VISCOSITY AND LIGHT SCATTERING STUDIES OF POLYMETHYLMETHACRYLATE IN METHYL ACETATE- ETHANOL
VISCOSITY AND LIGHT SCATTERING STUDIES OF POLYMETHYLMETHACRYLATE IN METHYL ACETATE- ETHANOL作者机构：Institute of Chemistry Academia Sinica
出 版 物：《Science in China,Ser.A》 (中国科学A辑(英文版))
年 卷 期：1962年第12期
页 面：1649-1658页
主 题：ETHANOL VISCOSITY AND LIGHT SCATTERING STUDIES OF POLYMETHYLMETHACRYLATE IN METHYL ACETATE
摘 要：A polymethylmethacrylate fraction of molecular weight 2.63×106 has been studied by viscosity and by light scattering in an iso-refractive solvent-non-solvent system, methylacetate-ethanol. The results show that d log [η]/d log （）1/2=3 as demanded by Flory-Fox’s theoretical interpretation of intrinsic viscosity. It is shown that the solution viscosity has reached the region of Newtonian flow at low shear rates under the conditions of ordinary viscometric determinations. The composition of θ-solvent of the system at 25.0° has been found to be γw（ethanol）=0.509. The molecular weight distribution of the sample was determined by the method of sedimentation velocity in ultracentrifuge at the vicinity of θ-temperature in acetone-ethanol. Thus a reliable polydispersity correction could be applied to the evaluation of Flory’s universal constant, which gave φ=1.61×1023, somewhat lower than generally accepted. From the integral distribution of sedimentation coefficients of the sample and the experimental values of w and [η]θ, it is possible to evaluate （） and （）θ in the relationss=（）sM1/2 and [η]θ=（）θM1/2for a hypothetical monodisperse system. The values found for polymethylmethacrylate in θ-solvent at 25.0°are （）s=3.02×10-15 and （）θ=4.59×10-2.
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