2.5. Characterization of chitin, chitosan and encapsulatedsamples
The chitin and chitosan samples obtained from crayfish and theprepared microcapsule samples were photographed using a scan-ning electron microscopy (QUANTA FEG 250). The samples werecoated with gold using a Sputter Coater (Cressingto Auto 108).The ATR FT-IR analyses of chitin, chitosan and microcapsulesamples were performed with a Perkin Elmer FT-IR spectrometerover the frequency range of 4000–625 cm−1. The TG/DTG curves atthe thermal degradation of chitin, chitosan and the encapsulatedsamples were analyzed at a heating rate of 10◦C min−1via an EXS-TAR S11 7300. X-ray diffraction analyses of the chitin, chitosan andencapsulated samples were made using a Rigaku D max 2000 sys-tem at 40 kV, 30 mA and 2 with a scan angle from 5◦to 45◦at theheating rate of 10◦C min−1.Molecular weight of the crayfish chitosan was measured usingan Ubbelohde Dilution Viscometer. Five different concentrations ofthe chitosan were prepared using the solvent system (0.1 M aceticacid + 0.2 M NaCl (1:1, v/v)) for determining the viscosity-averagemolecular weight. All the treatments were conducted at 25◦C intriplicate and the mean value was determined. Mark-Houwinkequation was followed for determination of molecular weight asgiven below;