Study On The Preparation And Mechanical Performance Of Pulp Fiber/Polymer Wood-Plastic Composite

The wood-plastic composites using both petrol-based resources and biomass resources is facing challenge from the requirement in environmental friendly development.The reinforcing performance of the most utilized particle-shaped filler is rather limited,which stops people from increasing the biomass content in wood-plastic composites.Pulp fibers with higher aspect ratio are considered promising reinforcement in polymer matrix.Combining pulp fibers with biodegradable matrix helps to fabricate fully biodegradable composites,which gives a promising future.First,bagasse thermomechanical pulp(TMP),unbleached alkaline bagasse pulp(UBABP)and bleached alkaline bagasse pulp(BABP)were used as reinforcement respectively to prepare HDPE based wood plastic composites.The influence of different pulp fibers on the properties of composites was studied.It was found that all three pulps showed certain reinforcing effect in HDPE matrix without compatibilizing,the mechanical property of composites at 50% fiber content could reach 30 MPa for tensile strength,50 MPa for flexural strength and 30 J/m for impact strength.The comparison between composites with particle-shaped filler proved the better reinforcing performance of pulp fiber.The introduction of maleic anhydride grafted polyethene(MAPE)could greatly improve the mechanical properties.With the effect of MAPE,the tensile strength and flexural strength of bagasse TMP/HDPE composites exhibited best performance with 50.3 MPa for tensile strength,65.9 MPa for flexural strength,44.3 J/m for impact strength and 2.5 GPa for tensile modulus.However,UBABP/HDPE composites and BABP/HDPE composites greatly exceeded TMP/HDPE in tensile modulus with the introduction of MAPE,reaching 3.7 GPa and 3.8GPa respectively.These results revealed the fiber content could be further brought up when replacing wood flour with pulp fibers,which is beneficial in both environment protection and reducing production cost.And then,fully biodegradable composites was prepared with poly(lactic acid)(PLA)as matrix,pulp fibers and microcrystalline cellulose(MCC)as reinforcement phase.The effect of different biomass filler,silane coupling agent and epoxidized soybean oil(ESO)on composites was discussed.The pulp fibers and MCC was found unable to improve the composites properties without any effort in improving the interfacial adhesion.Except for the tensile modulus of 3.5 GPa,pulp fiber/PLA composites at 30% fiber content showed certain decrease in tensile strength,flexural strength and impact strength,compared with neat PLA.However,the mechanical properties decrease in MCC/PLA without silane treatment is slighter.KH 550 silane coupling agent was proved to have negative influence on bagasse TMP/PLA composites.However,it could considerably increase the flexural strength by 27% and impact strength by 90% for both UBABP/PLA and BABP/PLA composites.The mechanical properties improving of MCC/PLA after silane treatment is not obvious as well.Comparing with BABP with MCC,it could be found that the morphology and chemical mechanical properties of fillers have more influence on composites.ESO could greatly reduce the brittleness of MCC/PLA composites,while the strength of composites decreased.Silane treated pulp fibers added into PLA matrix could improve the mechanical properties of composites and is also effective in lowering the cost.Finally,based on the importance of HDPE in the industry and the excellent performance of TMP in HDPE matrix,this study prepared thermomechanical pulp for reinforcement use from sugarcane bagasse and empty fruit bunch(EFB)with steam pretreatment.The effect of mechanical pulping on pulp fiber properties was studied.The result shows that the mean fiber length of bagasse TMP and EFB TMP is 514 ?m and 571 ?m respectively,And the aspect ratio is 17.8 and 29.3,which is way better than that of wood flour.The fiber width and fines content in bagasse TMP(28.8 ?m,67.3%)is much higher than that of EFB TMP(19.5 ?m,48.3%),indicating bagasse with broad size distribution needed more coarse refining during mechanical pulping process and bagasse pith should be removed before pulping.