Elastomer (Rubber) Testing

Elastomers, which are a particular kind of polymer, are a category of pliable plastic material that are good at insulating, withstanding deformation, and molding into different shapes.  Both natural and artifical rubber are considered elastomers, which are found in a wide varitey of applications, such as tires, hoses, linings, medical components, tennis shoes, and the insulation covering speaker caples and telephone lines.  Many industries including automobile, sports, electronics, and assembly line factories, rely on parts made from elastomers.  This is because elastomers are easy to sculpt when they are in a softened, resinous state.  Yet once they harden, they remain impervious to changes in temperature as well as stress like stretching or compressing.

Failure analysis of these components is critical to the environment and application to determine the root cause of a failure. Failures can range from the following basic causes.

• Manufacturing Issues
• Damage during Installation
• Unexpected Service Conditions
• Out of Dimensional Tolerances
• Out of Customers Specifications
• Incorrect Design
• Processing Issues
• Material Issues
• Product Misuse

To more advance range of failures as seen in rubber to metal or plastic parts can have a more complex root cause. In these types of applications the root cause can be more than one the above listed along with the following.

• Surface contamination
• Chemistry of failed layer
• Poor primer or adhesive
• Overheating of adhesive or primer
• Poor Phosphate Coating

The elastomer specialist has to use deductive reasoning and analytical methods to determine modes of failures in all types of elastomers and the environment in which the failure has occurred in order to conduct an accurate failure analysis.

Example 1: A connector for an electric connection system shorted out do to electrical serge from the connector connection. After carefully visual and analytical testing using Thermal Gravimetric Analysis (TGA) and manufacturing observations along with dielectrically testing of the suspect connector it was determined that cross contamination of carbon was introduce during performing of the material before vulcanization took place, thus resulting in a dielectric failure.

Example 2: A rubber manufacture had a quality issue with a rubber to metal connector seal. The connector seal was consistently forming blisters around the bonding area. After carefully visual and analytical testing using a Fourier Transform Infrared Spectrophotometer (FTIR) and manufacturing observations it was determined that surface contamination was introduced during the metal insert primer preparation, thus resulting in the blister failures.