A recently proposed mixing rule has been combined with a cubic equation of state to correlate the vapor-liquid equilibria of various polymer + solvent and solvent + long chain hydrocarbon mixtures. We find that the two-parameter version of this model can correlate the solvent partial pressure in concentratedpolymer solutions with high accuracy over a range of temperatures and pressures with temperatureindependent parameters. For the solvent + long chain hydrocarbon systems, for which accurate vapor-phase concentrations are also important, the model is best used as a three-parameter correlation. Advantages of this approach are that it extends the application of cubic equations of state to polymer + solvent systems in a simple fashion and that generally only temperature-independent parameters are required which allow for accurate interpolation and extrapolation of available data.

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Hydrogen peroxide (H 2 O 2 ) entrapment in silica hydrogels has potential to be used in various industrially important applications to increase H 2 O 2 stability. In this study, optimum conditions for hydrogel formation and H 2 O 2 stability were determined by varying the sodium content and initial H 2 O 2 concentration. Higher retention and better stability of H 2 O 2 were achieved with hydrogels at room temperature at low sodium concentration. Retention values of 89% were obtained with initial H 2 O 2 concentrations up to 10 wt %. H 2 O 2 decomposition in hydrogels followed a first-order reaction. Hydrogels were characterized by measuring their surface area, pore size, and pore size distribution by Brunauer−Emmett−Teller analysis and scanning electron microscopy. Mesoporous (3−24 nm) hydrogels with high surface area (1000−1400 m 2 /g) were obtained. In addition, the melting point of the entrapped H 2 O 2 -water mixture in the hydrogels was studied by low temperature differential scanning calorimetry.

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The effects of nucleating agent, temperature of crystallization, and degree of machine direction (MD) orientation on the mechanical, optical, and thermal properties of biaxially oriented polypropylene (BOPP) films were investigated. Addition of nucleating agent improved only the initial tear resistance in the MD; however, the other mechanical and optical properties did not change appreciably. In the set of experiments in which the crystallization temperature was increased, the degree of crystallinity also increased. Thus, Young's modulus, yield stress, and tensile strength increased in both directions with higher degree of crystallinity. The yield strain did not change significantly, but the strain at break was higher. Although the initial tear resistance was smaller in both directions with increasing crystallization temperature, the tear propagation resistance did not change. In this case, haze and diffuse transmittance were slightly higher, but the total transmittance was constant. In the set of experiments in which the machine direction orientation was increased, the degree of crystallinity also became higher. Owing to the effects of higher crystallinity and higher MD orientation, the modulus, yield stress, and tensile strength increased, but the yield strain and tear propagation resistance did not significantly change in both directions.