ASTM D3929-2003(2015) Standard Test Method for Evaluating Stress Cracking of Plastics by Adhesives Using the Bent-Beam Method《采用使用弯曲梁法的粘合剂评估塑料应力开裂的标准试验方法》.pdf

《ASTM D3929-2003(2015) Standard Test Method for Evaluating Stress Cracking of Plastics by Adhesives Using the Bent-Beam Method《采用使用弯曲梁法的粘合剂评估塑料应力开裂的标准试验方法》.pdf》由会员分享，可在线阅读，更多相关《ASTM D3929-2003(2015) Standard Test Method for Evaluating Stress Cracking of Plastics by Adhesives Using the Bent-Beam Method《采用使用弯曲梁法的粘合剂评估塑料应力开裂的标准试验方法》.pdf（5页珍藏版）》请在麦多课文档分享上搜索。

1、Designation: D3929 03 (Reapproved 2015)Standard Test Method forEvaluating Stress Cracking of Plastics by Adhesives Usingthe Bent-Beam Method1This standard is issued under the fixed designation D3929; the number immediately following the designation indicates the year oforiginal adoption or, in the c

2、ase of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method describes a procedure for determiningthe compatibility of adhesives with

3、 plastics based on whetherthe adhesive causes cracking of stressed samples.1.2 Specimen configurations and test fixture designs aregiven.1.3 This test method is suitable for products in the form ofsheet or strip. It can also be used on injection molded tensilespecimens or flexural bars.1.4 The value

4、s stated in SI units are to be regarded as thestandard. The inch-pound units given in parentheses are forinformation only.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-

5、priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D638 Test Method for Tensile Properties of PlasticsD790 Test Methods for Flexural Properties of Unreinforcedand Reinforced Plastics and Electrical Ins

6、ulating Materi-alsD907 Terminology of Adhesives3. Terminology3.1 DefinitionsMany of the terms in this test method aredefined in Terminology D907.3.2 Definitions of Terms Specific to This Standard:3.2.1 cracking, na continuous localized failure of theplastic, leading to loss of structural integrity.3

7、.2.2 crazing, napparent fine cracks at or under thesurface of a plastic.3.2.2.1 DiscussionThis is a form of localized yielding ofthe plastic due to the combined action of stress and an attackingmedium. Initial crazing may be detectable only by inspectionunder magnification.3.2.3 failure, nan arbitra

8、ry point defined by the initialdetection of cracks or crazes.4. Summary of Test Method4.1 This test method involves the qualitative determinationof the compatibility of adhesives with plastics by observing theeffect of adhesives applied in the liquid state on stressed plasticspecimens. Bars of plast

9、ic are bent in a three-point loadingfixture to cause a predetermined initial tensile stress on thesurface of the bar. The liquid adhesive is then applied to thearea of maximum stress which is checked periodically forcrazing or cracking.4.1.1 Due to the stress relaxation behavior of certainplastics,

10、initial stress only can be determined and the stresslevel may decrease significantly during the course of the test.5. Significance and Use5.1 This test method is designed for obtaining a qualitativeestimate of the compatibility of plastics and adhesives. Due tothe many process variables associated w

11、ith the fabrication ofplastic parts, it is not possible to use this test as a substitute forcompatibility tests on actual parts.5.2 The detection of cracks or crazes may be determinedwith or without optical aid. Make comparisons only amongtests employing crack detection methods of equivalent sensi-t

12、ivity.6. Apparatus6.1 Test FixturesBent beam test fixtures (see Fig. 1)3aredesigned to place the specimen in three-point bending. The1This test method is under the jurisdiction of ASTM Committee D14 onAdhesives and is the direct responsibility of Subcommittee D14.40 on Adhesives forPlastics.Current

13、edition approved Sept. 1, 2015. Published September 2015. Originallyapproved in 1980. Last previous edition approved in 2010 as D3929 03 (2010)1.DOI: 10.1520/D3929-03R15.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annu

14、al Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Detailed drawings are shown in Figs. 35. Also necessary to complete the testfixture are the following parts: 2 pieces at 6 by 38 mm (14 by 112-in.) dowel pinsand 2 pieces of M40.7 (832 unc)

15、by 32 mm (114-in.) socket head cap screws.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1amount of deflection is adjustable as well as the loading span.Other fixtures may be used as long as specimen deflection isknown.6.2 The amount

16、of deflection on the specimen is measuredby use of a dial gage indicator or a vernier caliper having adepth indicator (see Fig. 2). Use a measuring device capable ofreading to 0.025 mm (0.001 in.).7. Test Specimen7.1 The preferred specimen is a flexural bar designed inaccordance with Test Methods D7

17、90.Depth 6.4 mm (14 in.)Width 13 mm (12 in.)Length 130 mm (5 in.)Loading Span 100 mm (4 in.)L/d 16/1Tensile bars, such as Type I in Test Method D638, can alsobe used. Specimens of rectangular section may also be cut fromsheets or molded plastic articles.7.2 Mold specimens in a low-stress condition o

