Question

Intrinsic Viscosity of Polystyrene Samples

     Polystyrene Samples: PS100 (M = 100,000), PS500 (M = 500,000)

MHS Parameters: PS/toluene (25C): K= 7.5 x 10^-3 ml/g, a = 0.75; PS/Cyclohexane (35.5 C) K=80 x 10^-3ml/g, a =0.5

(25pts) Given the following solutions: PS500 in toluene (25 C) and in cyclohexane (35.5 C). - Calculate the intrinsic viscosity (IV) and c* for both cases.

Sketch on a single plot the Huggins equation to determine the intrinsic viscosity (IV). Indicate the important parameters directly on the plot (include slope and intercept).

(25pts) Given the following solutions: PS100 and PS500 in toluene (25 C)   - Calculate the intrinsic viscosity (IV) and c* for both cases.

Sketch on a single plot the Huggins equation to determine the intrinsic viscosity (IV).     Indicate the important parameters directly on the plot (include slope and intercept).

Answer 1

From MHS equation, intrinsic viscosity, [n]

C*=1/[n]

PS500 in toluene,

[n]=7.5*10^-3*(500000)^.75=141

C*=1/141=.007 g/mol

PS500 in cyclohexane

[n]=80*10^-3*500000^.5=56.56

C*=1/56.56=.017 g/ml

PS100 in toluene,

[n]=7.5*10^-3*(100000)^.75=42

C*=1/141=.0023 g/mol

To find [n], Plot reduced viscosty vs Intrinsic viscosity curve.

Intercept at x axis =X

=>X=[n]+Kh*[n]^2*c

Since [n] not equal to zero

=>Intrinsic viscositym[n] = (-1/Kh/c)^.5