Brominated Epoxy Resin Research Articles

A strategy for synthesis of copper nanoparticles from recovered metal of waste printed circuit boards

Abstract In order to achieve the goals of Circular Economy (CE) for the million tons of Waste Printed Circuit Boards (WPCBs) generated annually, this research aims to move from WPCB recycling to remanufacturing stage and use the recovered high purity Copper (Cu) as a raw material to synthesize Copper Nanoparticles (Cu-NPs) which are a high added value product. Chemical-ultrasonic treatment was used as an eco-friendly approach to separate all layers and components of WPCBs “as received” through dissolution of brominated epoxy resin by solvent Dimethylacetamide followed by liberation and purification of Cu foils to remove any remaining organic materials. Nanoparticle synthesis was performed in three steps: a) preparation of copper (II) acetate from recovered Cu foils by nitric acid and sodium hydroxide, b) preparation of sol-gel of copper (II) acetate solution mixed with poly (vinyl) alcohol, and c) synthesis of Cu-NPs by electrospinning at flow rates 0.2 ml/h and voltage 23–29 kV. SEM, HRTEM, XRD, AAS, and TGA were used to examine the structure of the obtained copper (II) acetate and Cu-NPs. The results showed that the produced Cu-NPs had an average size 5 nm with a synthesis yield 84% (Cu-NPs/mass of recovered copper). Based on the economic assessment, the preparation costs were >4 times lower than commercial prices of similar Cu-NPs.

Separation and Recovery of Copper Foil and Fabric from Waste Printed Circuit Boards by Decomposing Brominated Epoxy Resin Using Near Critical Water

Separation and Recovery of Copper Foil and Fabric from Waste Printed Circuit Boards by Decomposing Brominated Epoxy Resin Using Near Critical Water

Recovery of gold, other metallic and non-metallic components of full-size waste random access memory

In order to increase environmental and economic benefits of waste Random Access Memory (RAM) recycling, this research aims to separate all metallic and non-metallic components of RAM by using chemical treatment and subsequent leaching process to liberate gold from gold-plated components. Chemical treatment was employed to separate metal (copper foils, contacts, through-hole pads) from non-metal by performing organic solvent Dimethylacetamide (DMA) and ultrasonic treatment at a low temperature (50 °C) in order to dissolve Brominated Epoxy Resin (BER) and separate all layers of waste RAMs. The process was carried out in a simple reactor developed specifically for this purpose. After the dissolution process, a rotary decompression evaporator was used to extract epoxy resin from DMA/BER solution and regenerate the solvent. At the same time, leaching by nitric acid was used to liberate gold from parts with high gold concentration, in particular from contacts. SEM-EDS, TGA, DSC, FTIR, and UV-VIS spectroscopy were used to characterize the recovered epoxy resin, metal, and regenerated DMA. Additionally, metallographic microscope was used to examine the DMA/BER solution. The results showed that RAMs were composed of seven layers of plain woven fiberglass, four copper foil layers, conductive tracks, contacts, solder joints of integrated circuits, epoxy resin, and soldermask. Moreover, gold with purity >94% was successfully recovered as a result of applying developed treatment technique with yield ∼12 times higher than traditional milling followed by leaching approach.

Mechanical and thermal characterizations of non-metallic components recycled from waste printed circuit boards

In the framework of reuse of non-metal (woven fiberglass layers (WFG) and epoxy resin (ER)) recovered from waste printed circuit boards (WPCBs) as received and maximization of economic and environmental benefits, this research aims to investigate mechanical and thermal properties of recycled woven fiberglass and ER extracted from WPCBs after separation by using chemical (organic solvent) and ultrasonic treatment The experiments were conducted on five samples cut from five different types of waste motherboards according to ASTM D5035 standard. Also, another sample not containing any notches or holes was cut from a blank PCB in order to be used as a reference for strength tests when compared with motherboard samples. Di-methyl formamide (DMF) was used to dissolve ER of all six samples at a low temperature in a simple reactor developed specifically for this purpose (WPCB separator). The new separator was equipped with a high-frequency ultrasonic wave generator used to accelerate the rate of breakage of internal van der Waals’ bonds of brominated epoxy resin (BER) by DMF thus reducing the dissolution time and facilitating separation of woven fiberglass layers against metal layers. After that, a rotary decompression evaporator was used to extract ER from DMF/ER solution. Universal testing machine was used to characterize mechanical behavior of recovered woven fiberglass, while thermogravimetric (TG-DTG) and calorimetric analyses (DSC) were used to investigate the thermal behavior of recovered ER. The results showed that the average strength of recovered fiberglass decreased by 48% in comparison with the blank PCB due to the presence of notches and degradation while the reduction in elastic modulus was slight. Also, the recovered ER showed high properties in terms of melting temperature and crystalline degree.

