in a copolymerization of two monomer A and B the instantaneous copolymer contains equal mol fractions...

in a copolymerization of two monomer A and B the instantaneous copolymer contains equal mol fractions of A and B when the feed composition is given by (A) = 3 (B) , while an azeotropic copolymerization occurs if (B) = 3 (A) . Show that r1=1/13 and r2=9/13 for this pair of monomers .

Solutions

Expert Solution

r1 and r2 are the reactivity ratios

There is an equation relating mole fractions in the monomer feed and the copolymer to the reactivity ratios

The equation is

f(1-F)/F = r2 - r1(f²/F)

where f is the mole fraction in the monomer

F is the mole fraction in the copolymer

r1 and r2 are the reactivity ratios

A plot of f(1-F)/F versus f²/F will provide r1 as the slope and r2 as the intercept

Case1

f = 1/4 = 0.25

F = 0.5

f(1-F)/F = 0.25

f²/F = 0.125

Case 2

f = 3/4 = 0.75

F = 0.5

f(1-F)/F = 0.75

f²/F = 1.125

Thus a plot is made and from the slope and intercept of the plot, we obtain r1 = 1/13 and r2 = 9/13

queen_honey_blossom answered 1 year ago

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