Cloudpoint Studies of PMMA–MMA–n-Pentane Systems

Abstract

An attempt was made to determine the existence of LCST behavior for the PMMA–MMA–n-Pentane binary system at a reasonable temperature. For the cloudpoint studies, primary standard PMMA (HI < 1.1) was purchased from Pressure Chemical Corp. (Pittsburgh, PA), with a molecular weight of 6,500 g/mol. As-received MMA was used in the determination of cloudpoint. The same apparatus was used in this study, as the one used for cloudpoint experiments in Sect. 1.1 of Caneba (2010). A constant proportion of PMMA relative to MMA of 52.4 g/g was used. The proportion of n-Pentane relative to MMA+PMMA was varied, by adding certain amounts of n-Pentane to aliquots of the PMMA–MMA mixture. The inverse-temperature cloudpoint was obtained by slowly raising the PMMA–MMA–n-Pentane temperature until the solution became turbid. The exact cloudpoint temperature was obtained at the onset of cloudiness. Thus, Table 13.1 shows cloudpoint temperature values of starting PMMA–MMA–n-Pentane mixtures used. It should be noted that at 28 wt% MMA, the system did not exhibit a clear LCST-based cloudpoint temperature, because the fluid was always turbid from room temperature up to 110°C. This supports the contention that an hourglass-shaped phase envelope was obtained from the PMMA–n-Pentane system.