Permeability organic liquids

The liquid-liquid patition systems discussed above are in fact very similar to various membrane-type interfaces and may serve as a model for them.A good example is, for instance, the distribution of a dissociated salt between an aqueous solution and a permeable organic polmer. ... 

In order to compare the values of Tc calculated each for the ten organic liquid peroxides charged each in the container and placed each in the atmosphere under isothermal conditions with one another, however, it is required to calculate the individual values of T assuming that these peroxides are each placed under the same conditions of shape and size. The same is true of powdery chemicals of the TD type and of gas-permeable oxidatively-heating substances. 

The result is quoted as a transmission rate with the test conditions stated. It. should be remembered that some polymers swell when in contact with organic liquids, hence the thickness and the permeability are not constant throughout the test. Steady-state conditions must also have been achieved before the transfer rate is calculated. 

POP s. See Persistent Organic Pollutants, porosity. An expression of the degree of permeability to liquids and large organic molecules in ion exchange resins. 

Eq. VI - 74 is the basic equation for liquid transport and it is the same as that for gas transpon (see eq. VI - 46) and vapour transpoit. However, due to the (high) interaction between organic liquids and polymer the permeability coefficient Pj is dependent on composition and temperature. Both solubility and diffusivity are concentration and temperature dependent as have been discussed in chapter V Eq. VI - 74 illustrates the important parameters involved, the permeabilitj coefficient is a membrane- or material-based parameter. Other parameters of interest are the effective membrane thickness I and the partial pressure difference Apj. The permeation rate is inversely proportional to the membrane thickness and proponional to the partial pressure difference across the membrane. In general eq. VI - 74 can be w ritten as... 

Perluorosulfonated ionomer membranes have high water permeabilities and excellent selectivities for water over most gases and organic liquids. These membranes have been shown to be useful for dehydration applications. Water transport in these membranes is non-Fickian. Water permeability and solubility coefficient vary with water vapor pressure. Concentration dependent thermodynamic diffusion coefficients have been obtained by combining the steady state water permeability data and the equilibrium sorption data. These diffusion coefficients correspond to what would be obtained from an experiment with infinitismal partial pressure drop across the membrane. 

Nagase et al. have studied the grafting of polyacetylene and its derivative onto poly(dimethylsiloxane) (PDMS) for membrane applications [118-121]. Poly(l-trimethyl-silyl-l-propyne) (PTMSP) is a polymer known to have excellent gas permeability but suffers from relatively low selectivity and a decrease in gas permeability over time. Graft copolymers of poly(l-phenyl-1-propyne) (PPP) onto PDMS were found to have improved gas permeability and selectivity, and the performance was related non-linearly to the PDMS content. A minimum oxygen permeability coefficient was found for a copolymer with 55 mol% PDMS [118]. The same membrane series was also foimd to be permselective for a range or organic liquids, including an ethanol/water mixture, and was used in pervaporation applications... 

The FA polysulfide rubbers are prepared by reacting a mixture of bis(2-chloroethyl)formal and ethylene dichloride with sodium polysulfide. Cured compounds have exceptionally low permeability to gases, water, and organic liquids and exhibit excellent low-temperature flexibility. The FA polysulfide rubber compounds display excellent resistance to ozone, weathering, and exposure to UV light. In general, their resistance is superior to that of the ST polysulfide rubbers. If high concentrations of ozone are to be present, the use of 0.5 part of NBC per 100 parts FA polysulfide rubber will improve the ozone resistance. 

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