Water soluble polymers solution compatibility

HEC is generally compatible with other ceUulosic water-soluble polymers to give clear, homogeneous solutions. When mixed with an anionic polymer such as CMC, however, interactions between the two polymers may result in synergistic behavior, ie, viscosities higher than predicted and calculated. HEC has excellent compatibiUty with natural gums. 

HPC is compatible with many natural and synthetic water-soluble polymers and gums (50). Generally, blends of HPC with another nonionic polymer such as HEC yield water solutions having viscosities in agreement with the calculated value. Blends of HPC and anionic CMC, however, produce solution viscosities greater than calculated. This synergistic effect may be reduced in the presence of dissolved salts or if the pH is below 3 or above 10. 

Current sterilisation processes are generally not well adapted to polymers, except in the cases of water-soluble polymers and colloids, which can be sterilised by filtration in solution. The simplest process is autoclaving with steam at 120 °C for 20 min. This process can be detrimental to devices that include polymers with thermomechanical properties not compatible with the temperature used in the sterilisation process. 

TABLE 3.3 Compatibility of Water -Soluble Polymers Used in Aqueous Solution and of the Films Formed from Mixed ... 

Solutions of h. in water are compatible with other water-soluble polymers, they are less sensitive to electrolytes than MC, have pseudoplastic properties and are not very stable against enzymatic degradation. H. forms clear films, which can be plasticized by glycerol or polyglycols. They are water-soluble unless treated with dialdehydes. 

From the above discussion, it can be seen that the method adopted to prepare nanocomposites is highly dependent on the nature of the polymer. When the polymers or monomers are water soluble, they can be incorporated into the pristine LDH without any organo-modification due to their good affinity with the LDH. Additionally, the aqueous environment is compatible with the condition for the synthesis of LDH materials. Therefore, water-soluble polymer-LDH nanocomposites can be prepared using some special methods such as in situ synthesis, ion exchange and reconstruction. In the case of water-insoluble polymers and monomers, their nanocomposites are usually prepared in orga-nosolvent (solution intercalation method, exfoliation-absorption method and in situ polymerization method) or molten polymer (melt intercalation method). However, emulsion polymerization and suspension polymerization are methods that allow the incorporation of a water insoluble polymer into an LDH in water. The following sections are devoted to polymer-LDH nanocomposites obtained via emulsion polymerization and suspension polymerization. 

CMC is compatible with most water-soluble nonionic gums over a wide range of concentrations. When a solution of CMC is blended with a solution of a nonionic polymer such as hydroxyethjlceUulose or hydroxypropylceUulose, a synergistic effect on viscosity is usuaUy observed. Such blends... 

Spinning of homogeneous blends of two polymers usually imposes compatibility problems. However, these can be overcome by use of common solvents, solvent mixtures, or surfactants. The control of the position and distribution of the functionality within the fiber is a complex task, but essential for this form of functionalization. Several studies describe the ES of solution blends of PEO and PCL [185, 192, 195], Both polymers have a wide range of common solvents, but PEO is water-soluble, which means that a crosslinking step is required to preserve the meshes. 

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