Starch derivatives dispersibility

PregeEtinized Starches. Suspensions of starches and starch derivatives can be gelatinized/cooked and dried to yield a variety of products that can be dispersed in cold water to yield pastes comparable to those obtained by cooking granular starch products. These products are made for... 

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. 

EcoSynthetix markets EcoSphere biolatex binder dispersions as a replacement for petroleum-based styrene butadiene latex. EcoSphere biolatex binders are based on starch derived from crops such as com, potatoes, and tapioca. Although the product was originally developed for the paper coating industry, it can also be applied in the textile coating industry. EcoSynthetix also produces EcoMer , a biobased building block to synthesize waterborne sugar-acrylic adhesives and resins. 

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. 

Cationic Starches. The two general categories of commercial cationic starches are tertiary and quaternary aminoalkyl ethers. Tertiary aminoalkyl ethers are prepared by treating an alkaline starch dispersion with a tertiary amine containing a P-halogenated alkyl, 3-chloto-2-hydtoxyptopyl radical, or a 2,3-epoxypropyl group. Under these reaction conditions, starch ethers are formed that contain tertiary amine free bases. Treatment with acid easily produces the cationic form. Amines used in this reaction include 2-dimethylaminoethyl chloride, 2-diethylaminoethyl chloride, and A/-(2,3-epoxypropyl) diethylamine. Commercial preparation of low DS derivatives employ reaction times of 6—12 h at 40—45°C for complete reaction. The final product is filtered, washed, and dried. 

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. 

Although untreated starches do not swell sufficiently, certain modified forms, such as sodium starch glycolate, do swell in cold water and are better as disintegrants. Various cellulose derivatives, including methylcellulose and carboxymethylcellulose, have been used in this role, but with limited success due to the marked increase in viscosity they produce around the dispersing tablet mass. 

Another method of synthesis was also used. This involved the action of chloroacetaldehyde on the Grignard reagent derived from acetylene in order to obtain the meso divinylacetylene dichlorohydrin, CH2CI—CHOH—C=C—CHOH—CH C1, from which one passed to the corresponding hexynetetrol, CH2OH—CHOH—C=C—CHOH— CHjOH. This, in turn, was reduced to the hexenetetrol, CHjOH— CHOH—CH=CH—CHOH—CH2OH, by means of Bourguel s catalyst,8 a dispersion of colloidal palladium on starch. When the hexenetetrol was hydroxylated by the use of silver chlorate and osmic acid, two hexitols, dulcitol and allitol, were obtained. 

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