English Abstract

Lecture Course of Soft Matter Physics for Rubber Engineers
Chapter 5: Evaporation and Drying

Masao DOI
Beihang University, Handian, Beijing, China
Nippon Gomu Kyokaishi,(2020),93(11),352-357 General Review in Japanese

When a drop of coffee dries on a dish, many non-equilibrium processes are taking place. The water changes into vapor and diffuses out in air. Inside the coffee, liquid flow is induced by the surface tension, and coffee particles are convected to the edge of the droplets, leaving ring-like stains at the edge. This example demonstrates the complexity and the multi-physics nature involved in the phenomena we are seeing in our everyday life. Here as the last part of this series of lectures, I will discuss a few physics involved in evaporation and drying focusing on two problems, how the evaporation rate is determined, and how the structure of the dried material is determined.

Keywords: Evaporation Rates, Coffee Ring Effect, Structural Formation in Liquid Film, Skin formation, Cavitation