| Food packaging is widely used to protect food from outside influences,plays an important role in the food storage and transportation process.Paper packaging materials are widely used in food packaging because of their wide range of sources,low cost,renewable and easily degradable.Traditional paper-based food packaging materials are used in a composite form such as paper-plastic or paper-metal.With the use of these synthetic packaging,causing environmental problems continue to increase,as well as consumer demands for more environmentally friendly and safer food packaging materials,there is an urgent need to find new biodegradable new functional paper packaging materials to replace traditional synthetic materials.In this paper,the fiber was used as the substrate,and the biomass and non-toxic nanoparticles derived from renewable resources were used as raw materials.The methods of phase separation and self-assembly of layers were used to modify the fiber,with super-hydrophobic and antibacterial function respectively.And the preparation of antibacterial wrapping paper in the application of cooked beef for freshness evaluation test.Through the research of this paper,it is proposed to provide theoretical support and technical reference for the preparation of functional environmental protection food paper packaging materials.The specific research contents of this thesis include:A simple but effective method of fabricating super-hydrophobic paper with excellent moisture resistance was developed by precipitating carnauba wax onto the surface of cellulose fibers using a phase separation method.Taking the water contact angle of the sample surface as the response value,the optimum conditions for the phase separation process were optimized by Box-Behnken center composite design and response surface analysis method.The optimal treatment conditions were as follows:wax concentration,3.78%(w/v);immersion time,1.46 h;coagulation bath ratio,13/87(v/v);and coagulation bath time,2.63 h.Under these conditions,the experimental WCA reached 152.7°,which agreed closely with the predicted value of 154.1°.The relative error is 0.92%,which indicates that Box-Behnken center composite design combined with response surface methodology(RSM)was employed to optimize the process conditions for the preparation of super-hydrophobic paper by phase separation method.The surface morphology of the super-hydrophobic paper was characterized by scanning electron microscopy(SEM)and atomic force microscopy(AFM),and the images showed that cluster-like carnauba wax aggregation completely covered the fiber surface,resulting in increased roughness.Moreover,the moisture resistance of the obtained super-hydrophobic paper was evaluated.The results demonstrated that under high relative humidity conditions,the moisture resistance of the super-hydrophobic paper significantly improved,and its tensile strength remained high.Graft copolymerization of hexadecyltrimethoxysilane(HDTMS)onto the surface of nano-TiO2 by chemical modification got M-TiO2,then,the chitosan and the modified nano-TiO2 were deposited on the surface of the fiber by the method of self-assembly of electrostatic to construct CS/M-TiO2 multilayer.The results of FTIR showed that HDTMS is successfully grafted onto the surface of nano-TiO2.The modified Nano-particle size is 224.5 nm.XPS analysis results showed that,the content of characteristic elements,N,Ti and Si in CS/M-TiO2 multilayers increased with the increase of the number of self-assembled layers;The Zeta potential of the fiber surface is regularly reversed with the increase of the number of self-assembled layers,indicating that the growth of CS and modified TiO2 on the fiber surface is continuous and uniform.With the growth of CS/M-TiO2 multilayers on the surface of the fiber,the surface of the fiber is gradually covered with modified TiO2,and the surface roughness(RMS)of the fiber surface is gradually increased;the water contact angle of CS/M-TiO2 multilayers modified fiber surface increases with the increase of the number of layers.40 layers,the heat treatment samples water contact angle up to 151.3 °,at 60 layers,the water contact angle of the samples after heat treatment reaches 167.35 °,indicating that the super-hydrophobic surface is obtained;the tensile strength index of CS/M-TiO2 multilayers modified paper decreases with the increase of the number of self-assembled layers.After the subsequent heat treatment,the tensile strength of the pattern was improved.When the 40 layers were assembled,the tensile strength of the sample after heat treatment was improved by 3.9%compared with the untreated control.In order to impart the antibacterial properties of the fiber paper,?-polylysine/carboxymethyl cellulose sodium(?-PL/CMC)was used to construct a multilayer film on the fiber surface.The results showed that the content of characteristic elements N and Na of e-PL/CMC multilayers increased with the increase of the number of layers.The Zeta potential of the fiber surface showed regular alternation with the self-assembly.With the increase in the number of layers of s-PL/CMC cellulose,the gap between the fibers and the fibers is getting smaller and smaller,and the connection is more tight;The results of antibacterial test showed that the effect of polylysine in the outer layer was better than that of carboxymethyl cellulose sodium in the outer layer,the effect of Staphylococcus aureus was better than that of Escherichia coli.(e-PL/CMC)4.5 multi-layer film modified paper on Staphylococcus aureus,the inhibition rate was 93.3%,the inhibition rate of Escherichia coli reached 90.4%.The tensile strength test showed that the tensile strength of the paper was increased by 25.78%when the five bilayer of ?-PL/CMC cellulose sodium self-assembled film layer was constructed on the fiber surface compare to untreated control.Antiseptic paper prepared with s-PL/CMC modified to wrap cooked beef,PE fresh bags as a positive control,no packaging of cooked beef as a blank control,4 ? during the preservation of the packaging model wrapped in beef,the physical indicators of changes in the monitoring.The results showed that the antibacterial paper prepared by the modification of e-PL/CMC could effectively inhibit the growth of microorganisms,slow down the oxidation rate of cooked beef,reduce the TVB-N value,thus indicating that the antibacterial paper prepared by e-PL/CMC multilayered film could be used as an environmentally friendly cooked beef packaging paper to prolong the shelf life of cooked beef. |
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