Search

Computer simulations have a wide range of applications in crystallization of which crystal habit prediction is one of the most important. In the absence of routine experimental methods, computer simulations can provide a detailed picture of the kinetics of crystallization. The mechanism of crystal growth from solutions is subject to different processes. Present computational methods available as part of commercially available modeling software are based upon either the Bravais–Friedel–Donnay–Harker (BFDH), the attachment energy (AE) or the surface energy models and do not account for the influence of the growth environment of the crystal upon its growth. In order to control the growth of crystals and therefore their habit, it is necessary to understand the factors that govern individual face growth rates. Since crystal growth depends upon mass transport to the surface of the crystal whenever crystal growth occurs in solution, it is reasonable to assume that a quantitative description of the mass transport...

In this study, polyvinyl alcohol/organically modified montmorillonite (HDA/MMT; organoclay) com- posite was prepared for the intercalation processes. Firstly, the rheological behavior of aqueous montmorillonite dis- persions was investigated as a function of solid content. Hexadecylamine (HDA) was added to the montmorillonite dispersion (2%, w/w) in different concentrations in the range of 5 � 10 � 4 -9 � 10 � 3 mmol/L. The basal spacing of the organoclay (OMMT) was studied by X-ray diffrac- tion. The FTIR spectra are obtained from the modified montmorillonite products, which revealed the characteris- tic absorbencies after treatment with HDA. HDA/MMT /PVA composite, which was produced by the reaction of 1 wt % PVA solution with organoclay complex, is character- ized by the rheology, electrokinetic, XRD, FTIR, and SEM techniques. 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2315-2323, 2006

The modelling of the habit modifying effect of water on crystalline substances is still problematic, since the approaches for morphology prediction are investigated for organic molecules rather than for inorganic molecules. Therefore, selected well known 3-, 4- and 5-site water models have been implemented as the solvent in a molecular modelling method. By means of the surface docking method, the investigations on crystalline benzoic acid aimed to model the effect of water as a solvent. The modelling comprised additional geometry constraints of water as a flexible and a rigid molecule. By proof of experimental results, one 3-site water model was favoured for the application in morphology predictions. Future modelling work will be simplified, since it can focus on one single model of water. Furthermore, corresponding to the desired level of supersaturation, the best model can be taken from a modelling toolbox.