Opaque polymer formation

Formation of opaque polymer ("popcorn or "omega"-polymer) in gelation is of spontaneous character and is caused by a generation of free monomer radicals in the absence of photoinitiator participation. In the present experiment, this can be attributed to a non-fulfillment of proper storage conditions during transportation, in particular, to an increase of the monomer temperature to about 40 - 60°C. 

Lyotropic LCPs exhibit quite characteristic viscosity behavior in solution as the polymer concentration in solution is changed. Typically the viscosity follows the trend shown in Figure 5.6. As more and more polymer is added to the solvent, the viscosity increases while the solution remains isotropic and clear. At a critical concentration (which depends on the polymer and the solvent) the solution becomes opaque and anisotropic and there occurs a sharp fall in viscosity with further increase in the polymer concentration. This results from the formation of oriented nematic domains in which the chains are now aligned in the direction of flow, thereby reducing the frictional drag on the molecules. 

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