Polystyrene-water system, intensity

Figure 5. Scattering intensity per unit mass of particles as a function of particle diameter for a system in which the wavelength of the incident light is 632.8 nm, the scattering angle is 90°, the particle refractive index is 1.59, and the medium refractive index is 1.33 (for example polystyrene spheres in water).

A similar response to intensity changes was obtained by changing the applied US power at high US frequencies and variable powers for a heterogeneous system consisting of polystyrene particles in water. Filtration improved as the power was increased from 20 to 40 W, but not significantly from 40 to 50 W [85]. 

One of the most useful properties of polymerization systems involving styrene or the dienes is the appearance in the solutions of colour associated with the actual active centres. For example, living polystyrene solutions in tetrahydrofuran show a strong red colouration which disappears immediately on the introduction of a trace of oxygen, water or carbon dioxide. The source of this colour is a strong absorption band (e 10 ) in the near-ultraviolet region of the spectrum. The positions of the maximum and intensity of absorption are not very sensitive to changes in solvent or counter-ion (Fig. 1) [Xmax polystyryl anion 328—346 mp, 1.2—1.4 x 10 Xmax polyisoprenyl anion 270—315... 

In suspension polymerization the reaction mixture consists of a liquid-liquid biphasic system, one phase (typically water) of which is inert while the other phase is monomer. With intense mixing of the reactor, small droplets of monomer form in the aqueous phase. The added initiator is soluble in the monomer phase and starts the polymerization in the monomer droplets that are fully surrounded by the water, which acts as heat transfer fluid. The process results in spherical polymer beads of the size of the original monomer droplet if coagulation of the monomer droplets during mixing and polymerization can be avoided. In many suspension polymerization processes dispersants are added to achieve this. Important technical polymers produced by suspension polymerization are PVC and PMMA. In addition to these, spherical ion-exchange resins (typically polystyrene based) are also produced by suspension polymerization. 

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