| Softening |
Polyurethane in contact with or splashed by harmful solvents
Polyurethane exposed to excessively high temperatures (above 200°F) |
Shield from solvents
Insulate from heat source; provide cooling |
| Deformed part |
Softened by wear |
Reduce stresses by redesigning and/or reducing load carried |
| Hardening |
Crystallization of polyurethane |
Reformulate composition |
| Blow-out |
Internal heat buildup |
Redesign to: a) conduct heat away; b) reduce stresses or loading; c) reduce internal heat buildup by reformation (harder polyurethane) |
| Polyurethane to non-polyurethane bond failure |
Overstressing
Overheating |
Redesign to reduce stresses
Reduce heat exposure; provide cooling; reduce internal heat buildup |
| Swelling |
Polyurethane exposed to harmful solvent |
Provide shield from solvent |
| Large cracks |
Local overstressing |
Redesign |
| Fatigue effects |
Crack growth |
Unlikely to correct completely; look for more specific causes as above, and correct |
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