3. Result and discussion
3.1. Preparation of EHCs
The optimal condition for preparing EHCs was studied
by the orthogonal test. Three controllable variables, reaction
time (h), temperature and the molar ratio of HECs
to chloroethylamine hydrochloride, were selected, each at
three levels.The investigated variables and their test levels
are listed in Table 1. The test results are listed in Table 2.
As results indicated, in our study range, the order of influence
of each variable on the Mass is C1 > A1 > B1, while
A2 > C2 > B2 on NH2%. Thus the optimum reaction conditions
were determined as follows: Temperature 70–80 C;
the molar ratio of HECs to chloroethyl amine hydrochloride,
2:1 and the reaction time, 12 h. The experiment
showed that appropriate reaction condition was necessary
to prepare EHCs.