ISO/TC 45/SC 3/WG 4 - Natural rubber

This document specifies guidance on the specification of technically specified rubber (TSR). A grading system is proposed, based on the origin of the natural rubber content and on properties exhibited by the rubber. This document is intended for use by parties involved in the procurement of TSR and is intended to form a basis from which requirements for a particular case may be more closely specified. As such, it describes a number of criteria that need to be the subject of appropriate agreement between the interested parties.

This document specifies two methods to determine the colour of raw natural rubber according to a standard colour scale: — Method A: colour matching against standard coloured glasses; — Method B: colour determination using colour spectrophotometer. In case of dispute, the preferred method is Method B.

This document specifies a method for the determination of gel content for technically specified rubbers (TSR).

This document specifies a macro-method and a semi-micro method for the determination of nitrogen in raw natural rubber and in natural rubber latex using variants of the Kjeldahl process. NOTE The determination of nitrogen in natural rubber is usually carried out in order to arrive at an estimate of the protein content. Minor amounts of non-proteinous nitrogen containing constituents are also present. However, in the dry solids prepared from natural rubber latex, these materials can make a substantial contribution to the total nitrogen content.

ISO 2930:2017 specifies a method for determining the plasticity retention index (PRI) of raw natural rubber. The PRI is a measure of the resistance of raw natural rubber to thermal oxidation. A high resistance to thermal oxidation is shown as a high value of the index. PRI is not an absolute value and cannot give an absolute classification of plasticity number of different natural rubber after oxidation.

ISO 20299-2:2017 specifies the material and physical property requirements for non-strippable low density polyethylene film for wrapping natural rubber bales comprising of block natural rubber of 33,33 kg or 35 kg and natural rubber ribbed smoked sheets including bales of 33,33 kg, 35 kg, 50 kg and 111,11 kg, or any other bale weights as mutually agreed between the parties, and intended to keep the bales separate during transportation and storage.

ISO 1434:2016 specifies two methods for the determination of the amount of bale coating present on the outside wrapper sheets of bales of natural rubber: - ashing method; - brushing or scraping method. The ashing method is the preferred method.

ISO 249:2016 specifies a method for the determination of the dirt content of raw natural rubber. It is not applicable to dirt present as surface contamination.

ISO 1658:2015 specifies - physical and chemical tests on raw natural rubbers; - standard materials, standard test formulae, equipment and processing methods for evaluating the vulcanization characteristics of natural rubber (NR).

ISO 6225-1:2006 specifies a thin-layer chromatographic method for the determination of the castor oil and castor oil glyceride content of raw rubber. It is applicable to all grades of natural rubber. The lower limit of detection is approximately 0,05 % of castor oil glycerides.

ISO 16564:2004 specifies a method of determining the average molecular mass and the molecular-mass distribution of raw natural rubber dissolved in tetrahydrofuran. A set of polystyrene standards is used for calibration purposes (i.e. the method is a relative one). An alternative method, using cyclohexane as solvent and polyisoprene standards, is included in an informative annex.

Applicable to all grades of natural rubber. The principle is based on extraction of any free ricinoleic acid and conversion to the acetate of methyl ricinoleate. Extraction of any castor oil glycerides also present, hydrolysis to ricinoleic acid, and conversion to the corresponding acetate of methyl ricinoleate. Determination of the total acetate by gas chromatography by comparison either with a ricinoleic acid standard, or with ricinoleic acid prepared by hydrolysis of a castor oil standard.

Deals with the method given for uncompounded natural rubber and uncompounded synthetic rubbers which do not contain chlorine, and the corresponding uncompounding latices. Principle, reagents, apparatus, sampling and procedure, especially the preparation of the test piece are described. Special precautions and safeguards required are given.

ISO 1656:2014 specifies a macro-method and a semi-micro method for the determination of nitrogen in raw natural rubber and in natural rubber latex using variants of the Kjeldahl process.

ISO 249:2014 specifies a method for the determination of the dirt content of raw natural rubber. It is not applicable to dirt present as surface contamination.

ISO 2000:2014 provides guidance on the specification of technically specified rubber (TSR). A grading system is proposed, based on the origin of the natural rubber content and on properties exhibited by the rubber. ISO 2000:2014 is intended for use by parties involved in the procurement of TSR, and is intended to form a basis from which requirements for a particular case may be more closely specified. As such, it describes a number of criteria that need to be the subject of appropriate agreement between the interested parties.

ISO 17278:2013 specifies a method for the determination of gel content for technically specified rubbers (TSR).

ISO 4660:2011 specifies a method of determining the colour of raw natural rubber according to a standard colour scale.

ISO 2930:2009 specifies a method for determining the plasticity retention index (PRI) of raw natural rubber. The PRI is a measure of the resistance of raw natural rubber to thermal oxidation. A high resistance to thermal oxidation is shown as a high value of the index.

ISO 1658:2009 specifies physical and chemical tests on raw natural rubbers; standard materials, standard test formulae, equipment and processing methods for evaluating the vulcanization characteristics of natural rubber (NR).

ISO 2000:2003 provides guidance on the specification of technically specified rubber (TSR). A grading system is proposed, based on the origin of the natural rubber content and on properties exhibited by the rubber. This International Standard is intended for use by parties involved in the procurement of TSR, and is intended to form a basis from which requirements for a particular case may be more closely specified. As such, it describes a number of criteria that will need to be the subject of appropriate agreement between the interested parties.

Specifies a method for the determination of the dirt content of raw natural rubber. Not applicable to dirt present as surface contamination. Replaces the second edition which has been technically revised.

Describes an ashing procedure for the determination of the amount of bale coating present on the outside wrapper sheets of bales of natural rubber. Contains also a brushing and scraping procedure for the determination of the amount of bale coating on the outside wrapper sheets of all grades of smoked sheet rubbers. Replaces the first edition which has been technically revised.

Cancels and replaces the second edition (1981). Specifies a method for determining the plasticity retention index (PRI) of raw natural rubber. The PRI is a measure of the resistance of raw natural rubber to thermal oxidation. A high resistance to thermal oxidation is shown as a high value of the index.

Specifies physical and chemical tests on raw natural rubbers and standard materials, standard test formulae, equipment and processing methods for evaluating the vulcanization characteristics of natural rubber.

Specifies the minimum quality requirements and the corresponding methods of test for six grades of raw natural rubber. A table delivers the maximum dirt content and some other characteristics for these grades.