ASTM D572 04 - Standard Test Method For Rubber-Deterioration by Heat and Oxygen

 

 

Designation: D572 − 04 (Reapproved 2015)

Standard Test Method for

Rubber—Deterioration by Heat and Oxygen1 This standard is issued under the fixed designation D572; the number immediately following the designation indicates the year of  original origin al adoption or, in the case of revis revision, ion, the year of last revision. revision. A number in paren parenthese thesess indicates the year of last reappr reapproval. oval. A superscript epsilon (´) indicates an editorial change since the last revision or reapproval. This standard has been approved for use by agencies of the U.S. Department of Defense.

D865 Test Method for Rubber—Deterioration by Heating in D865 Test Air (Test Tube Enclosure) D3182 Practice D3182  Practice for Rubber—Materials, Equipment, and Procedures for Mixing Standard Compounds and Preparing Standard Vulcanized Sheets D3183 Practice D3183  Practice for Rubber—Preparation of Pieces for Test Purposes from Products D4483   Prac D4483 Practice tice for Eva Evalua luatin ting g Pre Precisi cision on for Test Met Method hod Standards in the Rubber and Carbon Black Manufacturing Industries

1. Sco Scope pe 1.1 Thi Thiss test method method cov covers ers a pro proced cedure ure to det determ ermine ine the relative deterioration resistance of vulcanized rubber in a high temperature and high pressure oxygen environment. There may be no ex exac actt co corr rrela elatio tion n be betw tween een th this is ac accel celer erate ated d te test st an and d natural natu ral agi aging ng of rub rubber ber because because of the var varied ied con condit dition ionss of  natural aging. This accelerated test is suitable for laboratory compound or product comparisons. NOTE  1—For evaluating rubber vulcanizates under less severe conditions more nearly approaching natural aging, the use of Test Methods D573 and D573  and  D865  D865 is  is recommended.

3. Summa Summary ry of Test Method

1.2 The values values stated in SI uni units ts are to be reg regard arded ed as the standard. The values given in parentheses are for information only.

3.1 Specim Specimens ens of vulcanized rubber rubber are exposed to a deteriorat rio rating ing infl influen uence ce at a spe specifi cified ed elev elevate ated d temp tempera eratur turee and oxygen pressure for known periods of time, after which their physical properties are determined. These are compared with the properties determined on the original specimens and the changes noted.

1.3   This standar standard d doe doess not purport purport to add addre ress ss all of the safet sa fetyy co conc ncer erns ns,, if an anyy, as asso socia ciated ted wi with th it itss us use. e. It is th thee responsibility of the user of this standard to establish appro priate safety and health practices and determine the applica(For specifi specificc bility bili ty of re regul gulato atory ry lim limitat itation ionss pri prior or to use use..  (For precautionar precau tionary y stateme statement, nt, see see Note  Note 2.)

3.2 Unless oth otherw erwise ise spe specifie cified, d, the det determ ermina inatio tion n of the physical properties shall be carried out in accordance with Test Methods D412 Methods  D412.. 3.3 Excep 3.3 Exceptt as ma may y be ot othe herw rwis isee sp spec ecifi ified ed in th this is te test st method,, the requirements method requirements of Practi Practices ces D3182  D3182 and  and  D3183  D3183 shall  shall be complied with and are made part of this test method.

2. Referenc Referenced ed Documents Documents 2.1   ASTM Standards:2 D15   Met D15 Method hod of Com Compou pound nd and Samp Sample le Pre Prepar paratio ation n for Physical Testing of Rubber Products (Withdrawn Products  (Withdrawn 1975)3 D412 Test D412  Test Methods for Vulcanized Rubber and Thermoplastic Elastomers—Tension D454 Test D454  Test Method for Rubber Deterioration Deterioration by Heat and Air Pressure D573  Test Met D573 Method hod for Rub Rubber ber—De —Deter terior ioratio ation n in an Air Oven

3.4 In case of conflict conflict bet betwee ween n the provisio provisions ns of this test method and those of detaile detailed d specifi specification cationss or test method methodss for a particular material, the latter shall take precedence. 4. Signi Significanc ficancee and Use 4.1 Rubber and rubber rubber products must must resist the deterioration of ph phys ysica icall pr prop oper ertie tiess wi with th tim timee ca caus used ed by ox oxid idati ative ve an and d thermal aging. This test method provides a way to assess these performanc perfo rmancee charac characteristic teristicss of rubbe rubber, r, under certain accelerated conditions as specified.

