ASTM D6845 - 12

    Standard Test Method for Silica, Precipitated, Hydrated—CTAB (Cetyltrimethylammonium Bromide) Surface Area

    Active Standard ASTM D6845 | Developed by Subcommittee: D11.20

    Book of Standards Volume: 09.01


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    Significance and Use

    The CTAB molecule is relatively large; so it is not adsorbed in micropores or on surface roughness. Thus, the CTAB surface area reflects only the surface of the silica that is available for interaction with rubber molecules.

    1. Scope

    1.1 This test method covers the measurement of the specific surface area of precipitated silicas exclusive of area contained in micropores too small to admit hexadecyltrimethylammonium bromide (cetyltrimethylammonium bromide, commonly referred to as CTAB) molecules. This test method is suitable for characterizing rubber-grade silicas of all types.

    1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.

    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 (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.

    ASTM Standards

    D1193 Specification for Reagent Water

    D1799 Practice for Carbon Black--Sampling Packaged Shipments

    D1900 Practice for Carbon Black--Sampling Bulk Shipments

    D4483 Practice for Evaluating Precision for Test Method Standards in the Rubber and Carbon Black Manufacturing Industries

    E177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods

    E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method


    ICS Code

    ICS Number Code 71.100.55 (Silicones)

    UNSPSC Code

    UNSPSC Code


    Referencing This Standard

    DOI: 10.1520/D6845-12

    ASTM International is a member of CrossRef.

    Citation Format

    ASTM D6845-12, Standard Test Method for Silica, Precipitated, Hydrated—CTAB (Cetyltrimethylammonium Bromide) Surface Area, ASTM International, West Conshohocken, PA, 2012, www.astm.org

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