Abrasion Failure

Performing laboratory tests to predict the abrasion performance of elastomers is difficult. Usually field tests are the only reliable means of testing parts. Polyurethane elastomers are generally very resistant to impingement abrasion and slightly less resistant to sliding abrasion.

Potential Causes

Incorrect Stoichiometry
Tear strength is related to abrasion resistance. In order to maximize abrasion resistance, the tear strength of the elastomer should be maximized.

Excessive Heat Buildup
Abrasion between the medium and elastomer can generate significant amounts of heat. This excessive heat generation can destroy the polyurethane. Also, as an elastomer increases in temperature, the tear resistance decreases. Since tear resistance and abrasion resistance are directly related, the abrasion resistance also generally decreases as the elastomer temperature increases.

Incorrect System Choice
As with many other elastomer problems, the correct choice of polyether versus polyester prepolymer will have a large impact on the performance of the finished part.

Solutions

Choose the Correct Stoichiometry
The tear strength of most elastomers is maximized around 100% stoichiometry. Producing elastomers at this stoichiometry should improve the abrasion resistance of the part.

Minimize Heat Buildup
Heat buildup can be dissipated with the use of a slurry, as is frequently used in mining applications.

Choose the Correct System
First and foremost, the formulation should be chosen based upon the exposure variables in the application. Polyether formulations are often chosen for systems exposed to impingement abrasion due to their higher rebound capability. For systems exposed to sliding abrasion, polyester-based formulations should be chosen. This is because polyester formulations typically have better tear resistance. Additives can also be used to lower the coefficient of friction, which results in better sliding abrasion resistance.