Preparation And Application Of Regenerated Cellulose Matrix Composites

Cellulose is one of the most abundant natural polymer materials in natural resources,which is not only easy to biodegrade and renewable,but also stable and excellent in property,so it is regarded as a substitute of petroleum derived materials in the future.Cellulose matrix membrane materials have good strength and positive barrier effect on oxygen,carbon dioxide and oil,but the polyhydroxy structure of cellulose leads to its inherent defects such as low mechanical strength and poor gas barrier under high humidity conditions.In order to solve this key problem,expand its application scope.In this paper,two ways of adding nano-filler and surface hydrophobic modification of film material are adopted to improve the defect of cellulose film sensitive to environmental humidity,and the process is applied to paper coating to prepare a kind of cellulose matrix coated paper with excellent barrier and degradability.Finally,according to the packaging characteristics of cellulose matrix composite films and cellulose matrix coated papers,studying their effects on different types of cheese.The research results are as follows:（1）Cellulose/organic montmorillonite（RC/OMMT）composite film is prepared by physical blending,and the surface of composite film is hydrophobic treated with alkylenone dimer（AKD）.The mechanical properties,water sensitivity,thermal stability,gas barrier,optical properties and microstructure characterization of the composite film are analyzed to explore the dispersion state of OMMT in cellulose matrix,the influence of OMMT addition amount on the composite film’s comprehensive properties and the improvement effect of AKD on the composite film’s comprehensive properties.The results show that the composite film has the best comprehensive performance when 3wt%OMMT.OMMT and AKD can significantly improve the sensitivity of the composite membrane to water.Even at high humidity（75%RH）,OMMT can still improve the oxygen barrier performance of the composite membrane.AKD hydrophobic treatment can significantly enhance the gas barrier of the composite film at different humidity.However,when the humidity is higher（75%RH）,the oxygen permeability coefficient of the composite membrane does not decrease significantly.（2）The paper is coated with RC/OMMT membrane forming solution to prepare cellulose matrix coated papers,and the paper is further treated with AKD hydrophobicity.Studing the enhancement effect of coating quantity on coated paper.The results show that with the increase of coating amount,the dry-wet strength,hydrophobicity and gas barrier of paper all show a rising trend,and the coating amount has a significant effect on the oil resistance and oxygen barrier of paper.When the coating amount is only 1.9 g/m²,the oil-proof grade of paper increases significantly to level 6,and stabilizes at level 12 after increasing to level 5.8 g/m²;When the coating amount is 9.7 g/m²,the oxygen permeability coefficient of the paper increases to 4.451×10^-14 cm³·cm·cm^-2·s^-1·Pa^-1,which is 1 order of magnitude lower than that of PE.When the coating amount continues to increase,the oxygen resistance of the paper increases slightly,only the coefficient changes.（3）According to the different barrier properties of RC matrix composite films and coated paper,it is applied to hard cheese and semi-soft cheese respectively in different packaging combinations.The fresh-keeping effect of cheese is evaluated by sensory evaluation,p H value and peroxide value of cheese.The results show that RC/OMMT/AKD composite material has better preservation effect than RC composite material.RC/OMMT/AKD composite film has a shelf life of more than 15 days for hard cheese,and can achieve short-term preservation（about6 days）for semi-soft cheese,which confirms its application accessibility in cheese packaging.（4）Comparing the properties of RC matrix composite films with common plastic film,the results show that RC/OMMT/AKD composite film has excellent transparency,hydrophobicity,thermal stability,tensile strength is far better than the common packaging film in the market,especially excellent oxygen barrier,comparable to EVOH.