Ethyl vinyl ether, radiation

The principal features of this radiation initiated ionic polymerization as understood at the present time has been recently presented and will not be repeated here. The unequivocal free ion nature of the polymerizations gives us an opportunity to study such reactions and compare the results with those obtained with, for example, chemical initiation with stable carbonium ion salts. This paper will describe the results of such studies with cationic polymerization and be limited to two vinyl ethers, ethyl vinyl ether, EVE, and isopropyl vinyl ether IPVE which behave in somewhat different ways. In particular, methods of estimating the rate constants for propagation will be presented and the results obtained discussed with particular emphasis on the effect of solvents on these values. 

Estimated Propagation Rate Constants and the Activation Energies by the Radiation and Chemically Initiated Polymerization of Ethyl and Isopropyl Vinyl Ethers at 30°C. 

When isobornyl acrylate was used in place of MCEA, cured films with good pressure-sensitive adhesive properties were again obtained although somewhat longer irradiation times were required. For example, blends of poly (vinyl ethyl ether ) in IBA displayed properties ranging from 2 pli with adhesive failure and over 90 hours of shear to nearly 9 pli (cohesive failure) and 1 hour of shear (Table 7). The latter product was examined closely for complete cure and found to have 1.6 percent unreacted monomer at 6 sec. radiation and 0.23 percent at 9 sec. Again, a large gel fraction was present in the cured adhesive as noted earlier. 

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