Polymers disintegrate

Polyaniline, polypyrrole, polyparaphenylene and polyacetylene (doped with SO , HSOj), added to the positive paste as powders or fibres, enhance the formation process and increase the capacity of the cells. The amount of polymers added to the paste should be within the range 0.8—2.0 wt%. Higher polymer loads impair the mechanical stability of PAM and hence the life of the battery is shortened dramatically. Polymers disintegrate on overcharge. Polyaniline has proved to be most stable on battery overcharge. 

Formation of a steadily growing partially crystalline polymer phase around the active center Cat. This can result in the catalyst particle breaking off from the polymer (disintegration), whereby under certain circumstances a new active center Cat can be formed the diffusion of the reactants (monomer, H2) can also be hindered by the growing polymer phase. 

Cured resins have excellent chemical resistance. This is probably because, although the resins have some reactive groupings, most of the reactions occurring do not result in the disintegration of the polymer molecules. Therefore, whilst surface layers of molecules may have undergone modification they effectively shield the molecules forming the mass of the resin. The resins have very good resistance to water penetration. 

Addition of such a complexing agent increases the total number of species present in the solution, affecting thus its viscosity — a phenomenon allowing one to determine the degree of disintegration. The concentration of P as a function of [S] and ofc — the total concentration of the polymers in whatever form, is determined by the stoichiometric equation ... 

Dissolution of polymers is a very slow process it can take days or even weeks for particularly high relative molar mass substances. Two stages are discernible during the process of dissolution. Firstly, a swollen gel is produced by solvent molecules gradually diffusing into the polymer. Secondly, this gel gradually disintegrates as yet more solvent enters the... 

Some tablets combine sustained-release and rapid disintegration characteristics. Products such as K-Dur (Key Pharmaceuticals) combine coated potassium chloride crystals in a rapidly releasing tablet. In this particular instance, the crystals are coated with ethylcellulose, a water-insoluble polymer, and are then incorporated into a rapidly disintegrating microcrystalline cellulose (MCC) matrix. The purpose of this tablet is to minimize GI ulceration, commonly encountered by patients treated with potassium chloride. This simple but elegant formulation is an example of a solid dosage form strategy used to achieve clinical goals. 

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