Dilute solution properties of four natural chitin in NaOH/urea aqueous system

Four kinds of natural chitin originating from crab (C1), shrimp (C2), silkworm chrysalis (C3) and flies shell (C4) were dissolved in 8 wt.% NaOH/4 wt.% urea aqueous solution. Dilute solution behavior of chitin was examined by laser light scattering and viscometry. The Mark-Houwink equation and the relationship between the z-average radius of gyration (R-g) and the average-weight molecular (M-w) for Cl in the solvent at 25 degrees C were determined to be [eta] = 0.26M(w)(0.56+/-0.02) (mL g(-1)) and R-g = 0.15M(w)(0.47+/-0.03) (nm), respectively. On the basis of the polymer solution theory, the conformation parameters of Cl to C4 samples were calculated to be in the range of 25-18 nm for the length of the Kuhn statistical segment (Q(k)), and 43-32 for the characteristic ratio (C-infinity). respectively. It indicated that chitin molecules existed in a random-coil chain conformation, and chain flexibility increases from C1 to C4 in NaOH/urea aqueous system. (C) 2010 Elsevier Ltd. All rights reserved.