ASTM D6739-11(2015)

3.1 The pH level of silica, as measured by this test method, is known to affect the vulcanization of some rubber compounds. Refer to Test Method E70 for a fuller understanding of pH and a more detailed procedure for making pH measurements.

1.1 This test method is used to measure the pH of a 5 % silica/water suspension or mechanical dispersion and is indicative of the relative acidity or alkalinity of the silica.

1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this 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.