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    ASTM D3124 - 98(2019)

    Standard Test Method for Vinylidene Unsaturation in Polyethylene by Infrared Spectrophotometry

    Active Standard ASTM D3124 | Developed by Subcommittee: D20.70

    Book of Standards Volume: 08.01

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    Significance and Use

    5.1 There are three types of olefinic groups present in sufficient concentrations to warrant consideration, one or more of which can normally be found in any polyethylene (4). The three types are: trans-vinylene, R - CH = CH - R, sometimes referred to as transinternal unsaturation; vinylidene or pendent methylene, RRC = CH2; and vinyl unsaturation, R - CH = CH2, also referred to as terminal unsaturation.

    5.2 The type and quantity of these groups can influence the chemical and physical properties of the resin. Information concerning their presence may also be used to characterize or identify unknown resins or blends of resins.

    5.3 Vinylidene unsaturation represents the major portion of the unsaturation present in most low-density polyethylenes.

    5.4 Infrared spectroscopy can be used for the determination of unsaturation in polyethylene (1, 3, 5). The values determined by infrared agree with those determined by IC1 uptake (5).

    1. Scope

    1.1 This test method is applicable to all types of polyethylenes, those ethylene plastics consisting of ethylene and α-olefin copolymers longer than propylene, and blends of the above in any ratio.

    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, health, and environmental practices and determine the applicability of regulatory limitations prior to use. Specific hazards statements are given in Section 8.

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

    1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

    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

    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

    E275 Practice for Describing and Measuring Performance of Ultraviolet and Visible Spectrophotometers

    ICS Code

    ICS Number Code 83.080.20 (Thermoplastic materials)

    UNSPSC Code

    UNSPSC Code 13111016(Polyethylene); 41115408(Infrared spectrometers)

    Referencing This Standard
    Link Here
    Link to Active (This link will always route to the current Active version of the standard.)

    DOI: 10.1520/D3124-98R19

    Citation Format

    ASTM D3124-98(2019), Standard Test Method for Vinylidene Unsaturation in Polyethylene by Infrared Spectrophotometry, ASTM International, West Conshohocken, PA, 2019, www.astm.org

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