|Akinosho, Hannah -|
|Wicker, Louise -|
Submitted to: Carbohydrate Polymers
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 28, 2013
Publication Date: October 1, 2013
Citation: Akinosho, H., Hawkins, S.A., Wicker, L. 2013. The characterization of hydroxypropyl methylcellulose through the analysis of its substituents. Carbohydrate Polymers. 98:276-281. Interpretive Summary: Hydroxypropyl methylcellulose (HPMC) is present in food, pharmaceuticals and other products. The concentration of certain functional groups affect how well HPMC gels in these products. This study sought to use analytical techniques to characterize the gelling capabilities and correlate them with the concentration of functional groups as measured using these techniques.
Technical Abstract: The methyl and hydroxypropyl substituents in hydroxypropyl methylcellulose (HPMC) affect the resulting gel properties. These substituents in five HPMC gels were characterized using Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, small-amplitude oscillatory shear measurements, and differential scanning calorimetry (DSC). In FT-IR spectra, the most intense peak appeared at 1053 cm-1, denoting the presence of the glucose ring. The ratio of peak intensities at 1452 cm-1, which represents –C-H absorptions, and at 1053 cm-1 (I1452/I1053) and percent methylation from gas chromatography exhibited a linear association (r2=0.6296). The broadening of the Raman spectra indicated that the relative crystallinity of HPMC decreases with increasing hydroxypropyl contents. DSC showed no linear relationship between the percent hydroxypropylation in HPMC and the percentage of free water in an HPMC gel. Small-amplitude oscillatory shear measurements revealed that the formation of an entanglements networks and/or weak gel depends on substituent