Influence of Microcrystalline Wax on the Properties of Model Wax-Oil Gels

Abstract

The influence of micro-crystalline wax addition upon the rheological properties of model wax-oil gels is investigated. Addition of less than 1 wt% micro-crystalline wax to a model oil consisting of 5 wt% macro-crystalline wax in dodecane shows no significant impact on the WAT and gelation temperature. Beyond 1 wt% added micro-crystalline wax, increases in WAT and gelation temperature are observed, and are attributable to the higher crystallization temperature of the micro-crystalline wax. The effect of micro-crystalline wax addition upon the WAT and gelation temperature are shown to be attributed to merely overlapping compositions of macro-and microcrystalline wax. However, a substantive effect of micro-crystalline wax addition is observed on the yield stress. Addition of 0.13 wt% micro-crystalline wax reduces the yield stress of waxy oil model from 238.0 to 22.5 Pa. Addition of 0.5 wt% micro-crystalline wax decreases the yield stress to 5.4 Pa, which is close in value to the yield stress of neat 5 wt% micro-crystalline wax gel.2 Microscopic images reveal two mechanisms leading to formation of a weak mixed wax gels. At low to medium addition of micro-crystalline wax, micro-crystalline crystallites formed during cooling provide nucleation sites for subsequent precipitation of macro-crystalline wax. Macrocrystalline wax crystals formed in contact with micro-crystalline crystallites are smaller in size and the growth is localized, in comparison to neat macro-crystalline wax. Modified macro-crystalline wax precipitation leads to uneven dispersion of the macro-crystalline crystals in the liquid phase.At high concentration, micro-crystals form throughout the sample prior to precipitation of macrocrystalline wax. Hence, only small and discrete space remains for macro-crystalline crystals to grow, forming small crystals. Interlocking among macro-crystals is spatially hindered by the presence of micro-crystalline crystallites. In this condition, the system completely behaves as a micro-crystalline gel. This investigation provides a plausible mechanistic account for the known gel weakening activity of micro-crystalline wax.

New Method for Gelation Temperature Measurement without Disturbing the Crystal Network

“…The macrocrystalline wax (Sasolwax 5405) consists of 78% w/w n -alkane with carbon number C 20 –C 44 and 22% w/w branched and cyclic alkanes with carbon number C 20 –C 41 . More detailed information about properties and composition analyses is available in previous studies. ,, Additionally, the gelation characteristics of the agar gel sample prepared using 1.5% agar in water and two commercial products (A and B) are also experimentally investigated.…”

“…The temperature of crude oil falls below the wax appearance temperature (WAT) during transportation at subsea conditions. The temperature at which the first wax crystal precipitates is called the WAT or the cloud point temperature. , Due to the lower solubility of paraffins in the crude oil at low temperatures, wax crystals precipitate . During flow shutdown conditions, the crude oil inside a pipeline undergoes prolonged cooling, resulting in the precipitation of more wax crystals .…”

Influence of Measuring Geometry on Rheomalaxis of Macrocrystalline Wax–Oil Gels: Alteration of Breakage Mechanism from Adhesive to Cohesive

“…The composition of wax is dominated by lower carbon-number n-alkanes and higher carbon-number iso-alkanes and cyclo-alkanes. 1 Paraffin wax is often categorized as micro-crystalline or macro-crystalline, which may be isolated from distillate fractions above and below 460 ℃, respectively. 2 Macrocrystalline wax contains predominantly linear alkanes, with a smaller content of branched and cyclic alkanes.…”

Lipsticks History, Formulations, and Production: A Narrative Review

“…There are two forms of paraffin waxes: macrocrystalline wax and microcrystalline wax, both of which have significant physical differences in various aspects. Microcrystalline wax is opaque, plastic, malleable, and sticky, whereas macrocrystalline wax is translucent, glossy, slippery, and brittle [61]. Microcrystalline wax is derived from heavy distillates and used in a variety of applications such as cosmetics, rubber compounds, candles, and metal casting to take advantage of its unique flexibility, viscosity, temperature tolerance, and adhesive properties [61].…”

“…Microcrystalline wax is opaque, plastic, malleable, and sticky, whereas macrocrystalline wax is translucent, glossy, slippery, and brittle [61]. Microcrystalline wax is derived from heavy distillates and used in a variety of applications such as cosmetics, rubber compounds, candles, and metal casting to take advantage of its unique flexibility, viscosity, temperature tolerance, and adhesive properties [61]. Recent evidence suggests that the microcrystalline wax was utilized in lipsticks production as a lipstick base and stiffening agent [62,63].…”