Experimental Considerations in the Measurement of Thermal Relaxation and Recovery of Strained Seals

Kurt Miller

Axel Products, Inc.

www.axelproducts.com

Available at: www.axelproducts.com.

Overview

• Elastomer Seals• Stress, Strain and Temperature• A Particular Experiment

Elastomer Seals

• Normally Compressed• Fill a Space• Provide a Reaction

Force• Survive Temperature

Changes• Survive Chemical

Attack

Stress, Strain and Temperature

• Mental Experiment• Actual Experiment

Stress, Strain and Temperature

Stress, Strain and Temperature

• Short Term Stress Relaxation

• Some Softening

Stress, Strain and Temperature

Stress, Strain and Temperature

• Thermal Expansion • Elastomer > Steel

• Thermal Softening• Thermal Degradation• Additional Crosslinking

Stress, Strain and Temperature• Thermal Expansion vs Thermal Softening

Stress, Strain and Temperature

• NOT Long Term Stress Relaxation

Stress, Strain and Temperature

Stress, Strain and Temperature

• Thermal Contraction• Reduced Reaction Force

Stress, Strain and Temperature

Stress, Strain and Temperature• Additional Thermal Contraction• Reduced or Possible Loss of Reaction Force• The Seal May go into Tension!

A Particular Experiment

A Particular Experiment

A Particular Experiment

• Example Data, Constrained Seal

A Particular Experiment

• Example Data, Constrained Seal

A Particular Experiment

• This does not replace aging experiments.

A Particular Experiment

• This does not replace aging experiments.

A Particular Experiment

• This does not replace:– Thermal Expansion by TMA– Compression Set

Overview• Bad Things Happen When Hot,

Become Evident When Cold• Experimental data is Helpful