Latex mixing method

PBAs are generally prepared by three commercial methods [57,124] latex mixing, solution mixing, and melt mixing. 

Because the unique properties of IPNs arise from the intimate mixing of the component polymer systems, the synthetic methodology used to produce these materials is critical. Presently, there are three main routes utilized to produce IPNs simultaneous, sequential and latex. The method employed is determined by the component polymers selected, polymerization mechanisms, miscibility and the anticipated end use of the IPN. 

Method of Mixing PEO and Latex. Again in contrast to other polymers (10, 34), no effect of mixing method on either agglomeration rate or coagulum formation was detectable in this system. Whether or not it has noticeable effect on particle size distribution remains to be elucidated by evaluating electron micrographs. 

Methods of Blend Preparation. Most polymer pairs are immiscible, and therefore, their blends are not formed spontaneously. Moreover, the phase structure of polymer blends is not equilibrium and depends on the process of their preparation. Five different methods are used for the preparation of polymer blends (60,61) melt mixing, solution blending, latex mixing, partial block or graft copolymerization, and preparation of interpenetrating polymer networks. It should be mentioned that due to high viscosity of polymer melts, one of these methods is required for size reduction of the components (to the order of /ttm), even for miscible blends. 

Other latexes which have been produced by this method include poly(butyl methacrylate), poly(butyl acrylate) and poly(styrene/DVB) [161]. Additionally, polymer blends were produced by mixing, under high shear, HIPEs of partially polymerised monomer, followed by completion of polymerisation. The conversion prior to blending had to be less than 5%, to allow efficient mixing of the highly viscous emulsions. The materials thus produced resembled agglomerates of latex particles, due to copolymerisation at the points of contact of partially polymerised droplets. 

Adsorption Studies Appropriate amounts of cleaned latex and surfactants were mixed, equilibrated for 24 hours and the excess surfactant in serum analyzed after separation by centrifugation. Igepal CO-630 and Alipal surfactants were analyzed by colorimetric titration with cetyltrimethylammonium chloride in the presence of methylene blue and a chloroform layer similar to the method of Epton (9). Some non-ionic surfactants and solubil-... 

The interest in papain increased enormously after the publication by Kimmel and Smith D ] of a modification of the purification procedure of Balls and Lineweaver [5j. This modification permitted the isolation of pure papain from papaya dried latex and was used for many years as the standard method for the production of papain. The crystalline papain of Kimmel and Smith consists of three components active papain, reversibly oxidized papain, and irreversibly oxidized papain. Reversibly oxidized papain can be converted into active papain by reduction of the active-site thiol by low molecular weight thiols [10], sodium borohydride [11], or CN [12]. In active papain, the Cys-25, which is essential far catalytic activity, is present in a reduced form, while in reversibly oxidized papain the Cvs-25 forms a mixed disulfide with cysteine. Drenth et al. reported that in irreversibly oxidized papain the Cys-25 has been oxidized to the sulfuric acid... 

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