Preparation And Evaluation Of Enzymatic Hydrolysis Lignin-plastic Composite

Lignin is the second abundant natural resource that can be widely found in the cell wall of most land plants.The preparation and evaluation of lignin/plastic composites is one of the research hotspots for lignin’s high value utilization.But lignin containing a large amount of polar functional groups such as hydroxyl group and phenolic hydroxyl group has poor interfacial compatibility with non-polar polyolefin.Plasticizers and silane coupling agents are often used to improve interfacial compatibility between the filler and the polymer matrix.Commonly used plasticizers,such as DOP,DBP et al,are potentially harmful to the human body.In recent years,the application of lignin/plastic composites has been extensively studied.However,the research on green and nontoxic interfacial modifiers giving good mechanical properties for lignin/plastic composites has been rarely reported.In the view of this point,this paper attempts to study the effects of different interfacial modifiers on the comprehensive properties of enzymatic hydrolysis lignin / HDPE composites,trying to get some nontoxic or less toxic interfacial modifiers that may be beneficial for the development of lignin/polyolefin composites.The different interfacial modifiers,such as aluminum stearate,ATBC,TBC,oleic acid,epoxidized soybean oil,SDS,KH570 and stearic acid are used to investigate the effects on the comprehensive properties of enzymatic hydrolysis lignin/plastic composites.The break elongation of this composites with 10 phr lignin and 90 phr HDPE was 63% and the tensile strength was about 25 MPa.TBC,oleic acid,SDS and stearic acid improved the mechanical properties of the composites nearly 2 times compared to those without the interfacial modifier.The section was smooth and had no obvious macropore.The different amounts of interfacial modifiers,such as TBC,SDS,oleic acid and stearic acid were used to investigate the effects on the comprehensive properties of enzymatic hydrolysis lignin/plastic composites.After adding 2 phr TBC,oleic acid and SDS respectively,the break elongation of composites was increased by 50~60%.The toughening effect of oleic acid is the best.The break elongation of the composite can reach 125%.Thermal stability test showed that the 50% weight loss temperature of the composites prepared by adding TBC,SDS and oleic acid was higher than those of the composites without additives.The increase range was about 15℃.The addition of interfacial modifier had certain protective effect on the thermal stability of the composites at the later stage after 450℃.The SEM showed that when the magnification was 2000 times,there was no obvious interfacial gap between the enzymatic hydrolysis lignin and the HDPE after the addition of interface modifier.The break elongation of the composite reached about 120% and the tensile strength was about 23 MPa.The composite interfacial modifier was prepared by mixing TBC,SDS and oleic acid as modifier in different proportions,the total dosage of the hybrid interfacial modifier was controlled at 2 phr.After adding 2 phr of designated interface modifiers(TBC,SDS and oleic acid),the break elongation of the composite can reach 120% and the tensile strength is about 22 MPa.There are synergistic and antagonistic effects between the two different modifiers.When the ratio of TBC/oleic acid was 3:1 and the amount of TBC/oleic acid was 2 phr,the break elongation of composites reached to the maximum and the maximum value was 240%.Also,the tensile strength was 21 MPa.The thermal stability of lignin/HDPE composites with hybrid interfacial modifier was better than that with the single interface modifier.The SEM showed that when the ratio of TBC / oleic acid was 3:1,the effect of composite interface modifier on the toughening of the composites was the best.Enzymatic hydrolysis lignin was homogeneously distributed in HDPE.The Vicat softening temperature of the composites did not change obviously with the single interface modifier.In summary,the proportion of TBC / oleic acid ratio of 3:1 and the amount of 2phr are the best formula.At this time,the break elongation of the composite can reach about 240% and the tensile strength is about 21 MPa.The effects of different interfacial modifiers on the comprehensive properties of enzymatic hydrolysis lignin/plastic composites were studied in this paper.It was found that three kinds of interface modifiers(TBC,SDS and oleic acid)had better toughening performance.With the 3:1 proportion of TBC/oleic acid and the amount of 2phr,the break elongation of the composite can reach about 240% and the tensile strength is about 21 MPa.This research had important significance to solve the shortcomings of common industrial interface modifiers and poor comprehensive performance of lignin/plastic composites.At the same time,it could broaden the application field of lignin in plastic industry.