Controlled viscosity

Mold Coolers for Plastic Injection Molding. Heat pipes are used for local temperature control in the injection molding of plastics (see Polymerprocessing). A heat pipe is often used to force local cooling within a mold to speed operation, control viscosity, retention of material in a difficult mold area, or to reduce thermal stresses on cooling. 

ASTM D883 defines a filler as "...a relatively inert material added to a plastic to modify its strength, permanence, working properties, or other quaHties or to lower costs." EiHers (qv) that modify the properties and characteristics of epoxies are employed in epoxy resins for a variety of reasons. Then principal functions are to control viscosity, reduce shrinkage and the coefficient of thermal expansion, effect a cost reduction, and color the epoxy resins. 

Starches are quite hydrophilic and the granules swell in water to several times their volume. In the preparation of starches for coating, the granules are heated at 93°C to ensure complete breakdown. The starch is then mixed with the pigment while it is fluid. Normal practice is to coat the paper at an elevated temperature to help control viscosity. 

CMC/PAC sodium carboxy-methyl cellulose anionic 140 filtration control, viscosity builder sensitive to salinity, multivalent ions... 

Neutral or alkaline salts, eg, KCl, K SO, K CO, or Na PO, are often present in synthetic latices in quantities of - <1%, based on the weight of the mbber. During emulsion polymerization the salts help control viscosity of the latex and, in the case of alkaline salts, the pH of the system. Many polymerizations are carried out at high pH, requiring the use of fixed alkaH, eg, KOH or NaOH. Very small amounts of ferrous salts can be employed as a component of the initiator system, in which case a sequesteriag agent, eg, ethyldiaminotetraacetic acid (EDTA) may be iacluded to complex the iron. Water-soluble shortstops, eg, potassium dithiocarbamate, may also be iacluded ia very small amounts (ca 0.1 parts). 

A wide range of polyurethane-type products has become available in recent years for coating applications. These include simple solutions of linear polyurethanes, two-pot alkyd-isocyanate and polyether-isocyanate systems and a variety of prepolymer and adduct systems. The coatings can vary considerably in hardness and flexibility and find use mainly because of their toughness, abrasion resistance and flexibility. Uses include metal finishes in chemical plant, wood finishes for boats and sports equipment, finishes for rubber goods and rain-erosion-resistant coatings for aircraft. One type of coating is potentially competitive with PVC leathercloth. Both alkyd-di-isocyanate and adduct-diisocyanate compositions may be coated on to fabrics from solutions of controlled viscosity and solids content. Such coated fabrics are soft, flexible and, unlike PVC leathercloth, free from plasticisers. 

Lignite muds are high-temperature resistant up to 230° C. Lignite can control viscosity, gel strength, and fluid loss. The total hardness must be lower than 20 ppm. 

In solution polymerisation, the reaction is carried out in presence of a solvent. The monomer is dissolved in a suitable inert solvent along with the chain transfer agent. A large number of initiators can be used in this process. The free radical initiator is also dissolved in the solvent. The ionic and coordination catalysts can either be dissolved or suspended in the medium. The solvent facilitates the contact of monomer and initiator and helps the process of dissipation of exothermic heat of reaction. It also helps to control viscosity increase. 

The reaction of barbiturate and 1,3 -dimethylbarbiturate ions with 2- and 4-nitrobenzaldehyde and 2,4-dinitrobenzaldehyde represented generally in Scheme 5 involves a diffusion-controlled (viscosity effects on rates) proton transfer from hydronium ion to an addition intermediate T in the slow step.14 The addition of water and ring-opening reactions of the protonated benzoxazines (14) involves the cyclic intermediate (15). At low buffer concentrations buffer-catalysed collapse of the intermediate is rate limiting but, at high buffer concentrations, the addition of water is the rate-limiting step.15 The anionic tetrahedral intermediate (16) is involved in the hydrolysis of the 2, 2, 2,-trifluoroethyl monoester of 1,8-naphthalic acid (17).16... 

Viscosity poses a similar problem in the production of pulp wash concentrate. Pulp wash consists of juice solids obtained by countercurrent washing of pulp after its separation from juice. On a °Brix basis, pulp wash liquids are higher in pectin than juice from which the pulp has been screened (19). Concentration of pulp wash above 40°Brix is at times hampered by excessive pectin levels (20). To control viscosity processors may be forced to reduce finisher pressure to minimize pectin extraction, thereby curtailing yield. A more effective solution is to treat pulp wash with pectinases to reduce pectin levels (21). If pectinases are incorporated into the wash water, this method has the advantage of increasing total solids yield by reducing juice retention in the pulp. 

Dispersions of starch have found wide use in papermaking and paper conversion due to their unique properties, viz., low-cost renewable adhesive, controlled viscosity, specific rheological characteristics, water-holding properties, electrostatic charge, film formation and bonding after drying. 

In fact, one reason we use polymer solutions is because of their viscosity. Examples include engine oil, paint, glues, shampoo, and hair conditioner. Say you were painting the walls in your bedroom. If the paint had the viscosity of water, it would be very difficult to apply and keep from running right down the wall—or down your arm. If your shampoo or hair conditioner had too little viscosity, it would feel watery and just rim out of your hair before it was able to do its job. Many personal care products contain polymers to control viscosity and texture. 

In general, these groups of cellulose ethers have been used for their innate adhesive properties and to provide thickening to adhesive formulations. They are used for plywood adhesives, industrial adhesives, wallpaper paste, library paste, and latex adhesives. For example, methylcellulose is used in some adhesives as an additive to control viscosity, especially in the heat-cure phenol-formaldehyde glues and other hot-pressing adhesives. Hydroxyethylcellulose is used as an ingredient in polyvinyl acetate emulsions, where it acts as a thickener and protective colloid. 

Figure 10). All heat-treated samples were less viscous than the unheated control. Viscosity remained similar for samples heated at 50 C for 15 to 45 min, Increased between 60 and 75 min, then declined at 90 min. In general, protein solubility declined In all of these suspensions. At 75 C, the viscosities declined for peanuts heated for 15 to 60 min, then Increased If heated for 90 min. Similar observations were noted for protein solubility In these suspensions. Emulsion viscosities of peanuts heated at 100°C Increased between 15 and 45 min, then remained fairly constant between 45 and 90 min protein solubility of these suspensions declined continually between 15 and 90 min. 

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