ASTM_D_4502_-_92_2011.pdf

Designation:D450292(Reapproved 2011)Standard Test Method forHeat and Moisture Resistance of Wood-Adhesive Joints1This standard is issued under the fixed designation D4502;the number immediately following the designation indicates the year oforiginal adoption or,in the case 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 The purpose of this test method is to estimate theresistance of adhesive-bonded joints to thermal and hydrolyticdegradation.1.2 This test method is primarily for wood-to-wood jointsbut may be applied to joints of wood to other materials.1.3 The effects of chemicals such as fire retardants,preservatives,and extractives in the wood upon joint degrada-tion resistance can be estimated.1.4 This test method does not account for the effects ofstress,the other principal degrading factor,nor does it accountfor cyclic or variable temperature or moisture levels.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-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2D897 Test Method for Tensile Properties of Adhesive BondsD905 Test Method for Strength Properties of AdhesiveBonds in Shear by Compression LoadingD907 Terminology of AdhesivesD2304 Test Method for Thermal Endurance of Rigid Elec-trical Insulating MaterialsD2307 Test Method for Thermal Endurance of Film-Insulated Round Magnet WireD2339 Test Method for Strength Properties of Adhesives inTwo-Ply Wood Construction in Shear by Tension Loading2.2 IEEE Standard:IEEE No.1 General Principles for Temperature Limits in theRating of Electrical Equipment33.Terminology3.1 Definitions3.1.1 For definitions of terms used in this test method,referto Terminology D907.3.2 shear strength,nin an adhesive joint,the maximumaverage stress when a force is applied parallel to the joint.3.2.1 DiscussionIn most adhesive test methods,the shearstrength is actually the maximum average stress at failure ofthe specimen,not necessarily the true maximum stress in thematerial.4.Summary of Test Method4.1 The degradation of adhesive joints is a physicochemicalprocess.The speed of degradation is related to the levels oftemperature,moisture(and other chemicals),and physicalstress to which the joint is exposed.This test method is basedon the principles of chemical kinetics and uses the Arreheniustemperature dependence relationship to estimate the long-termeffects of heat and moisture at the service temperature.4.2 Specimens whose unaged properties have been esti-mated by control tests are subjected to an accelerated thermalor hydrolytic aging environment in groups.Aging is acceler-ated by using elevated temperature.Periodically,a group ofspecimens is removed from the aging environment and tested.The estimated property after aging and the time of aging arerecorded.After several groups have been tested in this manner,the rate of property loss in the aging environment can beestimated.This basic experiment is repeated at several otherelevated temperatures,and the rates of property loss at thosetemperatures estimated.The rate of property loss relationshipto temperature is estimated.This relationship can be extrapo-lated to lower service temperatures for estimating service life.4.3 This test method employs a smaller version of the TestMethod D905 block shear specimen,but other shear strength ortensile strength specimens may also be used.1This test method is under the jurisdiction of ASTM Committee D14 onAdhesives and is the direct responsibility of Subcommittee D14.70 on ConstructionAdhesives.Current edition approved Jan.1,2011.Published January 2011.Originallyapproved in 1985.Last previous edition approved in 2004 as D4502 92(2004).DOI:10.1520/D4502-92R11.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3Available from Institute of Electrical and Electronics Engineers,Inc.(IEEE),445 Hoes Ln.,P.O.Box 1331,Piscataway,NJ 08854-1331,http:/www.ieee.org.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 5.Significance and Use5.1 This test method can serve as a useful tool for durabilityassessment and service life forecasting.5.1.1 This test method can be used to measure the effects ofheat and moisture and the effect of their interaction onadhesives and bonded joints.Knowledge of these effects isuseful to an adhesive formulator or manufacturer.Moist heataging is particularly useful for determining the effects of acidicadhesive systems on the hydrolysis of wood adherends.5.1.2 This test metho