The term rubber comes from the Indian word cau uchu, which means "a tree shedding tears.". Natural rubber is made by solidifying and drying the latex that flows out during the cutting of three leaf rubber trees. In 1770, British chemist J. Priestley discovered that rubber could be used to erase pencil handwriting, and the material used for this purpose was called rubber, a term that has been used to this day. The molecular chains of rubber can be crosslinked, and when the crosslinked rubber undergoes deformation under external forces, it has the ability to quickly recover and has good physical and mechanical properties and chemical stability. Rubber is a fundamental raw material in the rubber industry, widely used in the manufacturing of tires, hoses, tapes, cables, and various other rubber products. The three leaf rubber tree provides the most commercial rubber. It secretes a large amount of sap containing rubber emulsion when damaged, such as when the bark of the stem is cut open.
In addition, fig trees and some plants in the Euphorbiaceae family can also provide rubber. Germany attempted to obtain rubber from these plants during World War II due to the cut off of rubber supply, but later switched to producing synthetic rubber.
The original rubber trees grew in South America, but after artificial transplantation, Southeast Asia also has a large number of rubber trees planted. In fact, Asia has become the most important source of rubber.
Rubber made from silver chrysanthemum gum can reduce sensitivity.