Characterization of crosslinked starch materials with spectroscopic techniques

Abstract

ABSTRACT:The structure, mobility, and properties of crosslinked starch materials of various compositions were investigated with FTIR and NMR spectroscopy, and relaxation time measurements were taken with cross-polarization/magic-angle-spinning (CP-MAS) and magic-anglespinning (MAS) spectroscopy. Characterization by Fourier transform infrared spectroscopy confirmed the crosslinking reaction. The CP-MAS and MAS spectra allowed the assignment of the principal 13 C signals. The molecular mobility of these polysaccharides was analyzed in terms of the crossrelaxation time between the protons and carbons, the 1 H spin-lattice relaxation time in the rotating frame, and the 1 H longitudinal spin-lattice relaxation time. Relaxation studies showed that increasing the crosslinking degree increased the amorphous content, and the material became rigid as an increasing number of covalent bonds in the polymer network reduced mobility. The values of the spin-lattice relaxation in the rotating frame reflected the homogeneous nature of the materials. The correlation between the crosslinking degree, structure, and mobility and the sorption properties of these sorbents was examined.

Influence of some polysaccharides on the production of calcium carbonate filler particles

“…However, considerable changes are observed in the spectra of the samples precipitated in the presence of anionic (spectrum i) and of non-ionic (spectrum j) dextrans. The major differences appeared in the region of 1700-900 cm À1 , which is characteristic of the vibration frequencies of O-H bending (E1645 cm À1 ), C-O/C-C (1150-950 cm À1 ) and SQO (1250-1240 cm À1 ) stretching modes [34,37]. In the case of the non-ionic dextran (spectrum j), the absorption bands, characteristic both of carbonate ion normal vibrations (1500-1400 cm À1 ) [32] and of the dextran C-H bending mode (1455-1300 cm À1 ) [34], overlap and lead to a broad band formation.…”

Study of hydration of cross-linked high amylose starch by solid state 13C NMR spectroscopy

“…The multiplicity of the C1 resonance peak provides information on the crystallinity, the conformation of starch, and the double helix symmetry. [8][9][10][11][12][13]17 For the B-type conformation, the C1 resonance exhibits two peaks at 101 and 100 ppm and the A-type has three peaks at 102, 101, and 100 ppm. 11,13,18 The broad peak of C1 at 103 ppm is typical of a single helix organized in a V-type crystalline phase or dispersed in an amorphous phase.…”

Interaction between κ- and ι-carrageenan and anthocyanins from Vaccinium myrtillus

“…The signal at 805 cm −1 (peak C) is specific of the C O S vibration in 3,6-anhydrogalactose-2-sulfate and presents only in the FT-IR spectrum of -CARG. A wide peak (peak G) at about 1370-1430 cm −1 in the FT-IR spectrum of -CARG-C and at about 1410-1480 cm −1 in the spectrum of -CARG-C was originated and could be related to CH 2 groups of glyceryl bridges introduced during the cross-linking reaction with epichlorohydrin (Delval et al, 2002(Delval et al, , 2004. At the same time, the peaks typical of the sulfate groups remained in the spectra of CARG-C.…”

“…However, in the spectra of CARG with introduced ATCs the peaks D, E and F typical of the Cy-3-glc are present, but with a low intensity, and the peak F is shifted to the lower wavenumbers. It could be mentioned that in the spectra of CARG with the introduced ATCs, the peak at 1640 cm −1 (peak I) related to the water present in the polysaccharide (Delval et al, 2002(Delval et al, , 2004 disappears. It is possible that the sulfate groups of CARG were blocked by flavylium cations due to the electrostatic interaction, and the hydrophobicity of CARG/ATCs complexes increased.…”