Study On Inorganic Nano Materials Improving Performances Of Cellulose Preservative Films

The cellulose preservative films can be prepared by cellulose, and inorganic nano materials can be added into films in order to improve the performances of cellulose films such as barrier capabilities, anti-bacterium etc. Cellulose had been molecularly blended to form the true solution through strong dissolving of the solvent N-methyl-morphine-oxide (NMMO). The cellulose preservative films were prepared by solution melting. And nano-SiO2, mesopore SiO2, nano-CaCO3, nano-Ag composite TiO2or Ag composite mesopore SiO2powders were added into the casting films solution to acquire the biodegradable nano composite preservative films which have excellent mechanical properties, high oxygen permeation flux and good water vapor permeability.The surface modifications to the nano-SiO2powders and the nano-CaCO3powders were studied in this paper. Silane coupling agent (KH550, APTS) and titanate coupling agent(TM-38S) with active groups were used for the modification of nano particles. The results show that the dispersing characteristics of nano particles can be improved greatly by surface modification. The nano-SiO2and the nano-CaCO3with appropriate amounts of KH550and TM-38S were dispersed better, and the surfaces of nano particles were changed from hydrophilcity to lipophilicity. With the help of FT-IR, TEM, SEM and TGA, the nano particles were found to be modified.Under the same experiment conditions, the transparency of the casting films solution with the modified nano-Si02powder added was the best, and it can be well filmed. The nano-SiO2powders modified with5%KH550were used to improve the performances of the cellulose preservative films in the experiment. The results show that compared to pure cellulose films, the capabilities of cellulose with2%modified nano-SiO2powder added were improved largely.The tensile strength was increased from8.95MPa to17.37MPa and the maximum elongation was improved from41.11%to58.34%too. Not only the mechanics characteristics but also the thermal stability of cellulose was advanced through adding the nano-SiO2. When5%modified nano-SiO2was added, the thermal stability of cellulose was improved from17%to21%.Nano-SiO2, mesopore SiO2, nano-CaCO3, nano-Ag composite TiO2and Ag composite mesopore SiO2powders were used to improve capabilities of cellulose preservative films in the experiments. The results show that all of them can improve the capabilities of cellulose preservative films. In improving the mechanics capabilities, the modified SiO2is the best, and then nano-Ag composite TiO2, the mesopore SiO2is the worst. But in improving the anti-bacterium, the nano-Ag composite TiO2and the Ag composite mesopore SiO2are the best. When the additive amount was2%, the anti-bacterium characteristcs was increased to98%or97%. The different diameters of nano-SiO2particles and different additives of coupling agent also can improve the capabilities of cellulose preservative films. The results show that when the diameter of particles is30nm, the amount of coupling agent is5%, and the additive amount of nano-SiO2is2%, the capabilities of cellulose fresh films process the best.The additive amount of different kinds of inorganic nano materials is different. When the additive amount of modified nano-Si02, mesopore SiO2, modified nano-CaCO3, nano-Ag composite TiO2and Ag composite mesopore SiO2powders are2%,1.5%,1%,1.5%and2%, the cellulose composite films process the best.In conclusion, the completely biodegradable cellulose was utilized to prepare nano composite films through solution melting and addding inorganic nano materials such as SiO2etc. The cellulose films have high oxygen permeation flux, good water vapor permeability and excellent mechanical properties. And through the preliminary exploration, the films can be developed to replace the traditional plastic packaging films partly.