Appearance and molecular weight
 Pure chitin and chitosan is a white or gray translucent flake or powder solid, tasteless, odorless, non-toxic, chitosan slightly pearl luster. Organisms in the relative molecular mass of chitin 1 × 106 ~ 2 × 106, were extracted chitin relative molecular mass of about 3 × 105 ~ 7 × 105, Preparation of chitin and chitosan by the relative molecular mass of more low, about 2 × 105 ~ 5 × 105. In the manufacturing process, molecular weight of chitin and chitosan size, generally with low viscosity values ​​to represent. Chitosan products for different purposes depending on three different viscosity, high viscosity product is 0.7 ~ 1Pa · s, the viscosity of the product is 0.25 ~ 0.65 Pa · s, low-viscosity product <0.25 Pa · s. Manufacture of fiber products must be high viscosity of chitin or chitosan.

 Chemical properties
 In certain conditions, chitosan can occur hydrolysis, alkylation, acylation, carboxymethylation, sulfonation, nitration, halogenation, oxidation, reduction, condensation, and other complex chemical reaction, can generate a variety of different performance of the chitosan derivatives, thereby expanding the scope of application of chitosan. Chitosan molecules have hydroxyl and amino lively, they have a strong chemical reaction capabilities. In alkaline conditions, C-6 hydroxyl groups on the following reactions can occur: hydroxyethyl - chitosan reaction with ethylene oxide, available hydroxyethyl derivatives. Carboxymethyl - Chitosan and acid reaction will have to carboxymethyl derivatives. Acid esterification - the same as chitin and chitosan and cellulose, can be treated with alkali reacts with carbon disulfide sulfonic acid ester. Ethyl cyanide - acrylonitrile and chitosan addition reaction can occur to produce ethyl cyanide derivatives. The reaction of chitin and chitosan in the introduction of large side groups, undermines its crystal structure, and thus increase its solubility, water-soluble, carboxymethyl derivatives in solution shows the polyelectrolyte nature.