ASTM D3929-96e1

Standard Test Method for Evaluating Stress Cracking of Plastics by Adhesives Using the Bent-Beam Method

SCOPE
1.1 This test method describes a procedure for determining the compatibility of adhesives with plastics based on whether the adhesive causes cracking of stressed samples.  
1.2 Specimen configurations and test fixture designs are given.  
1.3 This test method is suitable for products in the form of sheet or strip. It can also be used on injection molded tensile specimens or flexural bars.  
1.4 The valuesstated in inch-pound units are to be regarded as the standard. The SI units given in parentheses are for information only.  
1.5 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.

General Information

• Status: Historical
• Publication Date: 01-Jun-1997
• ICS: 83.080.01 - Plastics in general
• ICS: 83.180 - Adhesives
• Technical Committee: D14 - Adhesives
• Drafting Committee: D14.40 - Adhesives for Plastics

Relations

• Replaced By: ASTM D3929-03 - Standard Test Method for Evaluating Stress Cracking of Plastics by Adhesives Using the Bent-Beam Method
• Effective Date: 10-Apr-2003
• Referred By: ASTM D6465-99(2016) - Standard Guide for Selecting Aerospace and General Purpose Adhesives and Sealants
• Effective Date: 02-Jun-1997

Standards Content (Sample)

NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
e1
Designation: D 3929 – 96
Standard Test Method for
Evaluating Stress Cracking of Plastics by Adhesives Using
the Bent-Beam Method
This standard is issued under the fixed designation D 3929; 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.
e NOTE—Editorial changes were made throughout in June 1997.
1. Scope 3.2.2.1 Discussion—This is a form of localized yielding of
the plastic due to the combined action of stress and an attacking
1.1 This test method describes a procedure for determining
medium. Initial crazing may be detectable only by inspection
the compatibility of adhesives with plastics based on whether
under magnification.
the adhesive causes cracking of stressed samples.
3.2.3 failure, n—an arbitrary point defined by the initial
1.2 Specimen configurations and test fixture designs are
detection of cracks or crazes.
given.
1.3 This test method is suitable for products in the form of
4. Summary of Test Method
sheet or strip. It can also be used on injection molded tensile
4.1 This test method involves the qualitative determination
specimens or flexural bars.
of the compatibility of adhesives with plastics by observing the
1.4 The values stated in inch-pound units are to be regarded
effect of adhesives applied in the liquid state on stressed plastic
as the standard. The SI units given in parentheses are for
specimens. Bars of plastic are bent in a three-point loading
information only.
fixture to cause a predetermined initial tensile stress on the
1.5 This standard does not purport to address all of the
surface of the bar. The liquid adhesive is then applied to the
safety concerns, if any, associated with its use. It is the
area of maximum stress which is checked periodically for
responsibility of the user of this standard to establish appro-
crazing or cracking.
priate safety and health practices and determine the applica-
4.1.1 Due to the stress relaxation behavior of certain plas-
bility of regulatory limitations prior to use.
tics, initial stress only can be determined and the stress level
2. Referenced Documents may decrease significantly during the course of the test.
2.1 ASTM Standards:
5. Significance and Use
D 638 Test Method for Tensile Properties of Plastics
5.1 This test method is designed for obtaining a qualitative
D 790 Test Methods for Flexural Properties of Unreinforced
estimate of the compatibility of plastics and adhesives. Due to
and Reinforced Plastics and Electrical Insulating Materi-
2 the many process variables associated with the fabrication of
als
plastic parts, it is not possible to use this test as a substitute for
D 907 Terminology of Adhesives
compatibility tests on actual parts.
3. Terminology 5.2 The detection of cracks or crazes may be determined
with or without optical aid. Make comparisons only among
3.1 Definitions—Many of the terms in this test method are
tests employing crack detection methods of equivalent sensi-
defined in Terminology D 907.
tivity.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 cracking, n—a continuous localized failure of the
6. Apparatus
plastic, leading to loss of structural integrity.
6.1 Test Fixtures—Bent beam test fixtures (see Fig. 1) are
3.2.2 crazing, n—apparent fine cracks at or under the
designed to place the specimen in three-point bending. The
surface of a plastic.
amount of deflection is adjustable as well as the loading span.
Other fixtures may be used as long as specimen deflection is
known.
This test method is under the jurisdiction of ASTM Committee D-14 on
Adhesives and is the direct responsibility of Subcommittee D14.40 on Adhesives for
Plastics.
Current edition approved March 10, 1996. Published May 1996. Originally Detailed drawings are shown in Figs. 3-5. Also necessary to complete the test
1 1
published as D 3929 – 80. Last previous edition D 3929 – 93. fixture are the following parts: 2 pieces at ⁄4by 1 ⁄2-in. dowel pins and 2 pieces of
8 1
Annual Book of ASTM Standards, Vol 08.01. ⁄32 by 1 ⁄4-in. socket head cap screws.
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NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
e1
D3929–96
7. Test Specimen
7.1 The preferred specimen is a flexural bar designed in
accordance with Test Methods D 790.
Depth ⁄4in. (6.4 mm)
Width ⁄2in. (13 mm)
Length 5 in. (130 mm)
Loading Span 4 in. (100 mm)
L/d 16/1
Tensile bars, such as Type I in Test Method D 638, can also
be used. Specimens of rectangular section may also be cut from
sheets or molded plastic articles.
7.2 Mold specimens in a low-stress condition or anneal so
that molded-in stresses will not have a significant effect.
7.3 Carefully cut or machine specimens in accordance with
the plastic manufacturers’ recommended procedures to avoid
introducing stresses at machined surfaces.
8. Procedure
8.1 Place the plastic test specimen in the test fixture at the
required loading (see Fig. 6).
8.2 Apply adhesive to be tested to the center point on the
length of the loaded specimen. Cover a specimen length of
FIG. 1 Test Fixture with Plastic Bar in Place
approximately 1 in. (25 mm). In general, apply the adhesive
only once, as would be the case in an actual end-use applica-
tion.
6.2 The amount of deflection on the specimen is measured
8.2.1 If the adhesive contains a solvent, allow it to evaporate
by use of a dial gage indicator or a vernier caliper having a at a normal rate.
depth indicator (see Fig. 2). Use a measuring devi
...