scholarly journals Molecular Weight Distribution Generated on Initiation of Free Radical Polymerization by Sequence of Laser Pulses

1995 ◽  
Vol 16 (2) ◽  
pp. 83-99 ◽  
Author(s):  
A. V. Evseev ◽  
A. N. Nikitin
Keyword(s):  
Molecular Weight ◽  
Free Radical ◽  
Radical Polymerization ◽  
Free Radical Polymerization ◽  
Laser Pulses ◽  
Stationary Regime ◽  
Arbitrary Sequence ◽  
Wide Range ◽  
Before And After ◽  
Short Laser Pulses

An investigation of molecular weight distributions (MWDs) resulting from initiation of free radical polymerization by an arbitrary sequence of short laser pulses has been undertaken. The analytical expressions have been derived to calculate MWDs for a polymerization scheme that contains reactions of chain initiation, propagation and termination by recombination or disproportionation. The MWDs produced by pulse-periodic irradiation have been calculated for a wide range of initiating pulses repetition rates (f = 0.05–100 Hz). The MWD dynamics in the act of polymerization and the influence of the duration of polymerization pseudostationary regime establishment upon the MWD have also been studied. The suitability of the derived expressions for describing the MWD generated by CW radiation before and after the establishment of polymerization quasi-stationary regime has been considered.

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

1996 ◽  
Vol 16 (3) ◽  
pp. 139-149 ◽  
Author(s):  
A. V. Evseev ◽  
A. N. Nikitin
Keyword(s):  
Molecular Weight ◽  
Free Radical ◽  
Radical Polymerization ◽  
Free Radical Polymerization ◽  
Laser Pulses ◽  
Polymer Chains ◽  
Arbitrary Sequence ◽  
High Concentration ◽  
Effective Lifetime ◽  
Irradiation Period

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.

The Kinetics of Free-Radical Polymerization: Fundamental Aspects

2002 ◽  
Vol 55 (7) ◽  
pp. 399 ◽  
Author(s):  
G. T. Russell
Keyword(s):  
Molecular Weight ◽  
Steady State ◽  
Free Radical ◽  
Radical Polymerization ◽  
Chain Length ◽  
Free Radical Polymerization ◽  
Length Dependence ◽  
Model Independent ◽  
Living Free Radical Polymerization ◽  
Kinetics Of

Some fundamental aspects of the kinetics of free-radical polymerization are reviewed. So-called classical results for rate and molecular-weight distribution are first of all presented. It is shown how this approach can be built upon when chain-length-dependent termination is allowed, which it always should be. Various termination models are considered, and it is illustrated that although the models are different, rather remarkably they give common, model-independent behaviour. Some leading experimental results regarding the chain-length dependence of termination are summarized, before the chain-length dependence of other reactivities, the variation of reactivities with conversion, and non-steady state experiments are briefly discussed. Finally, living free-radical polymerization as effected by a reversible termination agent is considered. An outline of the kinetics of these systems is given, with the oft-neglected importance of conventional termination being stressed.

Molecular Weight Characterization of Poly(N-isopropylacrylamide) Prepared by Living Free-Radical Polymerization

2000 ◽  
Vol 33 (18) ◽  
pp. 6738-6745 ◽  
Author(s):  
François Ganachaud ◽  
Michael J. Monteiro ◽  
Robert G. Gilbert ◽  
Marie-Anne Dourges ◽  
San H. Thang ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Free Radical ◽  
Radical Polymerization ◽  
Free Radical Polymerization ◽  
Living Free Radical Polymerization
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