The average degree of polymerization of polyvinyl alcohol (PVA) can be determined by several methods, among which the more commonly used methods are chromatographic method and gel permeation chromatography.
Chromatography
Chromatography is a traditional analysis method, which mainly determines the degree of polymerization of the sample to be tested by comparing it with standard samples of different degrees of polymerization of polyvinyl alcohol (PVA).
Specific steps are as follows:
The PVA samples to be tested and standard samples with different degrees of polymerization were dissolved in water to prepare solutions with different concentrations.
The sample solution and the standard solution were chromatographed on silica gel or paper along the same direction.
The chromatogram is dyed with dyestuff, compares the Rf value of each component, i.e. the colorimetric coefficient, then determines the average degree of polymerization of the PVA sample to be tested according to the standard curve.
gel permeation chromatography
Gel permeation chromatography is an efficient liquid chromatography method that can directly determine the average degree of polymerization of PVA samples.
Specific steps are as follows:
Dissolve the PVA sample in the mobile phase in high performance liquid chromatography.
The sample solution is injected into a gel permeation chromatography column, where separation is performed by the size and shape of the molecules in the interstices.
By detecting the residence time of the sample in the column, the average degree of polymerization of the sample can be calculated.
NBCHAO reminds you: Different determination methods will be affected by factors such as sample properties and analysis conditions, so it needs to be selected according to the specific situation in the experiment.
