The evaporation of water drops from a “Teflon” surface

✍ Scribed by R.F. Mangel Jr.; E. Baer

• Publisher: Elsevier Science
• Year: 1962
• Tongue: English
• Weight: 194 KB
• Volume: 17
• Category: Article
• ISSN: 0009-2509
• DOI: 10.1016/0009-2509(62)85029-5

✦ Synopsis

IN THIS note, an investigation of the mechanism and rate of evaporation of water drops from a "Teflon" surface is reported. The drop was placed on an adjustable stage in a transparent plastic chamber which was maintained at constant humidity by means of salt solutions. A parallel light beam illuminated the drop which was projected onto a screen through the eyepiece of a microscope [l]. The screen consisted of thin cross hatched paper which was placed between two pieces of transparent plastic. The entire apparatus was placed on an optical bench to minimize distortions. Photographs of the drop magnified twenty times were taken at regular time intervals from the opposite side of the screen with a Polaroid Land camera. The drop shape was analysed by projecting the negative onto a screen. In this manner, the dimensions of the drop could be obtained with high precision. The accuracy of the contact angle was f2". In all experiments, deionized distilled water was used. The "Teflon" was carefully cleaned using the procedure of Fox and Z~SMAN 121.

An interesting mechanism of drop evaporation was observed in all experiments as shown in Fig. 1. At first the con-