Study On The Preparation And Properties Of Cross-linked Carboxymethyl Potato Starch

With potato starch as raw materials, epichlorohydrin as crosslinking agent and chloroacetic acid as etherification agent, this experiment optimized the process of cross-linked starch, carboxymethyl starch and cross-linked carboxymethyl starch. Through measuring and comparing the performance of cross-linked starch, carboxymethyl starch, cross-linked carboxymethyl starch, the different degree of crosslinking of crosslinked starch as well as different cross-linking of cross-linked carboxymethyl starch, our can find the best process of cross-linked carboxymethyl starch. The main results are as follows:1. The best parameters of prepared of carboxymethyl starch are the weight ratio of NaOH/Starch 0.09, and the weight ratio of CH2ClCOOH/Starch 0.11, and the reaction temperature 45℃, and the reaction time 6h.By this process, our can obtained the CMS which the DS is up to 0.0842.2. The best parameters of prepared of cross-linked starch are the epichlorohydrin volume (ml) and starch (g) ratio was 1.4%, reaction temperature 50℃, pH of starch slurry 11, reaction time 8 h. By this process, our can obtained the cross-linked starch which the crosslinking is up to 0.95 or so.3. With the greatest degree of cross-linking cross-linked starch as raw materials, the best parameters of prepared of cross-linked carboxymethyl starch are the weight ratio of NaOH/Starch 11.5%, and the weight ratio of CH2ClCOOH/Starch 8%, ethanol concentration 85%, alkalization temperature 30℃, alkalization time 30 min, reaction temperature 60℃, reaction time 8 h. By this process, our can obtained the cross-linked carboxymethyl starch which the DS is up to 0.0488.4. Compared with the properties of potato starch, cross-linked starch, carboxymethyl starch and cross-linked carboxymethyl starch, the results showed that: carboxymethyl starch and cross-linked starch are modified significantly, and also obtained the good performance we need. With the greatest degree of cross-linking cross-linked starch as raw materials, the cross-linked carboxymethyl starch don't inherited the properties both cross-linked starch and carboxymethyl starch, but more inherits the properties of cross-linked starch.5. With the different degree of cross-linking cross-linked starches as raw materials and the best parameters of prepared of cross-linked carboxymethyl starch before as the parameters, our obtained several different cross-linked carboxymethyl starches, and measured their DS. The results showed that: it had no significant in the low degree of crosslinking and the degree of crosslinking conditions that the different degrees of cross-linking effect the D.S. of cross-linked carboxymethyl starches. However, the excessive cross-linking completely limited the space structure of starch granules, which reduced the D.S. of cross-linked carboxymethyl starch.6. Compared with potato starch, cross-linked carboxymethyl starch named N5 and N7 showed that: their capacity of starches viscosity, resisting shear strength, acid, alkali and non-electrolyte improve significantly. Their transparency has no change obviously, but the salt resistance of starches is poor.