Octadecane

• CAS: 593-45-3
• Catalog Number: ACM593453
• Category: Alkanes
• Molecular Weight: 254.49
• Molecular Formula: C18H38
• Melting Point: 28-31°C
• Flash Point: 166°C
• Density: 0.777
• Solubility: water, 9.358e-005 mg/L @ 25 °C (est)
• Appearance: Clear semi-Liquid
• Assay: 0.98
• EC Number: 209-790-3
• Hazard Statements: H304
• MDL Number: MFCD00009007
• Packaging: 1 kg
• Refractive Index: 1.439
• RIDADR: NONH for all modes of transport
• Stability: Stable. Combustible. Incompatible with strong oxidizing agents.
• Symbol: GHS08

Case Study

Silica-Shell Microencapsulated Octadecane as a Shape-Stable Thermal Storage Material

Tang, Fang, et al. Solar Energy Materials and Solar Cells, 2017, 160, 1-6.

Octadecane functioned as the phase change material (PCM) for thermal storage inside the microcapsules while the shell material made from methyltriethoxysilane (MTES) silica protected against the leakage of octadecane. The microcapsule phase change material (MPCM) produced demonstrates strong thermal stability which makes it suitable as a shape-stable phase change material for thermal energy storage applications.
Preparation of octadecane based MPCMs
· 1g of SDS and 15 g of octadecane were mixed with 100 mL of distilled water to make an oil-water emulsion of octadecane. Using a magnetic stirrer the mixture underwent stirring at 800 rpm while maintaining a temperature of 45 °C for a duration of 60 minutes. The mixture became a stable emulsion with uniformly dispersed octadecane in the distilled water after the pH reached 9-10 through ammonia solution addition.
· A beaker contained different combinations of MTES, anhydrous ethanol and distilled water with prescribed mass ratios. This mixture received hydrochloric acid treatment to achieve a pH range of 2-3 and was then stirred constantly at 45 °C for 20 minutes at 400 rpm. MTES experienced hydrolysis during this phase to produce a methyl silicate sol solution that acted as a precursor for microencapsulation.
· The stirring speed of the octadecane oil-water emulsion was then decreased to 300 rpm, while maintaining the same temperature. The methyl silicate sol solution was added dropwise to the emulsion, which continued to stir for 2 hours. In this step, the condensation of methyl silicate led to the formation of a silica shell around the octadecane droplets.

Microencapsulation Strategy of N-Octadecane Phase Change Material with Calcium Carbonate Shell

Yu, Shiyu, et al. Applied energy, 2014, 114, 632-643.

This work successfully created a phase change material (PCM) microcapsule that contains n-octadecane in its core and uses calcium carbonate (CaCO3) as its shell through self-assembly synthesis. High thermal conductivity CaCO3 shells enhance n-octadecane microcapsules' thermal conductivity while also boosting their anti-permeability performance and service life through protective dense CaCO3 shell formation.
Synthesis of microencapsulated n-octadecane with CaCO3 shell
· The syntheses were conducted in an oil-in-water emulsion using a mixed templating system of Tween 80 and Span 80. Microcapsules with varying core/shell mass ratios were produced through a self-assembly process with different proportions of n-octadecane and CaCl2.
· The standard synthesis process began with dissolving 22.2 grams of CaCl2 into 150 milliliters of deionized water. A three-neck round-bottom flask was used to mix 1.3 g of Tween 80 and 0.7 g of Span 80 with 100 mL of water containing 20.0 g of n-octadecane which was vigorously agitated for 10 minutes at 32 °C. The stable emulsion was formed by adding the prepared CaCl2 solution dropwise into the stirred mixture of n-octadecane and surfactants at 1000 rpm for three hours. Then, added dropwise 100 mL solution of 20.8 g Na2CO3 to the n-octadecane emulsion while being stirred carefully. The final product, microencapsulated n-octadecane with a CaCO3 shell, was collected as white powders through filtration.