| Zein is an alcohol-soluble prolamine proteins present in maize endosperm.Zein has a good quallity in the form of a thin film.In addition,the use of zein is as a functional film coating material for new edible film applications.Moreover,many studies have also been conducted to illustrate its potential as an active ingredient of direct compressed tablets and film-based delivery carriers.Poly(propylene carbonate)(PPC)is a new type of completely biodegradable aliphatic polyester and which is synthesized from propylene oxide and carbon dioxide(CO2).PPC has potential applications in packaging field owing to its excellent barrier properties,good ductility and low cost.On the other hand,PPC is biodegradable and biocompatible in favor of reducing the white pollution as an ordinary plastic in daily life and it is potential to be used as a biomedical material in the field of tissue engineering.In past few years,photocatalytic decomposition of organic pollutants in waste water or air using semiconductors has attracted much attention.Titanium dioxide(TiO2)has been considered to be one of the most promising photocatalysts because of its chemical stability,non-toxicity,low cost and superior activity.Numerous attempts have been made to develop the semiconductor photocatalytic materials which have wider light absorption range for more effectively utilizing the solar energy.In our study,zein,PPC and nano-TiO2 were used as the materials,glycerol as a plasticizer,zein/PPC/nano-TiO2 composite films were prepared by extrusion technology.The mechanical properties of the composite film,water properties,surface morphology,structure and thermal stability were investigated.And further we analysis photocatalysis and antibacterial effects of titanium dioxide content.The results showed that the use of extrusion technology to prepare a composite film have good transparency and uniform distribution of each substance.Glycerol and PPC are improved mechanical strength of the composite film,when the dosage of glycerol 20%,PPC content of 25%and titanium dioxide content of 0.5%,the tensile strength of the composite film reached the 25 MPa.Based on Halsey equation,a model which could predict the relationship between the tensile strength and relative humidity was established.Scanning electron microscopy(SEM)was observed zein and PPC and glycerol could be a very good combination together,forming a network structure orderly and uniform distribution of nano-TiO2 in the composite film.Differential scanning calorimeter(DSC)and thermogravimetric(TGA)analysis showed the composite film had better thermal stability.FT-IR indicated that the carboxyl groups in zein and the hydroxyl groups in PPC created the ester groups which ensured the stability of composite films.Moreover,there is a corresponding chemical bonds showed a stable nano-TiO2 present in the composite film.In this study,methyl orange dye was simulated contaminants.We investigated that glycerol and PPC of composite films have no significant effect in the photocatalytic,but nano-TiO2 added amount of different composite films showed different degradation rates,and different degradation rates were showed in the ultraviolet and natural light.When nano-TiO2 content of 0.5%,the ultraviolet irradiation conditions,the composite film showed the strongest photocatalytic,degradation rate reached 84.14%,and R2 of first-order kinetics equation parameters is 0.976.In microbiology experiment,the results show that the addition of nano-TiO2 composite film had a certain inhibitory effect under ultraviolet irradiation. |
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