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Author
Title Multiscale modeling and simulation of crosslinked polymers
URL
Publication Date
Date Accessioned
Degree PhD
Discipline/Department Aerospace Engineering
Degree Level doctoral
University/Publisher University of Michigan
Abstract The combination of physics-based modeling and coarse-grained molecular dynamics simulations is a powerful tool to understand how molecular properties and processes affect the mechanical properties of crosslinked polymers. In this dissertation polymer network structure and chain behavior are analyzed in order to connect these microscopic characteristics and deformation mechanisms to the macroscopic material properties of nonlinear elasticity and the shape memory effect. A new physics-based model of rubber elasticity is constructed which can capture the strain softening, strain hardening, and deformation-state dependent response of rubber materials undergoing finite deformations. This model is unique in its ability to capture large-stretch mechanical behavior with only three parameters that are each connected to the polymer chemistry and the important characteristics of the macroscopic stress-stretch response. Coarse-grained molecular dynamics simulations are used to analyze chain behavior during deformation. This work is the first to track primitive path length changes in a deformed polymer network. The primitive path of a polymer chain is defined as the shortest path from one end of the chain to the other which preserves the topological state of the network (i.e. retaining all inter-chain entanglements). Through a comparison of simulated networks with different structures, it is demonstrated that changes in average primitive path length are always nonaffine, even for long, entangled chain networks. A visualization of time-dependent chain conformations and the restraining “tube” in deformed networks demonstrates the viability of using primitive path analysis to quantify micro-macro deformation in crosslinked polymers. The shape memory effect in crosslinked polymers is the ability of a material to hold a deformed shape, then subsequently recover the initial shape when heated above the glass transition temperature. This work is the first to construct a suitable coarse-grained model for examining shape memory polymer behavior via molecular dynamics simulation. It is found that simply including monomer-monomer attraction in the simulation model is sufficient to reproduce the nonlinear thermomechanical trends seen experimentally. Because of the simplicity of the simulation model, these results give important information as to how to model and understand these systems.
Subjects/Keywords Multiscale Modeling; Polymer; Molecular Dynamics; Materials Science and Engineering; Mechanical Engineering; Engineering
Contributors Goulbourne, Nakhiah C. (committee member); Kieffer, John (committee member); Sundararaghavan, Veera (committee member); Arruda, Ellen M. (committee member); Waas, Anthony M. (committee member)
Language en
Rights Unrestricted
Country of Publication us
Record ID handle:2027.42/107284
Repository umich
Date Retrieved
Date Indexed 2019-06-03
Grantor University of Michigan, Horace H. Rackham School of Graduate Studies
Issued Date 2014-01-01 00:00:00
Note [thesisdegreename] PhD; [thesisdegreediscipline] Aerospace Engineering; [thesisdegreegrantor] University of Michigan, Horace H. Rackham School of Graduate Studies; [bitstreamurl] http://deepblue.lib.umich.edu/bitstream/2027.42/107284/1/jddavid_1.pdf;

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…236 xx 222 ABSTRACT The combination of physics-based modeling and coarse-grained molecular dynamics simulations is a powerful tool to understand how molecular properties and processes affect the mechanical properties of crosslinked polymers. In…

…capture large-stretch mechanical behavior with only three parameters that are each connected to the polymer chemistry and the important characteristics of the macroscopic stressstretch response. Coarse-grained molecular dynamics simulations are used to…

…suitable coarse-grained model for examining shape memory polymer behavior via molecular dynamics simulation. It is found that simply including monomer-monomer attraction in the simulation model is sufficient to reproduce the nonlinear thermomechanical…

…theoretical physics to study polymer 1 materials. This led to the successful ‘tube’ theory of polymer dynamics [33]. Currently, polymer physics is undergoing a third ‘revolution’ through the use of molecular simulations made possible by recent…

…connection is advantageous for many reasons, including material development and engineering design. The combination of physics-based modeling and coarse-grained molecular dynamics simulations is a powerful tool to understand how molecular properties and…

…that a useful model cannot be constructed without a basis in the underlying physics. In this dissertation I will demonstrate that coarse-grained molecular dynamics simulations are an essential tool in forming such a model. 2 Constitutive equations σ1…

…properties; making 10 this connection will facilitate material selection in the design process and lead to new material developments. In this dissertation, physics-based modeling and coarse-grained molecular dynamics simulations will be used to analyze…

…like materials with only 3 parameters. Other models which cover the same scope of material behavior contain 4 or 5 parameters. This model is used to analyze simulation results in the subsequent chapters. 11 5. Molecular dynamics simulations of…

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