ASTM D256-06

    Standard Test Methods for Determining the Izod Pendulum Impact Resistance of Plastics


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    1. Scope

    1.1 These test methods cover the determination of the resistance of plastics to "standardized" (see Note 0) pendulum-type hammers, mounted in "standardized" machines, in breaking standard specimens with one pendulum swing (see Note 0). The standard tests for these test methods require specimens made with a milled notch (see Note 0). In Test Methods A, C, and D, the notch produces a stress concentration that increases the probability of a brittle, rather than a ductile, fracture. In Test Method E, the impact resistance is obtained by reversing the notched specimen 180 in the clamping vise. The results of all test methods are reported in terms of energy absorbed per unit of specimen width or per unit of cross-sectional area under the notch. (See Note 0.)

    Note 0

    The machines with their pendulum-type hammers have been "standardized" in that they must comply with certain requirements, including a fixed height of hammer fall that results in a substantially fixed velocity of the hammer at the moment of impact. However, hammers of different initial energies (produced by varying their effective weights) are recommended for use with specimens of different impact resistance. Moreover, manufacturers of the equipment are permitted to use different lengths and constructions of pendulums with possible differences in pendulum rigidities resulting. (See Section .) Be aware that other differences in machine design may exist. The specimens are "standardized" in that they are required to have one fixed length, one fixed depth, and one particular design of milled notch. The width of the specimens is permitted to vary between limits.

    Note 0

    Results generated using pendulums that utilize a load cell to record the impact force and thus impact energy, may not be equivalent to results that are generated using manually or digitally encoded testers that measure the energy remaining in the pendulum after impact.

    Note 0

    The notch in the Izod specimen serves to concentrate the stress, minimize plastic deformation, and direct the fracture to the part of the specimen behind the notch. Scatter in energy-to-break is thus reduced. However, because of differences in the elastic and viscoelastic properties of plastics, response to a given notch varies among materials. A measure of a plastic's "notch sensitivity" may be obtained with Test Method D by comparing the energies to break specimens having different radii at the base of the notch.

    Note 0

    Caution must be exercised in interpreting the results of these standard test methods. The following testing parameters may affect test results significantly:

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

    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.

    These test methods resemble ISO 180:1993 in regard to title only. The contents are significantly different.


    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

    D618 Practice for Conditioning Plastics for Testing

    D883 Terminology Relating to Plastics

    D3641 Practice for Injection Molding Test Specimens of Thermoplastic Molding and Extrusion Materials

    D4066 Classification System for Nylon Injection and Extrusion Materials (PA)

    D5947 Test Methods for Physical Dimensions of Solid Plastics Specimens

    D6110 Test Method for Determining the Charpy Impact Resistance of Notched Specimens of Plastics

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

    ISO Standard

    ISO 180:1993 PlasticsDetermination of Izod Impact Strength of Rigid Materials Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http://www.ansi.org.


    ICS Code

    ICS Number Code 29.035.20 (Plastic and rubber insulating materials)

    UNSPSC Code

    UNSPSC Code 13102000(Thermoplastic plastics)


    Referencing This Standard
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    DOI: 10.1520/D0256-06

    Citation Format

    ASTM D256-06, Standard Test Methods for Determining the Izod Pendulum Impact Resistance of Plastics, ASTM International, West Conshohocken, PA, 2006, www.astm.org

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