Studies on poly(ester-urea-imide)s containing epoxy segment

Novel flame retardant poly(ester-urea-imide)s were prepared by diels–Alder (DA) polymerization reaction of various bisfuran derivatives (3a–e) containing amide linkages with brominated epoxy resin based bismaleimide (4). The so-called DA reaction was carried out by refluxing the mixture of both 3a–e and 4 monomers in THF solvent. The resultant DA adduct was formed which was treated with acetic anhydride at 135 °C. The final products were in aromatized form and designated as poly(ester-urea-imide)s (PEUIs, 6a–e). These polymers were characterized by elemental analysis, number average molecular weight and thermogravimetric analysis. The glass and carbon fiber reinforced composites of such PEUIs were fabricated by ‘in situ’ polymerization process.

Influence factors of determining optimal organic solvents for swelling cured brominated epoxy resins to delaminate waste printed circuit boards

In the previous study, organic solvent dimethyl sulfoxide (DMSO) could effectively delaminate waste printed circuit boards (WPCBs) by swelling cured brominated epoxy resins (CBER). To find more organic solvents which can swell CBER, the total and three-dimensional Hansen solubility parameters (3d-HSP) of CBER in WPCBs were calculated by a group contribution method and an equilibrium swelling degree method. During testing equilibrium swelling degree, seventeen industrial common organic solvents were used to swell CBER in WPCBs. The results were that the total solubility parameter of CBER (δt) was 24.6–26.4 (J/cm3)1/2, and 3d-HSP were that dispersion force (δd) was 20.9(J/cm3)1/2, intermolecular dipole interaction force (δp) was 11.1(J/cm3)1/2, and hydrogen-bonding force (δh) was 11.6 (J/cm3)1/2. Then, 3-cresol was chosen to swell CBER in WPCBs according to its total and 3d-HSP. Result indicated that the WPCBs were delaminated completely in 3-cresol solvent. Finally, experimental results and theoretical analysis showed that the glass transition temperature (Tg) and solubility parameter of CBER were two very important factors for choosing organic solvents to delaminate the WPCBs. In addition, interaction forces of molecular functional groups between CBER and organic solvents were also an influence factor.

Comparative study of printed circuit board recycling by cracking of internal layers using organic solvents-dimethylformamide and dimethylacetamide

Dissolution studies of the substrate resin of waste printed circuit boards (WPCBs) in two organic solvents have shown that dimethylacetamide (DMAc) is more effective than dimethylformamide (DMF). Variation of dissolution parameters elucidated that DMAc results in 20% more resin dissolution when the temperature is increasing from 120 °C to 140 °C. It also results in 217% higher dissolution efficiency when the WPCBs:DMAc (w/v) ratio is increased to 3:10 from 1:10. The DMAc showed higher dissolution of the resin than DMF, for WPCBs of different size under conditions viz.- 140 °C, and 3:10 (w/v) WPCB:solvent ratio. The WPCBs of 2.25 cm2 size were completely separated into glass fiber matrix and copper foils in 180 min. Dissolution of resin is associated with the hydrogen bonding interaction with parent DMAc molecule. Spent DMAc has been regenerated by rotary decompression evaporator and it’s chemical structure and boiling point were found similar to pure DMAc. Dissolved solute in the DMAc has been recovered as the residue during regeneration. The residue and exhibits a thermal degradation profile and chemical structure similar to untreated brominated epoxy resin.

Dissolution and separation of brominated epoxy resin of waste printed circuit boards by using di-methyl formamide

