Isobaric binary state diagrams ofn-alkanes

Asbach, G. I.; Kilian, H. G.; Stracke, F.

doi:10.1007/bf01465434

Cited by 26 publications

(14 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In terms of the initial rearrangement of the solid to produce a better ordered solid solution, the growth of the fractionated solid takes a very long time (weeks, months, years). After, e.g., 1 year's equilibration, a transition enthalpy on the isotherm for nC30H62|nC36H74 does not differ from that of samples equilibrated for only 1 week, although the peak temperature of this transition increases from ca. 49 to ca.…”

Section: Resultsmentioning

confidence: 91%

Chain length and the cosolubility of n-paraffins in the solid state

Dorset¹

1990

Macromolecules

122

View full text Add to dashboard Cite

found in earlier analyses, solid solutions are formed. As indicated by theoretical calculations of the melting point line, they are nearly ideal in their behavior. Outside of this chain length difference eutectics are formed, with liquidus curves also corresponding closely to the freezing point depression of an ideal liquid solution. Depending on chain length difference, the eutectic solid will be composed of an incommensurate layer structure (crystallized from a metastable solid solution) coexisting with the longer chain component. If no cosolubility is possible, a mixture of the two pure components separates. A boundary domain also exists before strict eutectic separation when a critical temperature is reached. Here, at the miscibility gap, metastable solid solutions fractionate, with a structure very similar to that of a secondary eutectic solid for binary combinations where limited solid solubility still exists. However, the incommensurate solid changes continuously with concentration unlike the mixed lamellar stacking in the eutectic, which has a constant composition. It is therefore possible to describe a progression of crystalline arrays between the stable solid solution and fully separated eutectic.

show abstract

Section: Resultsmentioning

confidence: 91%

Chain length and the cosolubility of n-paraffins in the solid state

Dorset¹

1990

Macromolecules

122

View full text Add to dashboard Cite

show abstract

“…Denoting this difference by ( , ), we can use the equation bH, =s -( , ) -(xA/f,°( 7) + (1 -) 2°( )\ (2) to determine the excess enthalpy. In this equation, °( ) and 2°( ) are the values measured for the neat components.…”

Section: Calorimetric Resultsmentioning

confidence: 99%

Structure of the n-alkane binary solid n-C19H40/n-C21H44 by infrared spectroscopy and calorimetry

1985

View full text Add to dashboard Cite

“…The relative values of T E and T C are found to be more useful for a quantitative understanding of these systems than the melting point differential. If T C is greater than or equal to T E , then for T < T E eutectic crystallisation results . This is the situation for bulk C 30 D 62 /C 36 H 74 …”

Section: Discussionmentioning

confidence: 91%

“…The relative values of critical temperature and eutectic temperature have been shown to be important on the form of temperature-composition phase diagrams . These have been determined for the four possible isotopic combinations in bulk C 30 /C 36 mixtures .…”

Section: Discussionmentioning

confidence: 99%

Microphase Separation in Graphite-Adsorbed Paraffin Solid Solutions

1996

View full text Add to dashboard Cite

Using time-resolved small-angle neutron scattering (SANS), the time-dependent microphase separation occurring in metastable, quenched binary paraffin mixtures C 30 H(D) 62 /C 36 D(H) 74 doped into porous graphite has been observed. In the presence of graphite, microphase formation is enhanced compared to the bulk mixtures and the isotopic dependence of the demixing process reported for these systems when quenched to 20 °C is not apparent. We relate the enhanced microphase separation to an elevation of the eutectic temperature relative to the critical temperature, due to stabilization of the paraffins at the graphite basal plane. For 1:1 mixtures, the microphase forms an alternating lamellar structure, while the 1:4 and 4:1 mixtures exhibit an increase in scattering at lower angles associated with significantly longer repeat-spacings. An increase in quench temperature from 20 to 27 °C increases the strength of the microphase scattering over the time period studied, but quenching to 35 °C results in a significant reduction in this signal. Parallel small-angle X-ray scattering (SAXS) studies provide complementary information, with the immediate appearance of strong peaks on quenching, indicating the rapid formation of a solid solution with a lamellar structure. On aging, additional weaker peaks are observed, which, for 1:1 mixtures, are consistent with the formation of alternating lamellae. For all mixtures, except 1:4 C 30 H 62 /C 36 D 74 , there is a constant offset in Q between the strong and weak peaks. The scattering can be understood to arise from a mixed lamellar system in which incommensurate deviations from the mean structure occur. For 1:4 C 30 H 62 /C 36 D 74 , two sets of peaks are observed, one corresponding to the alternating lamellar structure and the other to pure C 36 D 74 .

show abstract

Isobaric binary state diagrams ofn-alkanes

Cited by 26 publications

References 15 publications

Chain length and the cosolubility of n-paraffins in the solid state

Chain length and the cosolubility of n-paraffins in the solid state

Structure of the n-alkane binary solid n-C19H40/n-C21H44 by infrared spectroscopy and calorimetry

Microphase Separation in Graphite-Adsorbed Paraffin Solid Solutions

Contact Info

Product

Resources

About