The relationship between two-phase and three-phase solutions to heterogeneous distillation simulation and optimization problems is studied. Simulation results illustrate that bifurcation points can occur in the two-phase solutions and that, in regions of steady-state two-phase solution multiplicity, not

The performance of solvent-annealed cellophane membranes was investigated for the pervaporation of a mixture of methanol and ethylene glycol. Higher permeabilities and selectivities were exhibited by the glycol-conditioned membrane (CEG-30), a t 30 "C, as compared to those of the untreated membrane for low methanol concentrations in the feed. The poor performance of membranes conditioned in the stronger plasticizing component, methanol, indicates that only an optimum degree of plasticization is necessary to improve membrane performance. Studies on sorption, diffusion, permeation, and the polymer-liquid interactions indicate a higher interaction of glycol a t higher methanol concentration in the feed, thus lowering the corresponding selectivities. Our results also indicate that the plasticizing coefficients of permeants may not always account for their plasticizing capabilities alone but may sometimes account for some weak bonding and clustering of permeants in the membrane matrix, thus resulting in an anomalous sorption-diffusion vis-&vis transport behavior.

The intrinsic reaction rates for anhydrous vapor-phase HF saccharification of celluloslc materials in Bigtooth aspen were determined in order to characterize and assess this process for the production of fermentable sugars. Maximum glucose yields of 3.0 mmol/g of wood were recovered from wood chips reacted for 2 min with a pure HF flowstream at 30 °C and 1.0 atm. The intrinsic glucose yield vs. time profile was sigmoidal. The glucose production rate decreased nonHnearfy with decreasing HF partial pressure from 1.0 to 0.2 atm at 30 °C. Surprisingly, the glucose production rate decreased with increasing reaction temperature from 28 to 108 °C at an HF partial pressure of 1.0 atm. It is proposed that physical adsorption of HF onto the lignocellulosic matrix and hydrogen-bond breaking of cellulose microfibrils are prerequisites to the cellulose-cracking reaction and therefore may strongly influence the global rate of glucose production.

Castor oil and Its polyol derivatives have been used as a matrix to prepare controlled-release (2,4-dichlorophenoxy)acetlc acid (2,4-D) formulations, and their release characteristics have been studied both in vivo and in vitro. The initial release rate has been found to be dependent on the hydrophllicity of the formulations. The pH of the hydrolysis also strongly affects the release characteristics; the release rate Increases sharply in the alkaline range (pH 10). Cross-linking via carbamate linkage has been found to retard the release rate. Compared to formulations based on natural or synthetic polymer matrices, such castor oil-based preparations are likely to be more suitable for agricultural applications requiring shorter release period of the toxicant.

Polymer blends were prepared from shellac and polyamideimide. The polyamideimide was synthesized by reacting rosin maleic anhydride Diels-Alder adduct with 4,4'-diamino diphenylmethane. The compatibility of these blends was studied by solubility parameter, heat of mixing data, solution viscosity, and differential scanning calorimetry. It was found that the composition of 40 : 60, shellac : polyamideimide produces a compatible blend. The thermal behaviour of the blends was investigated. ZUSAMMENFASSUNG: Es wurden Blends aus Schellack und Polyamidimid hergestellt . Das Polyamidimid wurde durch Reaktion eines Kolophonium-Maleinstiureanhydrid-Diels-Alder-Addukts mit 4,4 '-Diaminodiphenylmethan synthetisiert. Die Vertrtiglichkeit dieser Blends wurde anhand von Loslichkeitsparameter, Mischungswtirme, Losungsviskosittit und DSC-Messungen untersucht. Es zeigte sich, da8 die Zusammensetzung von Schellack : Polyamidimid = 40 : 60 eine vertriigliche Legierung bildet. Das thermische Verhalten dieser Blends wurde untersucht.