Study On The Separation And Degradation Of Epoxy Resin In Non-metallic Materials Of Waste Printed Circuit Board (NWPCB)

Printed Circuit Board?PCB?has been widely used in all electronic and electrical products.With the rapid development of electronic product innovation technology,the service life of electronic products is shortened,so that the production quantity of the waste circuit board?WPCB?is rising rapidly.The non-metallic materials recycled from WPCB are mainly composed of glass fiber reinforced thermosetting resins,accounting for about 70%to 80%of WPCB.As a kind of solid waste,NWPCB is difficult to be used as a resource,and how to deal with it effectively and avoid secondary pollution has aroused global concern.Whereas,the relevant research at home and abroad on this aspect is very limited at present.In this paper,the NWPCB powder was chosen as the research object and was directly added into the hydrothermal reaction kettle together with the reaction solvent to carry on the experiment,which can effectively separate and recover the glass fiber and epoxy resin without secondary pollution.The research in this paper can be summarized as following aspects.Firstly,the physicochemical properties of NWPCB materials were analyzed by Scanning electron microscopy?SEM?,Fourier transform infrared spectroscopy?FT-IR?and Thermogravimetric test?TGA?,which showed that the NWPCB powder in the experimental material was a composite of glass fiber and tetrabromobisphenol an epoxy resin through amine curing agent.The initial temperature of the epoxy pyrolysis was 240°C,and the glass fiber and the epoxy resin respectively accounted for about 70%and 30%.Secondly,the NWPCB powder was dissolved through four reaction systems?ZnCl₂/ethanol?60 wt%?,ZnCl₂/acetic acid?15 wt%?,AlCl₃/acetic acid?15 wt%?,and AlCl₃/ethanol?60 wt%??.The reaction residue was observed by SEM,which showed the optimum reaction system for degradation of the epoxy resin was ZnCl₂/acetic acid solution?15 wt%?.Temperature,time,liquid-solid ratio and amount of ZnCl₂ were taken as the factors affecting the degradation rate of epoxy resin.Single factor experiment,L16?4⁴?orthogonal experiment and range analysis were carried out.It was found that the main and secondary factors affecting the degradation rate were temperature and liquid-solid ratio,then the time,and amount of ZnCl₂.At the same time,the optimum reaction conditions were determined as temperature was 190°C,liquid-solid ratio was 10 mL/g,reaction time was 8 h and amount of ZnCl₂ was 5g.Under these conditions,epoxy resin degradation rate reached 81.85%,then the solid and liquid phases products were collected and analyzed respectively.The degradation liquid product of epoxy resin was distilled under constant pressure and subjected to GC-MS and FT-IR tests.The results showed that the degradation products of epoxy resin were mainly hydrocarbons.At the same time,it could be found that phenol derivatives were the main components in the liquid decomposition product from GC-MS results,which accounted for more than 65%of the entire pyrolysis oil and the peaks of the corresponding functional groups could also be seen in the infrared spectrum.These key scientific results showed that the pyrolysis oil obtained under experimental conditions has great resource utilization value.Finally,the recovered glass fiber was added to polypropylene?PP?,high density polyethylene?HDPE?and polybutylene terephthalate?PBT?to abtain the modified composite material by extrusion and injection molding,the effect of glass fiber addition on the mechanical properties of composites was studied systematically.The results showed that when the glass fiber was added in an amount of 10%,the toughness of the PP composites increased up to 218.62%relative to the pure plastic,while the PBT composites increased by63.60%relative to the pure one;When the addition of glass fiber was increased to 20%,the increment of bending load of HDPE composites reached 60.50%relative to the pure plastic;When the addition of glass fiber was upped to 30%,the increment of bending load of PP composites reached 34.32%relative to the pure one.The experiment of glass fiber modified plastics showed that the recycled glass fiber could greatly enhance one or more mechanical properties of the composite plastics within a certain amount of addition.Glass fiber could obtain the great value of resource application value through this method.This study provides a theoretical basis and effective way for the green harmless treatment of NWPCB and the resource utilization of high-valued as well as full-component within it,and provides theoretical guidance for further promoting the industrialization of WPCB treatment process.