ASTM D256-02

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

SCOPE
1.1 These test methods cover the determination of the resistance of plastics to "standardized" (see Note 1) pendulum-type hammers, mounted in "standardized" machines, in breaking standard specimens with one pendulum swing (see Note 2). The standard tests for these test methods require specimens made with a milled notch (see Note 3). 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 breakage by flexural shock as indicated by the energy extracted from 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 4.)
Note 1—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 5.) 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 2—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 3—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 4—Caution must be exercised in interpreting the results of these standard test methods. The following testing parameters may affect test results significantly:Method of fabrication, including but not limited to processingtechnology, molding conditions, mold design, and thermaltreatments;Method of notching;Speed of notching tool;Design of notching apparatus;Quality of the notch;Time between notching and test;Test specimen thickness,Test specimen width under notch, andEnvironmental conditioning.
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. Note 5—These test methods resemble ISO 180:1993 in regard to title only. The contents are significantly different.

General Information

• Status: Historical
• Publication Date: 09-Aug-2002
• Technical Committee: D20 - Plastics
• Drafting Committee: D20.10 - Mechanical Properties

Relations

• Replaces: ASTM D256-00e1 - Standard Test Methods for Determining the Izod Pendulum Impact Resistance of Plastics
• Effective Date: 10-Aug-2002
• Replaced By: ASTM D256-02e1 - Standard Test Methods for Determining the Izod Pendulum Impact Resistance of Plastics
• Effective Date: 10-Aug-2002
• Referred By: ASTM D6098-16 - Standard Classification System and Basis for Specification for Extruded and Compression Molded Shapes Made from Polycarbonate (PC)
• Effective Date: 10-Aug-2002
• Referred By: ASTM D4020-18 - Standard Specification for Ultra-High-Molecular-Weight Polyethylene Molding and Extrusion Materials
• Effective Date: 10-Aug-2002
• Referred By: ASTM F561-19 - Standard Practice for Retrieval and Analysis of Medical Devices, and Associated Tissues and Fluids
• Effective Date: 10-Aug-2002
• Referred By: ASTM C470/C470M-23 - Standard Specification for Molds for Forming Concrete Test Cylinders Vertically
• Effective Date: 10-Aug-2002
• Referred By: ASTM D707-15(2023) - Standard Classification System and Basis for Specification for Cellulose Acetate Butyrate Molding and Extrusion Compounds (CAB)
• Effective Date: 10-Aug-2002
• Referred By: ASTM D5204-22 - Standard Classification System and Basis for Specification for Polyamide-Imide (PAI) Molding and Extrusion Materials
• Effective Date: 10-Aug-2002
• Referred By: ASTM F412-23 - Standard Terminology Relating to Plastic Piping Systems
• Effective Date: 10-Aug-2002
• Referred By: ASTM F3333-20 - Standard Specification for Chopped Carbon Fiber Reinforced (CFR) Polyetheretherketone (PEEK) Polymers for Surgical Implant Applications
• Effective Date: 10-Aug-2002
• Referred By: ASTM D3641-21 - Standard Practice for Injection Molding Test Specimens of Thermoplastic Molding and Extrusion Materials
• Effective Date: 10-Aug-2002
• Referred By: ASTM D4762-18 - Standard Guide for Testing Polymer Matrix Composite Materials
• Effective Date: 10-Aug-2002
• Referred By: ASTM F3430-20 - Standard Specification for Closed-Cell Cellular Polypropylene (PP) Corrugated Wall Stormwater Collection Chambers
• Effective Date: 10-Aug-2002
• Referred By: ASTM D4101-17e1 - Standard Classification System and Basis for Specification for Polypropylene Injection and Extrusion Materials
• Effective Date: 10-Aug-2002
• Referred By: ASTM D4673-23 - Standard Classification System for and Basis for Specification for Acrylonitrile–Butadiene–Styrene (ABS) Plastics and Alloys Molding and Extrusion Materials
• Effective Date: 10-Aug-2002

