含孔片状废旧PET增韧水泥基复合材料的制备及性能评价

Preparation and Properties of Waste Polyethylene Terephthalate Sheet with Hole Reinforced Cement Composites

废旧塑料高值化利用对促进塑料循环利用具有重要意义。从提高填充材料和基体的啮合强度出发,开发以含孔废旧塑料为增韧材料的增韧水泥基复合材料是废旧塑料高值化利用的有效途径之一。以含孔片状废旧聚对苯二甲酸乙二醇酯(PET)和水泥复合,制备了增韧水泥基复合材料,并考察其抗折强度、冲击性能和拉伸拔脱载荷,分析了其增韧机理。相比未用PET增韧水泥基体,增韧水泥基复合材料的冲击强度由14.6 J/m^2增加到36.7 J/m^2,增加了1.5倍,抗折位移也由0.66 mm陡增至7.4 mm,但抗折强度由7.67 MPa降低到2.85 MPa。上述结果表明,含孔废旧PET塑料片和水泥基体形成的互穿结构起到了传递、分散载荷的作用,使增韧水泥基复合材料由瞬态脆性破坏转变为渐进式韧性破坏,虽然水泥基体的抗折强度降低,但显著延长了水泥基体的弯曲断裂过程,使增韧后的水泥基复合材料具有更强的抵抗碎裂的能力。此外,在研究范围内,水泥基复合材料中废旧PET塑料片材越多,单位塑料片对复合材料的增韧贡献度越大,具有增韧“筷子效应”。

High value utilization of waste plastics had great significance to promote the recycling of plastics.In order to improve the strength of the filling material and the matrix,it was one of the effective ways of high value utilization of waste plastics to develop the high toughness cement-based composite material with the porous waste plastic as the toughening material.The cement-based composite toughened by porous waste polyethylene terephthalate(PET)was prepared.The flexural strength,impact property,pull-out load and the toughening mechanism were investigated.Comparing with the cement matrix which is not toughened by PET sheet,the impact strength of the composite could increase from 14.6 to 36.7 J/m^2,which is 1.5 times.The flexural displacement increases from 0.66 mm to 7.4 m,however,the flexural strength decreases from 7.67 to 2.85 MPa.The interpenetrating structure formed by the cement and the porous plastic plays a role of transmitting and dispersing load,which makes the toughened cement-based composite change from transient brittle failure to progressive ductile failure.The flexural strength of the cement matrix decreases,however,the bending fracture process of the cement matrix is prolonged significantly,which shows better resistance to fragmentation.In addition,in the range of study,the more waste PET plastic sheets in cement-based composite materials,the greater contribution of unit plastic sheet provides to the toughening of composite materials,and there seems to be a“chopsticks effect”.