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Quantitative Effect of Stoichiometric Imbalance

The stoichiometric imbalance of the two types of functional groups in a reaction mixture is determined by the ratio of the numbers of the two groups initially present. We consider below two specific cases (Hiemenz, 1984 Manaresi and Munari, 1989 Odian, 1991) of stoichiometric imbalance. [Pg.252]

Case 1 Polymerization of bifunctional monomers A—A and B B, one being present in excess. [Pg.252]

Extent of reaction of A groups, pa = fraction of A groups which have reacted = (Aao a)INao- Similarly, pb 4 fraction of B groups which have reacted = (Abo - Ab)/Abo. Since at any time, the number of A groups reacted must be equal to the number of reacted B groups, (Aaq - Aa) = (Abo - Ab). Therefore pB = rpA- [Pg.252]

If we assume for simplicity that any secondary reactions, such as intramolecular reactions leading to cyclic molecules with no end groups, can be neglected (which is justified in many cases), it is easy to see that [Pg.252]

AaAo + Abbo - (Aao - Aa) where the term in parentheses in the denominator represents the number of A functional groups that reacted and, hence, the decrease in the number of molecules. [Pg.252]

At any point of time during the polymerization process, let Naa and Nbb be the numbers (mol) of monomer species A—A and B—B, and Na and Nb those of functional groups A and B, respectively, with Nbb Iaa- Using the same symbols with an additional subscript o to denote quantities present iiutially, we may write Na = 2Naao, = 2)VbBo. and stoichiometric imbalance [Pg.228]


See other pages where Quantitative Effect of Stoichiometric Imbalance is mentioned: [Pg.339]    [Pg.252]    [Pg.228]   


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