Study On Preparation And Fresh-keeping Properties Of Nano-TiO₂/Ag+/Chitosan Films

Although chitosan films have many broad application prospects, the mechanical performances and preservation effect of chitosan films are poor, which can be improved by adding nano oxide and metal ions into chitosan base material. In this paper, chitosan composite films were prepared by adding nano TiO2 and Ag+ into chitosan through casting method. The structure of the films was tested by infrared spectroscopy (FTIR), scanning electron microscope (SEM). The mechanics, barrier performances of composite films and the fresh keeping performance on mulberry were analyzed. Finally, the optimal proportion of nano TiO2, Ag+ solution and chitosan were obtained using the orthogonal experiment.Results showed that the surfaces of composite films are smooth. The compatibility between the nanometer TiO2 particles and chitosan is better, the reunion of nano-particles in composite films is not being found. The stronger hydrogen bonding interaction was formed between nano TiO2 and chitosan molecules.Comparison of chitosan film, Ag+/chitosan film, nano TiO2/chitosan film and nano TiO2/Ag+/chitosan film, it can be found that transparency, gloss, smoothness, uniformity of single chitosan film are best. After adding nanometer TiO2 and Ag+, the apparent performances of composite films decline, but uniformity and softness remain unchanged. The mechanical performances of nano TiO2/ Ag+/chitosan composite film are the best, and tensile strength and break elongation increase by 154% and 36% compared with single chitosan film, respectively. The resistance wet performance of nano TiO2/Ag+/chitosan composite film is the best, and the minimum valve of water vapor through is 476.83 (g/m2,24 h). The preservation effect of Nano TiO2/Ag+/chitosan composite film is the best. There is no obvious mildew and rot phenomenon during 4 days fresh test. There are only a fraction of mildew can be found on the mulberries when the keeping fresh test along to 10 days, and mulberry can prolong preservation cycle 3d.It can be found by the analysis of the orthogonal experiment result for nano TiO2/Ag+/ chitosan composite films, that the optimal proportion are that nanometer TiO2 is 0.1g, chitosan is 4.0g and Ag+ is 0.1 ml in terms of the physical properties of the composite films. Considering the weightlessness rate of composite films, the optimal formula of composite films are that nanometer TiO2 is 0.1g, chitosan is 3.0g and Ag+is 0.4ml. Based on the decay index of composite films, the best proportion of composite films are that nanometer TiO2 is 0.1g, chitosan is 3.0g and Ag+ is 0.4 ml.