STANDARD MALAYSIAN

Malaysian and Indonesian natural mbber growers have estabUshed a system based on technical characteristics. The standard Malaysian specification scheme can be found in Reference 3. 

A significant revision to the SMR scheme was introduced in 1991 in response to consumer desire for greater consistency in natural mbber (13). Other producing countries have similar specification schemes (14), as does the International Standards Organization (ISO) (15). An example of the specifications for TSR is given in Table 1 for the present Standard Malaysian scheme. Except for SMR 5, rheograph and cure test data (delta torque, optimum cure time, and scorch) are provided. 

Table 1. Standard Malaysian Rubber (SMR) Specifications Scheme ...

Revisions to Standard Malaysian Bubber S cheme, SMB Bull 11 (1991). 

Compared with the natural material, raw SBR is more uniform in a variety of ways. Not only is it more uniform in quality so that compounds are more consistent in both processing and product properties but it is also more uniform in the sense that it usually contains fewer undesired contaminants. In addition, over a period of years it has been generally less subject to large price variations. These differences in uniformity have, however, tended to lessen with the advent of improved grades of natural rubber such as Standard Malaysian Rubber which have appeared in recent years. 

In solid form, the natural rubber is graded according to the content of dirt remaining from the precipitation of latex at the plantation. Eight basic NR types have been traditionally recognized internationally. Only the so-called ribbed smoked sheets and the pale crepes are normally used for adhesives. The predominant grade system, the Standard Malaysian Rubber system, has been used since 1965. 

This is the generic name for the scheme originally introduced in Malaysia as Standard Malaysian Rubber (SMR). In effect it is the same specification but apphed to rubber produced in other countries, e g., Standard Indonesian Rubber (SIR). Both SMR and SIR are Technically Specified Rubbers. 

Figure 9.5.1 Natural rubber prices - TSR 20 - FOB Kuala Lumpur. SMR = Standard Malaysian Rubber, SMR 20 is a medium grade...

Standardized Malaysian rubber Poly(styrene-co-of-methyl styrene) (DIN ISO NS) Suspension-polymerized PVC... 

In [31] a correlation is foimd between the Mooney viscosity and the apparent viscosity, obtained by means of a capillary viscometer. The investigations were carried out on both rheometers with 6 types of rubbers, namely NR crepe sheets (natural mbber), SMR-20 (Standard Malaysian Rubber, i.e., type natural rubber), SBR (styrene-butadiene rubber), NBR (acrylonitrile-butadiene rubber), MQ (silicone rubber), HR 268 R (butyl rubber) and their compounds. The following equation was obtained ... 

NR suffers from inconsistent properties. Multiple stages of handling and transportation, and proeesses, are subject to contamination of NR latex (Figure 1.5). The grading of NR was correlated with a visual inspection of its dirt content in early years. Uniformity and purity of NR latex and dry NR as the commodity materials are overcome by introduction and enforcement of conformity of NR to strict technical specifications, e.g. Standard Malaysian Rubber (SMR, introduced in 1965 and revised in 1973 and 1991), Standard Thailand Rubber (STR), Standard Indonesian Rubber (SIR) and Standard Vietnam Rubber (SVR). Under SMR, tolerable amounts of nitrogen, dirt, volatile matter, copper and manganese are specified. STR, SIR and SVR are prepared based on SMR. 

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