| In this essay, cassava starch、polyvinyl alcohol and chitosan as the main materials to make a biodegradable film. Research the effect of cassava starch content、polyvinyl alcohol content、chitosan content、plasticizer like glycerol、crosslinking agent like glutaraldehyde and drying temperature on the properties of the film by using the single-factor experiments;Designed two groups of L9(34)orthogonal experiments and looked the tensile strength、elongation 、 transmittance and water absorption of the films as main appraisal factors to ensure the best recipe to product the cassava starch/ polyvinyl alcohol/chitosan films; the structure of the film was characterized through differential scanning calorimetry(DSC) 、scanning electron microscope(SEM); through the buring experiment to show the degradation of the film; research the effect of glycerol、glutaraldehyde、drying temperature on the H2 O penetration,O2 penetration rate of the film.The results of the experiment were showed as follows:1 、 The single-factor experiments showed that: cassava starch protent has a great impact on the film,in the range from 0% to 3.0%,the film’s tensile strength 、 breaking elongation and transparency increasing firstly then decreasing compare with the increasing of cassava Starch protent。The properaty for water absorption saw a opposide trend, and the appropriate of cassava Starch is 2.0%.The trend of the effect of Polyvinyl Alcohol content on the properties of the film is similar with the cassava Starch, the appropriate of Polyvinyl Alcohol is 2.0%.The film’s tensile strength increasing with the chitosan content increasing in the range of chitosan content from 0% to 2.0%, in this range the breaking elongation and transparency increasing firstly then decreasing while the water absorption decreasing firstly then increasing,and the appropriate of chitosan content is 0.67%.2 、 The orthogonal experiments results showed that: the best process parameters of composite film is that the appropriate of cassava starch 、 polyvinyl alcohol 、 chitosan 、glycerol、glutaric dialdehyde、drying temperature are 2.0%、2.0%、0.67% 、1.0%、1.0% 、60℃ respectively。The impact of each factors in descending order of the composite film is that chitosan > cassava starch > polyvinyl alcohol; glutaric dialdehyde > drying temperature>glycerol.3、 Water vapor transmittance and oxygen transmittance experiments results showedthat: glycerol、glutaraldehyde、drying temperature are both have effects on film’s vapor transmittance and oxygen transmittance. Membrane has the highest water vapor transmittance and oxygen transmittance when the content of glycerol is 3.0%, membrane has the highest water vapor transmittance when the content of glutaraldehyde is 1.0%, has the highest oxygen transmittance when the content of glutaraldehyde is 3.0%, and membrane’s water vapor transmittance and oxygen transmittance keep increasing with the increasing of drying temperature.4 、 Using DSC and SEM to characterizate the structure of cassava starch/ polyvinyl alcohol/chitosan biodegradable film, the result showed that: cassava starch 、 polyvinyl alcohol 、 chitosan has great compatibility with each other, and make the structure of the membrane more close.5 、 Degradation experiment result showed that: cassava starch/ polyvinyl alcohol/chitosan film has great biodegradation.After 12 days, the loss weight of cassava starch/ polyvinyl alcohol/chitosan biodegradable film was over 60% both in the indoor condition and outdoor condition, after 131 days, the loss weight of cassava starch/polyvinyl alcohol/chitosan biodegradable film was over 65% in indoor condition, and the same loss weight in outdoor just used 71 days. |
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