1

This test method is under the jurisdiction of ASTM Committee D11 Committee  D11 on  on Rubber and is the direct respo responsibil nsibility ity of Subco Subcommitte mmitteee   D11.15 on D11.15  on Degradation Tests. Current Curre nt editio edition n appro approved ved July 1, 2015. Published Published Octob October er 2015. Originally Originally approved in 1940. Last previous edition approved in 2010 as D572 – 04 (2010). DOI: 10.1520/D0572-04R15. 2 For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [email protected]. For  Annual Book of ASTM  Standards volume information, refer to the standard’s Document Summary page on the ASTM website. 3 The last app approve roved d vers version ion of this historica historicall sta standa ndard rd is ref refere erence nced d on

4.2 Pl 4.2 Pleas easee re refe ferr to th thee An Anne nex x in Test Me Meth thod od   D573   for important information on standard compounds used for precision testing for accelerated test aging evaluation. 5. Oxygen-Pr Oxygen-Pressure essure Vessel Vessel NOTE   2—Caution:   Adequate Adequate safety provi provisions sions are impor important tant when heating oxidizable organic materials in oxygen since the rate of reaction

www.astm.org.

may become very rapid in some cases, particularly if large surface area is

Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States

1

 

 

D572 − 04 (2015) having its sen having sensiti sitive ve elem element ent dir directl ectly y exp expose osed d to the oxy oxygen gen within the pressure chamber. 5.1.6 Positive, rapid, and complete circulation of the heating medium shall be maintained so as to assure accurate, uniform heating. 5.1.7 The pressure pressure chamber shall be equip equipped ped with a reliable safety valve or rupture diaphragm set for release at 3450 kPa (500 psi) of pressure. 5.1. 5. 1.8 8 No co copp pper er or br brass ass parts parts sh shall all be ex expo posed sed to th thee

expo pose sed, d, an and d ve very ry hi high gh pr pres essu sure ress ma may y be de deve velo lope ped. d. If th thee sa same me ex equipment is used for the oxygen-pressure test and the air-pressure heat test, Test Method D454 Method  D454,, care must be exercised to see that the thermostatic controls are properly set, since the specimens may react very rapidly with oxygen at the temperature of the air-pressure heat test. Liquids acceptable as heating media for one test may be hazardous when used for the other test.

5.1 The oxygen-press oxygen-pressure ure chamber shall consist of a metal vessel designed to retain an internal atmosphere of oxygen gas under pressure, with provisions for placing rubber specimens within withi n it an and d su subj bject ectin ing g th thee wh whol olee to co cont ntro rolle lled d un unif ifor orm m temperature. Because of the superior temperature control and heat transfer, metal vessels completely immersed in a liquid medium are recommended for purposes of referee tests. The apparatus shall conform to the following requirements: 5.1.1 The size of the chamber shall be optional optional but shall be such that the specimens may be suspended therein vertically without undue crowding and without touching each other or the sides of the chamber. 5.1.2 5.1 .2 The source source of heat is opt option ional al but shall be loc located ated outside of the aging chamber proper. 5.1.3 The heating medium is optio optional. nal. Water Water,, air air,, or other fluids known to be safe in the presence of oxygen may be used. Water has an advantage because of its rapid heat transfer and noncombustible nature. If air is used, the heated air shall be

