Graduation Year


Document Type




Degree Granting Department

Chemical Engineering

Major Professor

Venkat R. Bhethanabotla, Ph.D.

Committee Member

Babu Joseph, Ph.D.

Committee Member

Scott W. Campbell, Ph.D.


QCM, VLE, Benzene, N-hexane, Dichloroethane, Chloroform


Thickness shear mode (TSM) sensors, also known as quartz crystal microbalances (QCM) are a class of acoustic wave sensors that have been used for gas phase sensing. In this thesis this device is used to measure vapor-liquid equilibrium data for copolymers of poly(styrene-butadiene) at 294K.

Copolymers of poly(styrene-butadiene) with varying percentages of styrene (85%, 45% and 21 %) were studied with benzene, n-hexane, dichloroethane and chloroform as solvents. Literature data for pure polystyrene/benzene and polystyrene/chloroform and polybutadiene/benzene were obtained to complement the measured data.

Obtained experimental data were fit with a modified Flory-Huggins model and compared with the predictions of three models (UNIFAC-FV, Entropic-FV, and GK-FV). Flory-Huggins model gave a good quantitative fit for the solvent activities in the copolymer solutions. All models UNIFAC-FV, GK-FV and Entropic-FV gave good predictions for poly(85% styrene-15% butadiene) copolymer/solvent and poly(45% styrene-55% butadiene) copolymer/solvent systems. All models could not predict well for poly(21% styrene-79% butadiene)/ chloroform system, yet the same models gave good predictions for the same copolymer with benzene, n-hexane and dichloroethane systems. All models predicted very well for 21% styrene in copolymer and n-hexane system and did not do well with chloroform as solvent. GK-FV and entropic-FV predicted better for 21% styrene in copolymer and solvents except chloroform.

A fully instrumented and automated test-bed consisting of a temperature controlled vapor dilution system, a precision impedance analyzer, and computer for data acquisition in Labview was developed in-house to evaluate the performance of the coated TSM devices in sensor applications as well as in sorption data measurement.