Present work investigates the effect of various parameters on the optimum dissolution of brominated epoxy resin (BER) from waste printed circuit boards (WPCBs) and separation of its different components (copper foil, glass fiber, solder mask etc.) by using dimethylformamide (DMF). Studies revealed that high temperature, high WPCB:DMF ratio and small size of fed WPCBs results in quicker dissolution of BER leading to efficient delamination and separation of WPCBs. Optimized condition ensuing most effective separation of WPCBs into copper foil, solder mask and glass fiber were- temperature- 135 °C, WPCB:DMF ratio- 300 g/L, WPCB size-1 cm × 1 cm, time- 4h. Under optimized conditions WPCBs of 2 cm × 2 cm and 3 cm × 3 cm were delaminated into copper foil and glass fiber in 180 and 240 min, respectively. Strong hydrogen bond formation affinity of DMF, enhanced vibrations and breakage of internal van der Waals’ bonds of BER at elevated temperature are responsible for hydrogen bonding between BER and DMF, leading to the dissolution of BER. The spent DMF is regenerated by using rotary decompression evaporation and analyzed by nuclear magnetic resonance spectroscopy, Fourier transform infra-red spectroscopy (FT-IR). The efficiency of regenerated DMF to dissolve BER is similar to unused DMF even after five usage cycles. Scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDS) and FT-IR technique have been used for quantitate composition and chemical structure analysis of residue obtained after evaporation. This novel and simple technique possess the capability of sorting of different components of WPCBs, recycling of used DMF, separation of BER and simultaneously reduces the cost of operation, effluent generation leading to cleaner processing of WPCBs.

Effect of Brominated Epoxy Resins on the Thermal Stability and Flame Retardancy of Long-Glass-Fiber Reinforced Polyamide 6

AbstractIn this work, the compounds of brominated epoxy resins and antimony trioxide (BER/Sb2O3) additives are analyzed and added into long-glass-fiber reinforced polyamide 6 (PA6/LGF) composites in order to solve the “candle-wick effect” caused by glass fibers. The thermal stability, flammability, and morphology of charred residues of the flame retardant PA6/LGF composites are investigated by thermogravimetric analysis (TGA), limiting oxygen index (LOI), UL-94 test, cone calorimeter test (CCT), and scanning electronic microscopy (SEM). The results show the addition of BER/Sb2O3 provides improvements in flame retardancy by increasing the LOI values, enhancing UL-94 rating, and reducing the heat release rate, total heat release and effective heat of combustion due to the formation of consolidated and thick charred residual structures on the surfaces of the LGF reinforced PA6 composites. When the content of BER/Sb2O3 is increased to 12 wt%, the LOI value and UL-94 rating of BER/PA6/LGF composites reach 24.8 and V-0, respectively. The TGA results exhibit that the decomposition temperature of the PA6/LGF composites decreases with the addition of BER/Sb2O3 additive, resulting in forming some high quality residual char layer. A possible flame retardant mechanism is proposed to illustrate the effect of the gaseous and condensed phases on the flame retardancy of the PA6/LGF composites.

The transfers of brominated epoxy resins and metals during exfoliation of waste printed circuit boards with ionic liquid

In this study, the exfoliation of waste printed circuit boards (WPCBs) layers was conducted in an ionic liquid, 1-ethyl-3-methylimizadolium tetrafluoroborate . The transformation of brominated epoxy resins (BER), the major ingredient in WPCBs, was characterised, and the result indicated that the concentration of BER in the achieved approximately 28 g·L−1 while WPCBs layers were separated completely. Moreover, the dissolution of WPCBs metals during the exfoliation was determined. This demonstrated that concentration of copper became the highest in solution among the metals being tested as the concentration of metals decreased in the order as Cu≫Al>Sn>Pb>Fe>Mg≈Zn>Cd>Cr>Ni≈Mn. The dissolution of the metals in N2 and air atmospheres was similar. Accordingly, the WPCBs exfoliation was carried out under various conditions, which revealed that smaller size (1 × 1 cm2) of WPCB pieces, a higher reaction temperature (240°C) and a longer separation time could improve the extent of the exfoliation. Therefore, the current work provides enhanced exfoliation conditions of WPCBs in the ionic liquid . Finally, could be recycled and enriched metals could be electro-deposited.

Advanced degradation of brominated epoxy resin and simultaneous transformation of glass fiber from waste printed circuit boards by improved supercritical water oxidation processes

