Date of Graduation

Spring 2018

Document Type

Honors Research Project

Degree Name

Bachelor of Science

Major

Chemical Engineering - Cooperative Education

Research Sponsor

Dr. Gary Doll

First Reader

Dr. Paul Shiller

Second Reader

Dr. Edward Evans

Abstract

Our hypothesis was that the thickener type and micelle concentration of grease affected its viscoelastic properties. Measurements were made using a TA AR G2 rheometer and calculations were made using TA rheometer analysis software to characterize the viscoelastic response of grease under oscillatory shear and frequency tests. The oscillatory frequency tests determined the critical micelle concentration. The oscillatory stress tests were taken at temperatures from 5 to 65 degrees Celsius to create a master curve based on time temperature superposition of the measurements. The crossover points of G’ and G” on the oscillatory stress tests demonstrated where the grease transitions from acting primarily as an elastic solid to acting primarily as a viscous liquid. For the soap thickened grease, it was found that regardless of concentration, the grease only transitioned from being liquid dominated to solid dominated. For the detergent thickened grease, it was found that the grease transitioned three times, regardless of concentration, starting from liquid to solid at low shear stress. Though micelle concentration did affect the crossover points, its exact effect was not definitive in the testing completed. The thickener type had the largest effect on the grease response to shear stress.

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