ASTM D3451:2006 (R2017) pdf free.Standard Guide for Testing Coating Powders and Powder Coatings.
ASTM D3451 covers the determination of the acid material, which disassociates in distilled water, that is present in sulfur. The acidity is determined by an electrometric or visual titration.
The values stated in SI units are to he regarded as the standard. The values given in parentheses are for information only.
2. Referenced liocuments
ASTM D44S3 Practice for Evaluating Precision for Test Method Standards in the Rubber and Carbon Black Manufacturing Industries.
3. Significance and Use
3.1 This test method provides a means of determining the acidity of sulfur and may be used for quality control, research and development, or for any other reason for which such a determination is required. A low acidity value indicates to the user that the sulfur used should not adversely affect the vulcanization system.
4. Apparatus
4.1 pH Meter, equipped with a glass measuring electrode and calomel reference electrode, operated according to the manufacturer’s directions for optimum performance.
4.2 10 cm3 Burette, with 0.05 cm3 graduations.
4.3 Lahm-uwrv Glassware, suitable for carrying out the procedure as written.
5. Reagents
5.1 Purity of Reagents—Reagent grade chemicals shall be used in all tests. Unless otherwise indicated. it is intended that all reagents conft)rm to the specifications of the Committee on Analytical Reagents of the American Chemical Society where such specifications are available.3 Other grades may be used. provided it is first ascertained that the reagent is of’ sulliciently high purity to permit its use without lessening the accuracy of the determination.
5.2 B roinothymo! Blue— Di SSO I ye 0. 1 g of 3’,3”— dihromothymolsulfrrnphthalein in 100 cm3 of 20 % methanol or use corn mercical preparations.
5.3 Sodium Hydroxide, 0.01 N.
6. Procedure
6.1 Weigh 10.0 g of sulfur into a 500-cm2 beaker, and wet the sample with 25 cm3 of alcohol.
6.2 Add 2(X) cm3 of distilled water, and stir the wetted sulfur thoroughly.
6.3 Place the pH meter electrode in the solution and titrate with 0.01 N NaOH to a ph of 7.0. Stir the mixture constantly while titrating. When nearing the end of the titration, wait until the pH reading has reached cquilibriurn before adding additional NaOH solution to prcvcnt overshooting the end point.
6.4 If a pH meter is unavailable, add 10 drops of brornothymol blue indicator and titrate as above.ASTM D3451 pdf download.