Abstract
Nitrile butadiene rubber, NBR, structural foam of different apparent densities was obtained by using different concentrations of foaming agent, azodicarbonamide, ADC/K. The true stress–strain characteristics, in case of compression, of foamed samples after the application of cyclic stress–strain were measured. The effect of the cyclic stress–strain on strain energy density of ADC/K foaming agent-filled NBR rubber composites was studied. The mechanical parameters were found to depend on the foaming agent concentration and on the pre-cyclic fatigue number. Results also indicated that the strain energy decreased with filler concentration.
The effects of the cyclic stress–strain on the conductivity of ADC/K foaming agent-filled NBR rubber composites were studied. The electrical properties were found to depend on the foaming agent concentration, the strain amplitude and the number of stress–strain cycles of pre-strain. This study was assisted by the current–voltage characteristics which were measured under the effect of different compression ratios: 0%, 5%, 10%, 15%, 20%, 25% and 30%. The free current carrier mobility and the equilibrium concentration of charge carriers in the conduction band were produced as functions of compressive strain. Results also indicate that there is a linear variation between pressure and conductivity for all samples, which means that these samples can be used as a pressure sensor.