New ASTM reference oil adopted.

Some time ago, ASTM #2 and ASTM #3 oils were required to be labeled. As a result, some laboratories stopped using these materials for testing. However, there remained an inventory of the oils. In 1993, the manufacturer of the oils announced they would no longer be making these oils. ASTM and the CARS committee of SAE had been searching for suitable substitutes. ASTM #3 oil is the basis for classifying the oil resistance for automotive elastomers in SAE J200 and the ASTM D 2000 specifications. With the supply of the existing oils diminishing fast and a need existing for nonlabeled substitutes very strong, the search was intensified. Candidate oils from three oil companies were found and tested. These were compared to both the existing ASTM #2 and ASTM #3 oils.

Table 2 of SAE J200 rifled "Classification system for rubber materials list the basic requirements for establishing class by volume swell for elastomers. In addition, the new SAE J3000 specification for thermoplastic elastomers uses ASTM #3 oil for establishing oil classification. The classes and values from this table are shown in table 2.

[TABLE OMITTED FROM ORIGINAL PUBLICATION]

Testing

A round robin test program was set up and twelve different elastomers were tested with the six candidate oils. The goal was to have unlabeled oils with oil swell characteristics as close to the existing oils as possible. The two candidate oils from Calumet Oil Co. were found to be the closest. Although these were not exact matches and could not be expected to be so, they were very close. The results are shown in table 2.

The data above are only for one specific compound for each material. The results appear to agree closely. For most of the materials the new test oils gave a somewhat lower value for the volume swell than the old oils. The VMQ and TPV tested in No. 3 gave slighly lower values than in IRM903. For the No. 2 oil and IRM902 the same result was observed, as well as for the AEM material.

Two materials would be classified differently for the volume swell between the oil #3 and IRM903 oils. The results for the TPV material are above 80% for the IRM903 and below 80% for the No. 3 oil. The results for the ACM material are above and below 10% depending on the test oil. The remainder of the materials would be classified the same for No. 3 and IRM903 oil.

The classification of some of the compounds could change by using the IRM903 test oil in place of the No. 3 oil. When materials are at the break point of the system the differences in the results could shift where the materials are placed in the tables without changing the compounding of the material. The ways to account for or adjust the tables for these differences needs to be addressed.

Findings and actions taken

Although these oils were not exact matches, the results were accepted as the best possible matches and, at the ASMT D11 committee meeting in December, these oils were accepted as emergency substitutes. The CARS committee is meeting to determine what action is necessary to establish correlation between the old oils and the new oils. The new oils' designation are:

New OM

IRM 902 oil ASTM #2 oil

IRM 903 oil ASTM #3 oil

These oils are available commercially from R.E. Carroll Co. in Trenton, NJ. Currently, the automotive companies and their suppliers are doing correlation studies to determine the relative severity of the new oils compared to the old oils for specification purposes. At the SAE Congress in early March of 1994 in Detroit, MI the CARS committee will discuss whether any correlation studies are necessary for the J2000 table. Any interested parties are invited to attend. Information on the meetings can be obtained from the authors or from the SAE office in Warrendale, PA. Al Edmonson, Ford Motor Co., Dearborn, MI. (313)-845-4877, chairman, ASTM D11.30 responsible for D2000 table. Bill Klingensmith, Akron Rubber Development Lab, Akron, OH, [phone], chairman, CARS Committee responsible for SAE J200 table.

(1) For complete analysis of test data in round robin test program see Rubber and Plastics News, August 30, 1993.