Evaluation of the characteristic equilibration times of bulk polyimides via full-atomic computer simulation

Nazarychev, Victor M.; Larin, Sergey V.; Lukasheva, N. V.; Glova, Artyom D.; Lyulin, Sergey V.

doi:10.1134/s0965545x1308004x

Cited by 27 publications

(70 citation statements)

References 35 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…To maintain the set lengths of the bonds between the atoms, the LINCS algorithm was used. 52,53,[60][61][62][63][64][65] The equilibration procedure included stages of the system compression from the initial low-density configuration (polymer gas), cyclic annealing within the temperature range of 600 to 290 K, equilibration at a high temperature for 1.5 μs, and further production run during 1 μs. Parametrization of the charges in this force field was done using the HF/6-31G* method.…”

Section: Model and Simulation Methodsmentioning

confidence: 99%

“…74 The values of the partial charges for the atoms of carboxyl groups attached to the CNT were taken as standard values for the Gromos53a5 force field 72 which was parameterized for simulating systems in the media with low permittivity. 52,62 Since the presence of EI slows down the diffusion of the polyimide chains in the melt approximately by two orders of magnitude, 52,61,62 the simulation with switched-on electrostatics was performed using the equilibrated configurations of the systems with switched-off electrostatics. 72,75 The same method was used to calculate the partial atomic charges in the considered polyimides.…”

Section: Model and Simulation Methodsmentioning

confidence: 99%

“…52,61,62 Therefore, all orientation characteristics of polyimide chains shown further in this section have been obtained for the Please do not adjust margins Please do not adjust margins systems simulated without electrostatic interactions, for the clarity. Also the values of the orientation characteristics for these systems display rather strong fluctuations 52 due to the mobility reduction of polymer chains observed in the simulation with EI switched-on.…”

Section: Orientation Of Flat Fragmentsmentioning

confidence: 99%

See 2 more Smart Citations

Influence of the carbon nanotube surface modification on the microstructure of thermoplastic binders

et al. 2015

Self Cite

View full text Add to dashboard Cite

The structural properties of polymer nanocomposites based on thermoplastic polyimides filled with the surface-modified carbon nanotubes (CNT) have been studied by means of the fully-atomistic molecular-dynamics simulations. The influence of a distibution of functional carboxyl groups over the CNT surface on the polymer-matrix density distribution, and the orientational ordering of polymer chains have been investigated. It was shown that the polymer shifts far away from the nanoparticle surface with increase of the CNT modification degree. The orientational ordering of PI chains was not observed in the case of nanocomposites filled with modified CNTs where carboxyl groups are distributed uniformly on the surface. However, in case of the edge-modified CNTs the polymer can interact with CNT surface; such edge-modified nanoparticle induces orientational ordering of crystallisable polyimide chains that can be considered as an initial stage of the polymer-matrix crystallization.

show abstract

Section: Model and Simulation Methodsmentioning

confidence: 99%

Section: Model and Simulation Methodsmentioning

confidence: 99%

Section: Orientation Of Flat Fragmentsmentioning

confidence: 99%

See 1 more Smart Citation

Influence of the carbon nanotube surface modification on the microstructure of thermoplastic binders

et al. 2015

Self Cite

View full text Add to dashboard Cite

show abstract

“…Constant temperature (600 K, that is 5K higher than the experimentally-determined value of the R-BAPB melting temperature) and pressure P ¼ 1 atm were maintained using a Berendsen thermostat and barostat, 48,49 with time constants of s T ¼ 0.1 ps and s P ¼ 0.5 ps, respectively. These parameters were used in our previous papers [42][43][44][45][46] and allowed us to reproduce successfully thermophysical properties of bulk PIs. All bond lengths were kept constant with the LINCS algorithm 50 .…”

