Permeation index number

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 number of 1 or even 2 may still be cautiously considered but will be less acceptable for more toxic penetrants. 

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. 

The determination of the molecular weight of nanoparticles is performed by gel permeation chromatography (GPC). The experimental setup consists of a high performance liquid chromatography system with a size exclusion column and a refractive index detector. The nanoparticles are usually freeze-dried and dissolved in tetrahydrofuran for analysis on the system. Poly(styrene) or poly(methylmethacrylate) standards are used to calibrate the column, to enable the determination of number average molecular weight (Mn), as in... 

Physicochemical Interactions between permeating molecules and the macromolecules which comprise the membrane structure are considered. Dispersive, polar and hydrogen-bonding Interactions are used to establish an Index which can be useful In membrane material selection. A number of material characterization and evaluation procedures are outlined. 

The Lipinski drug-like index (or rule-of-five, R05) is the first drug-like filter proposed to predict oral bioavailability of compounds that have achieved phase II clinical status [Lipinski, Lombardo et al., 1997, 2005]. This filter predicts that poor absorption or permeation is more likely when more than one violation is registered for the four following rules molecular weight (MW) < 500, log P < 5, number of hydrogen-bond acceptors HBA) < 10 number of hydrogen-bond donors HBD) < 5. 

Figure 4.25 A typical gel permeation chromatogram. The lower trace with short vertical lines is the differential refractive index while the upper curve is an absorption plot at a fixed ultraviolet frequency. The short vertical lines are syphon dumps numbered consecutively from the time of injection of the sample. The units of the ordinate depend on the detector, while those of the abscissa can be in terms of syphon volumes (counts) or volume of solvent.

Data about the imperviousness of a faultless liner system under defined boundary conditions for as large a number of pollutants and soil materials as possible form an important component of the characterisation of the efficacy of this liner for instance in comparison to equivalent alternative liner systems. Therefore, in the following, a parameterization will be discussed for the permeation rate (or the permeability) and the induction time for diffusive mass transport in the composite liner consisting of a geomembrane and a compacted clay liner (or more generally a porous mineral material). Quantities, which refer to the geomembranes, will be denoted with index 1, such as thickness d and diffusion coefficient D, and quantities referring to the mineral liner will have index 2 such as thickness d2 and effective diffusion coefficient D2. The porosity of the water-saturated mineral liner is denoted with 0 as above. 

The number average molar mass, Mn, and the polydispersity index, Mw/Mn, for the Pis (Table 1) were determined by gel permeation chromatography (GPQ measurements in N,N-dimethylformamide (DMF), on a PL EMD-950 evaporative tight scattering detector apparatus. Considering that the polymerization degrees of the PAAs and of the... 

Table 1 Average number of repeat DNP units and CBPQT " rings, molecular weights, polydis-persity indexes, and retention volumes by gel permeation chromatography of polymeric DNP threads and their corresponding D-A polyrotaxanes...

The molecular weight and its distribution of prepolymers were determined in THF by gel permeation chromatography (Waters Associates). Four different pore size columns (10, 10, 10 and 10 A i -Styrogels) and a refractive index detector were used. The instrument was calibrated with polyisoprene samples which were prepared similarly in this laboratory and whose number-average molecular weights were determined with a vapor phase osmometer (Wescan, Model 232 A) in toluene at 50 C. 

---