Latex distinguishing

Neoprene latex type Comonomer Emulsifiers Chlorine content, wt % pH at 25° C Standard soHds, wt % Distinguishing features Primary appHcations... 

The main distinguishing features of evaporated latex is that 100% mbbet recovery is achieved, but unlike the other methods, the nonmbbets ate also concentrated. The most weU-known evaporated latex is Standard Revertex (trade name from Revertex). 

Models for emulsion polymerization reactors vary greatly in their complexity. The level of sophistication needed depends upon the intended use of the model. One could distinguish between two levels of complexity. The first type of model simply involves reactor material and energy balances, and is used to predict the temperature, pressure and monomer concentrations in the reactor. Second level models cannot only predict the above quantities but also polymer properties such as particle size, molecular weight distribution (MWD) and branching frequency. In latex reactor systems, the level one balances are strongly coupled with the particle population balances, thereby making approximate level one models of limited value (1). 

Processing and Products. The main distinguishing feature of rubber products made from latex rather than dry rubber is the mbber thickness, which is limited to a few millimeters. The diffusion of water through mbber is so slow that the drying times of thicker-walled products would be unpractically long. 

Aloe is one of the few medicinal plants that have maintained their popularity for a long period of time. Aloe latex is used for its laxative effect and should be distinguished from aloe gel, used both in cosmetics and in ointments for skin ailments. Aloe whole leaf is another preparation, used as an oral medicine for a wide range of human diseases including cancer, AIDS, ulcerative colitis, etc. 

Sols and emulsions are by far the most important types of colloidal dispersion. The term sol is used to distinguish colloidal suspensions from macroscopic suspensions there is, of course, no sharp line of demarcation. When the dispersion medium is aqueous, the term hydrosol is usually used. If the dispersed phase is polymeric in nature, the dispersion is called a latex (pi. latices or latexes). 

Finally, the time of growth of each chain is found by determining how many distinguished latex particles stopped growing at any particular instant. This is obtained readily from the product of the number concentration of the different types of distinguished particles and the (known) rate coefficient for the appropriate kinetic event. Of course, the growth time of each chain determines the molecular weight of the polymer produced on termination. 

Ni = relative number of latex particles containing i free radicals. N-j/ = relative number of latex particles containing one distinguished free radical and (i-1) nondistinguished radicals. 

Theoretical calculations have demonstrated the feasibility of distinguishing a core-shell latex from a homogeneous latex. 

Other Classification Criteria. Other levels of classification should be superimposed on the above. These include latex, suspension, and bulk type syntheses, all of which result in different properties of the final materials. Uses of plastic-forming and elastomer-forming monomers and crystalline and amorphous structures must be distinguished. The tacticity of the polymers is sometimes important. Of course, the ratio of both polymer masses dictates the overall morphology. Physical operations such as swelling, annealing, and orienting must be considered in any complete treatment. 

Errera examined the distribution of alkaloids in plant tissues by histochemistry and found that alkaloids were present in active tissues near the vegetative points, ovule, epidermis and the layer just inside of it, hair, peripheral layers of fruits and seeds, vascular bundle, cork cambium, cork tissues, and latex tube (9). Molisch microscopically investigated 15 kinds of alkaloids as distinguishable crystal forms after treatment with acids or alkaloid reagents, and then histochem-ically examined them in plant tissue and cell sections following treatment with acids or alkaloid reagents (9). Tunmann and Rosenthaler observed histochemi-cally the distribution of alkaloids in tissues and cells of 36 families of plants 10). 

The development here follows that of Lichti et af. (1980). By analogy with the MWD calculation for bulk and solution polymerizations presented earlier, the MWD formalism for monodisperse emulsion systems requires the evaluation of certain types of free-radical growth time distributions. Because of the variable nature of the reaction loci (depending on the state i), a separate growth time distribution is required for the population of particles in each state i. It is therefore convenient to define the distribution of singly distinguished latex particles in state i. denoted as the... 

This has been derived in detail by Lichti et al (1980). In brief, this equation states that singly distinguished latex particles in state i form (i) by entry into an, type particle, (ii) by desorption of nondistinguishing radicals from an particle, (iii) by termination among any of the (i +1) non-... 

The two free radicals which started at t and t + f are termed distinguishing, and the latex particle ceases to be doubly distinguished when either or both of these distinguishing free radicals cease growth. Obviously, the minimum value of i for which 1V is nonzero is 2. 

Clostridium difficile can be cultured from the stool, and toxins A and B can be assessed by different techniques (116). The most accurate method is still a cytotoxin tissue culture assay. This detects the cytopathic effect of cytotoxin B, which can be neutralized by Clostridium sordellii antitoxin, but it takes 24 8 hours to show a result. Alternative tests that produce faster results have been developed. A latex agglutination test lacks sensitivity and specificity, and does not distinguish toxigenic from non-toxigenic strains. An enzyme immunoassay for toxin A may be an acceptable alternative to the cell cytotoxin assay and the results are rapidly available. A dot immunobinding assay has not yet been extensively studied (164). 

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