Preparation And Characterization Of Soy Protein Isolate/Poly（Lactic Acid）/TiO₂Composite Materials

Composite materials were prepared by soy protein isolate （SPI）, poly （lacticacid）（PLA）, and tetrabutyl titanate, including SPI/PLA composite films, SPI/TiO₂composite films, SPI/TiO₂/tetracycline （Tet） composite films, PLA/TiO₂composite films,and SPI/PLA blend fibers. The structures and properties of the composite materialswere characterized.SPI/PLA composite films were prepared by solvent casting method. SPI/TiO₂composite films, SPI/TiO₂/Tet composite films, and PLA/TiO₂composite films wereprepared by sol-gel method and solvent casting method. In SPI/PLA composite films, theSPI layer and the PLA layer adhered to each other closely, and the mechanical and waterbarrier properties were improved. With1wt%TiO₂, the SPI/TiO₂composite films had thebest comprehensive performance. The drug loading of all kinds of SPI/TiO₂/Tetcomposite films is higher than60%; with the increase of drug loading the antibacterialproperties of the composite films improved; the composite films with5wt%Tet had thebiggest tetracycline percentage released in72hours. PLA/TiO₂composite films with2wt%TiO₂had the strongest mechanical properties and those composite films with5wt%TiO₂photodegraded the most efficiently.SPI/PLA blend fibers were prepared by electrospinning technique usingmodified SPI and PLA. Fourier transform infrared spectroscopy （FTIR） showedthat SPI adhered to PLA through hydrogen bonds. From scanning electronmicroscopy （SEM）, voltage and receiving distance influenced the morphology ofthe fibers. With the voltage and receiving distance increased the diameters of theblend fibers got smaller. The water absorption experiment and degradationexperiment results showed that the hydrophility and degradability increasedcompared with pure PLA fibers and became better with the SPI content increased.