Comparative Studies on the Organogel Formation of a Polyester in Three Different Base Oils by X-ray Analysis,...

Area of Science:

• Materials Science
• Tribology
• Polymer Chemistry

Background:

• High-performance greases commonly use polyurea as a thickener.
• Polyesters are under investigation as potential alternatives to polyureas.
• Polyester gelation is less understood due to the absence of hydrogen bonding.

Purpose of the Study:

• To investigate the gel formation of polyester-based thickeners in different base oils.
• To evaluate the impact of base oil type on polyester gelation and mechanical properties.
• To explore polyesters as a viable alternative thickener material in grease formulations.

Main Methods:

• Synthesis of poly(hexane dodecanoate) with 1-octanol endgroups.
• Preparation of grease formulations using mineral oil, polyalphaolefin, and castor oil.
• Characterization using Small- and Wide-Angle X-ray Scattering (SAXS/WAXS) and Infrared (IR) spectroscopy.
• Measurement of gel yield point (γF) to assess mechanical stability.

Main Results:

• Polyester exhibited strong interaction with castor oil, unlike mineral oil and polyalphaolefin.
• Increased polyester concentration (5-40 wt.%) led to a higher crystalline fraction in castor oil.
• Gel formation was observed in castor oil at a minimum polyester concentration of 20 wt.%.
• Greases thickened with polyester in castor oil showed significantly higher yield points (5.9%) compared to those in mineral oil (0.8%) and polyalphaolefin (1.0%).

Conclusions:

• Polyester thickeners can form stable gels in specific base oils like castor oil.
• The strong polyester-castor oil interaction enhances the mechanical stability of the resulting grease.
• Polyesters represent a promising alternative thickener for high-performance grease applications.