Research On The Preparation Of Green Composites Based On Multi-scale Plant Fiber Reinforced Polyethylene Based On Coffee Husks

With the progress of society,people's attention to the ecological environment has been increasing,and environmentally friendly green composite materials have received continuous attention from the scientific community,Among them,the enhancement and modification of composite materials has been a research hotspot.This article uses waste coffee husks to reinforce polyethylene to prepare composite materials.On the one hand,multi-scale plant fiber reinforced composite materials are used,and on the other hand,three different vinyl polymers are used.Monomers(methyl methacrylate(MMA),butyl methacrylate(BMA)and styrene(ST))modify the coffee husks to enhance the interface bonding strength of the material.Firstly,wood-plastic composite materials are prepared by using recycled polyethylene and coffee husks as raw materials and using a twin-screw granulation and hot pressing process.Urea ball milling system was used for coffee shell powder to prepare sub-micron cellulose mixture CCMC(containing hemicellulose and lignin),and coffee shell powder was also used to prepare nano-sized cellulose mixture CSNC(containing a small amount of hemicellulose and lignin)with complex process.),Compare the two as a reinforcing phase for wood-plastic composites.The results show that when 4% CSNC is added,the flexural modulus of the composite is increased by 35%,but both the bending strength and impact strength are reduced.After adding 4% CCMC,the impact strength and flexural strength of wood-plastic composites increased by 7%.The DMA test results show that the addition of 4%CCMC can increase the storage modulus of the material,reduce the inelastic deformation of the wood-plastic composite,and improve the stiffness of the composite.In terms of water absorption,CSNC significantly increases the water absorption of the material,and the addition of CCMC has little effect on the water absorption of the material.The water absorption test of the material found that 2%RPNC can reduce the water absorption of the composite.Secondly,using high-density polyethylene(HDPE)and coffee husks as raw materials,the twin-screw granulation process is used to prepare wood-plastic composite materials.Nano-cellulose RPNC was prepared by using refined cotton(M30)as a raw material and using a urea-bath phosphoric acid treatment ball milling method as a reinforcing phase to reinforce wood-plastic composite materials.The conclusion shows that the addition of 2% RPNC improves 100% and the bending strength increases 52%.When the additive amount is 8%,the flexural modulus reaches a maximum of 2.95 GPa,which is 39% higher than that of the blank group.In addition,RPNC can significantly increase the hardness and Vicat softening point temperature of the material.After adding 2% of RPNC,the hardness and Vicat softening point temperature of the material increase the most,increasing by 36% and6%,respectively.Adding 2% and 8% RPNC increased the storage modulus of the composite,and the loss factor of the composite decreased when the temperature was higher than 65? compared with the blank group.Thermogravimetric analysis results show that 6% RPNC can improve the thermal stability of the material.It can be seen from the SEM pictures that RPNC can improve the bonding strength of the composite interface.Finally,the effects of adding three different vinyl polymer monomers(MMA,BMA,and ST)on the properties of composite materials were studied by spraying the surface of coffee husks while stirring at high speed.FTIR shows that spraying vinyl polymer monomer under high speed stirring can coat the monomer on the surface of coffee husks.When the addition amount of the vinyl polymer monomer is 4%,the impact strength of the composite material increases the most,increasing by 35%,20%,and 47%,respectively.The increase in flexural strength and flexural modulus of composites was the most significant with the addition of 6% MMA,which increased by 9.8% and 13% respectively compared to the blank group.When the amount of the vinyl polymer monomer was 4%,the material hardness increased by 18%,22%,and24%,respectively.When testing the Vicat softening point temperature of the material,it was found that the highest Vicat softening point temperature was the composite with4% BMA added,which was 8? higher than the blank group.DMA shows that the addition of 4% BMA can increase the storage modulus of the composite,and the addition of 4% MMA and BMA can reduce the material's loss factor.Thermogravimetric analysis shows that the addition of 4% of the three vinyl polymer monomers can improve the thermal stability of the composite,and the thermal stability of the composite with 4% ST is the best.SEM photos of the bending section of the composite material show that all three vinyl polymer monomers can improve the interface bonding strength of the material.The water absorption test of the material proves that all three vinyl polymer monomers can reduce the water absorption of the composite.