Bulk Modulus of Elasticity of Various Elastomers: Theory and Experiment

摘要

A simple theoretical model for the bulk modulus of elastomers based upon the free volume concept is described. It gives a static (zero frequency) bulk modulus which exhibits a temperature dependence similar to chain theories of shear and Young's moduli. At higher temperatures, the model gives an Arrhenius-type behavior. The frequency dependence is developed from generalization of a single relaxation time hereditary model using the method bolic functional dependencies of the storage and loss moduli upon frequency. These function are consistent with the time-temperature superposition principle and can be used to construct master curves using the WLF frequency shift method. Experimental data have been obtained for a number of rubbery elastomers using an acoustic coupler method. Details of the experimental arrangement are described together with results obtained. Generally, values of the bulk modulus are found to closely resemble those of typical organic liquids. Recent data have permitted construction of master curves for several samples, and the parameters for these curves are given.