atmosphere, nor valves leading to used it. in the pressure chamber and tubing or

thoroughly circulated by means of mechanical agitation, and baffles shall be used as required to prevent local overheating and dead spots. Oils or other combustible fluids are extremely hazardous in the presence of oxygen and should not be used as heating media for this test. 5.1.4 Automa Automatic tic temperature temperature control of the heating medium by means of thermostatic regulation shall be used. The regulation system shall be provided with power failure protection and over-shoot protection to prevent accidental runaway temperature increase. 5.1.5 5.1 .5 The temp tempera eratur turee sho should uld be aut automa omatica tically lly rec record orded ed overr the ent ove entire ire tes testt per period iod usi using ng a temp tempera eratur ture-m e-measu easurin ring g device dev ice cap capabl ablee of mea measur suring ing at the spe specifi cificc tem temper peratu ature re to within   61°C 1°C.. For app appara aratus tus not equ equipp ipped ed wit with h aut automa omatic tic recordi reco rding ng cap capabi abiliti lities, es, temp temperat erature ure sha shall ll be mea measur sured ed with suffficient frequency to ascerta suf ascertain in that the temper temperature ature limits specified in   10.2   are adhered to. If the pressure chamber is completely immersed, the temperature may be taken as that of  the heating medium. The sensit sensitive ive element of the temperaturetemperaturemeasuring device shall be close to the pressure chamber but not touchi tou ching ng it. If the pre pressu ssure re cha chambe mberr is not completel completely y immersed in the heating medium, the sensing element may be placed plac ed in a ther thermom mometer eter well ext extend ending ing int into o the pre pressu ssure re chamber. chambe r. The thermometer thermometer well should be filled with water water,, or oil, oi l, to a de dept pth h su sufffici icien entt to co cove verr th thee el eleme ement nt,, in or orde derr to facilitate heat transfer. If it is confirmed by actual check that the temperature of the oxygen within the chamber is the same as that of the heating medium, the temperature temperature may be taken in the heating medium instead of in the thermometer well. If air is used as the heating medium, a check of the oven temperature shall sha ll be mad madee by mean meanss of temp tempera eratur ture-i e-indi ndicati cating ng dev devices ices placed in various parts of the oven to verify the uniformity of  heating hea ting.. In any cas case, e, it is des desirab irable le to ver verify ify the rec record orded ed temperature tempera ture by checki checking ng with a temper temperatureature-indica indicating ting device

meet the specifications.

6. Sampl Sampling ing 6.1 6. 1 Th Thee sa samp mple le si size ze sh shall all be su sufffic icien ientt to all allow ow fo forr th thee determination of the original properties on three specimens and also on three or more specimens for each exposure period of  the test. At least 24 h must elapse between completion of the vulcanization of the samples and the start of the aging test. 6.2 When minimum minimum requirements requirements are specified, one test on three dumbbells shall be considered sufficient. But if the results are below the specified requirements, two additional specimens shall be prepared from the original sample and tested. Should thee re th resu sults lts of eit eithe herr of th thes esee tes tests ts be be belo low w th thee sp speci ecifie fied d requirements, the sample shall be considered to have failed to

7. Test Specimens 7.1 Dumbb Dumbbell-sha ell-shaped ped specimens prepared as descri described bed in Test Methods   D412  shall be considered standard. Their form shall be such that no mechanical, chemical, or heat treatment will be required after exposure in the pressure chamber. If any adjust adj ustmen ments ts (fo (forr exa exampl mple, e, to thi thickn ckness ess)) are nec necessa essary ry,, the they y should be performed prior to exposure. 7.2 The cro crossss-sect section ional al dim dimens ension ionss of test spe specim cimens ens for calculating the physical properties shall be measured prior to exposure in the aging chamber. Gage lines used for measuring elonga elo ngation tionss sha shall ll be app applied lied after the spe specim cimens ens hav havee bee been n aged. Only specimens of similar dimensions having approximately the same exposed areas may be compared with each other. 8. Numbe Numberr of Test Specimens Specimens 8.1 At least three test specimens specimens shall be used to determ determine ine the original physical properties of each sample and also three or mor moree spe specim cimens ens of the same mate materia riall for each exp exposu osure re period of the test. 8.2 When min minimu imum m req requir uireme ements nts are spe specifie cified, d, one test shall be made for tensile strength and elongation. If the results are below the specified requirements, two additional specimens shall be prepared from the original sample and tested. Should thee re th resu sults lts of eit eithe herr of th thes esee tes tests ts be be belo low w th thee sp speci ecifie fied d requirement requi rements, s, the sample sampless shall be consi considered dered to have failed to meet the specifications. 9. Tests of Unaged Specimens Specimens 9.1 Determ Determine ine the stressstress-strain strain properties properties or tensile strength and ultimate elongation and any other required properties of  2

 

 

D572 − 04 (2015)

the original unaged specimens within 96 h of the start of the aging period. Discard results on specimens that are found to be imperfect and retest.