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: D 256 – 02
Standard Test Methods for
Determining the Izod Pendulum Impact Resistance of
1
Plastics
This standard is issued under the fixed designation D 256; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
NOTE 4—Caution must be exercised in interpreting the results of these
1. Scope *
standard test methods. The following testing parameters may affect test
1.1 These test methods cover the determination of the
results significantly:
resistance of plastics to “standardized” (see Note 1) pendulum-
Method of fabrication, including but not limited to processing
type hammers, mounted in “standardized” machines, in break-
technology, molding conditions, mold design, and thermal
treatments;
ing standard specimens with one pendulum swing (see Note 2).
Method of notching;
The standard tests for these test methods require specimens
Speed of notching tool;
made with a milled notch (see Note 3). In Test Methods A, C,
Design of notching apparatus;
Quality of the notch;
and D, the notch produces a stress concentration that increases
Time between notching and test;
the probability of a brittle, rather than a ductile, fracture. In
Test specimen thickness,
Test Method E, the impact resistance is obtained breakage by
Test specimen width under notch, and
Environmental conditioning.
flexural shock as indicated by the energy extracted from by
reversing the notched specimen 180° in the clamping vise. The
1.2 The values stated in SI units are to be regarded as the
results of all test methods are reported in terms of energy
standard. The values given in parentheses are for information
absorbed per unit of specimen width or per unit of cross-
only.
sectional area under the notch. (See Note 4.)
1.3 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
NOTE 1—The machines with their pendulum-type hammers have been
responsibility of the user of this standard to establish appro-
“standardized” in that they must comply with certain requirements,
priate safety and health practices and determine the applica-
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 bility of regulatory limitations prior to use.
different initial energies (produced by varying their effective weights) are
NOTE 5—These test methods resemble ISO 180:1993 in regard to title
recommended for use with specimens of different impact resistance.
only. The contents are significantly different.
Moreover, manufacturers of the equipment are permitted to use different
lengths and constructions of pendulums with possible differences in
2. Referenced Documents
pendulum rigidities resulting. (See Section 5.) Be aware that other
differences in machine design may exist. The specimens are “standard- 2.1 ASTM Standards:
2
ized” in that they are required to have one fixed length, one fixed depth,
D 618 Practice for Conditioning Plastics for Testing
2
and one particular design of milled notch. The width of the specimens is
D 883 Terminology Relating to Plastics
permitted to vary between limits.
D 3641 Practice for Injection Molding Test Specimens of
NOTE 2—Results generated using pendulums that utilize a load cell to
3
Thermoplastics Molding Extrusion Materials
record the impact force and thus impact energy, may not be equivalent to
D 4000 Classification System for Specifying Plastic Mate-
results that are generated using manually or digitally encoded testers that
3
measure the energy remaining in the pendulum after impact. rials
NOTE 3—The notch in the Izod specimen serves to concentrate the
D 4066 Classification System for Nylon Injection and Ex-
3
stress, minimize plastic deformation, and direct the fracture to the part of
trusion Materials
the specimen behind the notch. Scatter in energy-to-break is thus reduced.
D 4812 Test Methods for Unnoticed Cantilever Beam Im-
However, because of differences in the elastic and viscoelastic properties
4
pact Resistance of Plastics
of plastics, response to a given notch varies among materials. A measure
E 691 Practice for Conducting an Interlaboratory Test Pro-
of a plastic’s “notch sensitivity” may be obtained with Test Method D by
5
gram to Determine the Precision of Test Methods
comparing the energies to break specimens having different radii at the
base of the notch. 2.2 ISO Standard:
ISO 180:1993 Plastics—Determination of Izod Impact
1
These test methods are under the jurisdiction of ASTM Committee D20 on
2
Annual Book of ASTM Standards, Vol 08.01.
Plastics and are the dir
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