Study On Chitosan, Chitin/Polyurethane Composite Materials

Several series of polyurethane elasomer membranes with different structure and hard segment content were synthesized using hydroxyl-terminated polybutadiene (HTPB) or polypropylene glycol (PPG) as soft segment, liquefaction modified MDI or TDI as hard segment and ethylene glycol (EG) or glycerol (GL) as chain extender. The influence of the soft segment kinds and the molecular weight of HTPB, the kinds and content of chain extender and the kinds of diisocyanate were studied. The structure, morphology, thermal stability and mechanical properties of the above samples were characterized by wide angle X-ray diffraction, Fourier transform infrared spectrometer (FTIR), scanning electron microscopy (SEM), tensile test, hardness test, differential scanning calorimetry (DSC), thermogravimery (TG). In order to looking for a better preparation condition for the chitosan –polyurethane composite membranes, the condition of film forming and the performance of chitosan membranes were discussed in this article. Result shows that the initial concentration of Chitosan solution and dry temperature of membrane has very great influence on the performance of the membrane. The chitosan membranes have preferable mechanical properties, swelling ratio, hygroscopic ratio and water vapor transmission in the condition that the concentration of chitosan solution is 20g/L and the dry temperature is 60℃.Using the polyurethane membranes with different hard segment content as the basal membrane, the chitosan and polyurethane composite membranes were prepared by casting method. The mechanical properties, swelling ratio, hygroscopic ratio, water vapor transmission and electrical properties of the composite membranes were studied. The adherence ability of the composite membranes was discussed from their stress and strain curves. It has been determined that the adherence of composite membranes was caused by the molecular interaction on the interface for membranes. The results of research show that the PU membrane has the stress-strain behavior of elastomer and CS membrane has the stress-strain behavior of plastomer. The PU-CS membrane has the stress-strain behavior of plastomer. The stress-strain curves can be found four cases according to the different adherence ability of the composite membranes in the course of tensile. Therefore we can judge the firmness of interface adhesion according to stress strain behavior. The performance of compound membranes will have difference since basal membranes are not same.Blend films of chitin and polyurethane were prepared by a blend technique from corresponding polyurethane prepolymer. The influence of blend compositions on mechanical properties, thermal stability, swelling ratio and hydroscopic ratio of the blend films was studied. The degradability of blend films in different conditions was also investigated. The performance of blend films will show different change with the amount of chitin change.