Change of volume of rubber on stretching: Effects of time, elongation, and temperature

Abstract

The change of volume on stretching was studied for four rubber compoundsj two were pure gum, and one each contained 10 percent by volume of carbon black and whiting, respectively. Samples were made in the form of narrow molded rings. Measurements of the change with time up to about 20 minutes were made with a water-filled dilatometerj for longer periods a mercury-filled dilatometer was used. The whiting compound increased in volume on stretching, presumably on account of the formation of vacuoles around the coarse particles of filler. With the other compounds the volume remained constant up to an elongation of 200 or 300 percent, above which it decreased by an amount which was greater the higher the elongation, the lower the temperature, and the longer the time the rubber was kept stretched. The decrease was an approximately linear function of the logarithm of the time from a few minutes after stretching, to about 4 weeks, the duration of the experiment. The volume thermal expansivity of the stretched rubber was greater than that of the unstr etched. Increased vulcanization of a given compound, in general, decreased the volume change on stretching. The results indicate that, in the absence of coarse fillers, Poisson's ratio for rubber is 0.5 or greater, the numerical value depending upon the composition, the temperature, the time after stretching, and other factors.

Effects of the amount of fillers and of the crosslink density on the mechanical behavior of carbon‐black filled styrene butadiene rubbers

“…Part of this damage may result from cavitation and cavity growth that can be monitored by measuring the volume changes during the material stretching. Actually, substantial volume changes have been reported within filled rubbers when first stretched 22–25. The volume change may be attributed to decohesion at the filler–rubber interface and to vacuole formation in the rubber matrix 23, 26.…”

Rheological Effect of Zinc Surfactant on the TESPT-Silica Mixture in NR and S-SBR Compounds

“…The crystallization is accompanied by an increase in density (i. e. decrease in volume) and volume changes [56,57]. Nucleation may occur spontaneously and homogeneously throughout the amorphous phase at lower temperature or be`seeded' by foreign surfaces or structure discontinuities.…”

A Review of Volume Changes in Rubbers: The Effect of Stretching

“…4,9,10 Certain authors developed their own procedure to measure the volume change, which can be determined by calculating the change in specific gravity, 8 measuring the hydrostatic weighting, [11][12][13] or measuring the relative pressure using the Farris principle. They use various technologies whose accuracy differs from one to another.…”