Modeling light scattering by spherical pores for calculating the transmittance of transparent ceramics – All you need to know

In this paper transmittance predictions based on residual pore scattering in transparent ceramics with cubic crystallites via Mie theory and its approximations (Rayleigh, Fraunhofer, van de Hulst and Rayleigh-Gans, including the small- and large-size limits) are recalled and systematically compared. Due to the high phase contrast, the difference between different types of ceramics is of secondary importance, so that the essential conclusions are of general validity for all types of transparent ceramics. It is shown that the Rayleigh-Gans approximation and its large-size limit provide surprisingly good transmittance predictions, although it has not often been used in the ceramic literature. The main conclusion of this paper is that, of all the approximations presented here and used in ceramic science so far, the van de Hulst approximation is the one that most closely approaches the exact Mie results, although it has been largely ignored in the literature on transparent ceramics so far.     

The effect of limited monomer solubility in heterogeneous step-growth polymerization

Limited monomer solubility imposes very intriguing features on poly(p-phenylenebenzobisoxazole) polymerization. Only one type of functional group is detected at oligomer chain ends, and a high-molecular-weight polymer is obtained even when an excess of the monomer with low solubility is used. These remarkable phenomena are interpreted as an unprecedented "spoon-feeding-of-monomer" mechanism. A novel apparatus for staged polymerization is described that was triggered by the uniqueness of the heterogeneous step-growth polymerization. Hyperbranched polyesters and a polyurethane/polyethylene blend, which represent two phases in the polymerization process, are also discussed.     

Simulation and experimental study of microwave heating of single lap adhesive‐bonded polypropylene joint

Microwave heating of modeled single lap adhesive‐bonded polypropylene joint was simulated using a computer program. The modeled joint was heated in an applicator based on a standard rectangular waveguide WR340 operating at 2.45 GHz with TE₁₀ mode. The heating process was represented by a 2‐dimensional numerical model developed previously by the authors. The temperature distribution in the adhesive layer and the heating rate of the joint were predicted. The simulated results were validated by experiments. It was found that the simulation gave reasonably accurate prediction of the microwave heating of an adhesive joint. Polym. Eng. Sci. 44:728–735, 2004. © 2004 Society of Plastics Engineers.     

Application of NRTL and uniquac models to liquid-liquid systems with halogen salts (Part I)

Binodal curves, tie lines, and plait points for benzene-halogen salt solutions-n-propanol systems were determined, and Othmer-Tobias equation was employed for a system without salt and Eisen-Joffe equation for systems with salt to test consistency. Halogen salt solutions were prepared with aqueous solution of 5% KF, 5% NaCl, 5% NaBr and5% Nal, respectively. Compositions of two splitting phases on liquid-liquid equilibria (L-L-E) condition were calculated and the parameters were estimated by correlating experimental tie lines with the NRTL and the UNIQUAC (or modified UNIQUAC) models. The effects of addition of four halogen salts (KF, NaCl, NaBr, Nal) to benzene-water-n-propanol system were considered.