Deconstruction And Reorganization Of High Amylose Starch In Chloride Solution And Preparation Of Conductive Materials

In recent years,with the increasing pollution of disposable plastics,governments have issued"plastic bans",which greatly promoted the market demand of environment-friendly materials.Starch is a kind of common raw material for the environment-friendly materials.Among them,high amylose starch?HAS?has high linear long amylose chain content,long branches,high molecular chain entanglement,strong intermolecular force,the prepared materials are not only environmentally friendly,but also have excellent mechanical properties.However,the HAS granular particles are small,compact,and difficult to gelatinize,which have the higher gelatinization temperature?above 105??and require the synergistic effects between temperature,pressure and shear force to destroy the particles.Their processing property is difficult and needs high energy,which restricts its deep processing and industrial applications.Aiming at the bottleneck of HAS,this paper studies the influence of cheap chloride salt solutions on the deconstruction of HAS granular particles.Based on this,it prepared the environmentally friendly and responsive starch-based ion conductive material.The conclusions are as follows:In this paper,the deconstruction process of HAS particles with acidic ZnCl₂ solution,neutral MgCl₂ solution and alkaline CaCl₂ solution is studied.The results show that 33%ZnCl₂,27%MgCl₂ and 25%CaCl₂ solution can destroy the crystal structure of the HAS particles at 50°C,but the periphery still exists.The minimum salt solution concentration that can completely deconstruct starch granules is 43%ZnCl₂,34%MgCl₂ and 31%CaCl₂.Secondly,when the HAS particles are deconstructed in ZnCl₂ solution,the particles will swell first,and then disintegrate within 30 minutes,and deconstruct completely within 4 hours.When the HAS particles are deconstructed in MgCl₂ solution,their variations are similarly as those in ZnCl₂ solution,except some granular residues can be observed after 4 hours of deconstruction.When deconstructing in CaCl₂ solution,all starch particles become small fragments within 10 minutes.Thirdly,when the HAS particles are deconstructed in ZnCl₂solution,only 17°diffraction peaks exist after 5 minutes,and all other diffraction peaks disappear.The degree of crystallinity dropped to 3.6±0.3%after 4 hours of deconstruction.When deconstructing in MgCl₂ solution,after 10 minutes,there are only 13°and 20°diffraction peaks,and all other diffraction peaks disappeared.The crystallinity dropped to7.3±0.3%after 4 hours of deconstruction.When deconstructing in CaCl₂ solution,all the diffraction peaks disappear within 5 minutes and the crystallinity drops to 0.In addition,the flow activation energies of HAS/ZnCl₂,HAS/MgCl₂,and HAS/CaCl₂ solutions are21.516kJ/mol,24.035kJ/mol,and 27.22kJ/mol,respectively.This indicates that the entanglement and intermolecular force of the starch chain in the HAS/ZnCl₂ solution is the weakest,and those in HAS/CaCl₂ solution is the strongest.On the other hand,the structure and properties of HAS regenerated starch from chloride salt solution are investigated.The regenerated starch from ZnCl₂ solution only has one diffraction peak at 17°;those from MgCl₂ solution exhibits the V-typed crystalline structure,and those from CaCl₂ solution shows the absolute amorphous structure.Secondly,the granules of the regenerated starch from ZnCl₂ solution disappear completely,and the nanoparticles are formed to instead of them,so are the regenerated starch from CaCl₂ solution.But for those from MgCl₂ solution,besides the nanoparticles,little granular residues can also be observed.The nanoparticles are formed by the complexation between starch chains and cations.The amounts of Zn²⁺,Mg²⁺and Ca²⁺in regenerated starch are 53 mg/g,18.2 mg/g and 21.3 mg/g,respectively.Thirdly,the intrinsic viscosity of HAS is 73.58 mL/g,and those from ZnCl₂,MgCl₂ and CaCl₂ solutions are 25.88 mL/g,71.21 mL/g and 31.47 m L/g,respectively,which shows that the molecular chains of regenerated starch from acidic ZnCl₂and alkaline CaCl₂ solution are degraded,and those from neutral MgCl₂ solution are hardly degraded.Finally,based on the deconstruction process of HAS in three chloride salt solutions and the structure and properties of the regenerated starch,the deconstruction and reorganization models of HAS in three chloride salt solutions are established.Based on the deconstruction and reorganization of HAS in chloride solutions,the environment-friendly and responsive starch-based ion conductive material is prepared.The resistivity of the material ranges from 3.7 to 9.2??m,and it will decrease with the increase of calcium chloride content and environmental relative humidity.Secondly,the Young's modulus of the material ranges from 3.39 to 7.68 MPa,and the elongation at break ranges from 17%to31%.Young's modulus decreases with the more calcium chloride content in material and the low relative humidity in environment.The correlation of elongation at break with calcium chloride content and relative humidity is not significant.Thirdly,the electrical conductivity of the material is environmentally responsive.The current of circuit will increase by 15%when10?L of water dropped on the material.The amplitude of current change is 15.7%when the strain of the material was 20%.Therefore,it can be used as the sensor materials.In all,this paper has shown that HAS can be fully dissolved by cheap chloride salt solutions without the derivatization effect.The effects of ZnCl₂,MgCl₂ and CaCl₂ solutions on the deconstruction of HAS particles and reorganization of starch chains were discussed,and the model is established.Based on it,the environment-friendly and responsive starch-based ion conductive material is prepared.Therefore,this study provides a new method for breaking the processing bottleneck of high amylose starch,and moreover,it also provides new ideas for the design of environment-friendly and responsive conductive materials.