Natural Rubber is found in a number of different trees and shrubs that produce a milky white substance called latex. Over 400 different plants and trees produce latex but the latex used in natural rubber comes from the rubber tree plant (Hevea Brasiliesis). This tree is said to have originally come from the Amazon rainforest in Brazil. Most of the world’s latex actually comes from Asia, in particular, Indonesia, Malaysia and Thailand.
How is Natural Rubber made?
The first step in the rubber making process is to collect the latex from the trees. Large plantations of rubber trees are planted and early in the morning when it is cool slits are cut into the trunks of the trees. Special cups and buckets are attached to the trees under the slits to collect the dripping latex. These are left for a maximum of 3 hours and they are then quickly transported to a rubber factory for processing. If left to sit, latex will naturally coagulate causing it to become useless for making rubber. Once at the rubber plant, the latex is heated and mixed with the acid ammonia to form rubber curds. Sometimes sulfur is added to make the rubber harder and more stable. Crude rubber is made as the latex is heated and solid chunks rise to the surface of the liquid. This crude rubber is skimmed from the top and run through large, heavy rollers to remove excess water. This presses the rubber into long, thin sheets which are then transported to other factories to make rubber products. In factories that make specific products, the heated latex is poured into molds or preformed casts are dipped into the latex and left to set rather than being rolled into long sheets.
How Is Synthetic Rubber Made?
Synthetic rubber is made from substances such as petroleum, coal, oil, natural gas, and acetylene. The petroleum based chemicals are heated in the same way that natural latex is and form the same clumps of crude rubber. This rubber is then dried and transported to other factories where it is rolled into sheets and made ready for molding. There are 3 ways to mold synthetic rubber, extrusion, injection molding and compression molding. Extrusion is where the rubber is heated and forced through a small opening to make large strands of rubber. Injection molding is where the rubber is heated and then forced into a mold under high pressure. The rubber is then cooled in the mold and released. Compression molding is where the rubber is compressed around a particular mold under pressure to make it maintain a shape. When it is cooled it is released from the mold.