Effect of Pressure on the Mechanical Properties of Polymers. Part II. Measurement of the Time-Dependent Poisson's Ratio. Final Report

摘要

An attempt was made to measure the time-dependent Poisson's ratio on a styrene-butadiene rubber (SBR). Below -10 exp 0 C, water condensation occurred when the bath returned to room temperature. These experiments therefore had to be deferred. A sample of a styrene-butadiene block copolymer evinced considerable relaxation at room temperature. The Poisson's ratio is quite high. The high values of mu (t) recorded on the block copolymer could result from strain-induced anisotropy. Such anisotropy can produce E to G ratios well in excess of 3, the theoretical value for a homogeneous isotropic rubber. By the relation mu = E/2G - 1, an E to G ratio of 3.2 yields a Poisson's ratio of 0.6. mu (t) clearly shows an inflection around 15 minutes which is just barely noticeable in E. (ERA citation 09:050177)