from the reaction process, and then apply reverse mapping to the full atomistic model after thoroughly relaxing the system.[1]

In order to create the coarse-grained model for the reverse mapping, it is necessary to generate a potential parameter value reflecting the molecular chemical properties. To solve this problem, we used the J-OCTA COGNAC modeler to obtain the coarse-grained potential of an epoxy monomer before and after a reaction along with a hardening agent. We then performed a reaction calculation using coarse-grained molecular dynamics to create a cross linked structure of epoxy resin (Figure 1).

As shown in Figure 2, the density of a mixed system with the pre-reaction monomer plus the hardening agent was 0.91 [g/cm3]. After the reaction, the density increased to 1.28 [g/cm3].

We are currently working on easier way to apply reverse mapping to the full atomistic model.

Figure 1 Epoxy Resin Cross Link Using the Coarse-Grained Model
(Left) Image of single molecule during reaction, (Right) Reaction has progressed creating a state where the entire monomer has become a single molecule)

Figure 2 Increase in Density Due to Cross Linking

[1] P. V. Komarov, C.Yu-Tsung, C. Shih-Ming, P. G. Khalatur and P. Reineker, Macromolecules, 40, 8104, (2007)

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