A diffusionless transition in a normal alkane

Nene, Shailesh; Karhu, Eric; Flemming, R. L.; Hutter, Jeffrey L.

doi:10.1016/j.jcrysgro.2009.09.007

Cited by 3 publications

(5 citation statements)

References 18 publications

(32 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…At the same time, upon cooling, only one jump was observed in the temperature dependence of the scattered light intensity (only one phase transition). The similar effect of a significant decrease in the crystallization temperature of n -alkane (C 19 H 40 n -nonadecane) and suppression of the liquid-rotator phase transition was observed with a decrease in the droplet size of the emulsion down to 60 nm …”

Section: Resultsmentioning

confidence: 57%

“…There are no sharp changes in the temperature dependence of the intensity of the scattered light on the temperature interval C−D. It was not possible to observe changes in the optical properties of the emulsion associated with those observed for n-tricosane phase transitions 23 of R V − R I and R I −R II using the measurement technique used in this work. The temperature range D−E (47.4−47.8 °C) corresponds to the melting of n-tricosane in the dispersion.…”

Section: ■ Results and Discussionmentioning

confidence: 78%

“…The phase diagram of n -tricosane is well-understood. It was shown ,, that, when a given n -alkane is heated, its crystalline structure changes sequentially, passing through several phase states with the so-called rotator phases. For n -tricosane, from the ordered crystalline phase to the rotator phase, the R V transition occurs at +39.7 °C, the phase transition from R V to R I occurs at +42.3 °C, the R I –R II transition occurs at +44.6 °C, and the melting from the R II phase occurs at +47.6 °C.…”

Section: Resultsmentioning

confidence: 99%

“…The similar effect of a significant decrease in the crystallization temperature of n-alkane (C 19 H 40 n-nonadecane) and suppression of the liquid-rotator phase transition was observed with a decrease in the droplet size of the emulsion down to 60 nm. 23 Having carried out an analysis similar to the analysis of the data in Figure 1 for the temperature dependencies of the scattered light intensity of the studied emulsions, for each sample, it is possible to determine the melting temperature, the temperature of the crystallization onset, and the temperature of the phase transition to the rotator phase (if any). Figure 4 shows the dependence of the melting temperature and the phase transition to the rotator phase on the concentration of n-tricosane in the mixture for the studied emulsion samples.…”

Section: Energy and Fuelsmentioning

confidence: 99%

See 3 more Smart Citations

Study of Phase Transitions in n-Tricosane/Bitumen Aqueous Dispersions by the Optical Method

et al. 2019

View full text Add to dashboard Cite

The paper presents the results of studies of phase transitions in the mixture of n-alkane C 23 H 48 (n-tricosane) and natural bitumen at various concentrations of components. The initial samples of n-tricosane, natural bitumen, and their mixtures were studied by the light scattering as aqueous dispersions. The hydrodynamic radius of the dispersions measured by the dynamic light scattering method was about 100 nm and did not change over a wide temperature range within the measurement accuracy. The temperatures of melting, crystallization, and rotator phase transitions of paraffin in a mixture were determined from temperature-dependent measurements of the light scattering by the dispersions. The dependence of the supercooling value upon the concentration of n-alkane in the mixture was also determined. A new experimental method of investigation of paraffin phase transitions in oils is proposed.

show abstract

Section: Resultsmentioning

confidence: 57%

Section: ■ Results and Discussionmentioning

confidence: 78%

Section: Resultsmentioning

confidence: 99%

Section: Energy and Fuelsmentioning

confidence: 99%

See 2 more Smart Citations

Study of Phase Transitions in n-Tricosane/Bitumen Aqueous Dispersions by the Optical Method

et al. 2019

View full text Add to dashboard Cite

show abstract

“…The appearance of those higher order peaks, especially like (0010) and (008), reveals that C41 crystallized with fully extended crystallites. 25,29,50 Associated with the surface property-dependent crystallization behaviors shown in DSC cooling curves, there seems to be preferred orientation of C41 crystals that formed at each of the temperature ranges. Considering the XRD intensity and crystallization DSC curves, crystal orientation in which the aaxis is parallel with the pore axes is preferred for C41 crystals formed in the pristine AAOs, while another orientation in which (110) is parallel with the pore axis becomes dominant for C41 crystals developed in the surface-modified AAOs at the higher crystallization temperature range.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Influence of Surface Property on the Crystallization of Hentetracontane under Nanoscopic Cylindrical Confinement

2013

View full text Add to dashboard Cite

The crystallization behavior and the orientation of linear alkane hentetracontane (C41) confined in cylindrical nanoporous alumina templates with different surface energies were investigated by nonisothermal crystallization and X-ray diffraction. The surface of pristine nanoporous alumina was modified to have low surface energy by grafting with polydimethylsiloxane. In the pristine nanoporous alumina, C41 crystallized at two crystallization temperature ranges, lower than bulk, and exhibited the decreased Avrami exponents. C41 in the surface-modified nanoporous alumina showed the inhibition of crystallization at higher temperature range among the two crystallization temperature ranges but the enhancement of crystallization at much lower temperature ranges than in the pristine nanoporous alumina. It was clearly shown that those variations of crystallization behavior imply the surface effect on crystallization. The crystal orientation was also affected by surface-modification of the alumina template. The a-axis of orthorhombic C41 crystals in the pristine nanoporous alumina was preferentially oriented parallel to the pore axis, while b- and c-axes were perpendicular to the pore axis. C41 crystals in the surface-modified nanoporous alumina showed two types of orientation. One was identical to that in the pristine nanoporous alumina, and the other was the orientation that the crystals were tilted with respect to the c-axis as the (110) plane parallel to the pore axis.

show abstract

Simulation of multiple ordered phases in C23 n-alkane

Wentzel

Milner

2011

The Journal of Chemical Physics

View full text Add to dashboard Cite

Normal alkanes display multiple ordered phases, including an orthorhombic crystal (X) and two partially ordered rotator phases (RI and RII). The rotator phase transitions X-RI and RI-RII are of interest because they are weakly first-order, and because experiments suggest that crystalline polyethylene may nucleate via a metastable rotator phase. We have performed heating and cooling scans of all-atom NσT (isothermal, isostress) simulations of a pure C(23) solid. We find a sequence of phases, transition temperatures, structural and thermodynamic properties, all reasonably consistent with experiment, except that a monoclinic crystal is more stable in our simulations than the experimental orthorhombic structure. We find that the RI phase is well described as an orthorhombic crystal disordered by random ±90° rotations of molecules about their stem axis, and the RII phase can be represented as a loose hexagonal packing of parallel chain stems, which tend to orient with the in-plane projection of C-C bonds pointing between neighbors. To measure local orthorhombic, RI, or RII order, we define Potts- and Ising-like order parameters, from which global order parameters and correlation functions can be computed. We observe modest pretransitional fluctuations of local RI order in the RII phase near T(RI-RII), characteristic of this weakly first-order transition.

show abstract

A diffusionless transition in a normal alkane

Cited by 3 publications

References 18 publications

Study of Phase Transitions in n-Tricosane/Bitumen Aqueous Dispersions by the Optical Method

Study of Phase Transitions in n-Tricosane/Bitumen Aqueous Dispersions by the Optical Method

Influence of Surface Property on the Crystallization of Hentetracontane under Nanoscopic Cylindrical Confinement

Simulation of multiple ordered phases in C23 n-alkane

Contact Info

Product

Resources

About