Studies On The Structure Characterization And Properties Of Natural Polysacchride Blend Materials

With the wide use of non-degraded polymers, environmental pollution caused by the waste is increasing and the petroleum-based resource is exhausted day by day. Therefore, it is necessary to study and develop the novel polymer material mainly from natural polymer. Blend is handy and important way to exploit new material for polymer, and also a main method to prepare alloy. It can improve polymer's properties or bring out new functions, blend different polymers by physical and chemical ways, and it has become a new branch in polymer material science and engineering.Chitosan, starch, alginate acid and soy protein isolate have attracted the wide attention of many researchers because of their good biodegradability, renewability and plentiful resource. Rich hydroxyl groups and amino groups in chitosan, rich hydroxyl groups in starch, rich hydroxyl groups and carboxyl groups in alginate acid, rich amino groups in soy protein isolate facilitate the form of intermolecular hydrogen bonding with other polymers, which led to good miscibility, and subsequently novel function and property.The main contents in this thesis are as follows:The chitosan-starch-sodium benzoate blend films were prepared by solution method, and then characterized by FT-IR, XRD, transmittancy, percent water absorption, measurement of mechanical properties and antimicrobial activity. The results suggested that there was some strong interaction and good compatibility in the blend films. The starch content in the blend films can improve the mechanical properties of them, the tensile strength values increased by 31.9% in dry state and 26.4% in wet state when the starch content was 40%. The antimicrobial activity of blend films increased as sodium benzoate was added to the films, In one week, the antimicrobial activity against St.aureus and E.coli of the blend films increased by 10.4% and 31.2% each when the chitosan content was 80%.With bovine serum albumin (BSA) as a model drug, drug loaded films of chitosan (CS) and poly (vinyl alcohol) (PVA) were obtained by a casting/solvent evaporation method, and crosslinked by tripolyphosphate (TPP). The films were characterized by FT-IR, XRD and SEM. And then the influential factors of drug-loaded films on drug controlled release were studied. These factors included the component ratio of CS and PVA, the loaded amount of BSA, the pH and ionic strength (â… ) of the release solution, the cross-linking time with TPP, etc. The results showed that within 25 hours, if the drug loaded films' composition proportion of CS to PVAwere 90:10, 70:30, 50:50 and 30:50, the cumulative release rate of BSA were 63.3%, 72.9%, 81.8% and 91.8%; if the drug loaded amount were O.lg, 0.2g and 0.3g, the release rate were 100%, 81.8% and 59.6%, respectively; when the pH of the drug release medium were 1.0, 3.8, 5.4 and 7.4, the release rate reached 100%, 100%, 37.9% and 7.8%, respectively; the cumulative release of BSA were 78.4%, 82.3%, 84.3%, 91.7% as the release solution's I were 0.1M, 0.2M, 0.3M and 0.4M; when the crosslinked time of these drug films in the TPP solution were 0 min, 5min, 15min, 30min and 60min, the release rate attained 100%, 100%, 81.8%, 65%, 43.3%, respectively. All the results indicated that the CS/PVA film was useful in drug delivery system.Alginate and soy protein isolate blend fibers were prepared by spinning their solution through a viscose-type spinneret into a coagulating bath containing aqueous CaCfe, HCl and ethanol. The structures and properties of the fibers were studied with the aids of infrared spectra (IR) and X-ray diffraction (XRD). Mechanical properties and water-retention properties were measured. And with the sample of AS1 fiber(soy protein isolate weight content was 10%), the effects of the composition of the coagulating bath were also studied. The best values of the tensile strength of blend fibers, 14.10cN/tcx in the dry state and 3.46cN/tex in the wet state respectively, were obtained when soy protein isolate weight content was 10%. Both the dry state and wet state breaking elongation were also having the best value when soy protein isolate weight content was 10%. Mechanical properties of the AS1 enhanced with the CaCfe content increased in the coagulating bath. When the HCl content was 1%, the mechanical property of the fiber was best. Ethanol in the coagulating bath increased the wet mechanical properties of the fiber, but it had little effect on the dry mechanical properties. And the water-retention value (WRV) of blend fibers deceased as the amount of soy protein isolate was raised. The structure analysis indicated that there were strong interaction and a certain level of miscibility between alginate and soy protein isolate molecular.