Natural Rubber (Rubber Valley)
By：admin Updated：2014-03-19 13:58:27
Introduction
The so-called natural rubber is the latex collected from natural Brazilian rubber trees, formed into solid object with some elasticity through concreting, drying, etc. The natural rubber is a natural polymer chemical compound mainly consisting of polyisoprene with more than 90% of rubber hydrocarbon (polyisoprene) and small amount of proteins, aliphatic acid, sugar as well as ash, etc.
Product Classification and Quality Standard
Natural rubber can be classified into two categories according to its form: solid natural rubber (sheets and granules) and concentrated latex. The former is in the vast majority in our daily life. The rubber sheets are classified into ribbed smoked sheet, air-dried sheet, white crepes and brown crepes, etc. The granular rubber (i.e. standard rubber) is graded as per the unified international physicochemical performance as well as index, including dirt content, initial plasticity, Plasticity Retention Index (PRI), Nitrogen Content, Volatile Matter Content, Ash Content as well as Color Index. Thus, the granular rubber can be classified into 5L, 5, 10, 20, and 50 of five grades in term of its dirt content (dominating indicator).
The delivery grade specified in the contract of Tianjin Bohai Commodity Exchange (BOCE) for natural rubber is the TSR 20 produced from Thailand, Indonesia and Malaysia with the same technical specifications on the manufacture date of within one year (included) since the issuance of the original quality inspection certificate.
The specified indexes are shown as follows:
|
Specifications
|
SMR 20
|
STR 20
|
SIR 20
|
|
Dirt Content (% weight max.)
|
0.16
|
0.16
|
0.20
|
|
Ash Content (% weight max.)
|
1
|
0.8
|
1
|
|
Volatile Matter Content (% weight max.)
|
0.8
|
0.8
|
0.8
|
|
Nitrogen Content (% weight max.)
|
0.60
|
0.60
|
0.60
|
|
Initial Wallace Plasticity(P0), min.
|
30
|
30
|
30
|
|
Plasticity Retention Index(PRI),min.
|
40
|
40
|
50
|
|
ML(1'+4')100℃
|
-
|
-
|
-
|
Note: SMR, STR and SIR refer to Standard Malaysia Rubber, Standard Thailand Rubber and Standard Indonesia Rubber respectively. For detailed information of above-mentioned quality standards, please see the International Standards of Quality and Packing for natural rubber Grades (Green Book revised in 1979). Besides, the technical standards in both Thailand and Indonesia are made with reference to the document mentioned above.
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