Some temperature-sensitive properties of pure linear alkanes and n-ary mixtures

Petitjean, D.; Schmitt, Jean-François; Fiorani, J.M.; Laine, V.; Bouroukba, M.; Dirand, M.; Cunat, Christian

doi:10.1016/j.fuel.2005.12.008

Cited by 10 publications

(13 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The structures of rotator phases in individual and binary mixtures of normal alkanes have been examined extensively with thermal analysis and X‐ray scattering, which have identified five distinct rotator phases involving spacing and tilt modifications to the low‐temperature crystal structure 7–11. In contrast, the rotator phases of real wax systems have been studied little primarily because of their complexity in composition 12–16…”

Section: Resultsmentioning

confidence: 99%

Dynamic rheological study of paraffin wax and its organoclay nanocomposites

Wang

Calhoun

Severtson

2008

J of Applied Polymer Sci

View full text Add to dashboard Cite

Dynamic rheological data for paraffin wax and its organoclay nanocomposites are reported. Dynamic mechanical analysis of paraffin wax for temperatures ranging from 240 to 558C showed a decrease of several orders of magnitude in the dynamic moduli and a significant shift toward viscous behavior, which resulted from the occurrence of two solid-solid phase transitions. In both the crystalline and mesophase regions, the dispersion of organoclay platelets in paraffin wax via ultrasonication increased the storage modulus, whereas the effect on the loss modulus was temperature-dependent. The melt rheology data of the wax-clay nanocomposites at 708C showed that the complex viscosities increased monotonically with clay addition and demonstrated shear-thinning behavior for frequencies between 0.1 and 100 rad/s. The complex viscosity versus angular frequency data were well fit by a power-law function for which the shear-thinning exponent provides a gauge for the extent of clay exfoliation. The nanocomposites exhibited low-frequency solid behavior, which indicated good exfoliation of the organoclay in the wax matrix.

show abstract

Section: Resultsmentioning

confidence: 99%

Dynamic rheological study of paraffin wax and its organoclay nanocomposites

Wang

Calhoun

Severtson

2008

J of Applied Polymer Sci

View full text Add to dashboard Cite

show abstract

“…Since aliphatic hydrocarbons are able to fit into a similar crystal lattice, the same process could occur in the wax of bitumen . With a faster growth rate, the shorter chains are trapped by the fast crystallization of the longer chains, which results in a solid solution formation. , The presence of another hydrocarbon facilitates the formation of the solid solution. , Thus, fast cooling in the bitumen results in the metastable dispersion of small, imperfect wax crystals suspended in the liquid oil phase. , …”

Section: Resultsmentioning

confidence: 99%

Interpretation of Double-Peak Endotherm on DSC Heating Curves of Bitumen

et al. 2020

View full text Add to dashboard Cite

Since the late 1960s, differential scanning calorimetry (DSC) has been used to characterize petroleum bitumen, in particular, for the determination of the crystallized fraction (CF) content. This procedure is based on the construction of a baseline after identifying the CF dissolution endotherm on the heating curve. However, many bitumens commonly exhibit double-peak endotherms during a DSC heating scan. In this case, the task of constructing the corresponding baseline does not have a unique solution because the interpretation of the heat flow profile is ambiguous. Several interpretations have been proposed earlier to explain the origins of the double-peak endotherm. However, the double-peak endotherm is currently still not fully understood, and a comprehensive consensus has not been achieved. If the determination of the baseline location is incorrect, the CF content can be over- or underestimated by 20–30%. In the current work, double-peak endotherm behavior was investigated by temperature modulation DSC. All of the earlier explanations were critically considered. The origin of the double-peak endotherm was discussed in detail, and a probable descriptive model for the formation of the double-peak endotherm was suggested. The endotherm pattern is assumed to be governed by three overlapping thermal events: a broad endothermic background and a twin “recrystallization exotherm–dissolution endotherm” pair. The onset of the recrystallization exotherm and the intensity of both events depend on the annealing temperature and time. The study promotes a better understanding of the relationship between the thermal effects on the DSC curves and the structural changes of bitumen. A correct interpretation of the double-peak endotherm can provide a more exact determination of the CF content in bitumen.

show abstract

“…All the mixtures were analyzed by X-ray diffraction so as to determine their structural state. The X-ray diffractometer used in this study was previously described. − We only remind readers here that the apparatus uses the copper radiation λKα Cu and is equipped with a curved detector (CPS 120°), allowing the recording of the diffracted X-ray beam in the large angle range. A heating sample holder based on the Peltier effect makes possible the identification of structural modifications from room temperature to near 373 K. The preliminary protocol was the following one: the sample was heated to the melting point and then cooled slowly at 1 K·min −1 on a copper sheet until reaching room temperature.…”

Section: Methodsmentioning

confidence: 99%

“…Dynamic mechanical analyses (DMA) were carried out to study the thermomechanical behavior of the mixtures (S σ ). A METRAVIB viscoanalyzer (type VA 2000) was used for these experiments: the apparatus and the experimental protocol were described in detail in a previous paper, and we give only here the main characteristics of the experiments. The tension/compression test mode was used, and the parallel plates specimen holder was chosen because it is the most adapted to the tested products.…”

Section: Methodsmentioning

confidence: 99%

Influence of the Alkane Molar Distribution on the Physical Properties of Synthetic Waxes

et al. 2010

View full text Add to dashboard Cite

The purpose of this paper is to compare the structure and the mechanical properties of several model mixtures exclusively constituted of pure linear alkanes so as to better understand the conditions in which disorder appears within real systems. The molar distribution of all the studied mixtures is of "normal logarithmic type", and the only statistical parameter varying from one mixture to the other is the standard deviation (σ) of the distribution. This work was carried out by means of X-ray diffraction, differential scanning calorimetry (DSC), and dynamical mechanical analysis (DMA) according to temperature. The obtained results show that the number of crystallized phases increases with the standard deviation and that the structural evolution versus temperature of the mixtures also depends on this statistical parameter. With regard to the mechanical properties, the results of the dynamic mechanical analyses show that the storage modulus (E 0 ) and the loss factor (tan δ) are also affected by the standard deviation of the distribution.

show abstract

Some temperature-sensitive properties of pure linear alkanes and n-ary mixtures

Cited by 10 publications

References 16 publications

Dynamic rheological study of paraffin wax and its organoclay nanocomposites

Dynamic rheological study of paraffin wax and its organoclay nanocomposites

Interpretation of Double-Peak Endotherm on DSC Heating Curves of Bitumen

Influence of the Alkane Molar Distribution on the Physical Properties of Synthetic Waxes

Contact Info

Product

Resources

About