Moisture applications

Moisture Deteriorating effects of moisture are well known as reviewed early in this chapter (OTHER BEHAVIOR, Drying Plastic). Examples for high moisture applications include polyphenylene oxide, polysulfone, acrylic, butyrate, diallyl phthalate, glass-bonded mica, mineral-filled phenolic, chlorotrifluoroethylene, vinylidene, chlorinated polyether chloride, vinylidene fluoride, and fluorocarbon. Diallyl phthalate, polysulfone, and polyphenylene oxide have performed well with moisture/steam on one side and air on the other (a troublesome... 

Products Thick- Density Height Moisture Application ... 

Applications are induced by the barrier properties to gases and vapours, including oxygen, nitrogen, carbon dioxide, helium, hydrocarbons and fuels, flavours, aromas and various chemicals. The sensitivity to moisture very often requires use in multilayer form to protect EVOH from ambient moisture. Applications can be, for example, without claiming to be exhaustive ... 

Power economies can be made in densification as in other processes by proper attention to material size and composition, moisture application, blending, material orientation and feeding, and sizing electric motors. Power requirements for the entire production system are usually two to three times that of densification alone. 

For high moisture applications, polyphenylene oxide, polysulfone, acrylic, butyrate, diallyl phthalate, glass-bonded mica, mineral-filled... 

One of the most thoroughly researched applications of NIR to textile substrates is the measurement of substrate moisture content. Most of the textile moisture applications are for natural fiber products — wool, cotton, and so forth. For synthetic textile products, Elliott and coworkers [32] studied the spectral locations and the spectral influence of water on synthetic fiber spectra. Rodgers [17,33] measured the moisture content of nylon fibers by NIR spectroscopy both in the laboratory and at-line/ pseudo on-line. 

In spite of a price significantly higher than that of the commodity polyamides, PA 11 and PA 12 offer a combination of properties which allow their economic use in a variety of applications. PA 11, which is the longer established of the two, is more flexible than PA 6.6, is tougher, and is less affected by moisture. Applications include petrol pipes for cars, hydraulic pipe, brake fluid reservoirs and film for packaging cooked meat. 

Flexible foams are used in mattresses, cushions, and safety applications. Rigid and semiflexible foams are used in structural applications and to encapsulate sensitive components to protect them against shock, vibration, and moisture. Foam coatings are tough, hard, flexible, and chemically resistant. 

Separation Efficiency. Similarly to other unit operations in chemical engineering, filtration is never complete. Some soflds may leave in the hquid stream, and some Hquid will be entrained with the separated soHds. As emphasis on the separation efficiency of soHds or Hquid varies with application, the two are usually measured separately. Separation of solids is measured by total or fractional recovery, ie, how much of the incoming solids is coUected by the filter. Separation of Hquid usually is measured in how much of it has been left in the filtration cake for a surface filter, ie, moisture content, or in the concentrated slurry for a filter-thickener, ie, solids concentration. 

As a result of the development of electronic applications for NF, higher purities of NF have been required, and considerable work has been done to improve the existing manufacturing and purification processes (29). N2F2 is removed by pyrolysis over heated metal (30) or metal fluoride (31). This purification step is carried out at temperatures between 200—300°C which is below the temperature at which NF is converted to N2F4. Moisture, N2O, and CO2 are removed by adsorption on 2eohtes (29,32). The removal of CF from NF, a particularly difficult separation owing to the similar physical and chemical properties of these two compounds, has been described (33,34). 

Volatilization. The susceptibility of a herbicide to loss through volatilization has received much attention, due in part to the realization that herbicides in the vapor phase may be transported large distances from the point of application. Volatilization losses can be as high as 80—90% of the total applied herbicide within several days of application. The processes that control the amount of herbicide volatilized are the evaporation of the herbicide from the solution or soHd phase into the air, and dispersal and dilution of the resulting vapor into the atmosphere (250). These processes are influenced by many factors including herbicide application rate, wind velocity, temperature, soil moisture content, and the compound s sorption to soil organic and mineral surfaces. Properties of the herbicide that influence volatility include vapor pressure, water solubility, and chemical stmcture (251). 

Lime stabilization originated in Texas after World War II, and now it is used throughout the world. Lime is most commonly applied at a 4 wt % application or ca 11 kg/m (20 Ib/yd ) for 15 cm of compacted depth. It can be applied dry as hydrated time or granular quicklime or as a wet slurry. Distribution of the latter form is dusfless. Copious amounts (as much as 5—10%) of water are always needed in excess of the optimum moisture content of the soil. Then, a requisite for success is intimate mixing with a rotary mixer, followed by compaction to a minimum of 95% Proctor density. 

Food Applications. On the basis of intake, sucrose is the leading food additive (2). Its principal contribution to food is sweetness. However, it provides many other functionahties, eg, body, mouthfeel, texture, and moisture retention. Cereals and baked goods are the leading consumers of sucrose, followed closely by confectionery products (36). 

Dew-Point Method For many applications, the dew point is the desired moisture measurement. VHien concentration is desired, the relation between water content and dew point is well-known and available. The dew-point method requires an inert surface whose temperature can be adjusted and measured, a sample gas stream flowing past the surface, a manipulated variable for adjusting the surface temperature to the dew point, and a means of detecting the onset of con-densation. 

Suitable for materials that are easily suspended in a gas stream and lose moisture readily. Well suited to high capacities Suitable for materials that are easily suspended in a gas streatm. Well suited to high capacities. Product may suffer physical degradation Not applicable Not applicable Not applicable... 

The plate dryer is limited in its scope of apphcations only in the consistency of the feed material (the products must be friable, free flowing, and not undergo phase changes) and diying temperatures up to 320°C. Applications include speci ty chemicals, pharmaceuticals, foods, polymers, pigments, etc. Initial moisture or volatile level can be as high as 65 percent and the unit is often used as a final dryer to take materials to a bone-dry state, if necessary. The plate dryer can also be used for heat treatment, removal of waters of hydration (bound moisture), solvent removal, and as a product cooler. 

Where applicable, dry steam is passed through the dehquored cake to raise the temperature of the residual moisture, reduce its viscosity, and lower its content. The final diying or cooling period which follows steam filtration uses the residual heat left in the cake to evaporate some additional moisture. 

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