【作者】 郭杰；

【导师】 许振明； 饶群力；

【作者基本信息】 上海交通大学 ， 环境工程， 2011， 博士

【摘要】 废弃电路板(WPCBs)是电子垃圾的重要组成部分,WPCBs中的金属品位相当于普通矿物中金属品位的几十倍至上百倍,具有重要的回收价值。目前主要采用破碎-分选等物理法回收WPCBs中的金属,而回收过程中产生的大量非金属粉主要进行焚烧、填埋处理或露天堆放,增加了环境负荷及造成环境污染。为此,本文基于“废物—资源—产品”的原则,以破碎-分选WPCBs中非金属粉为研究对象,根据非金属粉的组成、颗粒大小、形状等特性,采用物理填充再利用的方法,代替木粉等其它有价材料,成功地制备了非金属粉填充改性的酚醛模塑料、木塑复合材料、再生板材和改性沥青等4种材料,分别研究了非金属粉填充材料的制备工艺和性能,探讨了非金属粉填充材料的制备反应机理、改性强化机制、微观界面结合和有害物质的固定化理论,为破碎WPCBs中非金属粉的综合利用提供理论基础和实验依据。非金属粉主要由电路板基板增强材料和树脂粉末组成,其形状分别为片状、长杆状和短切玻璃纤维与树脂粉末。玻布粉粒径为0.3-0.15 mm的物料为片状、粒径为0.15-0.125 mm的物料为长杆状,粒径<0.07 mm的物料以短切纤维与树脂粉末为主;纸基粉粒径为0.3-0.125 mm的物料为薄片状,粒径<0.07 mm的物料为粉末状。玻璃纤维和纸等增强材料具有良好的增强效果,为非金属粉的填充再利用提供了前提。1.非金属粉填充酚醛模塑料将破碎、分选所得的玻布粉和纸基粉分别代替部分木粉填充到酚醛模塑料中,研究不同酚醛树脂系统的固化反应动力学,探讨非金属粉的添加量和粒径对模塑料性能的影响。研究表明:40 wt %玻布粉填充耐热型酚醛模塑料时,其性能完全满足标准要求。纸基粉填充通用型酚醛模塑料时,可以提高模塑料的缺口冲击强度和热变形温度,但会降低酚醛模塑料的拉西格流动性。纸基粉加入量以20 wt %为佳,此时,模塑料的弯曲强度为70 MPa、缺口冲击强度为2.3 kJ/m2、热变形温度为168°C、介电强度为3.9 MV/m和拉西格流动性为103 mm,完全满足模塑料标准要求。2.非金属粉填充木塑复合材料将非金属粉代替部分木粉制备出具有木材外观的木塑复合材料。非金属粉的加入可以提高木塑材料的弯曲强度和拉伸强度,降低握螺钉力性能。非金属粉在木塑复合材料中的添加量可以达到40 wt %。经过加速老化试验后,40 wt %添加量木塑材料的性能为:弯曲强度21.6 MPa(老化前23.4 MPa),拉伸强度7.7 MPa(老化前9.6 MPa),冲击强度为4.35 kJ/m(2老化前3.03 kJ/m2),板面和板边的握螺钉力分别为109 N/mm(老化前121 N/mm)和104 N/mm(老化前115 N/mm)。3.非金属粉制备再生板材通过添加不饱和聚酯树脂及其它助剂,利用自制热液压机将非金属粉制备出再生板材。探讨不饱和聚酯/非金属粉树脂体系固化反应动力学,确定再生板材的模压条件,并研究非金属粉粒径及添加量对再生板材性能的影响。结果表明适宜的成型条件是:模具上/下压头温度为140/135°C,加压时间为5 min。当粒径<0.07 mm非金属粉添加量为20 wt %时,再生板材的机械性能最好,其弯曲强度为68.8 MPa、冲击强度为6.4 kJ/m2。4.非金属粉改性沥青将不同粒径非金属粉进行沥青改性,研究非金属粉对沥青常规性能和流变性能的影响。当非金属粉含量为25 wt %,粒径为0.09-0.07 mm时,改性沥青的综合性能最好,其指标为135°C粘度为1225 cP,25°C针入度为53.7 dmm,软化点为54°C,15°C延度为43.5 cm,60°C的车辙因子G*/sinδ为3995.27 Pa,极限使用温度为69.4°C,性能得到较大的提高和改善。通过对非金属粉填充材料的挥发物分析及毒性浸出实验得出,非金属粉填充材料的挥发物主要来自其它添加剂,挥发物组分主要有苯酚、苯乙烯等。毒性浸出实验表明非金属粉填充材料浸出液中的铜、铅等重金属离子的浓度均远低于浸出毒性限值,即填充法可以实现树脂基体对非金属粉的固定化作用,是安全环保的处置方法。本文成功地制备出铺板等木塑材料产品和窨井盖等市政设施产品,具有广阔的应用前景,解决了目前WPCBs中非金属粉只能进行填埋、焚烧处理或露天堆放的环境污染问题,使非金属粉实现了资源化利用。更多还原

