Research On Modification Of Montmorillonite And Its Properties With Chitosan Composites

Polymer/montmorillonite nanocomposites are a kind of emerging composites,which have become one of the hotspots in many fields because of their excellent performance.Chitosan and montmorillonite is a abundant natural material in nature.Chitosan/montmorillonite nanocomposites can achieve the advantages of two kinds of material performance complementarity,in the field of paper-based packaging is an excellent coating.But montmorillonite is a hydrophilic inorganic material,and the compatibility with chitosan is very poor,so it is necessary to take the appropriate method to make it better dispersed in the chitosan matrix.In this paper,the effects of montmorillonite modification and ultrasonic treatment on the properties of chitosan/montmorillonite composites were investigated.In addition,the effects of chitosan/montmorillonite composites prepared under different conditions on the barrier properties of coated paper were studied.The results obtained are as follows:(1)Single factor experiments and orthogonal experiments were used to investigate the effects of DTAB,CTAB,OTAB and ODBA and the modification conditions on the properties of Na-MMT,respectively.And the effects of modification were compared by fourier transform infrared spectroscopy(FTIR),X-ray diffraction(XRD)and transmission electron microscopy(TEM).The results showed that the four modifiers had entered the layer of Na-MMT,increasing the interlayer spacing of montmorillonite to some extent,and the modification effect of the ODBA was the best.In addition,the orthogonal test showed that the optimum conditions for the modification of Na-MMT by ODBA were reaction time 3 h,reaction temperature 80?,modifier dosage 1.2 CEC(cation exchange capacity),montmorillonite spacing increased from 1.152 nm to1.931 nm.(2)KH550,KH560 and KH570 were used to modify Na-MMT and modified montmorillonite,respectively.The results of FTIR and XRD showed that the layer spacing of Na-MMT and organic montmorillonite after modified by silane coupling agent KH560 and KH570 were almost unchanged,which indicating that the two modifiers did not enter the montmorillonite layer,and the surface modification of montmorillonite was mainly carried out.While the FTIR of two kinds of montmorillonites modified by KH550 were changed.KH550 not only had a surface modification effect on montmorillonite,but also can enter the interlayer of montmorillonite.The results of dispersion experiment showed that the montmorillonite obtained by double modification can be well dispersed in the organic solvent,which indicating that the compatibility of double modified montmorillonite and organic solvent was increased.This has created favorable conditions for the preparation of chitosan / montmorillonite composites.(3)The chitosan / montmorillonite composites were prepared by high-speed mechanical treatment and ultrasonic treatment,respectively.The dispersion of montmorillonite in chitosanand the effect on the barrier properties of composites coated paper were compared.The results showed that the dispersion of the composites obtained by the ultrasonic treatment was better than that of the high-speed mechanical treatment,and the barrier properties of the coated papers were better than those of the high-speed mechanical treatment.Moreover,the organic modification of montmorillonite can also increase the dispersion of montmorillonite in the chitosan matrix and the barrier property of the coated papers.(4)The chitosan / montmorillonite composites were prepared by mixing chitosan with several different montmorillonites.The structure and properties of the composites were compared by FTIR,XRD and thermogravimetric analysis(TGA).The results showed that chitosan was intercalated into the layer of Na-MMT and O-550-MMT,but did not enter the layer of O-560-MMT and O-570-MMT.In addition,the thermal stability of CTS/ O-550-MMT composites was higher than that of other composites,so the O-550-MMT was selected for the subsequent coating experiments.(5)The composites obtained by mixing O-550-MMT with chitosan were used to coat kraft paper.The effects of the amount of glycerol,the ratio of CTS and OMMT,and the ultrasonic time on the water resistance and water vapor resistance of coated paper were investigated.Through the detection of the properties of the base paper and coated paper,it was found that the flexibility of the coated papers increased with the increase of the amount of glycerin,while the water resistance and the moisture resistance decreased.In order to ensure the barrier property of paper,the dosage of glycerol was 15%?25%.The addition of organic montmorillonite to chitosan can improve the water resistance and moisture resistance of the coated paper,the more content of organic montmorillonite in the composite,the better water resistance of coated paper,while the performance of the water vapor barrier was first increased and then decreased,CTS and OMMT ratio of 1:0.5 was the best.The ultrasonic treatment time had a great influence on the water resistance and moisture resistance of the coated paper.The longer the ultrasonic time,the better the water resistance and the moisture resistance of the coated paper,and the water resistance and the moisture resistance of the coated paper were increased by 4.66% ? 18.43% and 9.8% ?12.6%,respectively.