Processing and moisture

When drying at ambient temperature and 50% relative humidity, the vapor pressure of water outside a plastic is greater than within. Moisture migrates into the plastic, increasing its moisture content until a state of 

The non-hygroscopic plastics collect moisture only on the surface. Drying this surface moisture can be accomplished by simply passing warm air over the material. Moisture leaves the plastic in favor of the warm air resulting in dry air. The amount of water is limited or processing can be destructive. 

Determine from the material supplier and/or experience the plastic s moisture content limit. Also important is to determine which procedure will be used in determining water content. They include equipment such as weighing, drying, and/or re-weighing. These procedures have definite limitations based on the plastic to be dried. Fast automatic analyzers, suitable for use with a wide variety of plastic systems, are available that provide quick and accurate data for obtaining the in-plant moisture control of plastics. 

All plastics, to some degree, are influenced by the amount of moisture or water they contain before processing. With minimal amounts in many plastics, mechanical, physical, electrical, aesthetic, and other properties may be affected, or may be of no consequence. However, there are certain plastics that, when compounded with certain additives such as color, could have devastating results. Day-to-night temperature changes is an example of how moisture contamination can be a source of problems if not adequately eliminated when plastic materials are exposed to the air. Moisture contamination can have an accumulative effect. The critical moisture content that is the average material 

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It has to be remembered that hydration processes and moisture exchange occur with old concrete when sprayed concrete is applied. Both processes can affect the potentials so that the protection current should only be switched on 4 weeks after... 

Liniger, E.G., et al., October 5—7, 2010. Processing and moisture effects on TDDB for CuAJLK BEOL structures. In Advanced Metallization Conference 2010, Albany, NY. 

A measurement of particle moisture content will normally be taken at the exit of the dryer. This allows the process operators to make such adjustments as may be needed to maintain moisture within the desired range. Various instmments are used, none of which are entirely satisfactory, and periodic hand samples are used in some mills. Considering the importance of moisture sensing and control at the dryers, it is unfortunate that a truly efficient, consistent, and accurate sensing system is not yet available to the industry. The primary reasons for the difficulty of measuring moisture at the dryer exit are the extreme and adverse conditions of heat, dust, and moisture present at this location. 

A combination of excellent chemical and mechanical properties at elevated temperatures results in rehable, high performance service to the chemical processing and related industries. Chemical inertness, heat resistance, toughness and flexibiUty, stress-crack resistance, excellent flex life, antistick characteristics, Htfle moisture absorption, nonflammability, and exceptional dielectric properties are among the characteristics of these resins. 

Value assumed from Fischer assay and moisture content. The addition of steam to the process prevented accurate measurement of water produced in retorting. 

The acacia trees produce gum arable only under adverse conditions, lack of moisture, poor nutrition, and hot temperatures. Gum arable is produced at wounded surfaces of the acacia trees. The wounds are generally produced deUberately in cultivated trees by stripping bark during the dry season. The gum is collected by hand over a period of several weeks with average yields of 250 grams per tree per year. Cmde exudates are hand sorted and exported before processing and milling to various specifications. 

Dielectric Film Deposition. Dielectric films are found in all VLSI circuits to provide insulation between conducting layers, as diffusion and ion implantation (qv) masks, for diffusion from doped oxides, to cap doped films to prevent outdiffusion, and for passivating devices as a measure of protection against external contamination, moisture, and scratches. Properties that define the nature and function of dielectric films are the dielectric constant, the process temperature, and specific fabrication characteristics such as step coverage, gap-filling capabihties, density stress, contamination, thickness uniformity, deposition rate, and moisture resistance (2). Several processes are used to deposit dielectric films including atmospheric pressure CVD (APCVD), low pressure CVD (LPCVD), or plasma-enhanced CVD (PECVD) (see Plasma technology). 

Commercial cmde lecithin is a brown to light yeUow fatty substance with a Hquid to plastic consistency. Its density is 0.97 g/mL (Uquid) and 0.5 g/mL (granule). The color is dependent on its origin, process conditions, and whether it is unbleached, bleached, or filtered. Its consistency is deterrnined chiefly by its oil, free fatty acid, and moisture content. Properly refined lecithin has practically no odor and has a bland taste. It is soluble in aflphatic and aromatic hydrocarbons, including the halogenated hydrocarbons however, it is only partially soluble in aflphatic alcohols (Table 5). Pure phosphatidylcholine is soluble in ethanol. 

Large quantities of evaporated milk are used to manufacture ice cream, bakery products, and confectionery products (see Bakery processes and LEAVENING agents). When used for manufacturing other foods, evaporated milk is not sterilized, but placed in bulk containers, refrigerated, and used fresh. This product is caHed condensed milk. Skimmed milk may be used as a feedstock to produce evaporated skimmed milk. The moisture content of other Hquid milk products can be reduced by evaporation to produce condensed whey, condensed buttermilk, and concentrated sour milk. 

Thermosetting-encapsulation compounds, based on epoxy resins (qv) or, in some niche appHcations, organosiHcon polymers, are widely used to encase electronic devices. Polyurethanes, polyimides, and polyesters are used to encase modules and hybrids intended for use under low temperature, low humidity conditions. Modified polyimides have the advantages of thermal and moisture stabiHty, low coefficients of thermal expansion, and high material purity. Thermoplastics are rarely used for PEMs, because they are low in purity, requHe unacceptably high temperature and pressure processing conditions. 

Sheet Drying. At a water content of ca 1.2—1.9 parts of water per part of fiber, additional water removal by mechanical means is not feasible and evaporative drying must be employed. This is at best an efficient but cosdy process and often is the production botdeneck of papermaking. The dryer section most commonly consists of a series of steam-heated cylinders. Alternate sides of the wet paper are exposed to the hot surface as the sheet passes from cylinder to cylinder. In most cases, except for heavy board, the sheet is held closely against the surface of the dryers by fabrics of carefuUy controUed permeabiHty to steam and air. Heat is transferred from the hot cylinder to the wet sheet, and water evaporates. The water vapor is removed by way of elaborate air systems. Most dryer sections are covered with hoods for coUection and handling of the air, and heat recovery is practiced in cold climates. The final moisture content of the dry sheet usually is 4—10 wt %. 

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