| With the development of the country's economy,people's awareness of environmental protection has become stronger.As a kind of green packaging,paper packaging occupies a very important position in the packaging industry.However,the paper itself is woven into a network structure by fibers and has a certain degree of hydrophilicity and porosity,so it is very limited in meeting the market needs of food packaging.In order to improve the barrier properties of the packaging paper,the barrier coating of chitosan/montmorillonite nanocomposite is used.Therefore,in order to lay the foundation for the future research and application of chitosan/montmorillonite nanocomposites,this article systematically studied the film formation and penetration properties of chitosan/montmorillonite nanocomposites as well as the effect on the barrier properties.The specific content and results are as follows:The influence of the concentration of chitosan,the stirring speed of chitosan,the ratio of acetic acid,the coating weight,and glycerol on barrier properties were discussed.The results showed that the chitosan layer was smoother than the surface of the uncoated kraft paper.Chitosan had better film formation,and that there was no chitosan penetration through the kraft paper.The barrier properties against water vapor were strongest when there was a higher concentration of chitosan solution at the optimum pH,stirring speed,and those with a thicker coating weight on the kraft paper.The addition of an appropriate amount of glycerol as a plasticizer not only improved the mechanical properties of the chitosan coated paper,but also improved its water permeation resistance properties.The influence of the content of montmorillonite,the dispersion rate of montmorillonite,the amount of dispersant and the coating weight on barrier properties were analyzed.The results showed that chitosan/montmorillonite nanocomposite had a poorer formation than pure chitosan,but it had better water vapor barrier properties.The paper coated with lower content of montmorillonite,or with higher dispersion speed and dispersant content,had better smoothness and elongation.Additionally,the coated paper had excellent barrier properties under the conditions of high montmorillonite and dispersant content,dispersion rate and coating weight..The permeation and migration process of methyl orange in chitosan/montmorillonite composite,chitosan solution and montmorillonite dispersion are as a simulation process in coating layer.Meanwhile,the differences between kraft paper,ivory board and coated paper,as well as the effect of different drying temperature and time conditions were studied.The results showed that the diffusion process of methyl orange in the chitosan/montmorillonite composite was the most stable,but existed the phenomenon of agglomeration and sedimentation in dispersion.The chitosan/montmorillonite composite has better film formation and higher elongation.The coated paper of chitosan/montmorillonite composite needed a suitable dryingtemperature and drying time to have better water permeation resistance and water vapor barrier performance.The effect of film formation and permeability of chitosan/oxidized starch composites and chitosan/polyvinyl alcohol complexes were analyzed,as well as the comparison of different chitosan/montmorillonite composite coating double coated papers.The results showed that the chitosan/montmorillonite composite coated paper after process improvement had better surface smoothness and elongation.What's more,the double-layered chitosan/montmorillonite composite coated paper has better water penetration resistance and water vapor barrier properties. |
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