Preparation And Property Study Of Chitosan Membrane And Its Blended Membranes

Chitosan (CS), poly (vinyl alcohol) (PVA) and poly (lactic acid) (PLA) are widely used as biomedical resources due to their unique properties including biological activity, nontoxicity, biodegradability, and biological compatibility. However, CS is a kind of rigid molecule. the mechanical property of the pure CS membrane is poor, and it also has a greater brittleness. The pure PVA membrane has poorer degradation, while the pure PLA membrane has poorer water solubility and greater brittleness. In order to improve the performance of the individual polymer. based on the analysis of CS properties, the blended membranes made of CS, PLA and PVA were studied, so as to find a proper way to enhance their mechanical property and biological property.In this study, the degree of deacetylation (DD), the molecular weight and the solubility of CS membranes were tested and analyzed. The CS membranes were prepared under different conditions. The surface micrographs of CS membrane obtained by SEM revealed its smooth matrix with good integrity and little pores. It was characterized by a compact. uniform, dense structure and homogenous appearance. The adding of glycerin could improve the moisture absorption property. the water solubility and water vapor permeability of CS membrane. The temperature factor has no evident effect on preparing the membrane.When CS and PLA were mixed, the mixing ratio had an influence on the compatibility of the blend solution. Once the CS dosage decreased to 50%, the phenomenon of delamination appeared in the solution, and it was more obviouswith the proportion of CS decreasing. CS90 showed the best performance on the breaking strength, and its breaking elongation was moderate. At the same time, the moisture absorption property and water vapor permeability in this ratio were excellent, but the water solubility was moderate. The membrane at this case meets the requirement of the effusion and permeability in tissue engineering. It was found that the surface morphology of the blend membranes were irregularity. There were holes and pores, coming out with cluster effects. And the number of the holes and pores increased with the increasing of PLA. IR XRD and DSC tests indicated that new covalent chemical bonds occurred and new crystal appeared in the blended membrane.The experimental results of CS/PVA/PLA blend membranes indicated that the changing of moisture absorption property and water solubility had the same variance tendency, CS60 had the best performance. Water vapor permeability reduced with the decreasing of CS. However, the breaking strength and breaking elongation had contrary changing trend. The breaking strength increased, but the breaking elongation played down. It can be seen from the SEM figures that the membrane had irregular surface, and the blend polymers had more serious phase separation. As the CS dosage reduced, the number of the holes and pores increased. By means of configuration analysis, the blend of the three polymers altered their crystal structure and molecular groups, thus the flexibility of the membrane enhanced.CS/PVA/PLA porous membranes were prepared by vacuum freeze-drying method. In the process of drying, the spongy material was got as the result of the sublimation of the ice particles. The porous membrane properties, including moisture absorption property and the water solubility, decreased with decreasing of the CS blending ratio. CS60 showed the best performance on water vapor permeability. There were the same variance tendency of breaking strength and breaking elongation, they both decreased first and then increased, and breakingstrength of CS60 has the lowest value. From the surface micrographs obtained by SEM, they were deformed porous structure and pore size, and some aggregating microspheres can be seen on the pore walls. Compared with normal-drying method, the different crystal structures and molecular groups were constructed, and the new hydrogen bonds were formed.The findings, thus, indicates that the CS blended membranes can combine the excellence of several substances. Better composing structure, mechanical property, compatibility and certain biological properties can be gained. It is beneficial for the blended membranes to be used more frequently in the biomedical field.