二元复杂共混体系组成的SEC-LS分析

提供了一种利用体积排阻色谱-光散射(SEC-LS)联用技术来解决二元复杂共混体系组成的定量分析问题.基于体积排除色谱的绝对定量化原则,首先从理论上分析了共混物的光散射响应因子与组成呈线性关系.通过分析六组复杂共混体系的光散射响应因子与组成的关系,验证了该线性关系确实存在.进而利用该线性关系计算了共混体系的组成.在某些共混体系中,通过光散射响应因子得出的组成比利用示差法得出的组成更加接近原料组成.通过分析这两种方法产生误差的来源,阐述了产生该现象的原因.

COMPOSITION ANALYSIS OF COMPLICATED BINARY MIXTURES BY QUANTITATIVE SEC-LS

Size exclusion chromatography(SEC) equipped with light scattering(LS) and refractive index(RI) detectors was employed to determine the compositions of complicated binary mixtures.The principle of absolute quantification of size exclusion chromatography was deduced for LS and RI detectors according to signals of both detectors and the injected mass.It is founded that the response factor of RI detector is only decided by the refractive index increment(ν) of the injected sample,while the response factor of LS detector is determined by both ν and the weight average molar mass(Mw) of the sample.By a theoretical analysis we conclude that the response factors of both LS and RI detectors are linear functions with the composition of a binary polymer blend.Six pairs of binary mixtures with weak interactive effect were employed to test the linear relationship.The experimental results show an excellent accordance with the theory.At last,the linear relationships between the response factors and the composition was utilized for the compositional analysis of binary mixtures.With a careful analysis,it is discovered that the compositions determined by LS detector are more accurate than the ones by RI detector in some cases.For RI detector,seven error points are out of the range from-10% to 10%,while only two error points are out of this range for LS detector.Specially,four bad points for RI detector are much more than one point for LS detector for the case at the low composition W=10%.For another case in the mixture of two kinds of polystyrene,the number of bad points for RI detector reaches four in the five compositions while none yields for LS detector.This SEC-LS method is effective for the compositional analysis of binary mixtures and can be derived to more complicated industrial mixtures.