ASTM_D_1329_-_08.pdf

Designation:D132908Standard Test Method forEvaluating Rubber PropertyRetraction at LowerTemperatures(TR Test)1This standard is issued under the fixed designation D1329;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 This test method describes a temperature-retractionprocedure for rapid evaluation of crystallization effects and forcomparing viscoelastic properties of rubber and rubber-likematerials at low temperatures.This test method is useful whenemployed in conjunction with other low-temperature tests forselection of materials suitable for low-temperature service.1.2 The values stated in SI units are to be regarded as thestandard.The values given in parentheses are for informationonly.1.3 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:2D832 Practice for Rubber Conditioning For Low Tempera-ture TestingD4483 Practice for Evaluating Precision for Test MethodStandards in the Rubber and Carbon Black ManufacturingIndustries3.Summary of Test Method3.1 This test method is carried out by(1)elongating thespecimen,(2)locking it in the elongated condition,(3)freezingit to a state of reduced elasticity,(4)releasing the frozenspecimen and allowing it to retract freely while raising thetemperature at a uniform rate,(5)measuring the length of thespecimen at regular temperature intervals while it is retracting,and(6)computing the percentage retraction at these tempera-tures from the data obtained.In practice,the temperaturescorresponding to 10%and 70%retraction are of particularimportance,and are designated as TR10 and TR70,respec-tively.4.Significance and Use4.1 The difference between the temperature at which avulcanizate retracts 10%(TR10)and the temperature at whicha vulcanizate retracts 70%(TR70)increases as the tendency tocrystallize increases.4.2 TR70 correlates with low-temperature compression set.4.3 TR10 has been found to correlate with brittle points invulcanizates based on polymers of similar type.4.4 In general,the retraction rate is believed to correlatewith low-temperature flexibility of both crystallizable andnoncrystallizable rubbers.5.Apparatus5.1 Specimen Rack,designed to maintain a slight tension onthe specimen of 7 to 21 kPa(1 to 3 psi),and to permit it to bestretched and anchored at any elongation desired up to amaximum to 350%.Means of measuring the length of thespecimen at any time during the test within an accuracy of 61mm(60.04 in.)shall be provided.The rack may be designedto hold a number of specimens at the same time.5.2 InsulatedCoolingBath,equippedwithstirrer,thermometer,and an immersion heater.A rheostat shall beincluded in the heater circuit.A suitable thermocouple-potentiometer measuring system may be substituted for thethermometer.5.3 Temperature Measurement,may be conducted in one oftwo ways:(a)a typical glass thermometer with appropriaterange and sensitivity(61C(62F);or(b)a more modernthermocouple or resistive element,electronic temperature mea-suring system,accurate to 61C.5.4 Liquid Coolant,which does not attack the test specimenunder the conditions of the test.Methanol cooled with dry iceis satisfactory for most samples.Gaseous media may beemployed as the coolant when the design of the apparatus issuch that tests using it will duplicate those obtained with thestandard liquid media.1This test method is under the jurisdiction of ASTM Committee D11 on Rubberand is the direct responsibility of Subcommittee D11.10 on Physical Testing.Current edition approved July 1,2008.Published July 2008.Originally approvedin 1954.Last previous edition approved in 2002 as D1329 02.DOI:10.1520/D1329-08.2For 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.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 5.5 An apparatus specially designed for the TR test3,4isschematically illustrated in Fig.1.The sample rack is shown onthe left,and the overall assembly on the right.The bath consistsof an unsilvered Dewar flask that is contained in an insulatingwooden frame,0.The frame contains a wide slot in front,through which the test can be observed and the temperaturesread.Other details of the apparatus are given in Section 8.6.Test Specimens6.1 The test specimens may be prepared by dieing out witha die of the design shown in Fig.2.The choice of die length isgover