HW7
1
ChemE 178 HW7 Due Oct31 1.) The following osmotic pressure data was obtained for polystyrene in toluene at 25 0 C. Concentration (g/cm 3 x 10 3 ) (cm toluene) 2.56 0.325 3.8 0.545 5.38 0.893 7.8 1.578 8.86 1.856 The density of toluene is 0.8618g/cm 3 and g=981 cm/s 2 . a) Calculate the number average molecular weight. b) Calculate the second virial coefficient c) What is the quality of the solvent? d) Will the chain of polymer in dilute toluene solution have a radius of gyration larger, smaller, or the same as the same chain of this polymer in melt? Why? 2.) Y&L problem 3.11 3.) Six poly(methyl methacrylate (PMMA) standards of varying molecular weights with polydispersities of < 1.1 were synthesized. Below are their intrinsic viscosity data determined from solutions of these polymers in benzene at 25 0 C. Determine their Mark-Howink-Sakurada constants, K and a. Molecular weight (g/mol) (dL/g) 46000 0.258 82000 0.408 152000 0.663 253000 10.893 348000 1.226 856000 2.210
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Transcript of HW7
ChemE 178 HW7Due Oct31
1.) The following osmotic pressure data was obtained for polystyrene in toluene at 250C.Concentration (g/cm3 x 103) (cm toluene)2.56 0.3253.8 0.5455.38 0.8937.8 1.5788.86 1.856The density of toluene is 0.8618g/cm3 and g=981 cm/s2. a) Calculate the number average molecular weight.b) Calculate the second virial coefficientc) What is the quality of the solvent?d) Will the chain of polymer in dilute toluene solution have a radius of gyration larger, smaller, or the same as the same chain of this polymer in melt? Why?
2.) Y&L problem 3.11
3.) Six poly(methyl methacrylate (PMMA) standards of varying molecular weights with polydispersities of < 1.1 were synthesized. Below are their intrinsic viscosity data determined from solutions of these polymers in benzene at 250C. Determine their Mark-Howink-Sakurada constants, K and a.
Molecular weight (g/mol) (dL/g)46000 0.25882000 0.408152000 0.663253000 10.893348000 1.226856000 2.210
