Temperature, color control

The digestion and hydrolysis temperatures are controlled between 110 and 125°F. During hydrolysis, approximately 2 parts of water per 100 parts of reaction product are added to convert acid anhydrides to sulfonic acid. Both the oleum and S03 sulfonation processes are quite exothermic and almost instantaneous. In order to prevent decomposition and maintain optimum product color, an efficient reactor heat removal system is necessary. 

Because both rate of color development and total color intensitv are extremely sensitive to temperature, a control was maintained with each rate measurement. This control was prepared by heating an identical aliquot of the sample solution with the required amount of HCl for 30 minutes and then mixed with other reagents color intensity was read along with that of the sample. 

Gel Networks for Reversible Transparency and Color Control with Temperature. A novel class of polymer gel networks which change both their color and transparency with changing temperature has been developed (61). Starting from a... 

Thermochromic Gel Networks for Reversible Color Control with Temperature... 

Among the variety of methods for making rose wines, immediate pressing and drawing off are the most common. Carbonic maceration (Section 12.9) is not very widely used, but it produces interesting, complex aromas in full-bodied rose wines (Adre et al., 1980). However, it frequently results in wines that are too deep in color for a classic rose, even if the anaerobic phase is short and the temperature is controlled (35 C for 36 hours or 25°C for 48 hours), so they must be blended with lighter-colored wines. 

Due to the importance of s. in modem surfactant manufacturing, there are batch and continuous processes that are carried out in many different types of sophisticated equipment. Because the reactions are highly exothermic, all process principles focus on temperature and color control. Subsequent neutralization also raises a problem of temperature control. Here again, modern continuous processes are offered by equipment manufacturers. 

Because of the high melt viscosity of polyolefins, normal spinning melt temperatures are 240—310°C, which is 80—150°C above the crystalline melting point. Because of the high melt temperatures used for polyolefin fiber spinning, thermal stabilizers such as substituted hindered phenols are added. In the presence of pigments, the melt temperature must be carefully controlled to prevent color degradation and to obtain uniform color dispersion. 

By-products of these reactions are reclaimed and recycled. The color depends on the size of the particles formed. Size is controlled by regulating the calcination profile, ie, time and temperature. The calcined product is ground, washed, and classified. 

Storage tanks, lines, and pumps should be heat traced and insulated to enable product handling. Temperature control is required to prevent product degradation because of color alkan olamines have poor heat transfer properties. Exposure to air will also cause product discoloration. Storage tanks should be nitrogen-padded if low color product is required. 

The refluxing solvent provides a constant wash to the reactor and brings back reactants that had escaped from the reaction mixture. The reaction temperature is better controlled by the constant refluxing, and the viscosity of the reaction mixture is lower, which improves the effectiveness of the agitation. The product usually has better color and is more uniform than material made by the fusion process. Ordinarily, the reactor requires no more than... 

Some of the important parameters in the Bnchamp process are the physical state of the iron, the amount of water used, the amount and type of acid used, agitation efficiency, reaction temperature, and the use of various catalysts or additives. When these variables are properly controlled, the amine can be obtained in high yields while controlling the color and physical characteristics of the iron oxide pigment which is produced. 

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