Viscose production

Plastics and Other Synthetic Products. Sulfur is used in the production of a wide range of synthetics, including cellulose acetate, cellophane, rayon, viscose products, fibers, and textiles. These uses may account for 2% of sulfur demand in developed countries. Sulfur intermediates for these manufacturing processes are equally divided between carbon disulfide and sulfuric acid. 

Liquid Asphalt. Liquid asphalt products comprise cutback asphalts and emulsions. A number of grades of different viscosities are available, which permit appHcation from ambient temperatures to 150°C. The lower viscosity products are used for dust-laying purposes and as tack coats, prior to laying asphalt surface courses. The heavier grades are used for mix-in-place road mixes. 

Oxidized castor oils are excellent nonmigrating, nonvolatile plasticizers (qv) for ceUulosic resins, poly(vinyl butyral), polyamides, shellac, and natural and synthetic mbber (see Rubber, natural). The high viscosity products are also used as tackifiers in gasket compounds and adhesives (qv) because of good oil and solvent resistance. They also serve as excellent pigment grinding media and as a base for inks (qv), lubricating oils, and hydrauHc oils (62). 

The isocyanurate reaction can be both beneficial and troublesome. It can be the bane of production engineers. Low levels of alkaline impurities present in urethane raw materials such as polyols, tackifiers, etc., can cause problems in prepolymer production, resulting in high viscosity products at levels of 5 ppm or less. At higher levels of alkaline impurities, more serious problems can occur, including poor shelf life, poor caulkability, or poor sag resistance. At levels of 15 ppm or higher, the alkalinity can cause an isocyanurate reaction in a prepolymer that can result in a gelled reactor. 

It s most commonly seen on the surface of high viscosity products such as artists products and children s paints. 

P.R.89 affords a very bluish shade of red, referred to as pink. It exhibits good tinctorial strength and good lightfastness. Full shades in a combination nitro lacquer, for instance, equal step 7-8 on the Blue Scale. Somewhat poor overall fastness restricts the applicability of P.R.89. The pigment was considered a spe-cialpurpose product for artists colors. It used to be employed also in spin dyeing viscose products. 

Fig. 6. Limiting single ion mobility-viscosity product vs. reciprocal of estimated crystallographic radii of alkali metal ions...

Fig. 10. Limiting single ion mobility-viscosity product for alkali metal ions vr. solvent Lewis basicity (as measured by enthalpy of reaction with SbCl5)...

Low-APl fuel oil (heavy industrial fuel oil) is a medium-viscosity product that are highly variable and often blended with lower-boiling products. The blends may be unstable and the oil may separate when spilled onto the ground or onto a waterway. The oil may be buoyant or sink in water,... 

The shear-mode acoustic wave sensor, when operated in liquids, measures mass accumulation in the form of a resonant frequency shift, and it measures viscous perturbations as shifts in both frequency and dissipation. The limits of device operation are purely rigid (elastic) or purely viscous interfaces. The addition of a purely rigid layer at the solid-liquid interface will result a frequency shift with no dissipation. The addition of a purely viscous layer will result in frequency and dissipation shifts, in opposite directions, where both of these shifts will be proportional to the square root of the liquid density-viscosity product v Pifti-... 

It is recommended that any higher-viscosity product such as residual oil or heavy distillate fuel be evaluated for changes in low-temperature handling properties over time. Testing for reversion in pour point by the Shell Amsterdam Reversion Test or the British Admiralty Pour Point Reversion Test are recommended. Also, viscosity increase versus temperature decrease determinations are recommended for products stored at low temperatures for extended periods of time. 

Sometimes, reversion tendencies cannot be overcome by the addition of higher treat rates of a wax crystal modifier. Under these circumstances, only dilution by low-viscosity products or the constant addition of heat will keep the oil fluid at temperatures below its base pour point. 

Contamination of fuel with high-viscosity products or operation at excessively low temperatures can increase the viscosity of fuel and result in fuel pumping problems. Also, if diesel fuel viscosity at 0°F (-17.8°C) is greater than 45 cSt, fuel pumping problems are likely to occur. 

