IN this paper a brief review of the development of synthetic rubbers is first given. The difficulty encountered in substituting the synthetic for natural rubber is discussed, and it is pointed out that, from the consideration of their molecular structure, one should not expect the two rubbers to be inter-changeable in every way, but that special handling technique undoubtedly will have to be developed.
Results of certain vulcanizable synthetic rubbers in two typical rubber formulas are compared with one another and with natural rubber.
A new dynamic test is described, and the results of these same rubbers in the same formulas as used for the compounding tests are given.
Data on the dynamic modulus, internal friction, resilience and heat build-up are also presented.
It also is shown that, with one particular type of synthetic rubber, a relatively low loading of carbon black is necessary in order to give physical properties which approach those of natural rubber when measured by the same test.