Recycling Waste Nonmetallic Printed Circuit Boards for Polyvinyl Chloride Composites

Activated Carbon Based on Recycled Epoxy Boards and Their Adsorption toward Methyl Orange

With the swift progress of the electronics industry, discarded circuit boards have become an important source of non-degradable waste. In this work, discarded epoxy resin was collected as a precursor to prepare activated carbon (AC) through stepwise carbonization/activation methods. The rough carbon materials with a certain graphite and amorphous structure reveal the multiple oxygen-containing groups on their surface. In the process of studying the adsorption of methyl orange by activated carbon, it is found that the adsorption is in accordance with the quasi-secondary kinetic model, and equilibrium adsorption amounts can reach 41.051 mg/g. The adsorption isotherm of AC is more in line with the Langmuir model, and the saturation adsorption amount at three different temperatures is 23.137 mg/g, 30.358 mg/g, and 37.202 mg/g, respectively. The enthalpy (ΔH) is 17.30 KJ/mol in the adsorption process, which indicates that is a physical process with heat-absorbing capabilities. This work is of great significance with regard to the recycling of waste to reduce pollution and in terms of gaining economic benefits.

High Value-Added Reutilization of Waste-Printed Circuit Boards Non-Metallic Components in Sustainable Polymer Composites

The reutilization non-metallic components from a waste-printed circuit board (WPCB) has become one of the most significant bottlenecks in the comprehensive reuse of electronic wastes due to its low value and complex compositions, and it has received great attention from scientific and industrial researchers. To effectively address the environmental pollution caused by inappropriate recycling methods, such as incineration and landfill, extensive efforts have been dedicated to achieving the high value-added reutilization of WPCB non-metals in sustainable polymer composites. In this review, recent progress in developing sustainable polymer composites based on WPCB non-metallic components was systematically summarized. It has been demonstrated that the WPCB non-metals can serve as a promising reinforcing and functional fillers to significantly ameliorate some of the physical and chemical properties of polymer composites, such as excellent mechanical properties, enhanced thermal stability, and flame retardancy. The recovery strategies and composition of WPCB non-metals were also briefly discussed. Finally, the future potentials and remaining challenges regarding the reutilization of WPCB non-metallic components are outlined. This work provides readers with a comprehensive understanding of the preparation, structure, and properties of the polymer composites based on WPCB non-metals, providing significant insights regarding the high value-added reutilization of WPCB non-metals of electronic wastes.

The Development of Environmentally Sustainable Poly(vinyl chloride) Composite from Waste Non-Metallic Printed Circuit Board with Interfacial Agents

The recycling of non-metallic printed circuit boards (NMPCB) as a filler in poly(vinyl chloride) (PVC) composite would help to encourage the use of waste NMPCB, thus, reducing some environmental concerns with regard to e-waste. The objective of this study was to comprehensively evaluate the effect of different interfacial agents, namely polypropylene grafted maleic anhydride (PP-g-MAH) and ϒ-aminopropyltriethoxy silane (ATPS) on the morphology and properties of PVC/NMPCB composites. A PVC/NMPCB composite was prepared by melt compounding with varying amounts of NMPCB ranging between 10, 20 and 30 wt.%. Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR) analysis revealed the interactions between PVC and NMPCB when using both PP-g-MAH and ATPS interfacial agent. The properties and morphology of PVC/NMPCB composites were significantly dependent on the interfacial agent treated on the NMPCB surface. The phase morphology and mechanical properties of PVC/NMPCB composites (30 wt.% of NMPCB) were improved and the result also indicated that the higher compatibility of composites with ATPS as an interfacial agent led to our obtaining the maximum Young's modulus of 484 MPa. The dynamic mechanical analysis revealed the interaction at the interface, with the T_g shifting to a lower temperature in the presence of PP-g-MAH and strong interfacial adhesion noted with the improved T_g in the presence of the ATPS interfacial agent. Further evidence of the improved interaction was observed with the increment in density in the presence of ATPS when compared with PP-g-MAH in PVC/NMPCB composite. Hence, of the two interfacial agents, ATPS showed itself to be more effective when employed as an interfacial agent for NMPCB in PVC composite for industry.

PMMA-Grafted Calcium Sulfate Whiskers for Applications as Fillers in PVC

Calcium sulfate whiskers (CSWs) were hydroxylated with a sodium hydroxide (NaOH) solution and isolated for subsequent treatment with an ethanolic 3-(methacryloxy)propyltrimethoxysilane (KH570) solution to introduce C=C double bonds on the CSWs' surfaces. Then, CSW-g-PMMA was prepared by grafting polymethyl methacrylate (PMMA) onto the surface of modified CSW using in situ dispersion polymerization. The CSW-g-PMMA was used as a filler and melt-blended with polyvinyl chloride (PVC) to prepare PVC-based composites. The surface chemical structure, PMMA grafting rate, and hydrophobic properties of CSW-g-PMMA were analyzed using X-ray diffraction, diffuse reflectance Fourier-transform infrared spectroscopy, thermogravimetric analysis, and water contact angle measurements, respectively. The effects of the CSW-g-PMMA filler on the mechanical properties of the CSW-PMMA/PVC composites were also investigated. The results showed that NaOH treatment significantly increased the number of hydroxyl groups on the surface of the CSWs, which facilitated the introduction of KH570. PMMA was successfully grafted onto the KH570 with a grafting rate of 14.48% onto the surface of the CSWs. The CSW-g-PMMA had good interfacial compatibility and adhesion properties with the PVC matrix. The tensile, flexural, and impact strengths of the CSW-g-PMMA/PVC composite reached 39.28 MPa, 45.69 MPa, and 7.05 kJ/m², respectively, which were 38.55%, 30.99%, and 20.10% higher than those of the CSW/PVC composite and 54.52%, 40.80%, and 32.52% higher than those of pure PVC, respectively. This work provides a new method for surface modification of inorganic fillers, resource utilization, and high value-added application of CSWs from phosphogypsum.