Analysis of polysaccharide-poly(ethylene-co-acrylic acid) composites by fourier-transform infrared spectroscopy

Abstract A method, based on absorbances in FTIR spectra of the CO singlebond stretch band of the polysaccharide and the CH stretch band of poly(ethylene- co -acrylic acid) (EAA) at 2851 cm −1 , was developed for the determination of EAA in composites with either dextran or starch. Spectral subtraction of the polysaccharide component was necessary for quantitative determination of EAA. The accuracy of this analytical procedure is affected by the fact that absorbances of these two bands are not equally dependent on particle size of the sample in the KBr pellet; the absorbance ratio, as calculated from FTIR spectra therefore varies with sample preparation conditions. To ensure the necessary particle size uniformity during the preparation of KBr pellets, a method based on relative intensities of two bands in the CO region of the spectrum was developed as an indicator of particle size in the pellet. This method was also used for monitoring sample size in the polysaccharide standard used for spectral subtraction, since particle size uniformity between sample and polysaccharide standard was also necessary for accurate determination of EAA.