1、Designation: D1329 08D1329 16Standard 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
2、 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-retraction procedure for rapid evaluation of crystallization effects
3、 and forcomparing viscoelastic properties of rubber and rubber-like materials at low temperatures. This test method is useful whenemployed in conjunction with other low-temperature tests for selection of materials suitable for low-temperature service.1.2 The values stated in SI units are to be regar
4、ded as the standard. The values given in parentheses are for information only.1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and deter
5、mine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D832 Practice for Rubber Conditioning For Low Temperature TestingD4483 Practice for Evaluating Precision for Test Method Standards in the Rubber and Carbon Black Manufacturing Industries3. Summary
6、 of Test Method3.1 This test method is carried out by (1) elongating the specimen, (2) locking it in the elongated condition, (3) freezing it toa state of reduced elasticity, (4) releasing the frozen specimen and allowing it to retract freely while raising the temperature at auniform rate, (5) measu
7、ring the length of the specimen at regular temperature intervals while it is retracting, and (6) computingthe percentage retraction at these temperatures from the data obtained. In practice, the temperatures corresponding to 10 % and70 % retraction are of particular importance, and are designated as
8、 TR10 and TR70, respectively.4. Significance and Use4.1 The difference between the temperature at which a vulcanizate retracts 10 % (TR10) and the temperature at which avulcanizate retracts 70 % (TR70) increases as the tendency to crystallize increases.4.2 TR70 correlates with low-temperature compre
9、ssion set.4.3 TR10 has been found to correlate with brittle points in vulcanizates based on polymers of similar type.4.4 In general, the retraction rate is believed to correlate with low-temperature flexibility of both crystallizable andnoncrystallizable rubbers.5. Apparatus5.1 Specimen Rack, design
10、ed to maintain a slight tension on the specimen of 7 to 21 kPa (1 to 3 psi), and to permit it to bestretched and anchored at any elongation desired up to a maximum to 350 %. Means of measuring the length of the specimen atany time during the test within an accuracy of 61 mm (60.04 in.) shall be prov
11、ided. The rack may be designed to hold a numberof specimens at the same time.1 This test method is under the jurisdiction of ASTM Committee D11 on Rubber and Rubber-like Materials and is the direct responsibility of Subcommittee D11.10 onPhysical Testing.Current edition approved July 1, 2008Nov. 1,
12、2016. Published July 2008November 2016. Originally approved in 1954. Last previous edition approved in 20022008 asD1329 02.D1329 08. DOI: 10.1520/D1329-08.10.1520/D1329-16.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Ann
13、ual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be
14、 technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive
15、, PO Box C700, West Conshohocken, PA 19428-2959. United States15.2 Insulated Cooling Bath, equipped with stirrer, thermometer, and an immersion heater. A rheostat shall be included in theheater circuit. A suitable thermocouple-potentiometer measuring system may be substituted for the thermometer.5.3
16、 Temperature Measurement, may be conducted in one of two ways: (a) a typical glass thermometer with appropriate rangeand sensitivity (61C (62F); or (b) a more modern thermocouple or resistive element, electronic temperature measuring system,accurate to 61C.5.4 Liquid Coolant, which does not attack t
17、he test specimen under the conditions of the test. Methanol cooled with dry ice issatisfactory for most samples. Where methanol-dry ice combination is not appropriate, other cooling media may be used to achievethe prescribed test temperatures. Gaseous media may be employed as the coolant when the de
18、sign of the apparatus is such that testsusing it will duplicate those obtained with the standard liquid media.5.5 An apparatus specially designed for the TR test3,4 is schematically illustrated in Fig. 1. The sample rack is shown on theleft, and the overall assembly on the right. The bath consists o
19、f an unsilvered Dewar flask that is contained in an insulating woodenframe, 0. The frame contains a wide slot in front, through which the test can be observed and the temperatures read. Other detailsof the apparatus are given in Section 8.3 A modified Scott T-50 tester has been used by some investig
