关键词: 顺丁烯二酸二乙酯, 正构烷烃, 临界区, 浊度, 光散射

A series of turbidity measurements have been made for binary solutes of diethyl maleate in heptane, octane, nonane, and decane in the critical regions at various wavelengths and temperatures. Critical amplitudes ξ~0, χ~0 and B corresponding to the correlation length, osmotic compressibility and coexistence curve are related through R= ξ~0[B^2/(4k~BT~cχ~0)]^1^/^3, where the value of R is 0.65-0.67. The corresponding critical exponents γ, ν and β are related through the sum rules: 3ν=2β+γ. By using these two relations the turbidity data are fitted to the Ornstein-Zernike equation to obtain γ and ν, which are consistent with the theoretical values within experimental uncertainties. The experimental data have also been analyzed to determine critical amplitudes when the value of γ and ν are fixed at their theoretical values 1.241 and 0.63 respectively. The results show that ξ~0 and χ~0 may be expressed by: ξ~0Φ~c^0^.^8^5∝M^n and χ~0Φ~c^-^1^.^2^0∝ M^g (where Φ~c is the critical volume fraction of diethyl maleate, M is the molar mass of n-alkane) with n=0.22±0.03 and g=-0.07±0.09, which are in agreement with the theoretical values of 0.18 and -0.06 proposed by us recently.

Key words: NORMAL PARAFFIN, CRITICAL REGION, TURBIDITY, LIGHT SCATTERING