Preparation,Modification And Properties Of PEO/Lg Composites Based On Regulate The Micro-morphology Of Lignin

Lignin(Lg)is a natural based polymer with a three-dimensional network structure.It has good biocompatibility and reproducibility,and has a wide range of applications in biomedicine and industry.In this paper,polyethylene oxide(PEO)is selected as the matrix material,and the dispersion of Lg in the PEO matrix is improved by various methods.PEO/Lg and PEO/Lg/Urea,PEO/Lg/ polyethylene glycol(PEG),PEO/Lg/urea/PEG composite materials are designed and prepared.The structure and properties of composite materials are studied,and the results are as follows:1.The micro-morphology of Lg was adjusted by various solvents,and PEO/Lg composites under different solvents were prepared.It was found that after treating Lg with methanol,ethanol,and a mixed solvent of methanol/ethanol,a more uniform Lg nanosphere could be obtained.Lg microspheres have a weaker promotion effect on PEO crystallization than Lg particles.Urea can weaken the hydrogen bonds and intermolecular forces between Lg molecules and hinder the crystallization process of PEO.PEO/Lg composites prepared from aqueous solutions have better crystallization properties,and their storage modulus and loss modulus are lower than those of pure PEO.These research results provide theoretical support for subsequent research.2.Using acetone to fractionate Lg to obtain acetone-soluble Lg(CAc-Lg)and acetone-insoluble Lg(NAc-Lg).Infrared spectroscopy(FT-IR)shows that CAc-Lg has stronger intra-and intermolecular hydrogen bonding absorption peaks and lower methyl and methylene than NAc-Lg.The characteristic peak of CH stretching vibration also caused the difference in the internal phase morphology of the two Lg and PEO blends.The mechanical properties show that the mechanical properties of PEO/CAc-Lg composites are lower than PEO/NAc-Lg,and the mechanical properties of composites with all components are higher than those of pure PEO.3.PEO/Lg composites with different ratios were prepared by solution blending.Lg particles were well dispersed in PEO/Lg composites.The addition of Lg can increase the Tg of PEO,and Lg can promote the crystallization process of PEO.The mechanical properties of PEO/Lg composites and PEO are approximately equal.Ultraviolet absorption performance tests show that PEO/Lg composites have excellent ultraviolet absorption performance,and the performance is enhanced with the increase of Lg content in the composite.By adding Lg to PEO,the complex viscosity of the composite material first increases and then decreases,but the complex viscosity of all PEO / Lg composite materials is higher than that of pure PEO.The PEO / Lg foamed sample was successfully prepared by the supercritical carbon dioxide method,and it was found that the cell diameter of the foamed sample conformed to the complex viscosity change of the composite.At the same time,PEO/ Lg composite foamed samples also have good UV absorption properties.4.The effects of different contents of urea,PEG and urea/PEG on the mechanical properties,thermal properties and rheological properties of PEO/Lg matrix were compared.Urea,PEG and urea / PEG can improve the dispersion of Lg in PEO,and the effect of low molecular weight PEG is more significant.The internal phase morphology of PEO/Lg/urea and PEO/Lg/urea/PEG composites has a dense network structure,and the network structure of PEO/Lg/urea/PEG is more dense.PEG can act as a plasticizer to affect the crystallization process of PEO / Lg matrix.Urea and urea/PEG have different degrees of hindrance to the crystallization process of PEO.The elongation at break of the material is positively correlated with the amount of urea added.The molecular weight of PEG has different effects on the mechanical properties of PEO/Lg/PEG composites.When the amount of PEG200 is15% wt,the elongation at break of the composite material reaches 330%.These research results will help expand the application of Lg-based composites.