Milling crystallinity

Confectionery factories normally use sucrose in a number of forms (for examples of particle size and forms commonly used in different confectionery products see Tables 3.2 and 3.3) granulated, i.e. crystalline milled sugar, icing sugar and possibly a 66% sugar syrup (see also... 

Milling not only provides intimate mixing, but also eliminates variation in ribbon thickness and cmshes lumpy materials, eg, overdried soap, which might impact finished bar texture. Milling is also used for the formation of the proper bar soap crystalline phase, which plays a critical role in both the performance properties of the soap bar and the handling characteristics of the in-process soap. For example, too hot a milling temperature can create sticky soap that is difficult to process further. 

Talc products are also characterized by their crystallinity or relative platiness. Mycrocrystalline talc products typical of Montana and AustraUa tend to have very fine natural grain sizes and thus are ea sily milled to very fine products of higher surface area (10—20 m /g). Macrocrystalline talc ores... 

Boric acid crystals are usually separated from aqueous slurries by centrifugation and dried in rotary driers heated indirecdy by warm air. To avoid overdrying, the product temperature should not exceed 50°C. Powdered and impalpable bode acid are produced by milling the crystalline matedal. 

Sol-Gel Techniques. Sol-gel powders (2,13,15,17) are produced as a suspension or sol of coUoidal particles or polymer molecules mixed with a Hquid that polymerizes to form a gel (see Colloids SoL-GELtechnology). Typically, formation of a sol is foUowed by hydrolysis, polymerization, nucleation, and growth. Drying, low temperature calciaation, and light milling are subsequently required to produce a powder. Sol-gel synthesis yields fine, reactive, pseudo-crystalline powders that can be siatered at temperatures hundreds of degrees below conventionally prepared, crystalline powders. 

The reactor effluent is rapidly quenched with aqueous mother Hquor in specially designed equipment operating at pressures essentially equal to the reactor pressure. This operation yields an off-gas consisting of ammonia and carbon dioxide vapor and a crystalline melamine slurry saturated with ammonia and carbon dioxide. The slurry is concentrated in a cyclone mill. The mother Hquor overflow is returned to the quenching system. The concentrated slurry is redissolved in the mother Hquor of the crystallization system, and the dissolved ammonia is stripped simultaneously. 

Many crystalline products, including fine chemicals, foodstuffs and pharmaceuticals, require a final particle size that is significantly smaller than that produced during the crystallization or precipitation step. One way of achieving the required particle size is to employ a subsequent size-reduction step using some form of comminution device, frequently a mill. 

Elliot [38] has reported that interfacial adhesion in the NR-PP blend can be enhanced by the addition of small amounts of HOPE. Addition of HDPE does give some improvement in the notched Izod impact strength of NR-PP blend (Fig. 7). The effect of HDPE on the impact modification of NR-PP is associated with the improved crystallinity of PP, enhanced by HDPE. During the mill mixing of NR and PP, chain scission may occur to give polymeric radicals that, on reaction with... 

RAW SUGAR The product of sugar cane factories or mills. An intermediate, colored crystalline product resulting from the clarification and evaporation of water from sugar cane stalk juice. 

A. Saleki-Gerhardt, in Estimation of Percent Crystallinity in Milled Samples of Sucrose, M. S. Thesis, University of Wisconsin—Madison, 1991. 

Fig. 7.13. X-ray powder diffraction pattern of digoxin, whose degree of crystallinity was reduced to 40% by ball-milling. The figure was adapted from data contained in Ref. [32],...

Pigment-related aspects, which involve the chemical constitution, crystalline modification, particle size distribution, particle shape, surface structure, preparation, and processing of the pigment powder, especially in terms of drying and milling. 

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