Polyethylene {201} crystal surface: interface stresses and thermodynamics

Hütter, Markus; Veld, Pieter J. in ’t

doi:10.1016/j.polymer.2005.05.160

Cited by 32 publications

(63 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…In the current work, results for linear PE using both PYS and TRaPPE-UA are reported, for purposes of comparison to our previous work as well as to that of Ramos et al 43 The interlamellar domain was modeled using a similar strategy as described in our previous publications. 25 We started with a crystal phase, modeled using 48 linear polyethylene segments, each having 112 UA sites in fully extended conformation, placed on a crystal lattice of 4 x 6 x 56 9 unit cells so that the crystal exhibits pseudo-hexagonal symmetry. The crystal lattice was oriented such that the {201} facet of the crystal was normal to the z direction of the simulation cell.…”

Section: Methodmentioning

confidence: 99%

See 1 more Smart Citation

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

Section: Methodmentioning

confidence: 99%

“…[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

show abstract

“…Adapting the Gibbs dividing surface technique employed by Hutter et al, 45 the gradual transition in X(z) from crystal to amorphous melt was approximated by a step function at z = D. The Gibbs dividing surface was chosen such that the integral of the difference between the true crystallinity profile and the step function approximation vanishes when the step function is located at z=D:…”

Section: Z X Ymentioning

confidence: 99%

Molecular Dynamics Simulation of Surface Nucleation during Growth of an Alkane Crystal

Bourque

Locker

2016

Macromolecules

Self Cite

View full text Add to dashboard Cite

Crystal growth from the melt of n-pentacontane (C50) was studied by molecular dynamics simulation.Quenching below the melting temperature gives rise to propagation of the crystal growth front into the C50 melt from a crystalline polyethylene surface. By tracking the location of the crystal-melt interface, crystal growth rates between 0.02-0.05 m/s were observed, for quench depths of 10-70 K below the melting point. These growth rates compare favorably with those from a previous study by Waheed et al (2005). Next, surface nucleation was identified with the formation of two-dimensional clusters of crystalline sites within layers parallel to the propagating growth front. Critical nucleus sizes, waiting times and rates for surface nucleation were estimated by a mean first passage time analysis. A surface nucleation rate of ~0.05 nm -2 ns -1 was observed, and it was nearly temperature-independent. Post-critical "spreading" of the surface nuclei to form a completely crystallized layer slowed with deeper supercooling.

show abstract

“…In similar studies concerning filler/polymer composites where some intermediate or interphase layer around fillers is incorporated into the modeling, the properties of this third phase have been treated alike . At the molecular simulation level, Hütter et al employed the concept of a sharp Gibbs dividing surface to define a set of interfacial properties corresponding to the interphase; they obtained interfacial stresses and interfacial internal energies, but were not able to extract a value for the interfacial tension owing to significant contributions from its dependence on interfacial strain. Although several studies have been devoted to the mechanical characterization of the central amorphous phase, to date no rigorous attention has been paid to the systematic, methodological elastic characterization of the interphase as is presented in this study.…”

Section: Introductionmentioning

confidence: 99%

Micromechanical characterization of the interphase layer in semi‐crystalline polyethylene

Ghazavizadeh

Rutledge

Atai

et al. 2013

J Polym Sci B Polym Phys

Self Cite

View full text Add to dashboard Cite

Semi-crystalline polyethylene is composed of three domains: crystalline lamellae, the compliant amorphous phase, and the so-called "interphase" layer separating them. Among these three constituents, little is known about the mechanical properties of the interphase layer. This lack of knowledge is chiefly due to its mechanical instability as well as its nanometric thickness impeding any property measuring experiments. In this study, the Monte Carlo molecular simulation results for the interlamellar domain (i.e. amorphous+ interphases), reported in (in 't Veld et al. 2006) are employed. The amorphous elastic properties are adopted from the literature and then two distinct micromechanical homogenization approaches are utilized to dissociate the interphase stiffness from that of the interlamellar region. The results of the two approaches match perfectly, which validates the implemented dissociation methodology. Moreover, a hybrid numerical technique is proposed for one of the approaches when the recursive method poses numerical divergence problems. Interestingly, it is found that the dissociated interphase stiffness lacks the common feature of positive definiteness, which is attributed to its nature as a transitional domain between two coexisting phases. The sensitivity analyses carried out reveal that this property is insensitive to the non-orthotropic components of the interlamellar stiffness as well as the uncertainties existing in the interlamellar and amorphous stiffnesses. Finally, using the dissociated interphase stiffness, its effective Young's modulus is calculated. The evaluated Young's modulus compares well with the effective interlamellar Young's modulus for highly crystalline polyethylene, reported in an experimental study. This satisfactory agreement along with the identical results produced by the two micromechanical approaches confirms the validity of the new information about the interphase elastic properties in addition to making the proposed dissociation methodology quite reliable to be applied to similar problems.

show abstract

Polyethylene {201} crystal surface: interface stresses and thermodynamics

Cited by 32 publications

References 19 publications

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

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

Molecular Dynamics Simulation of Surface Nucleation during Growth of an Alkane Crystal

Micromechanical characterization of the interphase layer in semi‐crystalline polyethylene

Contact Info

Product

Resources

About