Viscosity reducing process

Polypropylene-derived branched alkyl (0 2) benzene (BAB) has been batch sulfonated using 60—70% oleum in Hquid SO2 solvent at temperatures of — 1 to —8°C, with SO2 serving as a self-refrigerant and viscosity reducer in the process. After sulfonation and digestion, SO2 is stripped, recovered, and recycled (256). 

Blends with styrenic block copolymers improve the flexibiUty of bitumens and asphalts. The block copolymer content of these blends is usually less than 20% even as Httie as 3% can make significant differences to the properties of asphalt (qv). The block copolymers make the products more flexible, especially at low temperatures, and increase their softening point. They generally decrease the penetration and reduce the tendency to flow at high service temperatures and they also increase the stiffness, tensile strength, ductility, and elastic recovery of the final products. Melt viscosities at processing temperatures remain relatively low so the materials are still easy to apply. As the polymer concentration is increased to about 5%, an interconnected polymer network is formed. At this point the nature of the mixture changes from an asphalt modified by a polymer to a polymer extended with an asphalt. 

Plating bath viscosity can be lowered by raising the solution s temperature. This will result in reduced process solution volumes entrapped on the workpiece, and thus, less dragout. Raising the bath temperature of a water-like solution from 100° to 140°F results in a viscosity reduction of 30%. Figure 8-3 illustrates that the drag-out reduction from this temperature increment is about 17% (Meltzer 1989). 

The importance of hydrogen bonding is apparent from Table 1.1, which indicates that solvents with weak hydrogen-bonding capabilities have much shorter relaxation times. In addition, their lower viscosities reduce the interaction of molecules in the rotational process, which is induced by the microwave coupling and therefore will generally not heat as effectively in a microwave cavity. 

Polyurethane prepolymers may be liquid or semisolid at ambient temperatures. Before further processing can take place, they must be heated so that the material is fully melted and the viscosity reduced to a point that it can be dispensed successfully. 

For more than a decade, numerous research studies have been carried out on the flame-retardant properties conferred by nanoparticles and mainly by organo-modified layered silicates (OMLS). Earlier work at Cornell University and National Institute of Standards and Technology in the United States showed that nanocomposites containing OMLS reduced polymer flammability and enhanced the formation of carbonaceous residue (char).14 Owing to a strong increase in polymer viscosity, impairing processability, and also due to the breakdown of ultimate mechanical properties, the acceptable rate of incorporation for nanoparticles to improve flame retardancy is generally restricted to less than 10 wt %. 

An understanding of the rheological behaviour is necessary as PVC pastes are classified as non-Newtonian liquids and can be dilatent (shear thickening), pseudoplastic (shear thinning) or thixotropic (viscosity reduces with time under constant shear). Each process requires specific rheological characteristics and this is achieved by formulation of appropriate PVC grades and knowledge of the influence of shear rate and time under constant shear. 

Solutions may also be sterilized by autoclaving, although this process can decrease the viscosity of a solution/ The change in viscosity after autoclaving is related to solution pH. Solutions at pH less than 4 had viscosities reduced by more than 20% subsequent to autoclaving. ... 

Copolymers with all of the comonomers in Table VI have commercial value, but the copolymer containing vinyl acetate is the most important and is plasticized internally. Major uses include coatings, floor coverings, and phonograph records for which low melt viscosity, lower processing temperatures, freedom from external plasticizers, and solubility are required. Copolymerization with vinyl acetate reduces tensile strength, heat distortion temperature, abrasion resistance, chemical resistance, and heat stability. However, less heat stability is required because these copolymers can be processed at lower temperatures. 

Size press starch may be non-ionic, from in-mill enzymatic conversion or thermo-chemical conversion of native starch. It may be anionie if an oxidised starch is used. (Note this refers to chemically modified oxidised starch. Many American texts wrongly refer to any viscosity-reduced starch - including enzyme-converted and thermo-chetnically converted stareh - as oxidised stareh. Such processes do not form any carboxyl or carbonyl groups on the starch.) Furthermore, cationic and amphoteric starches are frequently tpplied on multi-purpose office paper for improved ink-jet printability. 

For EPDM rubber blended in PP (i.e, TPOs), calcium stearate and multifunctional aids such as Plastaid masterbatches from Fine Organics reportedly reduce viscosity during processing and may even enhance certain mechanical properties such as impact strength [11-12],... 

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