The Effect of Plasticization of Isoprene Rubber on the Tangent of Mechanical Losses of its Vulcanizates at 60 °C

Abstract

Continuation of work on the study of the effect of plasticization (P) on the properties of SKI-3 isoprene rubber and rubbers based on it.
The influence of the molecular weight of MM SKI-3 and its fractions: ultrahigh molecular weight (UHMF), high molecular weight (HMF),
medium molecular weight (MMF) and low molecular weight (LMF) on the tangent of the angle of mechanical losses of its vulcanizates at 60°C
(tg60) has been studied. It is shown that differences in the values of MM SKI-3 do not affect the value of tg60. tg60 measurements were carried
out on an RPA 2000 device (Alpha Technologies, USA) at a dynamic deformation amplitude of 5% and a frequency of 10 Hz. The corresponding
regression equation for calculating tg60 is obtained. According to a specially created program, regression equations were obtained for the
values of tg60 at different temperatures T and times t of each of the studied fractions of SKI-3 at P. It is shown that the calculated values of
tg60 practically coincide with the experimental ones. The dependence of these values on MM fractions is shown, different depending on T and
times t, i.e. on the mechanism of processes occurring at these T and t. The average effect of each fraction on tg60 vulcanizates is estimated.
It is concluded that in order to achieve the lowest values of tg60 vulcanizates, P SKI-3 must be carried out under temperature conditions
of mechanical cracking (T < 60 °C ) and small times (t < 100 s). The lowest values of tg60 will have SKI-3 vulcanizates obtained on the basis of
rubbers with a high content of HMF and LMF.