Computer Modeling of Polymer Crystallization

Rutledge, Gregory C.

doi:10.1002/9781118541838.ch6

Cited by 10 publications

(7 citation statements)

References 133 publications

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“…Unlike molecular models, which are capable of presenting many details of nucleation, macroscopic models are disadvantaged by the absence of molecular details, and consequently, the macroscale continuum model requires initial assumptions as input to build the quantitative relationship between flow strength and resultant nucleation features like density and orientation. A detailed comparison between different model methods and recent progress of coarse-grain kinetic Monte Carlo and molecular dynamics models can be found in the recent reviews of Graham and Rutledge …”

Section: Theories and Models Of Flow-induced Nucleationmentioning

confidence: 99%

“…Unlike molecular models, which are capable of presenting many details of nucleation, macroscopic models are disadvantaged by the absence of molecular details, and consequently, the macroscale continuum model requires initial assumptions as input to build the quantitative relationship between flow strength and resultant nucleation features like density and Carlo and molecular dynamics models can be found in the recent reviews of Graham 13 and Rutledge. 276 In this section, macroscale continuum models will be mainly discussed. Besides the potential application to practical processes, the macroscopic model can directly use experimental results to test and to improve mechanism understanding, in the form of assumptions.…”

Section: Macroscale Continuum Modelingmentioning

confidence: 99%

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Multiscale and Multistep Ordering of Flow-Induced Nucleation of Polymers

et al. 2018

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Flow-induced crystallization (FIC) is a typical nonequilibrium phase transition and a core industry subject for the largest group of commercially useful polymeric materials: semicrystalline polymers. A fundamental understanding of FIC can benefit the research of nonequilibrium ordering in matter systems and help to tailor the ultimate properties of polymeric materials. Concerning the crystallization process, flow can accelerate the kinetics by orders of magnitude and induce the formation of oriented crystallites like shish-kebab, which are associated with the major influences of flow on nucleation, that is, raised nucleation density and oriented nuclei. The topic of FIC has been studied for more than half a century. Recently, there have been many developments in experimental approaches, such as synchrotron radiation X-ray scattering, ultrafast X-ray detectors with a time resolution down to the order of milliseconds, and novel laboratory devices to mimic the severe flow field close to real processing conditions. By a combination of these advanced methods, the evolution process of FIC can be revealed more precisely (with higher time resolution and on more length scales) and quantitatively. The new findings are challenging the classical interpretations and theories that were mostly derived from quiescent or mild-flow conditions, and they are triggering the reconsideration of FIC foundations. This review mainly summarizes experimental results, advances in physical understanding, and discussions on the multiscale and multistep nature of oriented nuclei induced by strong flow. The multiscale structures include segmental conformation, packing of conformational ordering, deformation on the whole-chain scale, and macroscopic aggregation of crystallites. The multistep process involves conformation transition, isotropic-nematic transition, density fluctuation (or phase separation), formation of precursors, and shish-kebab crystallites, which are possible ordering processes during nucleation. Furthermore, some theoretical progress and modeling efforts are also included.

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Section: Theories and Models Of Flow-induced Nucleationmentioning

confidence: 99%

“…Unlike molecular models, which are capable of presenting many details of nucleation, macroscopic models are disadvantaged by the absence of molecular details, and consequently, the macroscale continuum model requires initial assumptions as input to build the quantitative relationship between flow strength and resultant nucleation features like density and Carlo and molecular dynamics models can be found in the recent reviews of Graham 13 and Rutledge. 276 In this section, macroscale continuum models will be mainly discussed. Besides the potential application to practical processes, the macroscopic model can directly use experimental results to test and to improve mechanism understanding, in the form of assumptions.…”

