凝胶渗透色谱测定涂料用树脂的相对分子质量及其分布

Determination of Molecular Weight and Distribution of Resin for Coating by GPC

凝胶渗透色谱(GPC)法是研究高聚物相对分子质量及其分布的最有效的手段,涂料行业经常使用以四氢呋喃(THF)为流动相、示差折光检测器(RI)为常规检测器的GPC体系。文中就该GPC体系在测试过程中的影响因素和注意事项通过一系列的实验展开系统的讨论。研究发现:流速、浓度和温度等因素在一定范围内的变化对试验结果影响不大(误差小于2%);在保证分离度的同时,可最大限度地提高流速以提高工作效率;在保证分子链段充分舒展的同时可适当增大样品浓度,将噪音的影响降到最小,从而增加结果的准确性;同时还可以利用温度对样品折射率的影响,通过升高或降低温度来调整折射率差,以解决样品在某个温度下不出峰的问题。

Gel permeation chromatography （GPC） is the most effective means to determine the molecular weight and distribution of polymer. In coatings field, the GPC often uses tetrahydrofuran（THF） as the mobile phase and the differential refractive index detector （R1） as a conventional detector. Through a series of experiments, the influencing factors and the matters needing attention in the testing process are discussed. It is found that the variation of flow velocity, concentration and temperature in a certain range has little effect on the test results;The flow velocity can be increased enough to improve the working efficiency if only the separation degree can be guaranteed;Providing that the full stretch of the molecular chain segment is ensured, the sample concentration can be increased properly to reduce the effect of the noise down to the minimum which is conducive for improvement of the testing accuracy; At the same time, the influence of temperature on the refractive index can be applied to adjust the refractive index difference by raising or lowering the temperature, so as to solve the problem that the sample does not have a peak at a certain temperature.