Inhibition Effect on Molecular Weight Distribution Generated Under Free Radical Polymerization by Laser Pulses

Molecular weight distributions (MWDs) under free radical polymerization initiation by an arbitrarysequence of radiation pulses have been investigated. Analytical expressions enabling to account for influenceof the polymer chains linear termination (for example, inhibition) have been obtained. On the basis of theseexpressions the MWDs generated by pulse-periodic radiation have been investigated theoretically. Thecalculated MWDs for polymerization in the presence of high concentration of retarder have been given andthe influence of the inhibitor burning within the irradiation process on the MWDs character have beenstudied. It has been shown that possibility to employ the PLP method for determination of polymerizationrate constant (k p ) depends significantly on the efficiency ofchains linear termination: the PLP method can beconfidently used at τ > T (where τ is the effective lifetime of growing radicals, T is the pulse irradiation period)and it is doubtful if τ < T/3. The expression for specifying of pulses number required for establishment ofpseudostationary polymerization has been obtained for the polymerization at high concentration of retarder.The calculated MWDs for polymerization of MMA are presented.