11. Test of Aged Specimens 11.1 Determ 11.1 Determine ine the tensile strength and ultimate elongation elongation or th thee st stre ress ss-s -str train ain pr prop oper ertie tiess of th thee sp speci ecime mens ns,, ag aged ed fo forr different intervals, as the intervals terminate, disregarding the fact that more specime specimens ns may still be aging. In determining determining the physical properties after aging, consider as the final values the median of results from three specimens except that under the following conditions expose and test two additional specimens and use the median of the values for the five specimens:

9.2 When rubber compounds compounds are to be tested for the purpose of dete determi rminin ning g com compli plianc ancee with spe specifi cificati cations ons,, it sha shall ll be permissible to determine the original properties required in 9.1 in  9.1 simultaneously with the determination of the values after the first aging period even though the elapsed time exceeds 96 h. 10. Procedur Proceduree for Accelerated Accelerated Aging

11. 1.1. 1.1 1 If on onee or mo more re va valu lues es do no nott mee meett th thee sp speci ecifie fied d requirementss when testing for compl requirement compliance iance with specifi specifications cations,, or 11.1.2 11 .1.2 If referee tests are being made. After completion completion of  the tests, examine the broken specimens visually and manually and note their condition.

10.1 Plac 10.1 Placee the specimen specimenss for aging aging in the aging chamber chamber after it has been preheated to the operating temperature. It is recommended that not more than 10 % of the volume of the pressure chamber be occupied by rubber or oxidizable substance. Avoid simultaneous aging of a mixed group of different different compounds if possible. For instance, high-sulfur should not be aged age d with low lower er-su -sulfu lfurr com compou pounds nds,, and tho those se con contain taining ing antioxidants should not be aged with those having no antioxidants. Some migration is known to occur occur.. When startin starting g a test, flush the air out of the oxygen-pressure chamber by releasing the oxygen pressure and refilling, and check the chamber to make certain the apparatus does not leak. 10.2 The operating operating temperature temperature shall be 70 1.8°F) determined in accordance with  5.1.5  5.1.5..

6

1°C (158

12. Calc Calculat ulations ions 12.1 Expre Express ss the results of the aging test as a percent of the change cha nge in each phy physic sical al pro proper perty ty (te (tensi nsile le str streng ength, th, ulti ultimate mate elongation, or tensile stress), calculated as follows: P 5 @ ~ A 2 O ! / O # 3 100

(1)

where: P   = percen percentage tage change change in prop property erty,, O   = ori origin ginal al valu value, e, and and  A   = val value ue afte afterr agin aging. g.

6

10.3 The pressure pressure of oxyg oxygen en supplied to the aging chamber shall be 2100   6   100 kPa (300   6   15 psi) as measured by a calibrated calibra ted press pressure ure gage.

12.2 Incre Increases ases will be indicated as positive and decreases decreases as negative.

10.4 10. 4 Star Startt the aging interva intervall at the time the specimen specimenss are placed in the heated chamber chamber and contin continue ue for a measur measured ed time inter in terva val. l. Th Thee sel selec ectio tion n of su suita itabl blee in inter terva vals ls of ag agin ing g wil willl depend on the rate of deterioration of the particular materials being tested. Time intervals frequently used are 24, 48, 72, and 96 h.

