rubber
Rubber is a flexible polymer. Rubber can be obtained from some plant sap, it can be man-made, both have a considerable number of applications and products, such as tires, washers, etc., then become an important cash crop. Rubber cultivation is mainly concentrated in Southeast Asia, such as Thailand, Malaysia, Indonesia. Rubber into the United Kingdom, people found that this material can be very effective to wipe the traces of pencil left, so invented the eraser. Rubber English name rubber is 1770 years by the British Priestrei found this substance can rub off (rub off) pencil handwriting. According to the different ways, rubber can be divided into two types of synthetic rubber and natural rubber. ...