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Polymer coupling and theory of on‐random crosslinking: an analytical solution
Author(s) -
Zhu Shiping,
Ma Min
Publication year - 1996
Publication title -
macromolecular theory and simulations
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.37
H-Index - 56
eISSN - 1521-3919
pISSN - 1022-1344
DOI - 10.1002/mats.1996.040050606
Subject(s) - polymer , polymer chemistry , gel point , work (physics) , coupling (piping) , chain (unit) , thermodynamics , materials science , reactivity (psychology) , molar mass distribution , chemistry , organic chemistry , physics , composite material , quantum mechanics , alternative medicine , pathology , medicine
Gel formation is an important feature in free‐radical polymer coupling. Due to the different possible combination reactivities of each polymer backbone radical, polymer chains are crosslinked in a non‐random manner. Equations of the moments have been derived to predict the pregel molecular weight development and the crosslink density at gel point. This work provides an analytical solution for the differential equations. The model agrees with the Flory‐Stockmayer gelation theory under the condition of random crosslinking. The magnitude of deviations from the classical theory for non‐random crosslinking depends on the product of the radical termination reactivity ratios ( r 1 r 2 ), the ratio of the rate constants of backbone radical generation ( k ), the ratio of the weight‐average chain lengths of primary polymers ( y ), and the polymer weight fractions ( w 2 ).