Polymerisation Stress-strain curve

In addition to the torque-rise behaviour the steepness of the curve may be expressed with the torque/time ratio, which is the stress/strain ratio, i.e., modulus. Between the two gum-rubbers in question, there is a significant difference in modulus. The gum rubber giving a steeper curve is stiffer than the other one. The peak may be interpreted as the failure point [4]. The stiffer rubber has a smaller strain to break and the softer rubber is more deformable. The former tends to fall in Region I of mill processability and the latter in Region II. The former may contain macrogel in a significant amount, if it is an emulsion-polymerised diene rubber. See Chapters 4 and 6 for additional information. 

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