| Waste printed circuit board (WPCBs) is one of the important contents of electronic waste. Present treatment technologies mainly focus on the processes of reusing precious metals and copper. After the recovery of metals, a great deal of nonmetals in WPCBs are generated and disposed by combustion or filling due to low economic value and lack of reusing method, which may cause secondary pollution and resource-wasting. Recycling boards with nonmetals of WPCBs can improve the value of reuse and provide new method for resource recovery of nonmetals. The detailed contents are listed below.(1).WPCBs basic characteristics of non-metallic materials. WPCBs non-metallic powder is primarily mixed by epoxy resin, phenolic resin and glass fiber, whose surface contains a large amount of polar bond. The particle size of most WPCBs non-metallic powder is between0.85mm to2mm, moisture content is about10%.(2).Research of preparing recycling boards by using non-metallic materials of WPCBs.Determine the compound formula:Determine aqueous phenolic resin as adhesives, sizing amount is about15%, add a small amount of polyethylene wax and stearic acid.Determine pressing process parameters:the press of lOMPa, the temperatures of130～140℃, warming and pressing time of10minutes. To avoid deformation of boards, we take three-stage buck. Elastic modulus may be up to1600MPa. Flexural strength may be up to110MPa.Research the effect of using different size material on the performance of the board. With the decrease of particle size, density and water absorption of the recycling boards show an increasing trend, while the elastic modulus and compressive strength of the boards increased first and then decreased.(3). Research of adaptated adhesives to recycling boards:according to the interface characteristics of non-metallic materials, by adjusting the type and quantity of active group in aqueous phenolic resin make the performance of adhesive meet the requirements. |
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