Preparation Of Natural Polymers Based Nano-composite Films And Study On Their Performance

Petroleum-based plastics have sufferd from the influence of many fators,whichdueto the limited fossil material and damage the ecological balance after discarded,for the study and development of highly efficient degradation of plastic to replace petroleum-based plastic has important strategic significance.It is generally acknowledged fact that starch is a natural rich renewable resources in nature,has a environmental health and biodegradability,and thus starch-based preparation of plastic film to become the best choice for completely degradable plastic.However,for starch-based films,it is necessary to further improved their own processing mechanical properties in order to promote andapply.At present,the inorganic nano-particles used in natural polymer matrix to achieve nano-scale composite research has been widespread concern.In this study,the nano-TiO₂ with the surface effect,quantum effect and small size effect and other unique properties,it is evenly dispersed in the modified starch and natural polymer film to achieve the inorganic and organic doping to improve the composite film,serie s of new nano-degradable composite films were prepared by casting process.The properties and structure of nanocomposite films were measured and characterized.Through the orthogonal test,the optimum conditions of the composite membrane were studied and determined,which provided some reference for the improvement of the process and the control of the cost.Adding the natural biopolymers such as carboxymethylcellulose（CMC）,Sodiumalginic（SA）,urea（UR）as strengthening agents and two kinds of plasticizers including sorbitol（SOR）and polyethylene glycol 400 into blended system of the Ultrasonic dispersion of nano-TiO₂ and acetate starch（PMS）and can effectively improve the mechanical properties and water resistance of the compositemembrane.It is concluded that the mechanical properties and water resistance of the composite membrane are obvious.n the SOR plasticizer systemwhen the content of nano-TiO₂ were 0.003 g showed the mechanical properties and water resistance of the film are the best,the tensile strength（TS）can be increased by 71.1%,the water absorption can be reduced by 4.14% and the elongation at break（E）reaches 53.87%.When the mass ratio of SOR and UR is 1:3,the tensile strength of the composite film is increased by 51.5% and the elongation at break（E）is increased by 61.8% in the blending system with the amount of nano-TiO₂ of 0.003 g,and addition the urea（UR）is used as a water resistance can further improve the water resistance of the membrane,and the water absorption rate is reduced to 72.12%.The tensile strength of the composite film was increased by 34.78% and 31.27% respectively with SOR and PEG400 as the plasticizer,and the water absorption was reduced to 71.74% and 88.10%,respectively,also the light transmittance increased to 60.21%,54.85%.Orthogonal test showed that the tensile strength of the composite film was 32.10 MPa,and the mechanical properties of the membrane were better observed under the conditions of 0.003 g nano-TiO₂ and 3.5g PMS,sorbitol 1.2g,urea 0.7g and CMC: SA =1:1.Infrared spectroscopy（FTIR）indicates that strong hydrogen bonds between the nano-TiO₂ and the components in the system were formed;Urea with the hydroxyl groups on the molecular chains of the polymer have a powerful interects.Electron microscopy（SEM）manisfed that the quiet contents nano-TiO₂ and blends Has a good compatibility,however,the composite films with excessive nano-TiO₂ will make the membrane structure is not uniform,the performance became poor.The addition of CMC and SA enhancers forms a solid structure with the system,which is compatible with the nano-TiO₂-promoted system and forms a more robust network structure.At the same time,the agglomeration of nano-TiO₂ can be improved.