Latex natural rubber grades

The Rubber Manufacturers Association has a further set of standards for quality and packing of latex natural rubber grades. Table 9.2 defines the eight types of rubber covered in their specifications. Here, coagulated latex is sheeted, dried, and packed into bales of up to 113.5 kg. Grading is by visual inspection. Quality assurance laboratories have sets of visual standards for inspections (The Rubber Manufacturers Association, 1979). 

The Rubber Manufacturers Association has a further set of standards for quality and packing of latex natural rubber grades. Table II defines the eight... 

The remaining latex is processed into dry rubber as sheets, crepes and bales. There is an International Standard for the Quality and Packing for Natural Rubber grades, the so-called Green Book , published by the Rubber Manufacturers Association. The following grades of NR listed in the Green Book are sold to visual inspection standards only ... 

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. 

Field latex and field coagulum are the source materials for all varieties and grades of dry natural rubber that include the conventional International grades as well as the Technically Specified Rubbers (TSR). 

Solution adhesive is obtained from solid rubber obtained by coagulation of latex as acquired from the tree. The coagulation is effected by dilute aqueous solution of organic acids. The solid rubber can be graded in terms of dirt content, ash content, nitrogen content, and volatile matter. It can also be categorized by plasticity retention index and Mooney viscosity. To maintain uniformity it is necessary to choose solid natural rubber of known characteristics. 

Materials High ammonia type centrifuged natural rubber latex from Pasir Waringin Rubber Plantation. FTP XI, West Jawa, lndone.sia was used (Table 1). Carbon tetrachloride and normal butil acrylate were used as sensitizer. Nocract 300 was used as antioxidant. All the chemicals were technical grade without further purification. 

See also Polyisoprene Natural rubber latex Synonyms Rubber latex, natural Definition Vise. liq. contg. > 60% rubber classified by method of concentration and type of preservative (e.g., low-ammonia centrifuged grade, creamed latex, evaporated latex)... 

Synonyms Diphenylamine, styrenated SDPA Empirical C28H27N Properties Liq. m.w. 377.54 Uses Antioxidant for natural and syn. rubbers, latex, polyesters, polyamides, polyolefins, POM, PU, lubricants, food-grade polymers/adhesives/rubbers for inner tubes sponge rubber seals/gaskets soles latex goods... 

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