Investigation of Solidification of Benzophenone in the Supercooled Liquid State

Graham, Daniel J.; Magdolinos, Peter; Tosi, M. P.

doi:10.1021/j100013a053

Cited by 10 publications

(11 citation statements)

References 4 publications

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“…At lower temperatures the metastable phase was found not to nucleate so easily, whilst below 203 K it has been suggested that a glassy phase, -benzophenone, exists. Recently, Graham et al (1995), who broadly con®rmed the results of the previous studies, investigated the formation of these different polymorphic modi®cations and developed a model of the solidi®cation process.…”

Section: Historical Backgroundmentioning

confidence: 96%

Metastable β-phase of benzophenone: independent structure determinations via X-ray powder diffraction and single crystal studies

Kutzke

Klapper

Hammond

et al. 2000

Acta Crystallogr Sect B

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Benzophenone was the first organic molecular material to be identified as polymorphic. It is well known that benzophenone crystallizes in a stable orthorhombic alpha-form (m.p. 321 K) with space group P2(1)2(1)2(1) and a = 10.28, b = 12.12, c = 7.99 A, [Girdwood (1998). Ph.D. thesis. Strathclyde University, Glasgow, Scotland]. Here we report two separate structure determinations of the metastable beta-form (m.p. 297-299 K). Crystalline material of the metastable polymorph was obtained from a melt supercooled to approximately 243 K. The structure was determined from X-ray powder diffraction data by employing a novel, computational systematic search procedure to identify trial packing arrangements for subsequent refinement. Unit-cell and space-group information, determined from indexing the powder diffraction data, was used to define the search space. The structure was also determined from single-crystal diffraction data at room temperature and at 223 K. The metastable phase is monoclinic with space group C2/c and a = 16.22, b = 8.15, c = 16.33 A, beta = 112.91 degrees (at 223 K). The structures derived from the individual techniques are qualitatively the same. They are compared both with each other and with the stable polymorph and other benzophenone derivatives.

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Section: Historical Backgroundmentioning

confidence: 96%

Metastable β-phase of benzophenone: independent structure determinations via X-ray powder diffraction and single crystal studies

Kutzke

Klapper

Hammond

et al. 2000

Acta Crystallogr Sect B

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“…in the Supporting Information). The recommended values of sublimation enthalpies at 298 15. K are Δ α g H m (298.15 K) = (94.96 ± 0.13) kJ•mol −1 and Δ β g H m Figure 6.…”

mentioning

confidence: 99%

New Static Apparatus for Vapor Pressure Measurements: Reconciled Thermophysical Data for Benzophenone

et al. 2016

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A newly developed static apparatus, capable of measuring the vapor pressure in the temperature range 273–368 K and in the pressure range 0.1–1333 Pa, is presented. The apparatus was calibrated by measuring the vapor pressure of recommended reference materials, naphthalene, n-decane, and ferrocene, and thoroughly tested. Subsequently, new vapor pressure data for benzophenone were measured in the temperature range 293–365 K with the aim to establish revised thermophysical data for this compound. Although benzophenone is another material recommended as the reference material for sublimation pressure and enthalpy measurements, the published sublimation thermodynamic data show a significant spread, and the recommendation was made with reservations which involved a reported metastable crystalline phase. We clarify this point based on reviewing the literature reporting the phase behavior and crystallographic studies and an extensive study on the polymorphic behavior of benzophenone performed in the present work. These findings are put in context with the studies reporting thermodynamic properties in which the authors were not aware of polymorphic behavior of benzophenone. The experimental data on vapor pressure for benzophenone were supplemented by ideal-gas heat capacities calculated by combining statistical thermodynamics and density functional theory (DFT) calculations. Calculated ideal-gas heat capacities and critically assessed experimental data on vapor pressure, condensed phase heat capacities, and sublimation enthalpies were subsequently treated simultaneously to obtain a consistent description of vaporization and sublimation thermodynamic properties of benzophenone.

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“…However, with granular shocks above jamming the front propagates through an already-jammed medium and its speed is governed by elastic energy stored in particles [32,33]. Although supercooled liquids, like the system here, are initially unjammed, their solidification fronts propagate at a constant, thermodynamically favored speed [37]. The data in Fig.…”

Section: Boundary Effectsmentioning

confidence: 81%

“…These behaviors are reminiscent of shocks in granular systems above jamming [32,33] or solidification fronts in supercooled glass-forming liquids [34][35][36][37]. However, with granular shocks above jamming the front propagates through an already-jammed medium and its speed is governed by elastic energy stored in particles [32,33].…”

Section: Boundary Effectsmentioning

confidence: 99%

Freely Accelerating Impact into Cornstarch and Water Suspensions

Waitukaitis

2014

Impact-Activated Solidification of Cornstarch and Water Suspensions

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While the experiments described in the previous chapter primarily focused on rheological measurements of dense suspensions, the focus of this thesis is surface impact. As a number of studies have shown, liquids and granular media typically flow around and provide little resistance to intruding objects [1][2][3][4][5][6][7][8][9][10][11], while suspensions can provide normal stresses that are large enough to support a person running across their surface. As discussed previously, this impact response has been attributed to suspension response under shear, linking it to hydrodynamic interactions [12][13][14][15][16][17] or a combination of granular dilation and jamming [18][19][20][21][22][23][24], but neither of these mechanisms alone can produce enough normal stress to explain impact. In this chapter, we describe a series of experiments designed specifically to study impact into dense suspensions. With techniques ranging from high-speed videography to embedded force sensing and X-ray imaging, we capture the detailed dynamics of the impact process as a metal rod strikes the surface of a dense cornstarch and water suspension. The data reveal that the impactor motion causes the rapid growth of a solid-like region directly below the impact site. These findings are in agreement with von Kann et al. but we go one step further by showing that this is mediated by "solidification fronts" and that no boundaries are necessary for the suspension to provide large normal stresses. Instead, as this solid moves and grows, it pulls on the surrounding suspension creating a quickly growing peripheral flow. Using the concept of added mass, we make a model that relates the sudden extraction of the impactors momentum to the growth of this flowing solid/peripheral region. Experimental SetupIn Fig. 2.1a we show a schematic of the experimental apparatus. An aluminum rod (mass m r = 0.368 kg, radius r r = 0.93 cm) is shot into the surface of a cornstarch and water suspension by gravity or by slingshot. Vertical motion is maintained by

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Investigation of Solidification of Benzophenone in the Supercooled Liquid State

Cited by 10 publications

References 4 publications

Metastable β-phase of benzophenone: independent structure determinations via X-ray powder diffraction and single crystal studies

Metastable β-phase of benzophenone: independent structure determinations via X-ray powder diffraction and single crystal studies

New Static Apparatus for Vapor Pressure Measurements: Reconciled Thermophysical Data for Benzophenone

Freely Accelerating Impact into Cornstarch and Water Suspensions

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