Rayleight ratios (Rθ) were obtained at 25℃ for a series of solutions of a
Rayleight ratios (Rθ) were obtained at 25℃ for a series of solutions of a
polystyrene sample in benzene, with the detector situated at various angles (θ) to the incident beam of unpolarized monochromatic light of wavelength 546.1 nm. The results are tabulated below.
| PS Concentration (g/dm3) | 104*Rθ/m-1 measured at θ = | |||
| 30 | 60 | 90 | 120 | |
| 0.50 | 72.3 | 69.4 | 66.2 | 64.3 |
| 1.00 | 89.8 | 65.7 | 81.3 | 78.2 |
| 1.500 | 100.8 | 97.1 | 92.0 | 88.1 |
| 2.00 | 108.7 | 104.8 | 99.7 | 95.9 |
Under the conditions of these measurements, the Rayleigh ratio and refractive index of benzene are 46.5*10-4 m-1 and 1.502 respectively, and the refractive index increment for the polystyrene solution is 1.08*10-4 dm3g-1. Determine:
a) the weight average molar mass of PS
b) the z-average radius of gyration
c) the second virial coefficient (A2) for PS-benzene interaction at 25℃.
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