Polystyrene polymers, energy dissipation

Energy dissipated by viscous flow in a macroscopic polymer forming process originates from friction between microscopic repeat units that constitute the polymer chain. The friction coefficient per repeat unit, the monomeric friction coefficient ( ), is a function of the geometry of the repeat unit and its chemistry. Molecules such as polystyrene and poly(methyl methacrylate) that possess stiff. 

With increasing concentration of DHB, the photoproduct forms more slowly, as evidenced by decreasing loss of fluorescence intensity (Table I, entries 1-3). Nevertheless, the concentration of photoproduct(s) and RET from the polymer to photoproduct(s) are expected to increase with time, and stabilization of the polymer will eventually depend upon the capability of the photoproduct(s) to dissipate excitation energy imparted in the RET process. The observed decrease in stabilization efficiency by DHB (based on film discoloration) with exposure time in an accelerometer indicates that DHB is more effective than the photoproduct(s) in dissipating the light energy. Similar spectroscopic studies on polystyrene have led to the same conclusion in this case, as well.6... 

Bulk Polymerization. Bulk or mass polymerization is conducted with undiluted monomers and prepolymers. It is most successful in reactions where the monomer, like styrene and methyl methacrylate, will dissolve its polymer. The major difficulty associated with bulk polymerization is dissipating the exotherm that accompanies the process. For example, conversion of a carbon-carbon double bond to a single bond evolves about 30 kilocalories/mole of double bond. For polystyrene this amounts to about 290 calories/g, enough energy to severely overheat the mass if a way is not provided to transfer this heat from the polymerizing bulk. 

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