木质素与咖啡壳粉制备木塑复合材料的性能研究

Study on Preparation and Properties of Wood Plastic Composites with Coffee Shell Powder and Lignin

以碱木质素与咖啡壳粉共同作为原料,与桉木粉、高密度聚乙烯以及助剂等,采用熔融混炼、挤出造粒、热压成型的方法制备木塑复合材料。分析木质素、咖啡壳粉的加入对复合材料力学性能、吸水性能、动态热机械性能等方面的影响;并且全组分测定了咖啡壳粉,分析其与木粉化学成分的差异。结果表明:咖啡壳粉主要化学成分与木粉接近,仅加入木质素制备的WPC,静曲强度与拉伸强度均随木质素含量的增加呈现先增加后降低的趋势。而加入木质素与咖啡壳粉制备的WPC力学强度得到显著的改善,静曲强度可以提高49.31%,冲击强度提高16.62%。木质素与咖啡壳粉加入后,各组分之间具有较好的相容性,能够形成均一的体系,表现出更高的热稳定性;同时断面更为密实均匀,体现出更为理想的界面结合性。添加木质素后,WPC耐腐朽性能得到改善,与仅添加木质素制备的WPC相比,加入木质素与咖啡壳粉制备的WPC具有更好的耐腐性。可见,碱木质素添加量为15%,咖啡壳粉为45%时,制备的木塑复合材料性能最佳。

Alkali lignin and coffee shell powder were researched as raw materials in this paper,and wood plastic composites(WPC)were prepared by alkali lignin,coffee shell powder,eucalyptus powder,high density polyethylene(HDPE)and additives through melt mixing,extrusion granulation and hot compression molding.The effects of alkali lignin and coffee shell powder on the mechanical properties,water absorption,dynamic thermal mechanical properties of WPC samples were studied as well,and the main chemical components of coffee shell powder were analyzed.The results showed that the main chemical composition of coffee shell powder was similar close to eucalyptus wood powder.Both the bending strength and tensile strength firstly increased and then decreased with the increasing of lignin content for the lignin group.Whereas,the mechanical properties of WPC samples prepared by alkali lignin and coffee shell powder were significantly improved,with the bending strength was increased by 49.31%,and impact strength was enhanced by 16.62%.The WPC samples prepared by alkali lignin and coffee shell powder displayed good compatibility and a desired uniform interior morphology,contributed to better thermal stability.Through observation on morphology of the fracture surface,it could be concluded that more compact and uniform interface bonding layer,which showed a more preferable interface bonding.Furthermore,the decay resistance against fungi of WPC samples was improved with the lignin addition,and the samples prepared by coffee shell powder and alkali lignin had preferable decay resistance against decay fungi compared with samples prepared with only lignin.Through multi-analysis of experimental results,the optimum formulation was proposed that the addition amount of alkali lignin was 15%,correspondingly the addition amount of coffee shell powder was 45%.