How it began
The Standard Malaysian Rubber scheme was introduced in 1965 by the Rubber Research Institute of Malaysia, an institute established in 1925. Under the scheme, natural rubber taken from Hevea trees was classified according to technical specifications. The stated purpose was quality control and compliance with standards, so that natural rubber could be marketed more effectively against the synthetic rubber industry.
How it works
SMR is natural rubber sold in grades defined by technical specifications. The scheme divides the rubber into categories such as SMR CV50, SMR CV60, SMR L, SMR 5, SMR GP, SMR 10 and SMR 20. The most important differences between grades are the plasticity retention index (PRI) and the ash content. PRI compares the plasticity of the rubber at the start with its plasticity after aging, and is treated as an important parameter for rubber buyers.
How it spread
The technically specified approach was taken up by other rubber producing countries. Major technically specified rubber schemes now include Standard Thai Rubber (STR), Standard Indonesian Rubber (SIR) and Standard Vietnamese Rubber (SVR) alongside Standard Malaysian Rubber. A Malaysian Rubber Board repository record titled "A decade of Standard Malaysian Rubber" states that in the ten years after 1965 these rubbers significantly changed the image of natural rubber.
Where it stands today
SMR grades remain a common form in which natural rubber is traded. Trade descriptions list SMR 20 as the most widely used grade. The rubber is used for car tires, aircraft equipment, rubber bands, rubber springs, hoses, automotive rubber parts and gloves. Suppliers describe it as elastic, flexible and resistant to water, though vulnerable to non-polar solvents such as benzene and chloroform.