This work investigated various supercritical water oxidation (SCWO) systems, i.e. SCWO1 (only water), SCWO2 (water+H2O2) and SCWO3 (water+H2O2/NaOH), for waste printed circuit boards (PCBs) detoxification and recycling. Response surface methodology (RSM) was applied to optimize the operating conditions of the optimal SCWO3 systems. The optimal reaction conditions for debromination were found to be the NaOH of 0.21g, the H2O2 volume of 9.04mL, the time of 39.7min, maximum debromination efficiency of 95.14%. Variance analysis indicated that the factors influencing debromination efficiency was in the sequence of NaOH>H2O2>time. Mechanism studies indicated that the dissociated ions from NaOH in supercritical water promoted the debromination of brominated epoxy resins (BERs) through an elimination reaction and nucleophilic substitution. HO2, produced by H2O2 could induce the oxidation of phenol ring to open (intermediates of BERs), which were thoroughly degraded to form hydrocarbons, CO2, H2O and NaBr. In addition, the alkali-silica reaction between OH− and SiO2 induced the phase transformation of glass fibers, which were simultaneously converted into anorthite and albite. Waste PCBs in H2O2/NaOH improved SCWO system were fully degraded into useful products and simultaneously transformed into functional materials. These findings are helpful for efficient recycling of waste PCBs.

Separation of WPCBs by dissolution of brominated epoxy resins using DMSO and NMP: A comparative study

Printed circuit boards (PCBs) in electrical and electronic equipment (EEE) abide of valuable and hazardous materials and due to its complex and discrete make up across manufacturers, processing of waste PCBs (WPCBs) is a massive challenge. And therefore either completely novel or improved processes are needed for recycling of WPCBs and recovery of valuable materials from it. Present comparative study, was performed for processing WPCBs using solvents N-methyl-2-pyrrolidone (NMP) and dimethyl sulfoxide (DMSO). Various parameters, which include WPCB sizes; solid to liquid (S/L) ratio; temperature and time, were investigated to understand the WPCBs processing by dissolving bromine epoxy resin using solvents. Results showed that the rate of removal and separation of the bromine epoxy resin (BER) increases with respect to increasing various parameters. Optimum condition of complete separation of WPCBs using NMP were S/L ratio of 1:5, WPCB size/area of 4mm/16mm2 and 100°C for 90minutes, whereas for DMSO the optimum dissolution of bisphenol A were obtained in S/L ratio of 1:2, size/area of 6mm/36mm2 at 90°C for 90min. Overall, NMP proves to be better solvent for bromine epoxy resin than DMSO in terms of bisphenol A dissolution and separation of various layers of WPCB. Used solvents can be vaporised–condensed under the decompression for regeneration. This novel process can be an eco-friendly and effective option for separation and recovery of various valuable materials such as metals, glass fibres, etc. from WPCBs. Further research and testing is needed for precise evaluation between two processes using NMP or DMSO solvents, in terms of the valuable material recovery from WPCB and process techno-economics.

Investigation on Dissolution of Brominated Epoxy Resin Using Ionic Liquid [Bmim]Cl from Waste Printed Circuit Boards

Treatment technology of brominated epoxy resin (BER) is still a big challenge to waste printed circuit boards (PCBs) recycling. In order to make full use of the materials, ionic liquid 1-butyl-3-methyl imidazole chloride ([Bmim]Cl) was used to dissolve BER to separate glass fibers from PCB nonmetallic powders. The effects of dissolving parameters including temperature, time and solid/ liquid ratio on the dissolution rate of BER were investigated. The dissolved BER were regenerated and were characterized by FTIR and thermal analysis. Results showed that [Bmim]Cl was a good direct solvent for BER dissolution and at a suitable condition of 170°Cfor 6 hours with solid/liquid ratio of 1: 20 (g/g), nearly 90% of BER in original powders were dissolved. The possible dissolution mechanism was also discussed.

WITHDRAWN: Removal and separation of bromine epoxy resin for recovering valuable materials from waste printed circuit board using organic solvent

This article has been withdrawn at the request of the author(s) and/or editor. The Publisher apologizes for any inconvenience this may cause. The full Elsevier Policy on Article Withdrawal can be found at http://www.elsevier.com/locate/withdrawalpolicy.

Application of supercritical water to decompose brominated epoxy resin and environmental friendly recovery of metals from waste memory module.

Waste Memory Modules (WMMs), a particular kind of waste printed circuit board (WPCB), contain a high amount of brominated epoxy resin (BER), which may bring a series of environmental and health problems. On the other hand, metals like gold and copper are very valuable and are important to recover from WMMs. In the present study, an effective and environmental friendly method using supercritical water (SCW) to decompose BER and recover metals from WMMs was developed instead of hydrometallurgy or pyrometallurgy simultaneously. Experiments were conducted under external-catalyst-free conditions with temperatures ranging from 350 to 550 °C, pressures from 25 to 40 MPa, and reaction times from 120 to 360 min in a semibatch-type reactor. The results showed that BER could be quickly and efficiently decomposed under SCW condition, and the mechanism was possibly free radical reaction. After the SCW treatments, the glass fibers and metal foils in the solid residue could be easily liberated and recovered, respectively. The metal recovery rate reached 99.80%. The optimal parameters were determined as 495 °C, 33 MPa, and 305 min on the basis of response surface methodology (RSM). This study provides an efficient and environmental friendly approach for WMMs recycling compared with electrolysis, pyrometallurgy, and hydrometallurgy.

