Molecular simulation of the intercrystalline phase of chain molecules

Balijepalli, Sudhakar; Rutledge, Gregory C.

doi:10.1063/1.477302

Cited by 72 publications

(71 citation statements)

References 35 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We used the IMC methodology of Rutledge and co-workers [9][10][11] as implemented in the EMC (Enhanced Monte Carlo) 14,15 version 9.3.6 software with a united-atom (UA) force field 10,16 to generate 100 starting configurations of semicrystalline PE. The typical simulation set-up is illustrated in Figure 1 (a).…”

Section: Interphase Monte Carlo Equilibrationmentioning

confidence: 99%

See 1 more Smart Citation

Mechanical and Structural Characterization of Semicrystalline Polyethylene under Tensile Deformation by Molecular Dynamics Simulations

2015

Self Cite

View full text Add to dashboard Cite

ABSTRACT. We have studied tensile deformations of semicrystalline polyethylene (PE) with molecular dynamics simulations at two different strain rates and temperatures. Compared to earlier studies, the modeled systems were approximately five times larger, which allowed significantly larger strains up to about 120% to be examined. Two different modes of structural transformation of semicrystalline PE were observed at the higher temperature of 350 K, depending on the strain rate. At the faster strain rate of 5×10 7 s -1 , cavitation in the non-crystalline region dominated, with little change in the crystalline region, resulting in monotonically declining stress with increasing strain after the yield point. However, in a small number of cases, 2 significant deviations from the average stress-strain profile were observed that correlated with topological constraints, such as bridges and bridging entanglements connecting crystalline regions separated by the non-crystalline region, and destabilization of the crystalline region. At the slower strain rate of 5×10 6 s -1 , we observed repeated melting/recrystallization events and significant oscillations in stress associated with variations of density in crystalline and noncrystalline regions and the displacement of polymer chains from crystalline to non-crystalline regions. When averaged over an ensemble of starting configurations for semicrystalline PE, the oscillations were found to be less coherent from microstate to microstate and offset one another.The post-yield stress became notably smoother, and began to resemble the plastic flow observed macroscopically, followed by stress hardening at the later stage of deformation. At the lower temperature of 250 K, cavity formation was the only mechanism observed, for both strain rates.The interplay between the thermodynamic stability of the crystalline region and the topological constraints imposed by bridges and entanglements in the non-crystalline region is crucial to understanding structural transformations of semicrystalline PE during tensile deformations.

show abstract

Section: Interphase Monte Carlo Equilibrationmentioning

confidence: 99%

“…Monte Carlo (IMC) method to prepare models of semicrystalline PE suitable for MD simulations 9,10 and conducted extensive simulation studies investigating the mechanical response of semicrystalline PE. 11 Recently, Kim et al 12 studied deformations of semicrystalline PE using MD simulations under constant lateral stress conditions.…”

Section: Introductionmentioning

confidence: 99%

Mechanical and Structural Characterization of Semicrystalline Polyethylene under Tensile Deformation by Molecular Dynamics Simulations

2015

Self Cite

View full text Add to dashboard Cite

show abstract

“…[22][23][24] The method has been applied to linear HDPE 25,26 and to isotactic polypropylene, with good results. 27 More recently, representative structures generated by this method have been used as the starting point for large strain deformations of HDPE using nonequilibrium molecular dynamics.…”

mentioning

confidence: 99%

Effect of Short Chain Branching on the Interlamellar Structure of Semicrystalline Polyethylene

2017

Self Cite

View full text Add to dashboard Cite

We use molecular simulations with a united atom force field to examine the effect of short chain branching (SCB) on the noncrystalline, interlamellar structure typical of linear low density polyethylene (LLDPE). The model is predicated on a metastable thermodynamic equilibrium within the interlamellar space of the crystal stack and accounts explicitly for the various chain topologies (loops, tails, and bridges) therein. We examine three branched systems containing methyl, ethyl, and butyl side branches, and compare our results to high density polyethylene (HDPE), without branches. We also compare results for two united atom force fields, PYS and TraPPE-UA, within the context of these simulations. In contrast to conventional wisdom, our simulations indicate that the thicknesses of the interfacial regions in systems with SCB are smaller than those observed for a linear polyethylene without branches, and that branches are uniformly distributed throughout the interlamellar region. We find a prevalence of gauche states along the backbone due to the presence of branches, and an abrupt decrease in the orientational order in the region immediately adjacent to the crystallite.3 Introduction:

show abstract

“…the region sandwiched between two crystalline lamellae 10 segments apart (y-axis on the right): (a) variation with We * at E η = 0.0, (b) variation with E η at We * = 0.108. ues shown in the figures) to a lower, more-or-less constant, "amorphous" value. This is typical for order parameter changes seen in equilibrium lattice [17,18,22] and off-lattice simulations [30]. Although we are not aware of a direct measurement of the thickness of the interfacial layer, there is indirect evidence as for example obtained from Raman spectroscopy on polyethylene samples [31] indicating and interfacial thickness of 8-12 Å, which corresponds to two to three chain segments, given the estimate of 3.5 methylene groups or Kuhn segment length of 4.5 Å for polyethylene [18].…”

Section: Application To 3d Lattice Simulations Interacting With a Bulmentioning

confidence: 95%

Flow-induced nonequilibrium thermodynamics of lamellar semicrystalline polymers

Mukherjee¹,

Wilson²,

Beris³

2004

Journal of Non-Newtonian Fluid Mechanics

View full text Add to dashboard Cite

Molecular simulation of the intercrystalline phase of chain molecules

Abstract: Monte Carlo simulations of the γ-β, α-γ, and α-β phase transitions of nitrogen

Cited by 72 publications

References 35 publications

Mechanical and Structural Characterization of Semicrystalline Polyethylene under Tensile Deformation by Molecular Dynamics Simulations

Mechanical and Structural Characterization of Semicrystalline Polyethylene under Tensile Deformation by Molecular Dynamics Simulations

Effect of Short Chain Branching on the Interlamellar Structure of Semicrystalline Polyethylene

Flow-induced nonequilibrium thermodynamics of lamellar semicrystalline polymers

Contact Info

Product

Resources

About