Study On The Molecular Simulation And Preparation Of Starch Biodegradable Materials

Traditional plastic is derived fromoil which led to a series of environmental problems because of itsnon-degradableproperty and toxics additive.Starch is regarded as the most potential biodegradable materials with some advantages such as low cost, natural biodegradable and renewable et al.Starch is natural biological macromolecule polymer and made up of glucose units,existing strong intramolecular hydrogen bonding interaction between each molecular that made its glass transition temperatureis higher than its decomposition temperature and difficult to process. In order to enhance its mechanical performance and application fields, starch need to be plasticized.At present, the mainly methodson the plasticized starch rely on Furier-Infrared spectrum test.And the plasticizing mechanism is that, plasticizerscan permeate into starch molecular chain, enlarge the distance and weaken the hydrogen bonding interaction between the starch molecular chain, led to the shield of intermolecular and intramolecularhydrogen bonding interaction of the starchmolecule, which make starch molecular chain tend to be more freedom. However, those research methods can’t observe intermolecular hydrogen bond reaction during plasticizing of starch, and this plasticizing theory is dubious.Molecular simulation method cancalculate intermolecular and the intramolecular bond energyunder different temperature conditions, soin order to clarify the starch plasticizing mechanism, a new simulation method is applied to further study.The quantum mechanics simulation is usedto study the influences of the number of glucose unit of model on charge distribution and Fourier-Infrared spectrumin this paper, and the influencesof different types of plasticizer including water, glycerin, 1,3-bis(hydroxymethyl)ureaand Diethylenetriamide on the hydrogen bonding energy is also investigated. Plasticized starch materialswith above plasticizers were prepared and the mechanical performanceof which is also tested. The hydrogen bonding energy of glycerol/starch models under the condition of different temperature and different glycerol plasticizer contents were calculatedusing the molecular dynamics mechanics simulationmethod,and glycerol/starch films were prepared according to the calculation temperature and glycerol plasticizer contents, the mechanical properties, crystallinity, light transmittance and water absorption of which is also tested.The results revealed that, the electronegativity of the equalatoms on the glucose unit will unaltered, however, the charge of whichis varying, and the spiral conformation of starch will be the final stable form. The spiral conformation of starch can be destroyed by plasticizer and the conformation of plasticizer is also changed; Plasticized starch materials with higher strength and elongation at break will be obtained with some plasticizers which can form strong hydrogen bonding with starch.Although the mechanism is different, reducing temperature or increasing the content of glycerol can all increase the hydrogen bond energy of starch models.The optimum dosage of plasticizer in the plasticizing process can be deduced bydynamics simulation results analysis, which is no use for the reaction temperature.