(1) Five grams of chitosan was added into a certain number
of sodium hydroxide solution(50%,by weight)
with stirring, then the mixture was put into refrigerator
at 18 C for 48 h for alkalization. After thawing,
Alkali chitosan and Isopropyl alcohol(10 ml) were
mixed and stirred to homogenization, then some
chloroethanol was added with continuous stirring at
80 C for 12 h. After filtration, the solid product
was washed with alcohol for two times. HECs yielded
was dried in an oven at 60 C.