13. Repo Report rt 13.1 The rep 13.1 report ort sha shall ll incl include ude the fol follow lowing ing res results ults cal calcuculated in accordance with Section  Section   12 12:: 13.1.1 13.1. 1 All observed observed and recorded data on which the calculations are based, 13.1.2 13.1. 2 Type of aging test, 13.1.3 13.1. 3 Aging interval, interval, 13.1.4 13.1. 4 Aging temperature, temperature, 13.1.5 13.1. 5 Durati Duration, on, temperature, temperature, and date of vulcan vulcanization ization of 

10.5 The aging interval 10.5 intervalss use used d sha shall ll be suc such h that the det deteerioration will not be so great as to prevent determination of the final physical properties. In experimental work, it is desirable to use a range of periods, while for routine tests of known materials, fewer intervals may be employed.

the13.1. rubber, if known, 13.1.6 6 Dates of original and final determinations determinations of physical physical properties, and 13.1.7 13.1. 7 Dimens Dimensions ions of test specime specimens. ns.

10.6 At the terminatio 10.6 termination n of the aging interval, interval, remove remove the specimens from the aging chamber, cool to room temperature on a flat surface, and allow to rest not less than 16 h nor more than 96 h before determination of the physical properties. In relievi reli eving ng the pre pressu ssure re fro from m the oxy oxygen gen-pr -pressu essure re cha chambe mberr preparatory to removing the aged specimens, it is essential that the release be slow and uniform, requiring at least 5 min so as to avoid possible formation of porosity in the specimen. Then apply to the specimens gage lines used for measuring elongations:

14. Pre Precisi cision on and Bias4 14.1 Thi 14.1 Thiss pre precis cision ion and bias section section has been pre prepar pared ed in accordance accord ance with Practic Practicee   D4483. D4483.   Refer Refer to this practice practice for terminology and other statistical calculation details. 14.2 A Type Type 2 (inter (interlabora laboratory) tory) precision precision was evalua evaluated ted in 1974. Both repeatability and reproducibility are short term, a period perio d of a few days separates replicate replicate test results. results. A test result is expressed on the basis of a median value, as specified by Test Methods D412 Methods  D412  obtained on three determinations or measurements of the property or parameter in question.

NOTE   3—Caution:  For the evaluation of rubber compounds intended for service at elevated temperatures, the above test methods may be used with an operating temperature of 80   6   1°C (176   6   1.8°F), employing time intervals as suggested in 10.4 in  10.4,,  or as otherwise agreed upon. It should be noted that by increasing the aging temperature to 80°C (176°F) from 70°C (158°F) the rate of oxidation may be expected to be approximately double, and if the rubber compound property change may be expected to be approximately double, and if the rubber compound is of a rapid aging type, or if it is contaminated with such materials as copper or manganese, the rate of oxidation may be catalyzed to such extent as to become violent.

4 Supporting data have been filed at ASTM International Headquarters and may be obtained by requesting Research Report RR:D11-1055.

3

 

 

D572 − 04 (2015)

different materials were used in the interlaboratory interlaboratory 14.3 Six different program, and were tested in three laboratories on two different days. These precision results were obtained for a variety of  compounds prepared in accordance with Methods D15 Methods  D15 prior  prior to its removal from the  Annual Book of ASTM Standards. Standards. Please see the Annex of Test Method  D573   for more details on this work.

14.4.1 The precision of this test method may be expressed in the format of the following statements that use an appropriate value val ue of   r ,   R, (r ), ) , or ( R), that is, that value to be used in decisio dec isions ns abo about ut test res result ultss (ob (obtain tained ed wit with h the test met method hod). ). The  appropriate value is that value of  r   r  or  R  associated with a mean level in the precision tables closest to the mean level under consideration at any given time, for any given material in routinee testing operat routin operations. ions.

14.4 The results of the precision calculations calculations for repeatabilrepeatability and reproducibility for both percent tensile strength change

14.5   Repeatability— The The repeatability,  r , of this test method

and pe and perc rcen entt elo elong ngati ation on ch chan ange ge ar aree gi give ven n in   Tab Table le 1, in ascending order of material average or level, for each of the materials evaluated.

has been established as the  appropriate value  tabulated in the precision tables. Two single test results, obtained under normal test method procedures, procedures, that differ differ by more than this tabulat tabulated ed r   (for (for any given level) must be con consid sidere ered d as der derived ived from different or non-identical sample populations.

