Starch binders

Special starch products have been developed for use as thickeners in coatings that are based on synthetic latex or resin binders. Starch-based thickeners can have associative properties when substituted with a hydrophobic reagent. They provide an alternative for cellulose-based thickeners, but their use is limited. 

Starch 5-25 Was once the most commonly used binder starch has to be prepared as paste, which is time consuming... 

The unknown sample is prepared by crushing a part of a tablet, adding this powder to a test tube or small vial along with an appropriate amount of ethanol, and then mixing the suspension. Not all of the tablet will dissolve, but enough will go into solution to spot the plate. The binder—starch or silica—will not dissolve. Try to prepare a 1% solution of the unknown. 

Many pharmaceutical tablets are held together with a binder to prevent the components from crumbling on storage or while being swallowed. A close reading of the contents on the package will disclose the nature of the binder. Starch is commonly used, as is microcrystalline cellulose and silica gel. All of these have one property in common they are insoluble in water and common organic solvents. 

Significant factors controlling densification are moisture, particle size, form, fibrous or nonfibrous nature, leafy legumes vs. stiff waxy resilient straws, and binders, starch or sugar content, type and quantity of binder. 

Cereal binders are used mainly in steel foundries to increase the strength and toughness of the green sand. There are two main types of cereal binder starch and dextrin. Starch is the basic material and is produced from a number of plant materials, with maize starch being the most commonly used for foundry purposes. Dextrin is a repolymerised form of starch, produced through a subsequent acid and thermal treatment of starch. 

Cereal binders Starch and dextrin are used mainly in steel foundries to avoid defects caused by silica expansion and to control moisture excess in the sand mix. Effective additions of cereal binders to new green sand facing mixes are between 0.5 and 0.75 %. In unit type green sands, part of the cereal is destroyed during the casting process. The recommended addition on each recycle is 0.1 to 0.25 %, depending on the amount of cereal burn-out and on the dilution by cores and new sand. 

Napac results from the transformation of Chinese reeds with a natural binder (starch and pine tree resin). These raw materials can be mixed with a colourant and extruded in pellets. The fibre concentration is around 70-75%. Pellets are then moulded by hot compression. This material is perfectly stable outdoors and is formulated to resist exposure to UV light. The applications are flower pots, CD boxes, interior car parts and non-food packaging. 

The lambda type is nongelling, and functions as a thickner. Iota-carrageenan has been recommended (45) for use in formulating low fat ground beef due to its abihty to retain moisture, especially through a freeze—thaw cycle which is typical for ground beef patties. Oat bran and oat fiber can also be used to improve moisture retention and mouth feel. Modified starches can be used as binders to maintain juiciness and tenderness in low fat meat products. Maltodextrins (dextrose equivalent less than 20) may be used as binders up to 3.5% in finished meat products. Other carbohydrates such as konjac flour, alginate, microcrystalline cellulose, methylceUulose, and carboxymethylceUulose have also been used in low fat meat products (see CELLULOSE ETHERs). 

Binders. Paper-coating biaders are either polymers derived from aatural sources or syathetic polymers. The largest volume, aaturally derived biader is starch (qv) (99). Starch is provided ia derivatized form or unmodified form pead com starch is used predomiaanfly for the latter. Unmodified starch is solubilized by thermal conversion or enzyme conversion. The most common derivatized products are acetylated [9045-28-7] oxidized, and hydroxyethylated starches. 

Carbonless Copy Paper. In carbonless copy paper, also referred to as pressure-sensitive record sheet, an acid-sensitive dye precursor, such as crystal violet lactone or /V-hen2oy11eucomethy1ene blue, is microencapsulated with a high boiling solvent or oil within a cross-linked gelatin (76,83,84) or in synthetic mononuclear microcapsules. Microcapsules that have a starch binder are coated onto the back of the top sheet. This is referred to as a coated-back (CB) sheet. The sheet intended to receive the image is treated on the front (coated-front (CF)) with an acid. When the top sheet is mechanically impacted, the dye capsules mpture and the dye solution is transferred to the receiving sheet where the acid developer activates the dye. 

Pyrotechnic mixtures may also contain additional components that are added to modify the bum rate, enhance the pyrotechnic effect, or serve as a binder to maintain the homogeneity of the blended mixture and provide mechanical strength when the composition is pressed or consoHdated into a tube or other container. These additional components may also function as oxidizers or fuels in the composition, and it can be anticipated that the heat output, bum rate, and ignition sensitivity may all be affected by the addition of another component to a pyrotechnic composition. An example of an additional component is the use of a catalyst, such as iron oxide, to enhance the decomposition rate of ammonium perchlorate. Diatomaceous earth or coarse sawdust may be used to slow up the bum rate of a composition, or magnesium carbonate (an acid neutralizer) may be added to help stabilize mixtures that contain an acid-sensitive component such as potassium chlorate. Binders include such materials as dextrin (partially hydrolyzed starch), various gums, and assorted polymers such as poly(vinyl alcohol), epoxies, and polyesters. Polybutadiene mbber binders are widely used as fuels and binders in the soHd propellant industry. The production of colored flames is enhanced by the presence of chlorine atoms in the pyrotechnic flame, so chlorine donors such as poly(vinyl chloride) or chlorinated mbber are often added to color-producing compositions, where they also serve as fuels. 

Starch pyrodextrins and British gums have the abiUty, in aqueous dispersion, to form films capable of bonding like or unlike materials. Thus, they have uses as adhesives for envelopes, postage stamps, and other products. These dextrins are used in glass-fiber siting to protect the extmded fiber from abrasion, and as binders for metal core castings, water color paints, briquettes, and many other composite materials (qv). 

Starch monophosphates are quite useful in foods because of their superior freeze—thaw stabiUty. As thickeners in frozen gravy and frozen cream pie preparations, they are preferred to other starches. A pregelatinized starch phosphate has been developed (131) which is dispersible in cold water, for use in instant dessert powders and icings and nonfood uses such as core binders for metal molds, in papermaking to improve fold strength and surface characteristics, as a textile size, in aluminum refining, and as a detergent builder. 

A number of different binder materials are in use for chopped strand mat and include starch, polyvinyl acetate and polyesters. The binder used depends on the end use of the laminate and the method of fabrication. 

A three-step nitration process of toluene is described. The advantages of the modified process are reduced waste, less hazardous operation, reduced oleum requirement, partial replacement of coned HN03 with dil HN03, and higher rate of toluene flow into the reactor (Ref 86) The continuous process of H.C. Prime (Ref 73) for preparing TNT was studied by thin-layer chromatography on silica gel with a starch binder and a fluorescent indicator. The nitration... 

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