Composition of natural rubber sheet

There are about 2,000 different plants in the world that produce polymers similar to natural rubber sheets, and different kinds of rubber have been obtained from 500 of them, but the one of real practical value is the Brazilian three-leaf rubber tree. When the surface of a rubber tree is cut, the milk ducts within the bark are severed and latex flows from the tree. The latex collected from the rubber tree is diluted and solidified with acid, washed, and then pressed, dried, and packaged to produce commercially available natural rubber. Depending on the method of rubber production, natural rubber can be made into smoke flakes, air-dried film, crepe flakes, technically graded dry rubber and concentrated latex.

Standard rubber, or granular rubber, is a new variety of natural rubber developed in the 1960s. Previously, the common smoke flakes, crepe flakes, air-dried flakes of these traditional products regardless of the grading method, manufacturing methods are bound to the development of natural rubber. Therefore, Malaysia began to implement the standard rubber program in 1965, the use of raw rubber physical and chemical properties based on grading the development of granular rubber production. Standard rubber is the rubber graded according to mechanical impurities, plasticity retention rate, plasticity initial value, nitrogen content, ash content, ash content, color index and other physical and chemical performance indicators. Standard rubber packaging is also more advanced, generally packaged in polyethylene film with distinctive markings, the package weight is small and easy to move. Malaysia's package weight of 33.3kg, China's regulations for 40kg.

Standard rubber grading is more scientific, so this grading method is quickly accepted by the major natural rubber producing countries and international standardization bodies, and has developed a standard rubber grading standards. These standards are generally the same, but not completely consistent. For example, ISO2000 provides five grades, China's standard GB8081-87, there are four grades.