Preparation And Study Of Chitosan/plant Protein Composite Packageing Film

All kinds of plastic packaging films because white pollution, degradation plastic limitationsand exhaustion of mineral resources are now facing the challenges of environmental protectionand security. Biodegradable packaging films for higher environmental protection and securityhas become a new hotspot. The degradable packageing composite films made from chitosan, soyprotein isolate and zein were developed. The chitosan/soy protein isolate and chitosan/zein filmswas prepared by co-soultion. The processing were optimized. The structure and properties ofthese films were inspected. The effect of glycerol and glutaraldehyde were studied onmechanical properties, optics properties and water absorption of the films. The main conclusionare follows:For the chitosan/soy protein isolate composite films, the influences of chitosan/soy proteinisolate mass ratio, pH value, soy protein isolate ultrasonic time and film forming temperaturewere investigated on the tensile strength of the composite films by the use of orthogonalexperiment and single factor experiments. As a result, the optimal technological parameters ofpreparation chitosan/soy protein isolate composite films had been obtained: chitosan/soy proteinisolate mass ratio was9:1, pH value was4, soy protein isolate ultrasonic time was20minutesand film forming temperature was40℃. At the same time, chitosan/soy protein isolatecomposite film tensile strength reached up to96.5MPa, breaking elongation was5.55%, watervapor transmission rate was1950.837g/m~224h, are better than pure chitosan film; transmittancewas88%, decreased slightly compared with pure chitosan film.For the chitosan/zein composite films, the influences of chitosan/zein mass ratio, mixingtemperature, and film forming temperature were investigated on the tensile strength of thecomposite films by the use of orthogonal experiment and single factor experiments. As a result,the optimal technological parameters of preparation chitosan/zein composite films had beenobtained: chitosan/zein mass ratio was9:1, mixing temperature was40℃and film forming temperature was60℃. At the same time, chitosan/soy protein isolate composite film tensilestrength was50.4MPa, transmittance was90%, decreased slightly compared with pure chitosanfilm; breaking elongation was5.84%, water vapor transmission rate was1786.332g/m g/m~224h,are better than pure chitosan film.Glycerol as plasticizers, could improve the composite film and made its integratedperformance better. As the range of volume fraction of glycerol was about0.1%～0.15%, itsmechanical properties reached better, chitosan/soy protein isolate composite film tensile strengthabout50MPa, elongation at break for about20%; chitosan/zein composite film tensile strengthabout30MPa, break elongation about20%. When the range of volume fraction of glycerol wasabout0.15%, chitosan/soy protein isolate composite film transmittance was89.5%, better thanno plasticizer. Comparing the two films, the chitosan/soy protein isolate composite filmplasticized was better.Fourier transform infrared(FTIR) analysis of two films with glutaraldehyde as crosslinkingagent indicated that there was crosslinking reaction between glutaraldehyde and the compositefilm and new chemical bond [C=N] produced, which improved its integrated performances,especially in water absorption. As glutaraldehyde volume fraction increased, tensile strength ofthe composite film increased while breaking elongation, transmittance and water absorptiondecreased. When the range of volume fraction of glutaraldehyde was between0.15%and0.20%,chitosan/soy protein isolate performance was very good. When the range of volume fraction ofglutaraldehyde was between0.10%and0.15%, chitosan/zein performance was very good.