The Possibility of using Complex Anti-Agers for Rubber Compounds Based on Polyisoprene Rubbers and Operating under Extreme Conditions

Abstract

The effect of complex anti-agers on the behaviour under extreme conditions of rubber compounds based on SKI-3 isoprene rubber was studied. Data for rubber compounds containing only N-isopropyl-N-phenyl-p-phenylenediamine (IPPD) or a complex salt that besides IPPD contains ∊-caprolactam (PRS-1N) were compared. The nominal tensile strength, f_t, and dynamic strength, N, were determined on an MRS-2 machine, the abrasive wear, α, on a Grasselli machine, and the amount of sol fraction (SF) on a viscometer, and the equilibrium degree of swelling in toluene, Q_equ, was also determined. IR spectra were obtained using a Nicolet-6700 Fourier IR spectrometer, and electron micrographs using an EM-14 microscope. Heat treatment of the rubber compounds under critical (for isoprene rubbers) temperature conditions (at 140°C) for different periods of time, τ, makes it possible to increase N considerably, and to reduce α. The values of N are practically the same for rubber compounds with IPPD and PRS-1N, and the maximum is achieved at τ = 25 h. The values of α are considerably lower for rubber compounds containing PRS-1N. The results with respect to SF, Q_equ, IR spectroscopy, and electron microscopy confirm the presence of a certain temperature-time zone in which physicochemical processes postponing catastrophic failure of the rubber compound occur. The use of complex anti-agers with synergy in their protective action enables the time before catastrophic failure of an article to be increased.