20、ators. See Svetlik, J. F., and Sperberg, L. R., “The T-R (Temperature Retraction) Test Characterizing theLow-Temperature Behavior of Elastomeric Compositions,” India Rubber World, May, 1951, p. 182.4 See Smith, O. H., Hermonat, W. A., Haxo, H. E., and Meyer, A. W., “Retraction Test for Serviceabilit
21、y of Elastomers at Low Temperatures,” Analytical Chemistry, Vol23, 1951, p. 322.FIG. 1 Retraction ApparatusD1329 1626. Test Specimens6.1 The test specimens may be prepared by dieing out with a die of the design shown in Fig. 2. The choice of die length isgoverned by the elongation required and the l
22、imitations of the specimen racks. For most work a 38 mm (1.50 in.) die is suitable.Thickness of the specimens shall be 2.0 6 0.2 mm (0.08 6 0.01 in.). Any other method of obtaining test specimens of uniformcross section is satisfactory, provided that a suitable clamp is used on the rack.6.2 Three sp
23、ecimens per material shall be tested.7. Initial Specimen Extension7.1 The initial extension (elongation) of specimens to be tested should be chosen with the following considerations:7.1.1 To study the effect of crystallization at low temperatures use a value of either: (1) 250 %, (2) half the ultima
24、te elongationif 250 % is unobtainable, or (3) 350 % if the ultimate elongation is greater than 600 %.7.1.2 To avoid the effect of crystallization, use an elongation of 50 %.7.2 For long exposures, the 50 % elongation may be used in combination with a conditioning procedure, in accordance withPractic
25、e D832. In such studies, crystallization of the long- time conditioned specimen is indicated by the displacement of the TRcurve toward the higher temperature. Tests conducted at 50 % elongation without previous long-time conditioning have been foundto correlate fairly well with stiffness tests.8. Pr
26、ocedure8.1 Instruments are now available that may use other procedures to obtain the results listed throughout this method in detailsthat employ techniques and devices that were not available when this method was introduced in 1954 and will produce test dataequal to or better than as described in th
27、is text.NOTE 1Different models of instruments for this test position the thermocouple in relationship to the heater and stirrer at different locations. This willhave an effect on actual bath temperature; a separate thermocouple placed in at least three locations will give the user confidence in repo
28、rted temperature.8.2 Fill the bath, N (Fig. 1) to within about 50 mm (2 in.) of the top with methanol. liquid coolant. Start the stirrer, P. Cool themethanol Reduce the temperature of the liquid coolant by dipping into it, for short intervals, a wire cage filled with chopped dryice. Care must be emp
29、loyed at the beginning of this operation to prevent excessive frothing. When the temperature drops to 70C(94F) chopped dry ice can be added directly to the methanol.liquid coolant.8.3 Insert one end of the test specimen, B, in the stationary clamp, C1, at the bottom of the sample rack, A, and the ot
30、her endin the movable clamp, C. Stretch to the length desired, reading the length by means of the indicator, E, attached to the connectingwire, F, and moving over the graduated scale, G. Anchor the specimen in the elongated position by tightening the thumb nut, D.Adjust the flexible cord, H, that is
31、 attached to the wire, F, at one end and to a counterweight at the other end, so that it moves freelyover the pulley, I. (The counterweight should be 3 to 5 g heavier than the clamp and wire that it counterbalances.) Repeat thisoperation for the other specimens in the rack. Insert the thermometer, K
32、, in the holder, L.8.4 Place the rack, A, in the bath. This must be done slowly to avoid frothing. Tighten the thumb nuts, that anchor the racksupport, M, to the bath.8.5 If the temperature of the batch rises above 70C (94F) when the rack is inserted, add a little dry ice to reduce thetemperature to
33、 between 70 and 73C.8.6 Let stand 10 min, then release the thumb nuts, D, and allow the specimens to retract freely.8.7 Turn on the heater, R, and maintain a temperature rise of 1C/min (2F/min) by adjusting the rheostat.8.8 Take the first reading at 70C (94F), and continue to read the length at 2 mi
34、n intervals until retraction is 75 % completed.NOTE 2When one standard specimen length and initial elongation are maintained, temperatures at which specific degrees of retraction occur maybe read directly.8.9 If a methanol-dry liquid coolant-dry ice system does not produce temperatures low enough to