18、r anneal sothat molded-in stresses will not have a significant effect.7.3 Carefully cut or machine specimens in accordance withthe plastic manufacturers recommended procedures to avoidintroducing stresses at machined surfaces.8. Procedure8.1 Place the plastic test specimen in the test fixture at the

19、required loading (see Fig. 6).8.2 Apply adhesive to be tested to the center point on thelength of the loaded specimen. Cover a specimen length ofapproximately 25 mm (1 in.). In general, apply the adhesiveonly once, as would be the case in an actual end-use applica-tion.8.2.1 If the adhesive contains

20、 a solvent, allow it to evaporateat a normal rate.8.2.2 If the adhesive is a curing type, cure in a normalfashion.8.2.3 If the adhesive is a hot melt, apply at the normalapplication temperature and then allow to cool. This is a lesssevere condition than would occur if the adhesive werecontinually ap

21、plied, but is more consistent with situations thatoccur in actual adhesive use.8.3 Control SpecimensConcurrently run one controlspecimen with the test specimens in the same location. Exces-sive molded-in stresses or airborne solvent vapors may causestress cracking even without application of adhesiv

22、e.9. Stress Calculations9.1 The equation given below is valid only for specimens ofrectangular cross section at stresses below the elastic limit ofthe material. The deflection is based on initial stress only. Thelevel of stress will normally decrease with time as the plasticundergoes relaxation. Def

23、lection is calculated based on thedesired stress level as follows:D 5 SL2/6 dE (1)where:D = deflection, m (in.),S = stress, Pa (psi),L = loading span, m (in.),d = specimen depth, m (in.), andE = modulus of the plastic, Pa (psi).NOTE 1This equation holds for rectangular specimens only.9.2 If it is de

24、sired to run tests on the basis of constant strain,the following formula can be used:D 5rL26 d(2)where r = strain, m m (in./in.).9.3 Tensile stress and strain values represent the maximumlevel at the surface of the specimen in the area to whichadhesive is applied. This is mid-span in the three-point

25、 loadingarrangement.10. Choice of Test Conditions10.1 Suggested stress levels for testing are 7, 14, and 21MPa (1000, 2000, and 3000 psi). For initial screening, 21 MPa(3000 psi) is recommended since incompatible adhesives willcause rapid crazing or cracking. Lower stress levels may beused for disce

26、rning finer differences in materials.10.2 Testing can also be based on constant strain if this ismore meaningful for particular end-use applications.10.3 The test duration is 5 days for adhesives that harden orcure. For adhesives that remain in the liquid state on thespecimens (for example, anaerobi

27、c adhesives), the test shouldbe extended to 10 days.10.4 Maintain environmental conditioning at 23 6 2C (736 3.5F), 50 6 5 % RH. Specify other conditions as agreed toby user and manufacturer.FIG. 1 Test Fixture with Plastic Bar in PlaceD3929 03 (2015)210.5 Since stress cracking is more likely to occ

28、ur immedi-ately after application of the adhesive, it is desirable to observethe specimens at frequent intervals in the beginning of the test.A suggested observation schedule is as follows: 1 min, 5 min,1 h, 24 h, and daily thereafter.FIG. 2 Measurement of Test Bar Deflection with Depth Gage of Vern

29、ier CaliperFIG. 3 Test Fixture Frame(All dimensions in mm (in.) unless otherwise stated.)D3929 03 (2015)311. Inspection of Specimens11.1 Determine the presence of cracks or crazes by carefulvisual observation.NOTE 2Magnification may be used upon agreement by user andmanufacturer.11.2 If adhesives ar

30、e not transparent, remove sufficientadhesive to determine if cracks or crazes are present.12. Report12.1 Report the results of the test as the absence or presenceof cracks or crazes at a given stress level. If cracks or crazes arepresent, the time required for their occurrence is also reported.Repor

31、t the following specific items:12.1.1 Specimen identification,12.1.2 Material name or specification code,12.1.3 Adhesive identification,12.1.4 Stress level,12.1.5 Type and orientation of specimen used and method offabrication (injection molded, tensile specimen, annealed, etc.),12.1.6 Detailed descr

32、iption of test environment (forexample, temperature, humidity, exposure time), and12.1.7 Remarks concerning the size and appearance ofcracks or crazes may be included if significant.NOTE 3Indicate magnification techniques used for inspection, if any.13. Precision and Bias13.1 No information is prese

33、nted about either the precisionor bias of Test Method D3929 for evaluating stress cracking ofplastics by adhesives since the test result is nonquantitative.14. Keywords14.1 adhesive compatibility; bent-beam; cracking; crazing;liquid adhesive; stress crackingFIG. 4 Test Fixture Center Loading Bar(All

34、 dimensions in mm (in.) unless otherwise stated.)FIG. 5 Test Fixture Top Plate(All dimensions in mm (in.) unless otherwise stated.)FIG. 6 Cut-Away View of Sample Mounted in Fixture(All dimensions in mm (in.) unless otherwise stated.)D3929 03 (2015)4ASTM International takes no position respecting the

35、 validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is

36、 subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Hea

37、dquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This st

38、andard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the Copyright Clearance Center, 222Rosewood Drive, Danvers, MA 01923, Tel: (978) 646-2600; http:/ 03 (2015)5