Stress-relaxation prediction techniques

Gillen, K.T., M. Celina, and R. Bernstein, Validation of improved methods for predicting long-term elastomeric seal lifetimes from compression stress-relaxation and oxygen consumption techniques. Polymer Degradation and Stability, 82(1), 25-35, 2003. 

The only stress relaxation tester commercially available is the Rapra/Monsanto SRPT (Stress Relaxation Processability Tester), although others have been described in the Uterature. The rationale behind this development is that viscosity alone is not able to predict rubber processability some elasticity characteristics must be taken into consideration. Further, since most processing problems are related to memory or relaxation effects, it makes sense to consider using stress relaxation. However, once again, this technique has found most application with compounded stock. It is claimed that the technique is sensitive to small variations in molecular weight distribution. Experience so far indicates that it may not be sensitive enough to differentiate levels of processability within grades. 

---