35、 freeze the specimens topractically a nonelastic state, then other cooling media may be employed.9. Calculations9.1 Calculate retraction values at any specific temperature as follows:retraction,%5Le 2Lt!/Le 2Lo!# 3100 (1)FIG. 2 Die for Preparing Test SpecimensD1329 163where:Lo = length of specimen i
36、n the unstretched condition,Le = length of specimen in the stretched condition, andLt = length of specimen at the observed temperature.9.2 Calculate the temperature at any specific retraction as follows:9.2.1 Determine the length of the test specimen at the desired retraction Lr, by means of the fol
37、lowing formula:Lr 5Le 2%retraction/100!Le 2Lo! (2)9.2.2 Note the nearest temperature corresponding to the length, Lr, and determine the exact temperature by interpolation.10. Report10.1 Report the following information:10.1.1 The median values of the following:10.1.1.1 Testing elongation, in percent
38、.10.1.1.2 Temperatures at which the specimen retracts 10, 30, 50, and 70 %.These temperatures shall be designated, respectively,as TR10, TR30, TR50, and TR70.10.1.1.3 Difference between TR10 and TR70 in degrees Celsius.10.1.2 The method or equipment used to measure temperature (glass thermometer, th
39、ermocouple, etc.).10.1.3 Length of the test specimens before elongation.10.1.4 Time and temperature of initial conditioning.10.1.5 Rate of temperature rise, and10.1.6 Coolant used.11. Precision and Bias511.1 This precision and bias section has been prepared in accordance with Practice D4483. Refer t
40、o this practice for terminologyand other statistical calculations details.11.2 AType 1 (interlaboratory) precision was evaluated in 1985. Both repeatability and reproducibility are short term, a periodof a few days separates replicate test results. A test result is the mean value, as specified in th
41、is test method, obtained on twodetermination(s) or measurement(s) of the property or parameter in question.11.3 Five different materials or compounds were used in the interlaboratory program, these were tested in two laboratories ontwo different days. One of the laboratories had two different operat
42、ors perform the testing so that a total of three different operatorswere involved. The statements are based on the testing of five compounds by three operators on two days.11.4 Standard vulcanized sheets were prepared by the supplying laboratory. Each participant die cut the test specimens. A testre
43、sult is defined to be the average of two separately prepared specimens. Precision statements were prepared for TR 10, 30, 50,70, and (70-10) where each operator determined test results in accordance with Section 9.11.5 Within laboratories, Sr values of zero were obtained for Sr for selected paramete
44、rs for several of the test compounds. Thesevalues are to no variation between the results obtained on two different test days by any of the three operators.11.6 Due to the occurrence of zero values for Sr, the values of Sr (and SR) were pooled for TR levels (10 to 70) and for materials.This was done
45、 to obtain a better estimate of the true Sr (and SR) for the expression of precision.Atabulation of the Sr and SR valuesand the results of the pooling calculations is given in Table 1. With the exception of Material 1, the values of Sr and SR areessentially constant for the other four materials. Bas
46、ed upon this the general precision for TR values (10 to 70) is given in Table2.11.7 The precision for the difference in TR (70-10) is given in Table 3. The precision of this test method may be expressed inthe format of the following statements that use what is called an appropriate value of r,R, (r)
47、, or (R), that is, that value to be usedin decisions about test results (obtained with the test method). The appropriate value is that value of r or R associated with a meanlevel in the precision tables closest to the mean level under consideration at any given time, for any given material in routin
48、e testingoperations.11.8 RepeatabilityThe repeatability r, of this test method has been established as the appropriate value tabulated in theprecision tables. Two single test results, obtained under normal test method procedures, that differ by more than this tabulated r(for any given level) must be
49、 considered as derived from different or non-identical sample populations.11.9 ReproducibilityThe reproducibility R, of this test method has been established as the appropriate value tabulated in theprecision tables. Two single test results obtained in two different laboratories, under normal test method procedures, that differ bymore than the tabulated R (for any given level) must be considered to have come from different or non-identical samplepopulations.5 Supporting data have been filed at ASTM International Headquarters and may be obtained b
