An experimental and theoretical study of the PVT equation of state of butadiene and isoprene elastomers to 200°C and 200 MPa

Publisher Website
Google Scholar
Abstract
We have performed and analyzed extensive pressure‐volume‐temperature (PVT) measurements on uncrosslinked polybutadiene and polyisoprene elastomers from ambient temperature to about 200°C and 200 MPa. In the polybutadiene series, 1,2 content varied from 8 to 87%, the remainder being similar amounts of cis‐1,4 and trans‐1,4. In the polyisoprene series the 3,4 content varied from 8 to 64%, the trans‐1,4 content was 12–16%, and the remainder was cis‐1,4, with < 4% 1,2 content. We report parameters describing the experimental data in terms of the empirical Tait equation, the cell model, the Simha‐Som‐cynsky equation, the Sanchez‐Lacombe, and the Flory‐Orwoll‐Vrij models. In general the parameters show systematic changes with the microstructure content. The agreement between theory and experiment is excellent for the Tait equation, and also for the Simha‐Somcynsky model and the cell model. The maximum deviation between theory and experiment was less than 0.004 cm3/g for the Simha‐Somcynsky theory, and less than 0.005 cm3/g for the cell model. Average absolute deviations are three to four times less. For the Sanchez‐Lacombe and the Flory‐Orwoll‐Vrij models, the maximum deviations are 5–8 times as large, and very systematic. Parameter derived from the Simha‐Somcynsky theory are discussed with respect to the microstructure, and with respect to the glass transition of these two series of materials. © 1993 John Wiley & Sons, Inc.