Rubber Modified Epoxy-Cyanate Ester Composites as Matrices for Tagging of Explosives

The present study deals with the possibility to utilize blends of rubber modified epoxy and cyanate ester resins as thermal and mechanical resistant polymeric matrices for tagging of explosives. It has been shown that a composite material consisting of a polymeric matrix made of cyanate ester resin and brominated epoxy resin modified with carboxyl-terminated butadiene acrylonitrile rubber, an ultraviolet light active pigment and a coding system represented by metal oxides mixture and iron powder bearing ferromagnetic properties could be successfully applied for tagging of explosives. A positive identification of a tested explosive comprising the tagging elements after detonation was proved.

An uninflammable film adhesive and an adhesive prepreg based on it

The properties of a composition that can be used as a film adhesive and a binding agent for glass-reinforced plastics are presented. The composition is developed based on brominated epoxy resins and is selfextinguishing. It is shown that the use of adhesives and binding agents based on brominated epoxy resins makes it possible to obtain glass-reinforced plastics with hot-performance capabilities coming close to the properties of structural inflammable materials.

Thermal Debromination of Waste Printed Circuit Boards by Iron-Based Catalyst

Pyrolysis appears to be a promising route allowing all-components recovery of the high value of potentially accessible products from waste printed circuit boards (WPCBs). However, bromine-containing pyrolysis oil must be dehalogenation, otherwise it will be a strong impact on thermal treatment. In the present study, an effective and environmental-friendly process using tri-iron tetroxide sorbent (Fe-O) to simultaneously degrade brominated epoxy resin from WPCBs was developed in pyrolysis process. The results show that brominated epoxy resins can be quickly decomposed under catalysis condition. Bromide concentration in pyrolysis oil decreases with the increase of the content of Fe-O. It can transfer the bromine from the gas phase and liquid phase to solid phase. When adding proportion to 1:1, bromine concentration of pyrolysis oil decreased by up to 98.2%. Fe-O can promote the decomposition of complex structure of benzene compounds to substance with simple structure. This study produces halogen free liquid products to recycle.

Pyrolysis Reaction Pathways of Waste Epoxy-Printed Circuit Board

Abstract This article elucidates pyrolysis reaction pathways of waste epoxy-printed circuit boards (e-PCBs). Non-isothermal thermogravimetric analyses showed that waste e-PCBs decomposed via a series of reactions distinguished by three apparent reaction regions. The first-stage reaction (<250°C) can be accounted for by the cleavage reaction of N-containing cross-linkage between brominated epoxy resin (BER) and non-brominated epoxy resin (NBER). Evolved gas analysis-mass spectrometry (EGA-MS) showed that the second-stage reaction (250–500°C) can be represented by two independent decomposition reactions of BERs and NBERs to yield thermally stable intermediates. BERs decomposed more rapidly (250–350°C), whereas NBERs decomposed over broader temperature regions (250–500°C) with slower decomposition rates. Multi-shot gas chromatography/mass spectrometry also indicated that brominated compounds, brominated phenol and brominated bisphenol A, are generated mainly at lower temperature zones of the second-stage reg...

Synthesis, Characterization, and Glass Reinforcement of Flame Retardant Acrylated Poly(Ester-Amide) and Flame Retardant Poly(Ester-Imide) Resins Based on Brominated Epoxy Resin

Bisphthalamic acids were prepared by reaction of phthalic anhydride and aliphatic diamines. Flame retardant poly(ester-amide)s were prepared by reaction of brominated epoxy resin with bisphthalamic acids and post reaction was carried out with acryloyl chloride to obtained acrylated flame retardant poly(ester-amide) resins. Bismaleimides were prepared by reaction between aromatic diamines and maleic anhydride. Carboxy terminated bismaleimides were prepared by Michael addition reaction of bismaleimides and 4-amino benzoic acid. Flame retardant poly(ester-imide)s were prepared by reaction between carboxy terminated bismaleimides and brominated epoxy resin. All the obtained products were characterized and analyzed by making composites.