Preperation of the Edible Dialdehyde Starch Films and Study on Their Performance
|Course||Polymer Chemistry and Physics|
|Keywords||Dialdehyde starch film Mechanical Properties Water Vapor Transmission Rate Dialdehyde starch composite film|
In recent years, people develop improved edible starch packaging film performance done a lot of delicate work, but so far almost no starch-based packaging film to give the industrial production and practical commercial applications, it is mainly due to the conventional edible starch packaging film mechanics poor performance, water resistant stability is less than ideal. Therefore, the the the starch film performance improvement has been the focus of attention, and the need to constantly explore. Firstly, prepared dialdehyde starch the different aldehyde content of potato, corn, peas, and three dialdehyde starch characterization and performance tests, initially proved dialdehyde starch the aldehyde content increases, the original starch granules The increase in the degree of oxidation, water absorption is also increased. In this paper, dialdehyde starch properties on the basis of the dialdehyde starch film-forming process, dialdehyde starch film properties, dialdehyde starch composite membrane performance exploring dialdehyde starch film-forming conditions final choice: 5% dialdehyde starch emulsion concentration glycerin as a plasticizing agent, the addition amount of 40% of the quality of the starch, the drying temperature is selected to 55 ° C, the time control in 6.5 hours, and the stirring speed is due to the different aldehyde contents are different, when the aldehyde content of 50% and less control 120 (r / min), when the the aldehyde content exceeds 50% control 180 (r / min). By scanning electron microscopy and X-ray spectrum shows the three kinds of dialdehyde starch film is good, the homogeneity of the microstructure, with the increase of starch oxidation degree, the film tends to be amorphous, the highest degree of oxidation of starch film has substantially no crystallization phenomena . Three kinds of dialdehyde starch films were tensile strength (TS) of the increase of the starch oxidation degree increased, the elongation at break (E) decreased trend. Compared with DPESF1 DPESF11 the TS 71.82% increase in E reduce the 44.96%; degree of oxidation increases the degree of crosslinking of the film increases, glycerin, with an aldehyde to form a hemiacetal of plasticizing agent, the water absorption of the film decreased; dialdehyde starch film With the the starch oxidation degree of the increase in water cut-off performance better, DPESF water vapor permeability coefficient from 13.11 (g.mm/m2.d.kPa) reduces to 3.97 (g.mm/m2.d.kPa,). After film formation is selected having a large elongation at break, but the tensile strength is not very satisfactory degree of oxidation of 30% potato dialdehyde starch as raw materials, through the addition of agar and sodium alginate as a reinforcing agent, to improve the dialdehyde starch film. The results showed that: add the amount in 5% agar - dialdehyde starch composite film with the added amount of 20% sodium alginate - the dialdehyde starch composite membrane performance optimal, both simple dialdehyde starch film performance compared to TS rose 91.71%, 92.92%, E decreased by 44.01%, 80.69%, both to achieve the purpose of improving dialdehyde starch film tensile strength, but a large decrease in elongation at break of sodium alginate composite membrane, the membrane brittle cracking of mechanical properties than agar composite film. Two composite membrane water content rate rise, and that the decline in water resistance, water-blocking performance has been very good improvement.