Limiting resistance

A is httle to no attack B, good resistance C, limited resistance and NR, not recommended (15). At a temperature of 21°C for metals unless otherwise indicated. 

This task can be avoided if a hydrocarbon stream is the limiting resistance by the use of the caloric temperature charts developed by Colburn [Ind. Eng. Chem., 25, 873 (1933)]. 

Cement and Concrete Concrete is an aggregate of inert reinforcing particles in an amorphous matrix of hardened cement paste. Concrete made of portland cement has limited resistance to acids and bases and will fail mechanically following absorption of crystalforming solutions such as brines and various organics. Concretes made of corrosion-resistant cements (such as calcium aluminate) can be selected for specific chemical exposures. 

The materizils in current use have limited resistance to the broad ranges of commonly spilled chemicetl solvents. In fact, no one suit material is known to resist attack by all chemicals. Rubber or polymeric materials eire all permeable to some degree but for some chemicals, there is no acceptable gairment available to provide adequate protection for the wearer. Consequently chemiczil response teams must rely on an inventory of suits constructed of different materials to provide adequate personnel protection. 

Very limited resistance to solvents, therefore it tends to be lifted or pickled if overcoated with paints containing stronger solvents (e.g. two-pack epoxies or urethanes) ... 

With infinite space, drying rate does not determine output rate, but usually space is at a premium and drying must be hastened, if possible, with heat (or other forms of energy). If heat cannot be used, fast air movement aids solvent removal, and lacquers based on linear polymers or emulsions dry fastest. They do not, however, confer more than limited resistance to solvents. 

Potyimides obtained by reacting pyromellitic dianhydride with aromatic amines can have ladder-like structures, and commercial materials are available which may be used to temperatures in excess of 300°C. They are, however, somewhat difficult to process and modified polymers such as the polyamide-imides are slightly more processable, but with some loss of heat resistance. One disadvantage of polyimides is their limited resistance to hydrolysis, and they may crack in aqueous environments above 100°C. 

Permeability-pH profiles, log Pe - pH curves in arhficial membrane models (log Pjpp - pH in cehular models), generally have sigmoidal shape, similar to that of log Dod - pH cf. Fig. 3.1). However, one feature is unique to permeabihty profiles the upper horizontal part of the sigmoidal curves may be verhcally depressed, due to the drug transport resistance arising from the aqueous boundary layer (ABL) adjacent to the two sides of the membrane barrier. Hence, the true membrane contribution to transport may be obscured when water is the rate-limiting resistance to transport. This is especially true if sparingly soluble molecules are considered and if the solutions on either or both sides of the membrane barrier are poorly stirred (often a problem with 96-well microhter plate formats). 

Since it is assumed that the only limiting resistance to moisture uptake is mass transport resistance, the basis for the model is contained with Eq. (39). It is assumed that the system is at steady state and that rectangular coordinates (uptake in one dimension) are appropriate. Since the system is at steady state and we are dealing with transport in one direction, the flux into a volume element must be equal to the flux out of that element. This condition is expressed as... 

NR is not oil resistant and is swollen by aromatic, aliphatic and halogenated hydrocarbons. It is resistant to many inorganic chemicals, but not to oxidising acids and had limited resistance to mineral acids. It is unsuitable for use with organic liquids in general, the major exception being alcohols of low molecular weight. 

For p-InP, proton implantation introduces damage-induced deep donors which compensate the shallow acceptors, and high resistivity materials can be achieved (Donnelly and Hurwitz, 1977 Focht et al., 1984). However, for n-InP, damage created by proton implantation induces deep donors that produce a limiting resistivity of a few thousands Q-cm (Donnelly and Hurwitz, 1977 Focht et al., 1984 Thompson et al., 1983). 

Resistance functions have been evaluated in numerical compu-tations15831 for low Reynolds number flows past spherical particles, droplets and bubbles in cylindrical tubes. The undisturbed fluid may be at rest or subject to a pressure-driven flow. A spectral boundary element method was employed to calculate the resistance force for torque-free bodies in three cases (a) rigid solids, (b) fluid droplets with viscosity ratio of unity, and (c) bubbles with viscosity ratio of zero. A lubrication theory was developed to predict the limiting resistance of bodies near contact with the cylinder walls. Compact algebraic expressions were derived to accurately represent the numerical data over the entire range of particle positions in a tube for all particle diameters ranging from nearly zero up to almost the tube diameter. The resistance functions formulated are consistent with known analytical results and are presented in a form suitable for further studies of particle migration in cylindrical vessels. 

The pigment exhibits good fastness to aliphatic and aromatic hydrocarbons but it shows only limited resistance to alcohols, esters, and ketones. It is largely acid and alkali resistant. P.Y.168 is not fast to overpainting. It is used in inexpensive industrial finishes wherever the application requirements, especially as far as lightfastness and durability are concerned, are not high. 

Deviations from the Carman-Kozeny equation (4.9) become more pronounced in these beds of fibres as the voidage increases, because the nature of the flow changes from one of channel flow to one in which the fibres behave as a series of obstacles in an otherwise unobstructed passage. The flow pattern is also different in expanded fluidised beds and the Carman-Kozeny equation does not apply there either. As fine spherical particles move far apart in a fluidised bed, Stokes law can be applied, whereas the Carman-Kozeny equation leads to no such limiting resistance. This problem is further discussed by Carman 141. 

Applications are curbed by low rigidity, weak HDTs and melting points, a propensity for electrostatic and dust build-up, poor creep resistance, limited resistance to acids, a certain lack of sources, and the cost. 

PVDC is currently handicapped by the ecological problems associated with chlorine, the limited number of producers, its cost, limited resistance to light and some organic chemicals such as aromatic hydrocarbons, ketones etc., impact sensitivity the more so as the temperature decreases, high density, fume toxicity and corrosivity in the event of fire. 

Good to limited resistance against vegetable oils, alcohols, aliphatic amines, beverages, condiments and numerous foodstuffs, polygjycols and numerous pharmaceuticals... 

Hydrolysis resistance is generally good versus hot water, weak acids and bases. Versus strong and concentrated acids and bases, PPE has a good to limited resistance. 

Good to limited resistance against oils, greases,... 

Solvents Polysulfones resist acids at medium concentrations, alcohols, aliphatic hydrocarbons, greases, oils, gasoline, chlorine water They are attacked by aromatic hydrocarbons, chlorinated solvents, ketones, esters, phenols, aldehydes, amines Good to limited resistance against oils, greases, aliphatic hydrocarbons, certain alcohols Unsatisfactory against aldehydes, esters, ethers, ketones, aromatic hydrocarbons, chlorinated solvents, amines, certain alcohols, phenols. .. 

Solvents PEI resists mineral acids, dilute bases (pH < 9), freons, oils, Good to limited resistance against oils, greases, ... 

In particular, from the analysis in the very low frequency region, the limiting capacitance Q can be evaluated (via the limiting resistance R ). Practical cases have given values of Cj, of about 20mFcm (Panero et al, 1989), i.e. values of the same order as those obtained by cyclic voltammetry, thus confirming the validity of the charge saturation model. 

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