Section: Macroscale Continuum Modelingmentioning

confidence: 99%

Multiscale and Multistep Ordering of Flow-Induced Nucleation of Polymers

et al. 2018

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“…There can be many thousands of atoms and this huge system of coupled differential equations is solved numerically to provide a detailed computer model of molecular motion [50][51][52]. A review of simulation techniques for polymer crystallisation was recently published by Rutledge [53]. The huge spatial and temporal resolution of MD means it can resolve individual nucleation events (for example see figure 1(a)).…”

Section: Molecular Dynamics Simulationsmentioning

confidence: 99%

“…Computational costs significantly constrain what can be achieved with MD [51,52]. Nucleation in polymers is at the edge of what can currently be achieved and this necessitates compromises in terms of box size, chain length and temperature [53,60,61]. The simulation cost per timestep is approximately ∝ L 3 where L is the box length.…”

Section: Computational Limitationsmentioning

confidence: 99%

Understanding flow-induced crystallization in polymers: A perspective on the role of molecular simulations

Graham

2019

Journal of Rheology

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Flow induced crystallisation in polymers is an important problem in both fundamental polymer science and industrial polymer processing. The key process of flow-induced nucleation occurs on a very rapid timescale and on a highly localised lengthscale and so is extremely difficult to observe directly in experiments. However, recent advances in molecular dynamics simulations mean that flowinduced nucleation can be simulated at an achievable computational cost. Such studies offer unrivalled time and lengthscale resolution of the nucleation process. Nevertheless, the computational cost of molecular dynamics places considerable constraints on the range of molecular weights, temperature and polydispersity that can be studied. In this review I will discuss recent progress, describe how future work might resolve or work around the constraints of molecular simulation and examine how multiscale modelling could translate molecular insight into improved polymer processing.

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“…The influence of the temperature gradient [29] and the confined volume [31][32][33][43][44][45][46] on the crystallization have also been further discussed. The primary and secondary nucleation of polymer crystals have been studied at the atomistic scale by molecular dynamics or Monte-Carlo methods [47][48][49][50][51][52][53][54][55][56][57][58][59]. Kinetic models have been developed for polymer to model thermal and athermal nucleation [60][61][62][63].…”

Section: Introductionmentioning

confidence: 99%

Numerical study of the relationship between the spherulitic microstructure and isothermal crystallization kinetics. Part I. 2-D analyses

Detrez

Roland

2019

Polymer

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In this paper, we proposed a numerical model to study the kinetic properties and the spherulite microstructure of a semi-crystalline polymer under isothermal crystallization, which further exhibits the potential in generating the 2D spherulitic structure according to the observations obtained by experimental techniques. Two characteristic parameters are introduced, namely, characteristic length L c and characteristic time t c , which are dependent on the growth rate, G and the nucleation rate, I. In addition, two non-dimensional parameters are introduced to model the nucleation saturation: L L / d c and t t / c , which is related to the thickness of nucleation exclusion zone L d , and the effective nucleation time t , respectively. In 2D modeling, the kinetics are confirmed by Avrami fitting, and the effects of the four characteristic parameters on the Avrami parameter n and the crystallization half-time t 0.5 are presented. The regularity of how the spherulite density or the mean radius of spherulites R change along with these parameters are also given, respectively. It shows that L c is the prominent parameter for the size of the spherulite, and t c controls t 0.5 as long as there is no nucleation saturation (= L 0 d and t). Besides, the existence of the nucleation saturation increases the mean radius of spherulites, but decreases n from 3 to 2 in 2-D modeling. Finally, a relationship between crystallization kinetics and microstructures is provided, giving a new perspective to estimate the nucleation rate.

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Computer Modeling of Polymer Crystallization

Cited by 10 publications

References 133 publications

Multiscale and Multistep Ordering of Flow-Induced Nucleation of Polymers

Multiscale and Multistep Ordering of Flow-Induced Nucleation of Polymers

Understanding flow-induced crystallization in polymers: A perspective on the role of molecular simulations

Numerical study of the relationship between the spherulitic microstructure and isothermal crystallization kinetics. Part I. 2-D analyses

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