Research On Synthesis And Properties Of PU-Gt/CS Composite Materials

The anionic PU solution was synthesized through prepolymerization, chain extension, neutralization and dispersion steps, and studied the impact of the salicylaldehyde amount, R-value and neutralization degree on the synthesized PU. The results showed that the optimum neutralization degree were85%or more, the most appropriate R-value was3:1,the most appropriate amount of salicylaldehyde was0.5%, the anionic PU solution under the best conditions was clear and stable, and has good acid, alkali stability, storage stability and high-temperature stability.A series of PU-GT/CS membranes were prepared and explored the impact of different factors on the PU-GT/CS complex membrans.Studies showed that with the introduction of CS increased the flexibility of the composite membrane, and the R value, neutralization degree etc. has certain influence on PU-GT/CS complex membrane,the optimum conditions were as follows:the pH was5-8; the neutralization degree was100%; the R-value was3:1; the amount of salicylaldehyde was0.5%; the PU solution concentrations was35-45%; the GT concentration was5-15%; the PU/GT mass ratio was7:3; the concentration of HAC and CS was2%. And with the increase of the molecular weight and content of CS, PU-GT/CS composite membrane feel softer. With the increase of GT content and molecular weight of PEG, membrane swelling rate increase as well. FTIR showed that PU was successfully connected on the gelatin and there was not formed new chemical structure between CS and GT, but hydrogen bonding.A series of PU-GT/CS microsphere was prepared and the results showed that the optimum PU/GT mass ratio was1:10, the concentrations of GT, PU, CS and CaC12was20-25%,35-40%,0.5%and8%or more. Before and after drying, the average diameter of the composite microspheres were3.13mm and2.21mm, both of the diameter distributions were both accord with normal distribution law. Though the scanning electron microscopy (SEM) figures we can know that the composite microsphere shape was round. And there were many tubular cavityies throughout the entire microspheres. The PU-GT/CS composite microsphere prepared has good toughness and mechanical strength, and unbreakable. The content of GT and CS molecular weight has a certain impact on the moisture content and swelling ratio of the composite microsphere, with the decreasing of the ratio of gelatin or the moisture content and swelling ratio will decreasing, and the impact of CS molecular weight was the same, with the join of GT and CS, the degradation of microspheres accelerated.With Tetracycline Hydrochloride (TH) as drug model the drug-carried PU-GT/CS composite microsphere was prepared. The study of drug-releasing indicated that we can delay the releasing behavior of TH though the composite microsphere. And with the increasing of drug concentration, the drug loadings of microspheres increased first and then leveled off, other the coating first increased and then decreased.With the decrease of the content of GT the drug release ratio decreased.