Study On The Preparation And Properties Of The Nano-TiO₂/high Amylose Starch Film

Biodegradable material gradually played an important role in the packaging industry.Starch was extremely popular with researchers because of its good film-forming,especially for high amylose starch,the film had better performance.In this article,the raw material was the corn-starch which was hydrolyzed by pullulanase to obtain high amylose starch,and it was mixed with PVA and nano-TiO2 to make the blend film by tape-casting method.Study the effect of amylose eontent and nano-TiO2 content on the film properties.The nain conclusions were as follows:1.Preparation of high amylose starchCom amylose starch was made from available ordinary com starch by enzymolysis method,and the amylose content of product was measxured according to the method in GB/T 15683-2008.After single factor and orthogonal experiment design of enzymolysis process,the optimal combination of processes of preparing com amylose starch are:enzymolysis temperature 40oC,enzymolysis time 2 hours,pH 3.8,pullulanase dosage 3U/g(dry starch),the amylose content was 53.42%;Judging by range analysis,the factors that effect amylose content are pullulanase dosage>pH>enzymolysis temperature>enzymolysis time.2.The preparation and properties of high amylose starch based filmStudy on the parameters of film preparation by single factor experiments,the optimum process condition showed as:concentration of starch suspension 12 g/100mL,mixing time 40 mins,dry temperature 40℃.With the increasing of amylose content,tensile strength of film increased generally,the maximum was 14.717 MPa with amylose content was about 46%,and elongation at break was 112.89%;water absorption rate reduced from 131%to 109%,water solubility rate increased from 11.44%to 25.16%;absorbance value decreased from 0.35 to 0.2;microstructure became more compact and smooth.3.Study on the nano-TiO2 modified high amylose.starch based filmStudy on the influence of different kinds of nano-TiO2 on the high amylose starch based film,the experimental results show that nano-TiO2 could improve the properties of film,but it had similar effects between different nano-TiO2 varieties.With the increasing of nano－TiO2,mechanical properties was improved,when the addition of nano-TiO2 was 0.06g,tensile strength peak was 17.276MPa,elongation at break was 137.64%;water resistance was improved,the addition was 0.08g,water absorption decreased froml57.12%to 82.54%,water solubility decreased from 17.40%to 10.98%as well;transmission of light was markedly reduced,absorbance value increased from 0.25 to 0.5;apart from those,the film was endowed with antibacterial performance,inhibition zone of Exoli and S.aureus was 13.34 mm and 11.94 mm respectively;hydrogen bonds and C-O-Ti bonds were formed between starch and nano-TiO2 molecular;crystallinity of PVA decreased,crystallization rate was delayed;nicrostructire was improved,the film became more porous and profect.