ASTM D790-03

Standard Test Methods for Flexural Properties of Unreinforced and Reinforced Plastics and Electrical Insulating Materials

SCOPE
1.1 These test methods cover the determination of flexural properties of unreinforced and reinforced plastics, including high-modulus composites and electrical insulating materials in the form of rectangular bars molded directly or cut from sheets, plates, or molded shapes. These test methods are generally applicable to both rigid and semirigid materials. However, flexural strength cannot be determined for those materials that do not break or that do not fail in the outer surface of the test specimen within the 5.0 % strain limit of these test methods. These test methods utilize a three-point loading system applied to a simply supported beam. A four-point loading system method can be found in Test Method D 6272.
1.1.1 Procedure A, designed principally for materials that break at comparatively small deflections.
1.1.2 Procedure B, designed particularly for those materials that undergo large deflections during testing.
1.1.3 Procedure A shall be used for measurement of flexural properties, particularly flexural modulus, unless the material specification states otherwise. Procedure B may be used for measurement of flexural strength only. Tangent modulus data obtained by Procedure A tends to exhibit lower standard deviations than comparable data obtained by means of Procedure B.
1.2 Comparative tests may be run in accordance with either procedure, provided that the procedure is found satisfactory for the material being tested.
1.3 The values stated in SI units are to be regarded as the standard. The values provided in parentheses are for information only.
1.4 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—These test methods are not technically equivalent to ISO 178.

General Information

• Status: Historical
• Publication Date: 09-Mar-2003
• ICS: 29.035.20 - Plastics and rubber insulating materials
• Technical Committee: D20 - Plastics
• Drafting Committee: D20.10 - Mechanical Properties

Relations

• Replaces: ASTM D790-02 - Standard Test Methods for Flexural Properties of Unreinforced and Reinforced Plastics and Electrical Insulating Materials
• Effective Date: 10-Mar-2003
• Replaced By: ASTM D790-07 - Standard Test Methods for Flexural Properties of Unreinforced and Reinforced Plastics and Electrical Insulating Materials
• Effective Date: 01-Sep-2007
• Referred By: ASTM E2639-12(2018) - Standard Test Method for Blast Resistance of Trash Receptacles
• Effective Date: 10-Mar-2003
• Referred By: ASTM D8069-17a - Standard Test Method for Determining Flexural Modulus of Full Section Pultruded Fiber Reinforced Polymer (FRP) Composite Members with Doubly Symmetric Cross Sections under Bending
• Effective Date: 10-Mar-2003
• Referred By: ASTM D6339-11(2019) - Standard Classification System for and Basis for Specifications for Syndiotactic Polystyrene Molding and Extrusion (SPS)
• Effective Date: 10-Mar-2003
• Referred By: ASTM D7774-22 - Standard Test Method for Flexural Fatigue Properties of Plastics
• Effective Date: 10-Mar-2003
• Referred By: ASTM C647-19 - Standard Guide to Properties and Tests of Mastics and Coating Finishes for Thermal Insulation
• Effective Date: 10-Mar-2003
• Referred By: ASTM F3390-20 - Standard Specification for 3 through 24 in. Lined Flexible Corrugated Polyethylene Pipe for Land Drainage Applications
• Effective Date: 10-Mar-2003
• Referred By: ASTM D705-99(2020) - Standard Specification for Urea-Formaldehyde Molding Compounds
• Effective Date: 10-Mar-2003
• Referred By: ASTM F3183-21 - Standard Practice for Guided Side Bend Evaluation of Polyethylene Pipe Butt Fusion Joint
• Effective Date: 10-Mar-2003
• Referred By: ASTM D4020-18 - Standard Specification for Ultra-High-Molecular-Weight Polyethylene Molding and Extrusion Materials
• Effective Date: 10-Mar-2003
• Referred By: ASTM F997-18 - Standard Specification for Polycarbonate Resin for Medical Applications
• Effective Date: 10-Mar-2003
• Referred By: ASTM D6272-17e1 - Standard Test Method for Flexural Properties of Unreinforced and Reinforced Plastics and Electrical Insulating Materials by Four-Point Bending
• Effective Date: 10-Mar-2003
• Referred By: ASTM F1504-21e1 - Standard Specification for Folded Poly(Vinyl Chloride) (PVC) Pipe for Existing Sewer and Conduit Rehabilitation
• Effective Date: 10-Mar-2003
• Referred By: ASTM F1871-20 - Standard Specification for Folded/Formed Poly (Vinyl Chloride) Pipe Type A for Existing Sewer and Conduit Rehabilitation
• Effective Date: 10-Mar-2003

