Material properties of the cross-linked epoxy resin compound predicted by molecular dynamics simulation

Fan, Haichao; Yuen, Matthew Ming Fai

doi:10.1016/j.polymer.2007.02.007

Cited by 270 publications

(169 citation statements)

References 12 publications

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“…This is illustrated in Figure 9, where a higher deviation from the Arrhenius temperature dependence of the characteristic relaxation time can be seen in more crosslinked and thinner films. The monotonic decrease of the β coefficient with decreasing mesh size is in agreement with previously published simulation results, 43 while similar results have also been obtained experimentally in bulk polymer networks. 52 …”

Section: B Segmental Dynamicssupporting

confidence: 92%

“…Values of β that are smaller than unity can be attributed either to the development of heterogeneous dynamics or to a single homogeneous (but non-exponential) relaxation mechanism. 43 The obtained characteristic relaxation times displayed a dependence on film thickness and mesh size that was similar to the dependence of the glass-transition temperature (compare Figures 3 and 6). The τ film q /τ bulk q ratio displayed a similar behavior, whereas (as we have already mentioned) the T film g / T bulk g ratio was not affected by the size of the crosslinked mesh.…”

Section: B Segmental Dynamicssupporting

confidence: 65%

“…43 β decreased linearly with a decreasing mesh size for L mesh > R g , after which a rather steep decrease was observed for mesh-size values smaller than R g , Figure 8.…”

Section: B Segmental Dynamicsmentioning

confidence: 88%

“…The LJ parameters ε and σ had the same values with their non-bonded counterparts. This particular choice of bonded and non-bonded interactions prevents chain crossings 16 and full crystallization 43,17,18 and allows the system to undergo a transition to a supercooled state, allowing thus the study of the glass-transition temperature in a generalized context (i.e., disregarding material-specific properties). Further, bead-spring polymer chains do not become stiffer with decreasing temperature.…”

Section: Simulated Models and Methodsmentioning

confidence: 99%

“…To account for the non-zero plateau values in the decay of S inc (q,t), we extracted the relaxation times of S inc (q,t) by fitting it with a modified form of the KWW (Kohlrausch-WilliamsWatts) stretched exponential function, 43 S inc (q,t) = (1 − a) exp…”

Section: B Segmental Dynamicsmentioning

confidence: 99%

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A coarse-grained molecular dynamics study of segmental structure and mobility in capped crosslinked copolymer films

Davris

Lyulin

2015

The Journal of Chemical Physics

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We present results from molecular-dynamics simulations of a generic bead-spring model of copolymer chains confined between solid walls and report on the glass-transition temperature and segmental dynamics as a function of film thickness and mesh size (the end-to-end distance of the subchains in the crosslinked polymer networks). Apparently, the glass-transition temperature displayed a steep increase for mesh-size values much smaller than the radius of gyration of the bulk chains, otherwise it remained invariant to mesh-size variations. The rise in the glass-transition temperature with decreasing mesh size and film thickness was accompanied by a monotonic slowing-down of segmental dynamics on all studied length scales. This observation is attributed to the correspondingly decreased width of the bulk density layer that was obtained in films whose thickness was larger than the end-to-end distance of the bulk polymer chains. To test this hypothesis, additional simulations were performed in which the crystalline walls were replaced with amorphous or rough walls. In the amorphous case, the high polymer density close to the walls vanished, but the dynamic response of the film was not affected. The rough walls, on the other hand, only slightly decreased the density close to the walls and led to a minor slowing-down in the dynamics at large length-scales.

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Section: B Segmental Dynamicssupporting

confidence: 92%

Section: B Segmental Dynamicssupporting

confidence: 65%

“…43 β decreased linearly with a decreasing mesh size for L mesh > R g , after which a rather steep decrease was observed for mesh-size values smaller than R g , Figure 8.…”

Section: B Segmental Dynamicsmentioning

confidence: 88%