【Abstract】 Waste printed circuit boards (WPCBs) are an important part of electronic waste (e-waste). The recycling of WPCBs is valuable as the purity of precious metals in WPCBs is more than 10 times higher than that of rich-content minerals. Mechanical process including crushing and separating is the main method for recycling WPCBs. A large number of nonmetals are generated when recycling metals. The treating methods for the nonmetals include incineration, landfill, or open dumping, resulting in environmental load and environmental pollution. Based on the principle of“waste-resource-product”, this paper studied the reuse of the nonmetals reclaimed from crushed WPCBs by physical filling method. According to the components, particle sizes, shapes and other physical properties of the nonmetals, the nonmetals replacing wood flour or other materials were used to prepare 4 kinds of nonmetal products successfully, including phenolic molding compounds (PMC), wood plastic composites (WPC), nonmetallic plate (NMP), and nonmetals modified asphalt (NMA). The paper provided a theoretical basis and experimental data by investigating reaction mechanism, reinforcing mechanism, micro-interfacial morphology, and solidification of hazardous materials.The nonmetals mainly consisted of reinforcing materials and resin powder. Glass-nonmetals with particle size 0.3-0.15 mm, 0.15-0.125 mm and <0.07 mm were in the form of sheet, long rod, short-cut glass fibers and resin powder, respectively. Paper-nonmetals with particle size 0.3-0.125 mm and <0.07 mm were in the form of sheet and powder, respectively. The reinforcing characteristics of glass fibers and paper in the nonmetals provided the possibility of treating the nonmetals with filling methods.1. PMC filled with nonmetalsGlass-nonmetals and paper-nonmetals reclaimed from laboratory crushing and separating were used to replace wood flour in the production of PMC. Kinetic mechanism of curing process of PMC was studied by differential scanning calorimetry (DSC). Effects of filling content and particle size of the nonmetals on the properties of PMC were also studied. The results show the PMC with 40 wt % glass-nonmetals qualified the standard. To ensure sufficient properties of PMC, the optimal added content of paper-nonmetals is 20 wt %, which results in a flexural strength of 70 MPa, a charpy notched impact strength of 2.3 kJ/m2, a heat deflection temperature of 168°C, a dielectric strength of 3.9 MV/m, and a rasching fluidity of 103 mm, all of which meet the national standard data.2. WPC filled with nonmetalsThe nonmetals were used to replace wood flour in the production of WPC. The results show that filling of the nonmetals in WPC improves the flexural strength and tensile strength, and reduces screw withdrawal strength. The filling content of nonmetals in WPC can be up to 40 wt %. To evaluate property durability against weather exposure, the effects of accelerated aging process on the properties of WPC are investigated. After solid WPC with 40 wt % nonmetals (S-40-WPC) underwent aging process, S-40-WPC had a flexural strength of 21.6 MPa (before aging 23.4 MPa), a tensile strength of 7.7 MPa (before aging 9.6 MPa), a charpy impact strength of 4.35 kJ/m2 (before aging 3.03 kJ/m2), and face/edge screw withdrawal strength of 109/104 N/mm (before aging 121/115 N/mm).3. NMP made from nonmetalsA new kind of NMP was produced by adding unsaturated polyester resins and other additives into the nonmetals using a self-made hot-press former. Kinetic mechanism of resin curing was studied by DSC method, and molding parameters are determined. Effects of content and particle size of the nonmetals on the properties of NMP were also studied. The results show that the optimum molding conditions are as follows: top/bottom molding temperature are 140/135°C, molding time is 5 min. When the filling content of the nonmetals with particle size less than 0.07 mm was 20 wt %, NMP had a flexural strength of 68.8 MPa and impact strength 6.4 kJ/m2.4. Asphalt modified with nonmetalsThe nonmetals were reused as a new modifier to improve the performance of asphalt. The classical and rheological properties of unmodified asphalt and NMA were determined. Specifically, the effects of content and particle size on these properties were studied. When the filling content of the nonmetals with particle size from 0.09 to 0.07 mm was 25 wt %, the NMA had a viscosity of 1225 cP at 135°C, a penetration of 53.7 dmm at 15°C, a ring and ball softening point of 54°C, a ductility of 43.5 cm at 15°C, a G*/sinδof 3995.27 Pa at 60°C, and an upper limit temperature (G*/sinδ= 1 kPa) of 69.4°C, all of which showed that the high temperature performance of asphalt was improved significantly.Tests of volatile compounds (VOCs) released from nonmetal products show that the VOCs, such as phenol and styrene, were mainly originated from added compounds when producing nonmetal products. Leaching tests on nonmetal products show that Cu and Pb concentrations in the leachates were far below the standard limits. It indicates that filling method was safe and environmentally friendly for treating the nonmetals as the hazardous materials could be well solidified in the resin matrix.Nonmetal products with potential applications such as decking boards and sewage lids were successfully produced. The paper not only tackled the environmental problems caused by treating nonmetals with the methods of landfill, incineration or open dumping, but also achieved the comprehensive utilization of the nonmetals.更多还原