The cloth raincoat is made of rainproof cloth (ordinary cotton cloth treated with waterproof agent). Waterproof agent is a kind of paraffin emulsifying slurry containing aluminum salt. When the paraffin wax is emulsified, it becomes small particles and distributes evenly on the cotton fibers. Paraffin and water are not compatible, water meets paraffin, form elliptic water bead, roll over paraffin wax. It can be seen that paraffin wax plays a role in preventing rain. In physics, this phenomenon of impermeability is called "non-wetting phenomenon". And when water meets ordinary cotton cloth, it permeates through the capillary between the fibers, which is called "infiltration phenomenon".
Objects are made up of molecules. The interaction between molecules of the same substance is called cohesion. The interaction between molecules of different substances is called adhesion. "Infiltration" occurs when the cohesion is less than the adhesion. Conversely, there will be "no infiltration". The waterproof coat is impervious to water because the cohesion of water is greater than the adhesion of water to the raincoat.
Common glass that looks smooth and shiny. Water in it, however, is tightly coiled, brought all sorts of trouble: when it rains, the rain on the car window obstructed the driver's line of sight, very insecure, so had to start the stroke unit and the rain comes to; When a person wearing glasses drinks hot water, the glasses are immediately covered with a layer of mist, blocking the view and making nothing visible.
People know the characteristics of the surface tension of water, to understand the relationship between water cohesion and adhesion after, not only ingeniously made the raincoat, but also made the novel "hate" sodium silicate - on common glass coating a layer of silicon organic compounds, it greatly weakens the fog of the adhesion to glass. With this kind of hydrophobic glass as the lens, the wearers of the glasses relieved the fog of distress; Put the glass on the front window of the car and the paddle won't be needed.