Study On The Effect Of Lignin On The Properties Of Epoxy Resin And Its Composites

In this paper,the lignin extracted from bamboo scrap was used as raw material to successfully prepare a good lignin/epoxy resin composite system.The effect of blending method of direct mechanical blending and solution-mechanical blending on the performance of epoxy resin was comparatively studied.The lignin-based epoxy resin was prepared by chemical modification of lignin,and the curing and mechanical properties of the system were studied.A lignin-bamboo flour modified epoxy resin composite was prepared by simultaneously introducing lignin and bamboo flour into the epoxy resin.The results are as follows:(1)Using DMF as a solvent,a lignin/epoxy resin system with good uniformity was successfully prepared by solution blending and mechanical stirring.Scanning electron microscopy was used to observe the morphology of the system.No occurrence of EL agglomeration on the fracture surface.The addition of lignin can significantly improve the mechanical properties of the material,and when the amount of lignin is 1.5%,optimal mechanical properties is obtained.Comparing with pure epoxy resin,the tensile strength,elongation at break and impact strength are increased by 3.1%,14.7%,and 13.5% respectively.However,due to the uneven distribution of lignin,the epoxy resin cannot form a good cross-linked network,and the performance of the lignin/epoxy resin prepared by direct blending is significantly reduced.The DSC results show that the addition of lignin will accelerate the curing reaction of epoxy resin in the early stage of the reaction.(2)The addition of lignin-based epoxy resin has a certain acceleration effect on the curing reaction of the epoxy resin.The addition of lignin-based epoxy resin increases the tensile modulus of the epoxy resin system,and its tensile strength and elongation at break increase firstly and then decrease.When the addition amount is 50 %,the tensile strength reaches the maximum value,the tensile strength and tensile modulus increase by 11.2% and 10.5%,respectively,and the elongation at break decreases by 1.8%.(3)The lignin and bamboo flour were simultaneously introduced into the epoxy resin,and a lignin-bamboo flour modified epoxy resin composite was successfully prepared.With the increase of lignin content,the tensile strength and tensile modulus show a trend of increasing first and then decreasing.Among them,when the addition amount of lignin is 1.5%,the epoxy resin composites have the best tensile properties.The tensile strength and modulus are increased by 27.8% and 37.8%,respectively.The addition of lignin and bamboo flour has a certain promoting effect on the curing reaction of epoxy.