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A new experimental technique has been developed to measure the solubility of gases and vapors in polymers and other sorbents at elevated pressures. The technique involves measuring the total weight of a vessel containing the sorbent material pressurized with a vapor, assessing the amount of vapor in the headspace of the vessel with an appropriate equation of state, and evaluating the total amount of vapor in (on) the sorbent material by the difference. Adsorption isotherms for carbon dioxide and nitrogen on an activated carbon were measured with the static sorption technique. These data were found to agree well with data taken with a standard volumetric technique. Sorption data obtained using this method for carbon dioxide in poly(vinyl acetate) and propylene in poly(propylene) compare well with data acquired by established techniques. The group-contribution lattice-fluid theory equation of state was used to predict solubility in these systems, and the Panayiotou−Vera equation of state was applied to correlate the solubility data.

The inverse gas chromatography method was used for the investigation of the partition and diffusion coefficients of polysulfone and polyetherimide with NMP, γ-butyrolactone, DMSO, acetic acid, propionic acid, THF, and water over a range of temperature from 200 to 270 °C. The weight-fraction infinite-dilution activity coefficients for the solvents, the Flory−Huggins interaction parameters, and the solubility parameters of the polymers are reported.

In some high-temperature applications, it is desirable to deliver the lubricant as a thin liquid film without recirculation. For these conditions, the buildup of the deposit on the hot surfaces outside the actual bearing contact area can be a problem. In this study, a mathematical model is developed which incorporates several chemical and physical processes which are taking place when a thin liquid film of lubricant is converted to a deposit at elevated temperatures. Specifically, the model utilizes kinetic studies of the degradation of tricresyl phosphate and the evaporation of this lubricant at modest temperatures, <280°C, and modest levels of TCP degradation to predict the final or terminal amount of deposit which will be produced over a broad range of temperature. The key to this model is incorporating the influence of the evaporation of the liquid lubricant on the diffusion of oxygen in the gas phase. The diffusion of the evaporated lubricant molecules away from the liquid phase inhibits the diffusion of the oxygen in the gas phase. Consequently, the oxidation of the liquid lubricant is significantly reduced by the unavailability of oxygen even when the liquid film is exposed to a moving stream of air.

The ability to predict the drying behavior of coating is of great importance to the coating industry. For this purpose, the model developed by Vrentas and Vrentas has been used to predict the concentration profile as well as the thickness and the temperature change of the polymer film as a function of time. The model incorporates the coupling between heat and mass transfer and diffusion induced convection which occurs when a single layer of a binary polymer solution is dried in a convection heated oven.The model was solved numerically by using the finite difference approximation and it was applied to the well characterized polyvinylacetate(PVAC)-toluene system. The effects of operating conditions on

While numerous scattering and rheological studies have investigated the disordering mechanism of low-molecular-weight poly(styrene-b-isoprene) (SI) diblock copolymers, relatively few efforts have addressed the real-space morphologies and transport properties of such copolymers at conditions near the order−disorder transition (ODT). In this work, the morphological features of seven compositionally symmetric (50/50 w/w S/I) copolymers ranging in molecular weight from 5000 to 20000, as well as several of their blends, are examined by transmission electron microscopy and small-angle neutron scattering. These results are used to interpret toluene gravimetric sorption data collected at various temperatures. At temperatures above the styrenic glass transition temperature, microphase-ordered copolymer melts are found to exhibit Fickian diffusion. In the case of a copolymer with an experimentally accessible ODT, anomalous sorption (as evidenced by equilibrium overshoot in gravimetric mass-uptake curves) is observed at temperatures near, but below, the ODT. Within the disordered state, Fickian diffusion is regained, indicating that the onset of anomalous diffusion is related to a solvent-induced ODT under isothermal conditions.

Diffusion and equilibrium coefficients in ternary polymer−solvent−solvent systems were measured using inverse gas chromatography (IGC). The technique provides a new approach to probe diffusion in ternary polymer−solvent−solvent systems. The self-diffusion coefficients of a solvent in a mixture of a polymer and a second solvent were measured. Experiments were performed for the diffusion of toluene and methanol in the poly(vinyl acetate) (PVAC)−toluene−methanol system and for diffusion of toluene and heptane in the polybutadiene (PDB)−toluene−heptane system. Predictions of diffusivities in ternary systems based on the free-volume theory are also critically analyzed and compared with the experimental data.

A simple method based on free-volume theory to predict the pressure-viscosity coefficients of liquid lubricants has been developed. The method only requires the viscosity-temperature relationship and the viscosity at the temperature of interest. The method provides good accuracy when it was tested for 162 data points for various fluid types over wide ranges of temperature and viscosity.