Engineering Rubber Properties Effects of Liquids

Effects of Liquids

Effects of Liquids

This test method attempts to simulate service conditions through controlled but accelerated testing. However, it does not give a direct correlation with actual part performance, since service conditions vary too widely. It does yield comparative data by which conclusions can be drawn as to expected service quality.

Importance

Certain rubber materials (i.e. seals, gaskets, hoses, diaphragms, and sleeves) may be exposed to oils, greases, fuels, and other fluids during service. The exposure may be continuous or intermittent, and may occur over wide temperature ranges. Properties of rubber materials deteriorate during exposure to these liquids, thus affecting the performance of the rubber part, which can result in partial failure.

Measurement

Property changes are determined for:

  1. Specimens of vulcanized rubber

  • Cut from standard sheets
  • Tensile strength, elongation, hardness, breaking resistance, burst strength
  • Cut from fabric coated with vulcanized rubber
  • Tear strength and adhesion
  • Finished commercial products
  1. Liquids used

  • That will come in contact with the specimen while in service
  • Liquid used in packing or shipping the specimen
  • Standard ATM and IRM oils
  1. Apparatus

  • Nonvolatile liquids: A glass tube with glass beads used as a bumper and to separate specimens
  • Volatile liquids: A tube tightly fitted with a stopper and a reflux condenser, suitable for the desired temperatures
  • Ovens: Suitable ovens that provide for suspending the tubes and for heating and circulating temperature-controlled air

Calculations

The change in properties are calculated as percentages based on appropriate equations as described in ASTM D471.

Results/Reporting

The following are normally included in the report:

  1. Description of the sample and its origin
  2. Date and temperature of testing room
  3. Duration, temperature, and date of vulcanization of test specimens
  4. Dates of the various periods of exposure
  5. Immersion liquid used
  6. Temperature of exposure
  7. Exposure period
  8. All observed and recorded data including the type of properties being reported
  9. Statement of condition of exposed specimens from visual and manual examination
  10. Test method used for determination of hardness
  11. Any deviations from standard test methods
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