Preparation,Characterization And Functional Study Of Starch And Its Composite Nanofiber Membrane

Starch is a kind of natural polymer with low price,easy access,bio-degradable and good bio-compatibility.Among them,starch-based food packaging film is considered as one of the most promising“green packaging materials”.However,due to the limitation of starch materials’own properties,the pure starch food packaging films often have some deficiencies such as low direct mechanical properties,poor hydrophobic properties,and lack of activity(such as necessary antioxidant and antibacterial).Electrospinning is a new technique for preparing nano-materials.The polymer can be directly prepared into nanofiber membrane by electrospinning.In addition,nanofiber membrane not only has large specific surface area and high porosity,but also has good mechanical properties.At the same time,different types of active substances can be loaded by simple blending method to improve the functional characteristics of nanofiber membrane.In view of this,the paper improved the electrostatic spinning technology and studied the preparation method of starch nanofiber membrane under temperature assisted conditions.At the same time,from the perspective of joint multiphase composite crosslinking modification,combined with scanning electron microscope,Fourier infrared spectrometer,X-ray diffraction,thermogravimetric analyzer and other characterization methods and mechanical property test,static water contact angle measurement,anti-oxidation and bacteriostasis analysis test method,discusses the functional transformation of starch nanometer fiber membrane formation law of sandstrom,and for the research and application of new type of starch based food packaging film development to provide theoretical basis.The main research contents and results are as follows:1.High amylose corn starch was used as raw material to prepare starch nanofiber membrane by temperature assisted electrostatic spinning method,and the effects of different spinning conditions on the formation of nanofiber microstructure in starch membrane were studied.Because of the structure of the nanofiber,the mechanical properties of the starch film prepared by the conventional fluidization method are better.In addition,it was cross-linked with glutaraldehyde vapor to study the hydrophobic properties of starch nanofiber membrane.The experimental results showed that the optimal process conditions for electrostatic spinning of starch nanofiber membrane were the spinning concentration of 25.0%,the spinning voltage of 20.0 k V and the spinning distance of 15.0 cm.When the crosslinking time is 12 h,the static water contact angle can reach 93.2~°.Through the above research,an effective preparation method of starch nanofiber membrane and a hydrophobic modification approach were obtained.2.On the basis of the construction of the starch nanofiber membrane,with high amylose maize starch and tea polyphenol as raw material,through mixing and preparation of starch electrostatic spinning method tea polyphenol compound nanofiber membrane,tea polyphenols were studied in the starch-tea polyphenol compound nanofiber membrane microstructure,mechanical strength and oxidation resistance.The hydrophobic property of the composite fiber membrane was improved by chemical crosslinking.The experimental results showed that the optimal process conditions for electrostatic spinning starch-tea polyphenol composite nanofiber membrane were starch mass fraction of 25%and tea polyphenol mass fraction of10%.When the crosslinking time is 2 h,the static water contact angle can reach86.5~°.Through the above research,an effective preparation method and law of starch matrix composite nanofiber membrane with hydrophobic and antioxidant properties were obtained.3.The preparation and functional changes of starch nanofiber membrane(i.e.,starch-polyvinyl alcohol-Ag~+composite nanofiber membrane)under ternary composite were further studied by using high amylose corn starch,polyvinyl alcohol and sodium zirconium phosphate as raw materials.The addition of polyvinyl alcohol can effectively improve the mechanical properties of starch nanofiber membrane.When the mass ratio of starch to polyvinyl alcohol is controlled at 60/40,its mechanical properties are the best(elongation at break is 61.45%,elastic modulus is6.32 MPa,tensile strength is 0.70 MPa)while maintaining the good morphology of the nanofiber in starch membrane(the average diameter of the nanofiber is 215.67±50.00 nm).On the basis of less compromise of microscopic properties,the starch-polyvinyl alcohol-Ag~+composite nanofiber membrane has better antibacterial properties when the loading amount of sodium zirconium phosphate silver is 4%.The hydrophobic property of the composite fiber membrane was further improved by using chemical crosslinking technology.When the crosslinking time was 12 h,the static water contact angle could reach 9.40~°.Through the above research,an effective preparation method and law of starch matrix composite nanofiber membrane with hydrophobic and antibacterial properties were obtained.