| Cellulose is a biodegradable polymer material that has been extensively used in packaging membranes in recent years.Cellulose membrane has good transparency and flexibility and it is a very promising,green and biodegradable packaging material.In this project,cellulose membranes were changed by surface cross-linking.The structure and properties of the modified cellulose membranes were also characterized.The modified cellulose membrane has excellent UV resistance,mechanical properties and water vapor barrier property.The UV transmission rate closed to zero;the maximum tensile strength was 67.8 MPa and the water vapor transfer was 56.69 g/(day·m~2).The antimicrobial factors contained in essential oil of plants with outstanding antimicrobial properties.When compounded with cellulose,it can improve the antimicrobial properties of cellulose materials,but the volatility of essential oil affects antimicrobial effect to some extent.Encapsulation of essential oil can be embedded in wall materials by microencapsulation technology to prepare antibacterial agent with microencapsulation structure,it can effectively reduce volatilisation and thus extend the duration of antimicrobial activity.Sodium lignin sulfonate and chitosan as the wall material,eugenol as the core material and sodium polyphosphate as the cross-linking agent to prepare antibacterial agent by complex coagulation method.The results showed that the antibacterial agent with good thermal stability and slow release property has the embedding rate was 17.6%,the entrapment rate was 15.23%,the yield was 33.04%.The effects of drying methods on the performance of antibacterial agent were investigated(dehydration and drying by isopropyl alcohol,drying with reduced pressure at room temperature and freeze drying):the antibacterial agent has the highest embedding rate and encapsulation rate with drying by isopropyl alcohol;the antibacterial agent obtained by drying under reduced pressure at room temperature has the best slow-release properties;the antibacterial agent with freeze drying has the best particle size.The obtained antibacterial agent was introduced into the modified cellulose membrane to prepare the modified cellulose-based antibacterial membranes.The study was carried out on fresh beef,and the actual effect of the antimicrobial cellulose membrane was measured in terms of weight-loss ratio,p H values change and microbial growth on the surface of the beef.The results of the study showed that eugenol had a significant effect on the preservation of beef,effectively inhibiting the growth of microorganisms;the addition of antibacterial agent slowed down the rise in p H value of meat,resulted 3 days extensions of the shelf life of beef and the weight loss rate decreased by 12.92%.The modified cellulose-based antimicrobial film prepared was effective in the preservation of meat foods represented by beef.The pyrolysis process of modified cellulose-based antimicrobial films is a solid state reaction process.In this paper,the thermal stability of modified cellulose-based antibacterial films was analyzed.It was established that pyrolysis consisted of three main stages:the initial stage of water and eugenol evaporation(<190?),the intermediate stage of pyrolysis of organic matter(190-430?)and char formation(430-600?).And the maximum weight loss peak in the decomposition phase of C-EM-RC gradually shifts towards the high temperature with the rate of warming increases.The kinetic processing of non-isothermal was studied by Kissing-Akahira-Sunose(KAS),Flynn-Wall-Ozawa(FWO)and Friedman methods.The average activation energies calculated by the KAS?FWO and Friedman methods were 195.1 k J/mol,194.3 k J/mol and 219.4k J/mol,respectively.The linear correlation between the pre-finger factor and the activation energy obtained by Friedman method indicates that the reactive model of C-EM-RC does not change during the pyrolysis process. |
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