The Effects of Temperature, Material, and Treatment Type on Contact Angle

Water can affect an automobile by reducing visibility on the windshield and therefore increasing the likelihood of an accident. Water can also leave streaks on the body decreasing its aesthetic value. The addition of a water-repellent to an automobile’s surface can reduce these effects. The effectiveness of such repellents can be determined by examining the contact angle between a water drop and the surface. High contact angles have less contact with a surface than low contact angles. Therefore, a surface material that has a high contact angle would be less affected by water due to having less contact with the surface. This experiment was designed to see if a homemade water repellent composed of isopropyl alcohol, ethanol, and silicone oil would be as effective as a commercial water repellent on three common automobile materials: glass, plastic, and aluminum. Three sheets of each material were cut into 8x8 inch squares treated with either the homemade or commercial water repellent or left untreated as a control. The sheets were then either heated or cooled to temperatures of 2° Celsius, 15°C, or 28°C. Water was dropped onto the sheets and a photograph would be taken and then the contact angle between the drop and the material would be found through the computer software, Geometer’s Sketchpad. After conducting an ANOVA statistical test, it was found that the commercial water repellent was more effective, though the significance of the effect of temperature or material type could not be determined.

Research Done By:

Eric Klug
Cousino High School

Robin Smith
Lake Shore High School