Study On The Modification Of The WG-SPI Compound Film

In this paper,WG-SPI edible compound film was preparated,three performance indexes(Tensile Strength,Elongation at break,Water Vapor Permeability) were mensurated in order to analyze the factors influence.On the Basis of the WG-SPI compound film,modification technic was used by adding modifier to improve its properties.After the right modifier were selected,the technologcial conditions was optimized.The optimal addition of each factor and the expectant effect were confirmed by software Design-Expert 6.0.10.Furthermore,the surface and the cross section of compound film before and after modified were observed by SEM.The results were indicated as follows:1,Addition of glycerol,pH,ethanol concentration and the mixed temperature were all play an important role in the properties of the WG-SPI compound film.The optimization experiment was performed by means of the orthogonal experiment.The optimum condition was:addition of glycerol is 1.8%,pH is 11,ethanol concentration is 40%,the mixed temperature is 80℃.2,In the experiment,tannic acid and oleic acid were selected.The Tensile Strength can be improved obviously by tannic acid and the Elongation at break can be improved obviously by oleic acid.3,Ethanol concentration,addition of glycerol,pH and addition of tannic acid all had a significant effect on the the properties of the WG-SPI compound film.Three mathematical models were made,all of them were significantly and the degree of fits were all good.The mathematical models of TS and E had good predictability,but the predictability of the mathematical model of P_v was not as good as TS and E.By analyzing the response surface plots as well as solving the quadratic equation,the optimum process parameters were obtained as:ethanol concentration35%,glycero1.9%, pH 11,tannic aid0.087%.And the predicted value of the three response value were: 3.35(MPa),154.57(%),6.06(10^-13g·cm/cm²Â·S·Pa).The properties of the compound film were improved obviously afrer modified by tannic acid,the Tensile Strength was increase of up to 44.4%,the Elongation at break was increase of up to 9.1%,the Water Vapor Permeability was decrease of up to 3.7%.4,Ethanol concentration,addition of glycerol,pH and addition of oleic acid all had a significant effect on the properties of the WG-SPI compound Film.Three mathematical models were made,all of them were significantly and the degree of fits were all good.The mathematical models of TS and E had good predictability,but the predictability of the mathematical model of P_v was not as good as TS and E.By analyzing the response surface plots as well as solving the quadratic equation,the optimum process parameters were obtained as:ethanol concentration30%,glycero1.8%, pH 11,oliec aid1.1%.And the predicted value of the three response value were: 2.79(MPa),171.86(%),6.07(10^-13g·cm²/cm²Â·S·pa).The properties of the compound film were improved obviously after modified by oleic acid,the Tensile Strength was increase of up to 20.3%,the Elongation at break was increase of up to 21.3%,the Water Vapor Permeability was decrease of up to 3.6%.5,Tannic acid can obviously improved the structure of WG-SPI compound film by SEM Observation.After modified by tannic acid,the surface of WG-SPI compound film was smooth and the cross section of it was dense.But oleic acid was not as good as tannic acid at film modification.