Effect of crystal morphology

Chikhalia V, Forbes RT. Storey RA, et al. The effect of crystal morphology and mill type on milling induced crystal disorder. Eur J Pharm Sci 2006 27 19-26. 

Titania-supported vanadia catalysts have been widely used in the selective catalytic reduction (SCR) of nitric oxide by ammonia (1, 2). In an attempt to improve the catalytic performance, many researchers in recent years have used different preparation methods to examine the structure-activity relationship in this system. For example, Ozkan et al (3) used different temperature-programmed methods to obtain vanadia particles exposing different crystal planes to study the effect of crystal morphology. Nickl et al (4) deposited vanadia on titania by the vapor deposition of vanadyl alkoxide instead of the conventional impregnation technique. Other workers have focused on the synthesis of titania by alternative methods in attempts to increase the surface area or improve its porosity. Ciambelli et al (5) used laser-activated pyrolysis to produce non-porous titania powders in the anatase phase with high specific surface area and uniform particle size. Solar et al have stabilized titania by depositing it onto silica (6). In fact, the new SCR catalyst developed by W. R. Grace Co.-Conn., SYNOX , is based on a titania/silica support (7). 

Perhaps the princ al area of ignorance in both the filtration and dewat g of precipitates is the effect of crystal morphology. Serious theoretical and practical problems arise in cases where the crystal in ct possesses internal porosity. Liquors bound inade a crystal will be iirposable to remove by normal dewatering methods. Agam, m process cakulaticms and correlations of e qrerimehtal results, uncertainties arise in the vabes of particle doisity fin these materials. 

Zimmerman, H.E., Alabugin, I.V, Chen, W., and Zhu, Z., Dramatic Effects of Crystal Morphology on Solid State Reaction Course Control by Crystal Disorder Mechanistic and Exploratory Organic Photochemistry, J. Am. Chem. Soc., 121, 11930-11931,1999. 

Compton RG, Daly PJ, House WA. The dissolution of Iceland spar crystals the effect of surface morphology. J Colloid Interface Sci 1986 113 12-20. 

Cornell, R.M. Giovanoli, R. (1988 a) Acid dissolution of akaganeite and lepidocrocite the effect on crystal morphology. Clays Clay Min. 36 385-390... 

In a similar program the Armour Research Foundation (Ref 41) irradiated both alpha and beta Pb azide in an intense X-ray beam. The dosages were not indicated but both types of crystals showed extreme deterioration, marked red discoloration, and a breakup of crystal morphology however they did not detonate. Another effect was the appreciable reduction of the intense absorption band starting at 270... 

The detailed description of each preparative procedure is followed by a description of the properties of the product and by conunents concerning possible variations of the method and their effects on the properties of the product. For thorough characterization numerous illustrations including color plates. X-ray diffractograms, absorption speetra (IR, Mossbauer) and electron micrographs are included. This eharacterization is necessary in view of the wide range of crystal morphologies and crystal sizes displayed by most iron oxides. It should enable the users of this book to obtain a particular product with the desired eharacteristics and also provides a check on the success of the users own efforts. 

Crystallization in block copolymers has a profound effect on their structure. This review article focusses on the morphology of semicrystalline block copolymers, and those containing two crystallizable blocks. The effect of crystallization on mechanical properties is briefly considered. The extent of chain folding upon crystallization is discussed, as is the orientation of crystal stems with respect to the microstructure. The effect of selective solvent on solution crystallization is also highlighted. Recent work on crystallization kinetics is summarized and finally the theories for crystallization in block copolymers are outlined. 

Chen, Y. Yang, D.C. Hu, Y.M. Zhang, X.Q. Effects of crystal growth conditions on morphology of crystalline syndiotatic 1,2-polybutadiene. Cryst. Growth Des. 2004, 4, 117. 

Garcia, S.P. and Semancik, S., Controlling the morphology of zine oxide nanorods crystallized from aqueous solutions The effect of crystal growth modifiers on aspect ratio, Chem. Mater, 19, 4016, 2007. 

In this part, the effect of crystallization temperature on the morphology is discussed by means of the dynamic mechanical properties (24,64) that are important informations on the characterization of injection-molded products as described in Section 9.4.2 (65). 

A method that may be applied to understand these discrepancies and why different morphologies are obtained from different solvents is the calculation of binding energies of the different solvents to the respective crystal faces and the ultimate effect on crystal morphology. This approach has been used previously (21) to good effect. This approach offers a route to investigate explicitly the role of crystal surface-solvent interactions and the impact on crystal morphology at the molecular level. This theoretical route will also be examined and an attempt to correlate the aforementioned crystallization studies with this method is currently underway. 

There are literally thousands of reports in the scientific literature concerning the effects of impurities on the growth of specific crystals, and it would be superfluous to attempt a summary here. General reviews on the influence of additives in the control of crystal morphology have been made by Kem (1965), Boistelle (1976), Davey (1979), Botsaris (1982), Nancollas and Zawacki (1984), van Rosmalen, Witkamp and de Vreugd (1989), Davey et al. (1991) and Pfefer and Boistelle (1996). 

The effect of compatibility, morphology, rfieology, mechanical properties of mixes of polysulfones and liquid-crystal polymers are studied in Refs. [203-205]. There are several contributions on the methods of synthesizing of copolymers of polysulfones and polyesterketones and on the production of mixes [206-210]. The method for the synthesis of aromatie copolyestersulfoneketones proposed in Ref. [206] allows one to decrease the number of components used, to lower the demands to the concentration of moist in them and to increase the safety of the process. The method is in the interaction without aseotropoformer in envirorunent of dimethylsul-fone of bisphenols, dihaloydarylenesulfones and (or) dihaloydarylenek-etones and alkali agents in the shape of crystallohydrated of alkali metal carbonated and bicarbonates. All components used are applicable without preliminary drying. 

Many of the performance related properties (Table 3) in a given application (Table 4) depend upon the crystalline characteristics of the part. Interestingly, the content of defect structures determines the crystalline form in the range of 11-14% levels, the beta form develops, whereas the alpha predominates at either extreme of this range (71,73,106). A detailed review of the effects of crystallization conditions upon the phases and morphology includes a summary of crystallographic, infrared, and thermal studies as well as related scanning electron... 

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