Viscoelastic measurements on cross-linked rubbers I. Width and time position of retardation spectrum

Abstract

Viscoelastic measurements were made on rubber samples cross-linked by sulphur amounts varying from 4% to 20%. The width of the viscoelastic retardation spectrum was decreasing with increasing sulphur amount in the sample. If the dependence on the sulphur content of the spectrum position on time axis is investigated, attention must be given to temperature at which the spectra attained for samples with different sulphur content are correlated. The theoretically predicted shift of the spectra to lower times with increasing cross-link densities may be obtained from experimental results only if the spectra are reduced to the individual characteristic temperatures of the samples, e.g. to the reduced temperaturesT _s .