The thermodynamics of narrow molecular weight distribution binary blends of polystyrene/poly(alpha-methylstyrene) (PS-P$\alpha$MS) have been studied. The range of miscibility of these blends as a function of molecular weight has been determined by differential scanning calorimetry and optical techniques. Neutron scattering in the miscible region using the random phase approximation was used to determine the interaction parameter and correlation length. The temperature and composition dependence of these parameters were also obtained. Flory-Huggins-Staverman theory and Koningsveld's empirical "g" parameter were used to fit the temperature and composition dependence of the interaction parameter determined from neutron scattering data. The interaction parameter shows a composition dependence, in contrast to some previous studies. The temperature dependence of the neutron scattering has been measured for the first time for this system, and suggests LCST behavior should be observed for this system in the molecular weight range studied. Previous researchers' work shows this system to have a UCST, but our phase behavior data are in agreement with equation of state LCST predictions of Cowie and McEwen. An explanation as to why the LCST behavior has not been observed by light scattering techniques is presented.
| Identifer | oai:union.ndltd.org:UMASS/oai:scholarworks.umass.edu:dissertations-8390 |
| Date | 01 January 1992 |
| Creators | Berard, Mark Thomas |
| Publisher | ScholarWorks@UMass Amherst |
| Source Sets | University of Massachusetts, Amherst |
| Language | English |
| Detected Language | English |
| Type | text |
| Source | Doctoral Dissertations Available from Proquest |
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