Detailed investigations of graphene-cis-1,4-polyisoprene (PI) interfacial traction-separation (τ-δ) behavior and its causative phenomena in the molecular scale are addressed in this work, using Molecular Dynamics (MD) simulations. Configurations of dense amorphous cis-1,4-PI network have been generated and validated. Effects of temperature, separation rate and compressive load on τ-δ behavior are studied. The molecular level physics during interface separation in opening mode is explained using void dynamics and chain straightening. It is found that the evolution of voids and τ-δ behavior are strongly correlated at quasistatic separation rate. Interestingly, a viscous behavior is seen to develop at the interface as the separation rate increases. The magnitude of traction in the opening mode is higher than that in the sliding mode by nearly two orders of magnitude. It is also seen that the amount of polymer bound to graphene following complete separation in opening mode was independent of temperature, while it decreased with increase in separation rate. © 2017 Elsevier Ltd

Narasimhan Swaminathan

Department of Mechanical Engineering

Jeeno Jose

Graphene

Mechanical properties

Models

molecular dynamics

Nanocomposites

Polymer matrix composites

Temperature

CIS-1 ,4-POLYISOPRENE

Effects of temperature

INTERFACE SEPARATION

INTERFACIAL STRENGTH

INTERFACIAL TRACTION

Molecular dynamics simulations

POLYMER MATRIX COMPOSITES (PMCS)

POROSITY/VOIDS

Separation

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Polymer

Comprehensive molecular simulations are conducted to show that polymer crosslinks preserve the strength of solid-polymer (melt) interfaces when they are subjected to repeated mechanical loading. The spatial variation of the diffusion coefficient and local stresses is also investigated along the polymer thickness, during deformation. After each loading cycle, a reduction in entanglement strength is observed at the fracture site. The work of adhesion also decreases over consecutive loading cycles, when fracture is induced at the same site. Reduction in both, the work of adhesion and the entanglement strength, decreases as the crosslink density increases. Diffusion coefficient and stresses vary significantly and in a complex manner along the film thickness during the entire deformation process. These variations were due to peculiar configurations occurring at each instance of separation, which are analyzed and explained in this work. The variation of diffusion coefficient during deformation suggests that other dynamic properties, such as viscosity, also vary spatially during polymer deformation. © 2019 the Owner Societies.

Physical Chemistry Chemical Physics

Response of adhesive polymer interfaces to repeated mechanical loading and the spatial variation of diffusion coefficient and stresses in a deforming polymer film

A cross-over in the interfacial strength, with increase in the separation rate, is observed between graphite-cis-1,4-polyisoprene and amorphous silica-cis-1,4-polyisoprene interfaces. Molecular dynamics simulations are used to compare the traction-separation characteristics of the two interfaces in the opening mode of separation at various separation rates and temperatures above the glass transition temperature of cis-1,4-polyisoprene. It was observed that various parameters governing the interface strength, such as strength modulus (ratio of peak traction to the separation at peak traction), peak traction, and the work of adhesion are higher for the silica substrated interface at very low separation rates. However, at higher rates, the graphite substrated interface showed higher values for the strength parameters. The reasons for this interface strength cross-over are explained using the potential energy, mobility, entanglement strength, tensile stiffness, and densities of the polymer over both substrates and the interface cohesive binding energy. Based on these observations, it is concluded that silica filled rubber nanocomposites are suitable for normal automobile tire applications; however, graphite fillers may be more suitable for resisting very large impact loads. © 2018 Author(s).

Fulltext

Journal of Applied Physics

Interfacial strength cross-over across silica- and graphite- cis -1,4-polyisoprene interfaces

Computational Materials Science

Molecular dynamics simulation on interfacial mechanical properties of polymer nanocomposites with wrinkled graphene

Composites Part B: Engineering

Load transfer of graphene/carbon nanotube/polyethylene hybrid nanocomposite by molecular dynamics simulation

The Journal of Chemical Physics

Multiscale modeling of polyisoprene on graphite

Computational Mechanics

Interface characteristics of carbon nanotube reinforced polymer composites using an advanced pull-out model

Journal of The Electrochemical Society

Molecular Dynamics Simulations of the Traction-Separation Response at the Interface between PVDF Binder and Graphite in the Electrode of Li-Ion Batteries

Insights into traction-separation phenomena of graphene-cis-1,4-polyisoprene interface using molecular dynamics

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Publisher	Data powered by TypesetElsevier Ltd
ISSN	00323861
Open Access	No