A Frozen Tube Model of Melting Point Depression of Solvents in Entangled Polymer Systems

Hoei, Yoshio; Ikeda, Yoshiyuki; Sasaki, Misao

doi:10.1021/jp020772c

Cited by 6 publications

(5 citation statements)

References 28 publications

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“…To verify our postulation, we first consider an ultimate case in cross-linked gels . The crystallization ability of crystallizable solvent in a gel is usually frustrated . Also, the crystallization is dramatically depressed if the crystalline polymer is cross-linked .…”

Section: Resultsmentioning

confidence: 96%

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Frustrated Crystallization in the Coupled Viscoelastic Phase Separation

2012

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The interplay between crystallization and phase separation has been intensively studied recently. In this study, we extended the research into a dynamically asymmetric blend composed of amorphous poly(methyl methacrylate) (PMMA) and crystalline poly(ethylene oxide) (PEO). The large dynamic asymmetry induces network stress in concentration growth. We find that crystallization is seriously frustrated when it couples with a simultaneous viscoelastic phase separation. In a single quench experiment, normal spherulites grew in a limited temperature range when crystallization was faster, while crystallization was frustrated at deep quenches when phase separation was faster. In a double quench experiment, crystallization was more difficult to occur after the prior phase separation at a higher temperature. The calorimetric results indicated that both melting temperatures and enthalpies of crystallization decreased in the coupled viscoelastic phase separation. We propose that it is the network stress in the concentration growth that leads to the frustration of crystallization.

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Section: Resultsmentioning

confidence: 96%

“…33 The crystallization ability of crystallizable solvent in a gel is usually frustrated. 54 Also, the crystallization is dramatically depressed if the crystalline polymer is cross-linked. 55 If the cross-linking density is very high in the network, the crystallization may be totally prohibited.…”

Section: Macromoleculesmentioning

confidence: 99%

Frustrated Crystallization in the Coupled Viscoelastic Phase Separation

2012

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“…Therefore, the GibbsÀThomson equation needs at least one term to include the depression of the melting point due to mixing thermodynamics. One approach 26 shows the resulting potential difficulties and implies that the observed melting point depression could be interpreted to be greater than what one expects without necessarily invoking size effects.…”

Section: Methodsmentioning

confidence: 99%

Characterizing Mesh Size Distributions (MSDs) in Thermosetting Materials Using a High-Pressure System

et al. 2011

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The thermoporosimetry method was adapted to determine the mesh size distribution of an acrylate thermoset clearcoat. This goal was achieved by increasing the solvent rate transfer by increasing the pressure and temperature. A comparison of the results obtained using this approach with those obtained by DMA (dynamic mechanical analysis) underlined the accuracy of thermoporosimetry in characterizing the macromolecular architecture of thermosets. The thermoporosimetry method was also used to analyze the effects of photoaging on cross-linking, which result from the photodegradation of the acrylate thermoset. It was found that the formation of a three-dimensional network followed by densification generates a modification of the average mesh size that leads to a dramatic decrease of the meshes of the polymer.

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“…mckenna@ttu.edu) developed by some researchers to deduce the size and size distribution of nanoscale heterogeneities in polymer networks by using melting (or freezing) point depression of the solvents. [9][10][11][12][13][14][15] In this method, the Gibbs-Thomson (GT) equation 16 is used in conjunction with the Flory-Huggins (FH) model 17,18 to obtain the size and size distribution of solvent crystals, which are comparable with the nanoscale mesh size and distribution in polymer networks. Nevertheless, previous results on the melting (or freezing) behavior of swelling agents confined in polymer networks are complicated and contradictory, and the mechanisms of melting (or freezing) point depression are not well understood.…”

Section: Introductionmentioning

confidence: 99%

Anomalous melting behavior of cyclohexane and cyclooctane in poly(dimethyl siloxane) precursors and model networks

McKenna

2008

J Polym Sci B Polym Phys

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Building on previous observations of anomalous melting behavior of solvents in polyisoprene, we have expanded our insight into the melting behavior of organic solvents in polymers and polymer networks through a calorimetric investigation of cylcohexane and cyclooctane in poly(dimethyl siloxane) (PDMS) precursors and model networks. The results are contrary to general expectations. Besides deviations between the predictions of the Flory-Huggins model and observed melting point depression of the small molecule organics, it is found that the melting point depression of cyclohexane in model networks is lower than that in the uncrosslinked precursors and unaffected by the molecular weight between crosslinks, which is not consistent with the general observation that higher crosslinking density leads to greater melting point depression. We interpret the observed phenomenon in terms of phase separation. In the case of cyclooctane, it exhibits a double melting peak in the model networks with high molecular weight between crosslinks. Furthermore, the heats of fusion of both cyclohexane and cyclooctane decrease with increasing polymer volume fraction which violates the underlying assumption that the heat of fusion of solvent in the polymer is the same as that in the bulk for both the Flory-Huggins model and the Gibbs-Thomson equation.

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A Frozen Tube Model of Melting Point Depression of Solvents in Entangled Polymer Systems

Cited by 6 publications

References 28 publications

Frustrated Crystallization in the Coupled Viscoelastic Phase Separation

Frustrated Crystallization in the Coupled Viscoelastic Phase Separation

Characterizing Mesh Size Distributions (MSDs) in Thermosetting Materials Using a High-Pressure System

Anomalous melting behavior of cyclohexane and cyclooctane in poly(dimethyl siloxane) precursors and model networks

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