Synthesis Of Epoxy Resin With DES-NiO Modified Lignin And Its Thermal Stability

Lignin is the only renewable resource containing aromatic rings.Lignin is rich in content,but its complex molecular structure,chemical inert and insoluble in most organic solvents,which makes it difficult to be fully utilized.By exploring the structural characteristics of lignin,the molecular structure and molecular weight of lignin were changed by chemical modification,the chemical reaction activity was enhanced,and the application field of lignin was expanded.This not only makes full use of lignin resources,but also has important practical significance for China's papermaking sewage and environmental control.In this paper,lignin-based epoxy resin?LGEPx?was prepared by epoxidation of modified lignin with epichlorohydrin?ECH?in DES-NiO system.The experimental methods are as follows:firstly,the effects of NiO on the physical and chemical properties of lignin were investigated by chemical modification of PL with DES-NiO system.And the modified lignin was obtained by comparing with blank test?ML₀?.The molecular structures and surface microscale changes of ML and ML₀ were qualitatively and quantitatively calculated by Fourier transform infrared spectroscopy?FT-IR?,Thermogravimetric analysis?TG-DTG?Scanning electron microscopy?SEM?and Atomic force microscope?AFM?and X-ray diffraction?XRD?et al.Then,LGEPx was prepared by adding ECH into the modified reaction system with the catalyet of NaOH.And the thermal kinetics of the synthesized epoxy resin was studied at the same time.Through the above experiments,the following conclusions are obtained:?1?After modification,the roughness surface of lignin increases,the thermal stability decreases,and the hydroxyl content increases obviously,which is more conducive to the further epoxidation of lignin under mild conditions.?2?The molecular structure of LGEPx was characterized by Fourier transform infrared?FT-IR?,thermogravimetric analysis?TG-DTG?,scanning electron microscopy?SEM?,atomic force microscope?AFM?,X-ray diffraction?XRD?,carbon spectroscopy nuclear magnetic resonance(¹³C-NMR).The synthesis of epoxy resin was proved to be successful.?3?The thermal stability kinetics of LGEPx was studied by differential scanning calorimetry?DSC?.The results showed that the wood-based epoxy resin system was the most stable and the epoxy value was the highest when ECH/MLG=5 was used.Figure[19]table[12]reference[99]...