Section: 47mentioning

confidence: 99%

“…Thus, we can conclude that the cell size is large enough and the effects observed are due to interaction of the polymer with the nanoller surface but not due to steric hindrance between parallel at surfaces. As shown in our recent studies, [42][43][44][45][46] in some cases the atomic partial charges could be taken equal to zero in order to make the long microsecond-scale equilibration possible with the available supercomputer resources. The accounting of the atomic partial charges in computer simulation may, in principle, inuence signicantly the nal results, especially when the compounds contain highly-polarized chemical groups.…”

Section: 47mentioning

confidence: 99%

Influence of the carbon nanofiller surface curvature on the initiation of crystallization in thermoplastic polymers

et al. 2014

Self Cite

View full text Add to dashboard Cite

Experimental results have shown that graphitizated carbon nanofibers initiate crystallization in R-BAPB polyimides twice as fast as single-wall carbon nanotubes (CNT) leading to the hypothesis that nanofiller curvature influences polyimide crystallization. Therefore, atomistic molecular-dynamics simulations have been performed for R-BAPB in the presence of a flat graphene sheet and the results were compared with those obtained in the presence of a small-radius CNT. The polyimide chain segments tend to lie parallel to the nanofiller surface and this tendency is stronger and the segments are closer to the graphene surface than to the CNT one. Moreover, the density of the polyimide in the near-surface layer is higher for composites filled with graphene than with CNT. This confirms the assumption that the nanofiller surface curvature is indeed a factor influencing the polymer patterning structure, and that a smaller curvature (i.e. flat surface) provides an enhanced initiation of polymer ordering. A IntroductionOne of the most promising ways to improve the performance of polymeric materials consists of developing polymer composites.1-3 Signicant changes aer addition of a ller are inuenced by the polymer and ller properties, but also by the interface interactions between both components. The use of nanoscalereinforcing llers leading to a considerable increase in the interaction area between the composite components has driven the interest of researchers in last years.4-11 Allotropic carbon compounds (carbon black, fullerenes, single-and multiwall nanotubes, nanobers and graphene sheets) are among the popular nanollers. 4,7,9,[11][12][13][14][15][16][17] Polymers with a relatively simple or complicated molecular structure have been and are currently used as matrices in nanocomposite materials. 4,[17][18][19] By combining different types of matrices and nanollers, it is possible to obtain composites with a wide range of physical properties. In some cases, a nanoller can initiate the crystallization of the polymer matrix, 18,20-25 signicantly accelerating the formation of crystallites, or even initiating their formation in the polymer under conditions which do not normally favor the crystallization, as in the case of ODPA-P3 polyimide.26 Crystallization of a polymer matrix in a nanocomposite may signicantly impact its mechanical and thermophysical properties, which should be taken into account when developing new composite materials.18,27,28 The advantage of using nanoparticles for initiation of crystallization is that the formation of a large number of nanoscale crystallites improves the strength of the nanocomposite preventing the typical failure on the boundary area between crystalline regions, thus improving the performance of the material. Therefore, the question arises on how the physical properties of carbon nanollers affect the initiation of crystallization in semicrystalline thermoplastic matrices.Yudin et al. 17,[23][24][25]29 investigated the crystallization initiation of the semicrystalline ther...

show abstract

Influence of the electrostatic interactions on thermophysical properties of polyimides: Molecular‐dynamics simulations

Falkovich

Lyulin

Nazarychev

et al. 2014

J Polym Sci B Polym Phys

View full text Add to dashboard Cite

show abstract

Evaluation of the characteristic equilibration times of bulk polyimides via full-atomic computer simulation

Cited by 27 publications

References 35 publications

Influence of the carbon nanotube surface modification on the microstructure of thermoplastic binders

Influence of the carbon nanotube surface modification on the microstructure of thermoplastic binders

Influence of the carbon nanofiller surface curvature on the initiation of crystallization in thermoplastic polymers

Influence of the electrostatic interactions on thermophysical properties of polyimides: Molecular‐dynamics simulations

Contact Info

Product

Resources

About