TABLE 1 Type 2—Precision Results—Aging at 70°C

14.6   Reproducibility— The The reproducibility reproducibility,,   R, of th this is te test st method has been established as the  appropriate value tabulated in the precision tables. Two single test results obtained in two differen dif ferentt labora laboratories tories,, under normal test method procedures, procedures, that differ by more than the tabulated   R  (for any given level) must mu st be co cons nsid ider ered ed to ha have ve co come me fr from om di difffe fere rent nt or no nonnidentical sample populations.

Part 1—Percent 1—Percent Change in Tensile Strength, Aged 48 h at 70°C Material or Compound CR (2D) NR (1G) SBR (9B) OESBR (10B3) IIR (2E) NBR (1F) Pooled Values:

Mean Test Level −0.4 −77.6 −3.0 −2.8 −5.9 −5.6 ...

Within Laboratories Sr 3.61 1.41 2.39 7.20 4.85 15.7 7.55

r 10.2 4.0 6.76 20.4 13.7 44.4 21.4

Between Laboratories SR 8.48 ... 5.96 10.1 6.8 15.1 9.83

R   24.0 ... 16.9 28.6 19.2 42.7 27.8

14.7 The precision precision results indicate indicate that the repeatability and reproduci reprod ucibili bility ty of bot both h per percen centt ten tensile sile str streng ength th cha change nge and percent change arenot essentially the same. Also the value of elongation  r   or   R, or both,  r  does vary with the magnitude of  percen per centt elon elongat gation ion or per percen centt ten tensile sile str streng ength th cha change nge.. No values are given for (r ) or ( R) because of the near zero average values for some of the materials.

Part 2 —Percent —Percent Change in Elongation, Average of 48, 96 h Aging Precision Values NR (1G) NBR (1F) SBR (9B) OESBR (10B3) CR (2D) IIR (2E) Pooled Values:

−92.0 −15.5 −13.8 −7.8 −0.0 −4.6 ...

0.99 9.4 3.53 5.54 5.32 5.50 5.64

2.80 26.6 10.0 15.7 15.1 15.6 16.0

9.6 9.4 7.58 7.54 7.59 5.50 8.00

27.2 26.6 21.5 21.3 21.5 15.6 22.6

14.8   Bias— In In test method terminology, bias is the difference between an average test value and the reference (or true) test proper pro perty ty val value. ue. Ref Refere erence nce val values ues do not exist for this tes testt method meth od sin since ce the val value ue (of the tes testt pro proper perty) ty) is exc exclus lusive ively ly defined by the test method. Bias, therefore, cannot be determined.

NOTE  1— Sr  =  = within laboratory laboratory stand standard ard devia deviation. tion. r   = repeatability (in measurement units). SR  = betwee between n labora laboratory tory standard deviation.  R   = reproducibility (in measurement units).

15. Keyw Keywords ords 15.1 elevate elevated d temper temperature; ature; oxidative oxidative aging; pressure pressure chamber; pressure vessel; rubber articles; rubber products; thermal

NOTE 2—Averaging both 48 and 96 h of aging for Part 2 increases the

aging

DF for precision estimates.

ASTM International International takes no positi position on respecting the validi validity ty of any patent rights assert asserted ed in connec connection tion with any item mentio mentioned  ned  in this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk  of infringement of such rights, are entirely their own responsibility. This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years and  if not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standards  and should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of the  responsible respon sible technical technical committee, which you may attend. If you feel that your comments have not receiv received ed a fair hearing you should  make your views known to the ASTM Committee on Standards, at the address shown below. This standard 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 above  address addr ess or at 610610-832832-9585 9585 (pho (phone), ne), 610610-832832-9555 9555 (fax (fax), ), or serv service@ ice@astm astm.org .org (e-m (e-mail) ail);; or thro through ugh the ASTM webs website  ite  (www.astm. (www .astm.org). org). Permission Permission rights to photocopy the standa standard rd may also be secure secured d from the Copyri Copyright ght Clearance Center, Center, 222  Rosewood Drive, Danvers, MA 01923, Tel: (978) 646-2600; http://www.copyright.com/ 

4