The Chitosan Carboxylic Acid Salts: Preparation By Solide-Phase Way, Structure, Properties And Application

Three kinds of chitosan carboxylic acid salts were prepared by the solid-phase way.The structure and their changes were characterized by FT-IR,NMR,elemental analysis and XRD. Their thermal properties,fluorescence,moisture-absorption and moisture-retention abilities were invested.The moisture-absorption kinetics of chitosan and its salts were studied.The chitosan oxalates were blended with starch and poly(vinyl alcohol)for application research. The relationships of temperature-viscosity,dehydration rate,distribution of particle size of the composite solution were studied.The IR spectra and DSC of their membranes were detected. The results showed that:1.The results of FT-IR,NMR and X-ray diffraction showed the chemical reaction between chitosan and acids and the existence of carboxyl in the product.The change of the FF-IR of the chitosan and its salts which were stored in different condition indicated the influence of the hydrone.2.The exothermic peaks of the chitosan salts were 310.6℃(chitosan oxalate),328.7℃(chitosan fumarate)and 337.7℃(chitosan salicylate),respectively.The endothermic peaks were 212.6℃(chitosan oxalate),203.6℃(chitosan fumarate)and 214.7℃(chitosan salicylate), respectively.These indicated the better thermostability of chitosan salts.3.The fluorescence results showed that the fluorescence intensities of chtosan salts were weaker than the chitosan.The chitosan salts had certain moisture-absorption and moisture-retention abilities.The abilities were related to the structure of the molecule.The moisture-absorption kinetics study revealed that the index were between 0.07 and 0.3 which indicated the way water infiltrating into the samples systems was non-Fickian.4.The result of the chitosan carboxylate applied characters indicated the chitosan oxalate/starch/poly(vinyl alcohol)composites propefities:(1)The viscosity of composite solutions increased with the poly(viayl alcohol)adding.(2)Poly(vinyl alcohol)could increase the dehydration rate of the starch/chitosan oxalate composite when it reached certain level.The dehydration rate of the composite expedited with the increased addition of poly(vinyl alcohol).(3)The distribution of composites size decreased with the additions of poly(vinyl alcohol).The range of the distribution of particle size became narrow.(4)The Fr-IR spectrum of the composite membrance without poly(vinyl alcohol)was different from the other spectra of the composite membrane.Those spectra indicated the new configuration which were associated by the the starch and poly(vinyl alcohol)through the hydrogen bond.(5)The exothermic and endothermic peaks in DSC of starch/chitosan oxalate composite membrance were at 181.2℃and 311.5℃.The phenomena of the composite membranes which were added poly(vinyl alcohol)were different.Two endothermic peaks at different position became sharp.It indicated the change of the thermostability.