Study On Cassava Starch/Chitosan/Polyvinyl Chloride/Gelatin Blended Membrane

In this study, we take cassava starch, chitosan, poly vinyl alcohol and gelatin as main raw material, gelatinize the cassava starch, and make chitosan soluble in dilute acetic acid solution, then blend with PVA solution and GEL solution according to a certain proportion, to prepare cassava starch/chitosan/poly (vinyl alcohol)/gelatin composite materials. The properties of CST/CS/PVA/GEL composite material under different ratio of the constituent, drying temperature, cassava starch contents, different amount of cross-linker and plasticizing agent were examined. The study shows: there were some strong mutual interaction forces between PVA and CS, PVA and CST, PVA and GEL. AT nitrogen atmosphere, both of the two blended membrane, CST/CS and CS/GEL had two phases of thermal gravimetry.Thermal stability of them were poorer. CST/PVA has three phases of thermal gravimetry. it’s thermal stability is better. Different preparative methods can influence the mechanical properties of the blended membrane greatly. The comprehensive mechanical properties of the blended membranes which were dried by the drying method at38℃is better than it which were dried with the freeze-drying method. While CS: PVA: GEL was1:3:1, the blended membrane had a better comprehensive mechanical properties and a better transmittance. While CS: PVA: GEL was1:1:3, the blended membrane had a better water absorbability and water-retaining property. While CS: PVA: GEL was2:1:2, the blended membrane had better water vapor permeability. The amount of cassava starch had great effect on the properties of the blended membrane. In the range of0-25%,the mechanical properties,the water absorbability and water-retaining property of the blended membranes decreased with the increase of the content of the starch, while the water vapor permeability increased with the increase of the content of the starch, the transmittance of the blended membrane increased firstly and then decreased. The drying temperature had an important impact on the properties of the blended membrane. While the drying temperature was60℃,the blended membrane had a better comprehensive mechanical properties and a better transmittance. while the drying temperature was50℃,the blended membrane had a better water absorbability and water-retaining property, the water vapor permeability increased with the increase of the drying temperature. Both the amount of the cross-linker and the amount of the plasticizing agent had important impacts on the properties of the blended membrane. In the range of0-5%,the elongation rate at break,the water absorbability and water-retaining property of the blended membrane decreased with the increase of the content of the cross-linker. The tensile strength, tear strength, water-retaining property and transmittance of the blended membrane increased firstly and then decreased. The elongation rate at break and the transmittance of the blended membrane increased with the increased of the amount of the plasticizing agent. The tensile strength, tear strength, water-retaining property, the water absorbability and water-retaining property of the blended membrane increased firstly and then decreased. While the amount of the plasticizing agent was1%, the tensile strength, the water absorbability and water-retaining property of the blended membrane were better. While the amount of the plasticizing agent was3%, the tear strength and the water-retaining property were better.