US EPA

6604480 

Journal Article 

Inhibition effect on molecular weight distribution generated under free radical polymerization by laser pulses 

Evseev, AV; Nikitin, AN; , 

1996 

1 

Laser Chemistry
ISSN: 0278-6273
EISSN: 1476-3516 

HARWOOD ACAD PUBL GMBH 

READING 

139-149 

WOS:A1996UU93600001 

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 (k(p)) depends significantly on the efficiency of 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. 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.