Permeate INDEX

Chemical permeation is rated in tests under EN 374-3. The breakthrough time of a chemical through a glove is quoted as a permeation index ... 

Perchloroethylene, 168 Periodic table, 22 Permeation index, 437 Permit-to-Work system, 16, 422 check-lists, 423... 

Relative to permeability, materials are rated by a five point scale of the permeation index number. The best choice of glove material has a permeation index number = 0. If the material has index 1 (permeability in the range from 1 to 10 mg m min ), the glove can be eventually accepted for harmful chemicals. Any higher index number makes justification for its use more difficult and in plain language such a glove should not be used with harmful chemicals. 

In addition to the properties of protective clothing materials, the toxicity of the penetrant should be considered. For less toxic solvents, materials with a permeation index... 

Numerous other fouling indexes are noted in the literature, including the ROFix (reverse osmosis fouling index)i° PI (permeation index) (Nakamura), and CFI (combined fouling index). None of these indexes have been as widely accepted as the SDI and, to a lesser extent, the MFI. ... 

MFI = melt flow index IV = intrinsic viscosity in CH2CI2 at 25°C From gel-permeation chromatography using polystyrene standards. 

If die time <10 minutes die index is 0. Clearly die greater die index die better die resistance to permeation. 

A more difficult criterion to meet with flow markers is that the polymer samples not contain interferents that coelute with or very near the flow marker and either affect its retention time or the ability of the analyst to reproducibly identify the retention time of the peak. Water is a ubiquitous problem in nonaqueous GPC and, when using a refractive index detector, it can cause a variable magnitude, negative area peak that may coelute with certain choices of totally permeated flow markers. This variable area negative peak may alter the apparent position of the flow marker when the flow rate has actually been invariant, thereby causing the user to falsely adjust data to compensate for the flow error. Similar problems can occur with the elution of positive peaks that are not exactly identical in elution to the totally permeated flow marker. Species that often contribute to these problems are residual monomer, reactants, surfactants, by-products, or buffers from the synthesis of the polymer. 

If paraffin permeates a white opaque paper, one can read letters through the paper because the paper becomes transparent. This phenomenon is based on the simple principle that micropores in the paper are filled with paraffin, which has a refractive index that is close to that of cellulose. If the porous PVA-PVAc composite film is soaked in organic solvents having the same refractive indices as that of PVA, the porous film is expected to become transparent again, according to the same principle as the phenomenon between paraffin and cellulose. On the basis of this consideration, subsequent experi-... 

Gel permeation chromatography studies using both refractive index and UV(260 nm) absorption detections have confirmed that both Acacia Senegal and Acacia seyal gums consist of three main components (Islam et al., 1997, Idris et al., 1998, Williams Phillips, 2000, Al Assaf 2006) ... 

Forsberg s electronic book consists of information from over 5,000 permeation tests on 6A0 chemicals or mixtures of chemicals. Over 7,000 breakthrough times and/or permeation rates are recorded. Along with this information are over 25,000 pieces of associated data such as the test material, manufacturer, model number, thickness, comments, a performance index number, and references. Over 200 different models of CPC are represented. 

If the time <10 minutes the index is 0. Clearly the greater the index the better the resistance to permeation. 

The vessels were indexed by the subscript "j" (j = 0 refers to the reactor and j from 1 to 4 to the UF cells) and oligomers were lumped in two categories "P" (Permeated) and "R" (Rejected). Let label "in" species entering a cell and "out" those leaving it. Instantaneous mass-balance in the stream leaving a cell and feeding the following one is ... 

Molecular weights were measured by gel permeation chromatography on a Perkin-Elmer Series 10 Liquid Chromatograph using tetrahydro-furan as solvent and refractive index as the detection mode. Standards were polystyrene, and reported molecular weights for the poly-siloxanes do not include a correction. 

Gel permeation chromatography was performed in tetrahydrofuran using a Waters pump system and a Model 410 differential refractive index detector for the eluant. Five Ultrastyragel columns with nominal porosities ranging from 500 to 105 angstroms were used for all the samples and the polystyrene standards. 

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