ASTM D256-06a

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 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.

General Information

• Status: Historical
• Publication Date: 30-Nov-2006
• ICS: 29.035.20 - Plastics and rubber insulating materials
• Technical Committee: D20 - Plastics
• Drafting Committee: D20.10 - Mechanical Properties

Relations

• Replaces: ASTM D256-06 - Standard Test Methods for Determining the Izod Pendulum Impact Resistance of Plastics
• Effective Date: 01-Dec-2006
• Replaced By: ASTM D256-06ae1 - Standard Test Methods for Determining the Izod Pendulum Impact Resistance of Plastics
• Effective Date: 01-Dec-2006
• Referred By: ASTM F3219-19 - Standard Specification for 3 to 30 in. (75 To 750 mm) Polypropylene (PP) Corrugated Single Wall Pipe and Fittings
• Effective Date: 01-Dec-2006
• Referred By: ASTM D4020-18 - Standard Specification for Ultra-High-Molecular-Weight Polyethylene Molding and Extrusion Materials
• Effective Date: 01-Dec-2006
• Referred By: ASTM F3333-20 - Standard Specification for Chopped Carbon Fiber Reinforced (CFR) Polyetheretherketone (PEEK) Polymers for Surgical Implant Applications
• Effective Date: 01-Dec-2006
• Referred By: ASTM D3965-21 - Standard Classification System and Basis for Specifications for Rigid Acrylonitrile-Butadiene-Styrene (ABS) Materials for Pipe and Fittings
• Effective Date: 01-Dec-2006
• Referred By: ASTM D1636-21 - Standard Specification for Allyl Molding Compounds
• Effective Date: 01-Dec-2006
• Referred By: ASTM D4203-17 - Standard Specification for and Basis for Specifications for Styrene-Acrylonitrile (SAN) Injection and Extrusion Materials
• Effective Date: 01-Dec-2006
• Referred By: ASTM D6713-21 - Standard Specification for Extruded and Compression Molded Shapes Made from Poly(Vinylidene Fluoride) (PVDF)
• Effective Date: 01-Dec-2006
• Referred By: ASTM D4066-13(2019) - Standard Classification System for Nylon Injection and Extrusion Materials (PA)
• Effective Date: 01-Dec-2006
• Referred By: ASTM D1562-22 - Standard Classification System and Basis for Specification for Cellulose Acetate Propionate Molding and Extrusion Compounds (CAP)
• Effective Date: 01-Dec-2006
• Referred By: ASTM D1039-16(2022) - Standard Test Methods for Glass-Bonded Mica Used as Electrical Insulation
• Effective Date: 01-Dec-2006
• Referred By: ASTM C1349-17 - Standard Specification for Architectural Flat Glass Clad Polycarbonate
• Effective Date: 01-Dec-2006
• Referred By: ASTM D1822-21 - Standard Test Method for Determining the Tensile-Impact Resistance of Plastics
• Effective Date: 01-Dec-2006
• Referred By: ASTM D707-15(2023) - Standard Classification System and Basis for Specification for Cellulose Acetate Butyrate Molding and Extrusion Compounds (CAB)
• Effective Date: 01-Dec-2006

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Please contact ASTM International (www.astm.org) for the latest information.
Designation:D256–06a
Standard Test Methods for
Determining the Izod Pendulum Impact Resistance of
1
Plastics
This standard is issued under the fixed designation D256; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (ϵ) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
comparing the energies to break specimens having different radii at the
1. Scope*
base of the notch.
1.1 These test methods cover the determination of the
NOTE 4—Caution must be exercised in interpreting the results of these
resistanceofplasticsto“standardized”(seeNote1)pendulum-
standard test methods. The following testing parameters may affect test
type hammers, mounted in “standardized” machines, in break-
results significantly:
ingstandardspecimenswithonependulumswing(seeNote2).
Method of fabrication, including but not limited to processing
technology, molding conditions, mold design, and thermal
The standard tests for these test methods require specimens
treatments;
made with a milled notch (see Note 3). In Test MethodsA, C,
Method of notching;
and D, the notch produces a stress concentration that increases
Speed of notching tool;
Design of notching apparatus;
the probability of a brittle, rather than a ductile, fracture. In
Quality of the notch;
Test Method E, the impact resistance is obtained by reversing
Time between notching and test;
thenotchedspecimen180°intheclampingvise.Theresultsof
Test specimen thickness,
Test specimen width under notch, and
all test methods are reported in terms of energy absorbed per
Environmental conditioning.
unitofspecimenwidthorperunitofcross-sectionalareaunder
1.2 The values stated in SI units are to be regarded as
the notch. (See Note 4.)
standard.Thevaluesgiveninbracketsareforinformationonly.
NOTE 1—The machines with their pendulum-type hammers have been
1.3 This standard does not purport to address all of the
“standardized” in that they must comply with certain requirements,
safety concerns, if any, associated with its use. It is the
includingafixedheightofhammerfallthatresultsinasubstantiallyfixed
responsibility of the user of this standard to establish appro-
velocity of the hammer at the moment of impact. However, hammers of
different initial energies (produced by varying their effective weights) are priate safety and health practices and determine the applica-
recommended for use with specimens of different impact resistance.
bility of regulatory limitations prior to use.
Moreover, manufacturers of the equipment are permitted to use different
NOTE 5—These test methods resemble ISO180:1993 in regard to title
lengths and constructions of pendulums with possible differences in
only. The contents are significantly different.
pendulum rigidities resulting. (See Section 5.) Be aware that other
differences in machine design may exist. The specimens are “standard-
2. Referenced Documents
ized” in that they are required to have one fixed length, one fixed depth,
2
and one particular design of milled notch. The width of the specimens is
2.1 ASTM Standards:
permitted to vary between limits.
D618 Practice for Conditioning Plastics for Testing
NOTE 2—Results generated using pendulums that utilize a load cell to
D883 Terminology Relating to Plastics
record the impact force and thus impact energy, may not be equivalent to
D3641 Practice for Injection Molding Test Specimens of
results that are generated using manually or digitally encoded testers that
Thermoplastic Molding and Extrusion Materials
measure the energy remaining in the pendulum after impact.
D4066 Classification System for Nylon Injection and Ex-
NOTE 3—The notch in the Izod specimen serves to concentrate the
stress, minimize plastic deformation, and direct the fracture to the part of trusion Materials (PA)
thespecimenbehindthenotch.Scatterinenergy-to-breakisthusreduced.
D5947 Test Methods for Physical Dimensions of Solid
However, because of differences in the elastic and viscoelastic properties
Plastics Specimens
of plastics, response to a given notch varies among materials.Ameasure
E691 Practice for Conducting an Interlaboratory Study to
of a plastic’s “notch sensitivity” may be obtained with Test Method D by
Determine the Precision of a Test Method
1
These test methods are under the jurisdiction of ASTM Committee D20 on
2
Plastics and are the direct responsibility of Subcommittee D20.10 on Mechanical For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Properties. contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Current edition approved Dec. 1, 2006. Published December
...