Astm D 5044 – 02 pdf free download

Standard Test Method for
Rubber Chemicals—Free 2-Mercaptobenzothiazole (MBT) in
Benzothiazyl Disulfide (MBTS)1

This standard is issued under the fixed designation D 5044; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of the last revision. A number in parentheses indicates the year of the last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.

1. Scope

1.1 This test method describes the procedure for estimation
of the acidic impurities in benzothiazole disulfide (MBTS).

1.2 The values stated in SI units are to be regarded as the
standard.

1.3 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

2. Referenced Documents

2.1 ASTM Standards:
D 1193 Specification for Reagent Water2
D 4483 Practice for Determining Precision for Test Method
Standards in the Rubber and Carbon Black Industries3

3. Summary of Test Method

3.1 A sample of MBTS is dissolved in a solvent. After
the addition of an acetate buffer, water, and starch solution, the
solution is titrated with iodine.

3.2 MBTS is sparingly soluble in any organic solvent. MBT,
a major impurity in MBTS, is very soluble. Stirring therefore
will dissolve MBT, MBTS could stay undissolved.

4. Significance and Use

4.1 2-Mercaptobenzothiazole (MBT) is usually the major
impurity in MBTS. Free MBT may be determined by this test
method.

4.2 MBT and MBTS are used for rubber and latex vulcanization acceleration. The amount of MBT in MBTS may be of
importance in predicting performance in rubber compounds
and for raw material purchase and control.

4.3 This test method may be used as a quality control tool
and for research and development work.