Research On The Preparation Of Super-hydrophobic And Enhanced Modified Food Packaging Paper Based On LBL Technology

With the growing global environmental problems,the concept of“green packaging”has been adopted by consumer.Paper-based packaging materials based on plant fibers are biodegradable,recyclable and recyclable,and can meet the requirements of“green packaging”.all-fiber packaging papers are inferior to the mechanical strength properties?such as tensile strength,elongation at break,rigidity,etc.?,moisture-proofing performance,and gas barrier performanc in the field of food packaging.Therefore,it is very realistic to modify the plant fiber to produce multifunctional super-hydrophobic paper.Frist we proposed a simple but effective method to fabricate superhydrophobic paper having improved paper strength and excellent moisture-proofing property,which is LBL deposition of TiO₂ nanoparticles/sodium alginate?ALG?multilayers on paper surface followed by an adsorption treatment of colloidal wax.The surface elemental compositions,zeta potential and surface morphologies of TiO₂/ALG multilayers on paper surface was characterized by X-ray photoelectron spectroscopy?XPS?,zeta potential measurement and scanning electron microscopy?SEM?,respectively.The contents of the two characteristic elements?i.e.,Na and Ti?increased with increasing bilayer numbers,indicating the growth of TiO₂/ALG multilayers on paper surface.The zeta potential of modified paper fibers was regularly inversed after each layer deposition,implying the reproducibility of deposition process.The SEM images showed that the relative smooth pristine paper surface gradually covered by granular TiO₂,resulting in the increased surface roughness.The water contact angle of paper modified with a wax-modified?TiO₂/ALG?_3.5 multilayer reached up to 151.4°,and this obtained superhydrophobic paper exhibited obvious anti-bacterial adhesion property.The adsorption of wax impaired the tensile strength property compared to that of TiO₂/ALG multilayer modified paper.However,when a wax-modified?TiO₂/ALG?_3.5 multilayer formed on paper surface,there was still a 4.1%increase in tensile strength index compared with that of the pristine paper.In additions,the superhydrophobic paper maintained a high tensile strength under high relative humidity condition,suggesting its excellent moisture-proofing property.A fluorine-free superhydrophobic paper was prepared by a facile and environment friendly method involving layer-by-layer deposition of cationic starch?CS?and ALG together with subsequent modification of trichloromethylsilane?TCMS?has been reported.The surface chemical components,functional groups,potentials and surface morphologies of the modified papers have been characterized by XPS,ATR-FTIR,zeta potential measurement SEM,respectively.The wetting behaviors and physical strength properties of the modified papers were investigated.After deposition of a?CS/ALG?₄ multilayer followed by TCMS treatment,the water contact angle of modified paper can reached up to 161.7°,and the tensile strength increased by 6.8%in comparison to that of pristine paper.This as-prepared superhydrophobic paper not only showed low bacterial adhesion property,excellent self-cleaning behavior,outstanding water repellency to various commercial liquid food,as well as high durability against deformation,chemical and time,but also possess remarkable moisture resistance under high relative humidity condition,which might has a great application potential in the liquid paper packaging.We proposed a green and facile method to fabricate superhydrophobic paper with enhanced air barrier in this study,which is LBL deposition of carrageen?CR?/chitosan?CH?/MMT/CH multilayers on paper surface followed by an adsorption treatment of carnauba wax.The formation of CR/CH/MMT/CH multilayer on paper surface was characterized by XPS,zeta potential measurement,SEM and AFM,respectively.The wetting property of modified paper was investigated by WCA measurement.Moreover,the modified paper tensile strength has been evaluated.The results showed that WCA of paper modified with a wax-treated?CR/CH/MMT/CH?₂ multilayer reached up to 151.3^?,and this obtained superhydrophobic paper exhibited improved tensile strength?compared to the pristine paper?,excellent moisture-proofing property and high strength stability under high relative humidity condition.The introduction of MMT results in the decrease of air permeability.The superhydrophobic paper prepared with a?CS/ALG?₄ multilayer modified fibers were used for biscuit packaging,The PE packaging were positive control group,no packaging of biscuit were control group,under 23?&RH 80%,the fresh-keeping effect of different packaging on biscuit was evaluated according to the biscuit preservation quality index.The experimental results show that:compared with the control group,superhydrophobic paper can effectively maintain the sensory quality,hardness,had little effect to moisture increase rate.The shelf life of biscuit can be extended.The superhydrophobic paper prepared with a?CR/CH/MMT/CH?₄-wax multilayer modified fibers to wrap fresh strawberry under the room temperature and room humidity.The effects of different storage time on respiration rate and storage quality of strawberry in terms of quality attributes such as sensory evaluation,overall apparent,weight loss rate,breathing physical,hardness,soluble solids acid,vitamin C content,titratable acidity and other physical and chemical indicators were studied.Strawberry stored in superhydrophobic paper presented the best appearance quality.Strawberry extend the storage period of two days,more than the original storage period doubled compared with the blank control.