ASTM D6645 - 01(2010)

    Standard Test Method for Methyl (Comonomer) Content in Polyethylene by Infrared Spectrophotometry

    Active Standard ASTM D6645 | Developed by Subcommittee: D20.70

    Book of Standards Volume: 08.03


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    Significance and Use

    This method determines the number of branches (that is, comonomer content) in copolymers of ethylene with 1-butene, 1-hexene or 1-octene. This information can be correlated with physical properties such as melting point, density, and stiffness, all of which depend on the degree of crystallinity of the polymer. Differences in the comonomer content thus may have a significant effect on the final properties of products made from these resins.

    1. Scope

    1.1 This test method covers the determination of methyl groups (that is, comonomer content) in polyethylenes by infrared spectrophotometry. The test method is applicable to copolymers of ethylene with 1-butene, 1-hexene, or 1-octene having densities above 900 kg/m3. High-pressure low-density polyethylenes (LDPE) and terpolymers are excluded.

    1.2 The values stated in SI units, based on , 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.

    Note 1—There is no known ISO equivalent to this standard.


    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

    D792 Test Methods for Density and Specific Gravity (Relative Density) of Plastics by Displacement

    D1505 Test Method for Density of Plastics by the Density-Gradient Technique

    D1898 Practice for Sampling of Plastics

    D2238 Test Methods for Absorbance of Polyethylene Due to Methyl Groups at 1378 cm-1

    D3124 Test Method for Vinylidene Unsaturation in Polyethylene by Infrared Spectrophotometry

    D5576 Practice for Determination of Structural Features in Polyolefins and Polyolefin Copolymers by Infrared Spectrophotometry (FT-IR)

    E131 Terminology Relating to Molecular Spectroscopy

    E168 Practices for General Techniques of Infrared Quantitative Analysis

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

    E932 Practice for Describing and Measuring Performance of Dispersive Infrared Spectrometers

    E1421 Practice for Describing and Measuring Performance of Fourier Transform Mid-Infrared (FT-MIR) Spectrometers: Level Zero and Level One Tests


    ICS Code

    ICS Number Code 19.100 (Non-destructive testing); 83.080.20 (Thermoplastic materials)

    UNSPSC Code

    UNSPSC Code 13111016(Polyethylene)


    DOI: 10.1520/D6645-01R10

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