Nitration. The nitration is usually carried out under conditions that promote the production of a low-viscosity product. Hence the process is carried out primarily with linters, at a relatively elevated temperature, commonly between 30 and 35°C. The clarity of nitrocellulose sulution increases, with nitration time to an optimum and then decreases [1]. 

We focus on the conductance data. In systems of the type considered here, the conductance is primarily determined by the degree of ion pair association a. However, at higher ion densities, substantial mobility effects come into play. In the absence of sufficiently accurate conductance theories for the region of interest, a reliable measure for estimating a. is the conductance-viscosity product Arj which is often denoted as the Walden product. Figure 7 shows isotherms for the Walden product at T Si Tc for Bu4NPic + 1-tridecanol [72] and Bu4NPic + 1-chloroheptane [137] as a function of the... 

Figure 7. Conductance-viscosity products Ai of tetra-n-butylammonium picrate dissolved in 1-tridecanol [72] (O) and 1-chloroheptane ( ) [137] as a function of the salt concentration along near-critical isotherms normalized to the values at the critical points.

The favorable working conditions of the thin-film evaporator enabled the equally successful application of the thin-film principle for fractionation (5), absorption, chemical reactions (6), and drying (7, 8). In these processes and applications, the thin-film apparatus is used mainly to treat heat sensitive and lower-viscosity products that flow on the influence of gravity alone. This particular type of apparatus in a special design can also be used to process highly viscous products to... 

Assuming the dissipation (friction) energy is equal to the rotor drive energy ff the coefficient heat transferred directly from the heating wall into the film. For low-viscosity products, some correlations for this coefficient in agitated film equipment are known (14). 

Figure 4.25. Profiles of axial velocities in the flow of a rheokinetic liquid through a tubular reactor. Row rate increases from (a) to (c). The dashed lines denote the boundary between the high-viscosity product (high degree of conversion) and the low-viscosity reactant (breaking through stream).

N-McLhylmorpholine-N-oxidc monohydrate, a tertiary, aliphatic amine N-oxide, is able to dissolve cellulose directly, i.e. without chemical derivatization, which is used on an industrial scale as the basis of the Lyocell process [ 1, 2], This technology only requires a comparatively low number of process steps compared for instance to traditional viscose production. Cellulose material - mainly fibers - are directly obtained from the cellulose solution in NMMO no chemical derivatization, such as alkalization and xanthation for rayon fibers, is required [3]. The main advantage of the Lyocell process lies in its environmental compatibility very few process chemicals are applied, and in the idealized case NMMO and water are completely recycled, which is also an important economic factor. Even in industrial production systems NMMO recovery is greater than 99%. Thus, compared with cotton and viscose the Lyocell process pertains a significantly lower specific environmental challenge [4]. Today, Lyocell fibers are produced on an industrial scale, and other cellulosic products, such as films, beads, membranes and filaments, are also currently being developed or are already produced commercially. 

The analogous large-volume series ZSK MEGAvolume with 8.7 Nm/cm3, a diameter ratio of 1.8, and screw speeds of up to 1800 rpm is used for compounds with a high solid matter content, such as those often found in the chemical/food/pharmaceutical industries. The maximum speeds of up to 1800 rpm are used mainly for low-viscosity products, such as pressure-sensitive adhesives and silicon sealants because they provide better elastomer and filler dispersion. Other processes often require large volume only and operate at very moderate speeds of 100 to 600 rpm to protect the product or for direct extrusion into films, sheets, or profiles. 

Amidoamine or polyamidoamine curing agents have reactivity with DGEBA epoxy resins that is similar to the polyamides. However, they are lower-viscosity products and are also lower in color. Amidoamines are derivatives of monobasic fatty carboxylic acids and aliphatic polyamines. Since the amidoamines have only one amide group per molecule, they are lower in molecular weight, viscosity, and amine functionality than the polyamides. 

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