Adaptation of the Rheovibron to the Measurement of Dynamic Properties of Vulcanizates at Elongations up to Sample Rupture

Abstract

Abstract The Rheovibron dynamic tester can be adapted to the measurement of dynamic properties of elastomers at high deformations, up to sample rupture. The method used is superimposing small sinusoidal oscillations on statically extended specimen. In order to obtain significant dynamic data it is necessary to determine the value of Kc exactly, the correction factor for instrumental displacements, as well Kv, to correct for the deformation of the part of the specimen held within the clamps. It appears that Kv is dependent on amplitude, frequency, temperature, and sample characteristics and must be determined for each sample at each imposed condition separately. At higher extensions Kv corrections assume a major ro^le in the measurements, greatly complicating the procedures. The method for calculation of the correction factors advanced by Massa for glassy polymers does not hold for elastomers. A novel specimen arrangement has been developed, resulting in a zero Kv correction, independent of amplitude, frequency or temperature. With elastomers the Kc correction is generally also zero, leading to greatly simplified measurements as well as to more accurate results. The temperature control system of the Rheovibron was modified to permit specimen temperatures in the range of − 70° to +120° C, either at programmed increases or decreases or at any constant temperature in the range. The movement of the extension clamp was motorized, to ensure a regular, reproducible motion.