Macroradicals Subject

Poly (methyl methacrylate) was also subjected to mechanical reaction in a vibrating mill in common solvent for several monomers (ethylene, acrylic acid and its esters, acrylonitrile and styrene) at temperatures from —196 to 20° C (22). The formation of macroradicals and their reactions were followed by EPR (electron paramagnetic resonance). The macroradicals reacted with vinyl monomers at temperatures less than —100° C, while quinones underwent reaction as low as —196° C. The same experiments were performed also with polystyrene and polybutylenedimethacrylate. The radicals from polystyrene were more reactive than those from poly(methyl methacrylate). 

One more type of nitroxyl macroradical is observed if a powdered TFE-HFP, y-irradiated in air and exposed to NO with subsequent evacuation, is subjected to light irradiation at A > 260 nm at 298 K [34], In this case, a new type of nitroxyl macroradical with the structure CF2-N(0 )-CF3 was registered. The following scheme provides an explanation for the radical formation in TFE-HFP under the action of light ... 

Other evidence for macroradical formation is the coreaction that occurs when two polymers are jointly subjected to mechanical action or when the polymerization of monomers is initiated by the presence of a shear-degraded polymer (see Chapter V). 

In the work [19] it was shown atthe oxidative destruction of carbon-chain polymers is connected with peroxyl and alkoxyl macroradicals. The oxidative destruction of polyvinyl alcohol evidently results in P(,j02 and (2) 2 radicals disintegration which are first subjected to isomerization ... 

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