Polyvinyl Alcohol Slimes: Measuring How pH Correlates to Viscosity in a Non-Newtonian Fluid

Overview

Objectives/Goals The objective of this project is to explore how the viscosity of slime (a non-Newtonian Fluid that happens to be fun) changes as the pH of the cross-linking solution (sodium tetraborate) increases, with the ultimate goal of determining the pH level at which the maximum degree of viscosity is obtained for any fixed volume of cross-linking solution. Methods/Materials Used weight measured quantities of sodium tetraborate mixed into distilled water to create solutions of sodium tetraborate ranging from 1 to 7 percent. In multiple trials for each solution strength, the pH of the sodium tetraborate solution was measured, and then 10ml of sodium tetraborate solution was mixed into 100ml of 4 percent polyvinyl alcohol (PVA) solution. After a cross-linked polymer was formed, the viscosity was measured in multiple trials by timing the descent of a metal bearing through the PVA slime to the bottom of a cylindrical container. Results For a ration of 10ml of sodium tetraborate solution to 100ml of 4 percent polyvinyl alcohol (PVA) solution, viscosity measurements plateaued at the 4 percent sodium tetraborate solution concentration and pH were observed to plateau just above that concentration, at the 5 percent sodium tetraborate solution concentration. Conclusions/Discussion For purposes of identifying polyvinyl alcohol (PVA) slime with optimal characteristics, understanding how different parameters impact viscosity permits the formulation of a recipe that is best suited to the application. For example, PVA-type slimes used for industrial clean-up purposes may have narrow ranges for operating viscosity because the slime must be piped over substantial distances. For commercial or recreational purposes, a child using slime as a toy would likely prefer an intermediate viscosity product that is highly elastic but still cohesive (cohesion also likely important to a parent, as the ability to clean up slime would depend upon its viscosity).

Awards (1)

• Third Place

Competition history

• CSEF 2018 Aerodynamics/ Hydrodynamics (Junior Division Only) · Entry J0114

Resources

• CSEF project summary ↗

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