Standards Content (Sample)

Designation:D 790–03
Standard Test Methods for
Flexural Properties of Unreinforced and Reinforced Plastics
1
and Electrical Insulating Materials
This standard is issued under the fixed designation D 790; 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.
This standard has been approved for use by agencies of the Department of Defense.
NOTE 1—These test methods are not technically equivalent to ISO 178.
1. Scope*
1.1 These test methods cover the determination of flexural
2. Referenced Documents
properties of unreinforced and reinforced plastics, including
2
2.1 ASTM Standards:
high-modulus composites and electrical insulating materials in
D 618 Practice for Conditioning Plastics for Testing
theformofrectangularbarsmoldeddirectlyorcutfromsheets,
D 638 Test Method for Tensile Properties of Plastics
plates, or molded shapes. These test methods are generally
D 883 Terminology Relating to Plastics
applicable to both rigid and semirigid materials. However,
D 4000 Classification System for Specifying Plastic Mate-
flexural strength cannot be determined for those materials that
rials
do not break or that do not fail in the outer surface of the test
D 5947 Test Methods for Physical Dimensions of Solid
specimen within the 5.0 % strain limit of these test methods.
Plastics Specimens
These test methods utilize a three-point loading system applied
D 6272 Test Method for Flexural Properties of Unrein-
to a simply supported beam. A four-point loading system
forced and Reinforced Plastics and Electrical Insulating
method can be found in Test Method D 6272.
Materials by Four-Point Bending
1.1.1 Procedure A, designed principally for materials that
E4 Practices for Force Verification of Testing Machines
break at comparatively small deflections.
E 691 Practice for Conducting an Interlaboratory Study to
1.1.2 Procedure B, designed particularly for those materials
Determine the Precision of a Test Method
that undergo large deflections during testing.
1.1.3 ProcedureAshall be used for measurement of flexural
3. Terminology
properties, particularly flexural modulus, unless the material
3.1 Definitions—Definitions of terms applying to these test
specification states otherwise. Procedure B may be used for
methods appear in Terminology D 883 and Annex A1 of Test
measurement of flexural strength only. Tangent modulus data
Method D 638.
obtained by Procedure A tends to exhibit lower standard
deviations than comparable data obtained by means of Proce-
4. Summary of Test Method
dure B.
4.1 Abar of rectangular cross section rests on two supports
1.2 Comparative tests may be run in accordance with either
and is loaded by means of a loading nose midway between the
procedure, provided that the procedure is found satisfactory for
supports (see Fig. 1). A support span-to-depth ratio of 16:1
the material being tested.
shall be used unless there is reason to suspect that a larger
1.3 The values stated in SI units are to be regarded as the
span-to-depth ratio may be required, as may be the case for
standard. The values provided in parentheses are for informa-
certain laminated materials (see Section 7 and Note 8 for
tion only.
guidance).
1.4 This standard does not purport to address all of the
4.2 The specimen is deflected until rupture occurs in the
safety concerns, if any, associated with its use. It is the
outer surface of the test specimen or until a maximum strain
responsibility of the user of this standard to establish appro-
(see 12.7) of 5.0 % is reached, whichever occurs first.
priate safety and health practices and determine the applica-
4.3 Procedure A employs a strain rate of 0.01 mm/mm/min
bility of regulatory limitations prior to use.
[0.01 in./in./min] and is the preferred procedure for this test
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 March 10, 2003. Published April 2003. Originally Standards volume information, refer to the standard’s Document Summary page on
approved in 1970. Last previous edition approved in 2002 as D 790 – 02. the ASTM website.
*A Summary of Changes section appears at the end of this standard.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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D790–03
TABLE 1 Flexural Strength
Values Expressed in Units of %
3
3 of 10 psi
Material Mean, 10 psi
A B C D
V V r R
r R
ABS 9.99 1.59 6.05 4.44 17.2
DAP thermoset 14.3 6.58 6.58 18.6 18.6
Cast acrylic 16.3 1.67 11.3 4.73
...