| 초록 |
α, β, γ-formed chitin were isolated from crab shell, squid pen, beetles cuticles by acid, alkali treatment and its structural characterization was analyzed by FT-IR, solid state CP/MAS 13C NMR spectrophotometer, TGA and XRD. The degree of acetylation of α, β, γ-chitin were 79.2 %, 67.7% and 55.3%, respectively. At FT-IR spectra, α, β-chitin showed doublet and singlet at amide I band, respectively, and γ-chitin showed intermediate form between α- and β-chitin. From solid state CP/MAS 13C NMR spectra, two signals appeared at around 73 and 75 ppm assigned to C3 and C5 carbon atoms in α-chitin are sharply resolved, the signals of C3 and C5 in β-chitin shows singlet at around 74 ppm. In case of γ-chitin, two signals show at around 73 and 75 ppm assigned to C3 and C5 carbon atoms. From the X-ray diffraction results, α-chitin was observed four crystalline reflections, shown at 9.6, 19.6, 21.1, and 23.7 by crystalline structure. Also, β-chitin was observed two crystalline reflections, shown at 9.1, and 20.3 by crystal structure. γ-chitin with structure of both antiparallel and parallel was close to X-ray diffraction patterns of α-chitin. The thermal decomposing activation energies of α, β, and γ-chitin calculated by TGA were 60.56, 58.16, and 59.26 kJ mol-1, respectively.
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