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

Molecular weight distributions (MWDs) under free radical polymerization initiation by an arbitrary sequence of radiation pulses have been investigated. Analytical expressions enabling to account for influence of the polymer chains linear termination (for example, inhibition) have been obtained. On the basis of these expressions the MWDs generated by pulse-periodic radiation have been investigated theoretically. The calculated MWDs for polymerization in the presence of high concentration of retarder have been given and the influence of the inhibitor burning within the irradiation process on the MWDs character have been studied. It has been shown that possibility to employ the PLP method for determination of polymerization rate constant (kp) depends significantly on the efficiency ofchains linear termination: the PLP method can be confidently 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 of pseudostationary polymerization has been obtained for the polymerization at high concentration of retarder. The calculated MWDs for polymerization of MMA are presented.