An. Nikitin et Av. Evseev, MOLECULAR-WEIGHT DISTRIBUTION GENERATED UNDER FREE-RADICAL POLYMERIZATION INITIATION BY SEQUENCE OF RADIATION PULSES, Journal of macromolecular science. Pure and applied chemistry, A33, 1996, pp. 187-195
Molecular weight distributions (MWDs) under free radical polymerizatio
n initiation by an arbitrary sequence of radiation pulses have been in
vestigated. Analytical expressions have been obtained for polymerizati
on scheme which contains reactions of chain initiation, propagation an
d termination by combination or disproportionation and chains linear t
ermination (for example, inhibition). On the basis of these expression
s the MWDs generated by pulse-periodic radiation have been investigate
d theoretically. Results of calculation of the MWD dynamics in the pro
cess of polymerization are presented. The MWDs for polymerization of M
MA for different laser pulse fluences are calculated. The influence of
the inhibitor burning within the irradiation process on the MWDs char
acter have been studied. It has been shown that possibility to employ
the PLP method for determination of polymerization rate constant (k(p)
) in the case of retardation depends significantly on the efficiency o
f chains linear termination: the PLP method can be confidently used at
tau>T (where tau is the effective lifetime of growing radicals, T is
the pulse irradiation period) and it is doubtful if tau<T/3.