Dispersants, oxidized starch

Phosphated, oxidized starch with a molecular weight of 1500 to 40,000 Dalton, with a carboxyl degree of substitution of 0.30 to 0.96, is useful as a dispersant for drilling fluids [926]. 

E. K. Just and R. G. Nickol. Phosphated, oxidized starch and use of same as dispersant in aqueous solutions and coating for lithography. Patent EP 319989, 1989. 

Oxidized Starches. Alkaline hypochlorite treatment introduces carboxyl and carbonyl groups, effects some depolymerization, and produces whiter (bleached) products that produce softer, clearer gels. Ammonium persulfate is used in some paper mills with continuous thermal cookers to prepare in situ bigb solids, low viscosity dispersions. Most of the hypochlorite-oxidized starch and all the ammonium persulfate-oxidized starch is used in the paper industry. The low solution viscosity and good binding and adhesive properties of these products make them especially effective in high solids, pigmented... 

Starch for use in papermaking has to meet specific purity requirements in residual oil, protein, bran and ash content. Industrial starches have a protein content (N X 6.25), ranging from about 0.05% for potato starch to 0.3-0.6% for com starch, depending on separation efficiency during production. Excess protein content will induce foaming in dispersions of starch and affect the quality and strength of the coated surface. Starch for use in the paper industry should not contain more than 0.4% protein. Oxidized starches tend to have the lowest protein content. Residual oil will cause retrogradation due to complex formation with amylose. 

An alternative method to apply starch to paper, especially to paperboard grades, is to use a water box at the calender. Water boxes are used for wet-finishing of paper-board prior to coating application. Use of starch in the water box will increase surface strength and lessen fiber reswelling after coating application. Dilute dispersions of oxidized starch are used, frequently in conjunction with a lubricant to prevent calender roll picking. 

Oxidized starch loses its ability to gel, thereby making low Tfi dispersions. Glucose dialdehyde is a glucose oxidation compound used to crosslink agarose (linear) and dextran (branched) for their performance as adsorbents. Oxidized celluloses are a substitute for glues manufactured from animal by-products. 

Products obtained by the action of oxidizing agents on raw starches are of considerable industrial importance, particularly as sizing materials, but their chemical natures are still unknown. Because of the increased fluidity of dispersions of oxidized starches as compared with untreated starches, they are classified with acid-treated ( acid-modified O starches as Hhin-boiling starches. In addition they produce clearer solutions with a lower... 

Com and rice starches have been oxidized and subsequently cyanoethylated (97). As molecular size decreases due to degradation during oxidation, the degree of cyanoethylation increases. The derivatized starch shows pseudoplastic flow in water dispersion at higher levels of cyanoethylation the flow is thixotropic. Com and rice starches have been oxidized and subsequently carboxymethylated (98). Such derivatives are superior in the production of textile sizes. Potato starch has been oxidized with neutral aqueous bromine and fully chemically (99) and physically (100) characterized. Amylose is more sensitive to bromine oxidation than amylopectin and oxidation causes a decrease in both gelatinization temperature range and gelatinization enthalpy. 

Internal treatment-related problems may take the form of organic material present in deposits of iron oxide corrosion debris and salt scales. The material typically is present as carbonized organic components and may originate from water treatment chemicals such as quebracho, wattle, pymgallol, or other tannin derivatives. Also, acrylates, starches, sulfonated lignins, and other sludge dispersants may be present. 

The oxidative cleavage of v/c-diols to give two carbonyl functions (Eq. 5.3) by periodates was first observed by Malaprade and has since been widely applied to the carbohydrate area.50 Since both the reagent sodium periodate and the carbohydrate substrate are water soluble, the reaction is usually carried out in aqueous media.51 The reaction has been applied to polysaccharides such as starch.52 The periodate oxidations of sodium alginate in water as well as a dispersion in 1 1 ethanol-water mixture have been compared.53 Because sodium alginate forms a highly viscous solution, the oxidation was observed to be more extensive in ethanol-water. 

Starch Oxidation. In order to produce starch derivatives with improved water dispersibilities and reduced retrogradation potential two oxidative reagents were tested sodium hypoch-... 

Starch (amylose and amylopectin) hydrolysis along with ester-fication, etherification or oxidation have been previously discussed as available methods for producing starch derivatives with improved water dispersibilities and reduced retrogradation potential (, ). Since oxidative and hydrolytic reactions are simple, easily controlled chemical modifications, starch-derived polymers made by hydrolysis alone or oxidative and hydrolytic processes were developed and tested. 

Following preliminary hypochlorite treatments, a coherent process path was identified and implemented. Corn starch was oxidized with 6.4% (w/w) hypochlorite for two hours and given a combined base-heat gelatinization process (Method A). This base material exhibited excellent physical characteristics (i.e., stable emulsion with 20% db lemon oil incorporation into an aqueous dispersion, low lemon oil vapor phase flux (low headspace content), lack of inherent flavor and aroma) and when finally tested for spray dried lemon oil (20% db) retention efficiency in a lab-scale mini-dryer, the viability of this polymer was ascertained. Nearly 70% of the added lemon oil was retained following the drying of this DE 1.45 starch, a measure of functionality matched only by gum arabic (34). 

It is based on the addition of Mn2+ solution, followed by die addition of a strong alkali to die sample in a glass-stoppered bottle. Dissolved 02 rapidly oxidizes an equivalent amount of the dispersed divalent manganous hydroxide precipitate to hydroxides of higher valence states. In die presence of iodide ions in an acidic solution, the oxidized manganese reverts to die divalent state, with die liberation of a quantity of iodine equivalent to die original dissolved 02 content. The iodine is then titrated with a standard solution of thiosulfate. The titration end point can be detected visually with a starch indicator, or by potentiometric techniques. The liberated iodine can be determined colorimetrically. 

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