Converting Low-Value E-Waste into Phenolic Resole Resins: A Route to Value-Added, High-Performance Advanced Materials...

Area of Science:

• Materials Science
• Sustainable Chemistry
• Polymer Chemistry

Background:

• Electronic waste, specifically the nonmetallic fraction (NMF) of waste printed circuit boards (WPCBs), presents a significant disposal challenge.
• Recycled pyrolysis oil derived from WPCBs contains valuable phenolic compounds suitable for resin synthesis.

Purpose of the Study:

• To develop a sustainable method for producing resole-type phenolic resins using recycled pyrolysis oil from WPCBs.
• To characterize the synthesis, mechanical properties, thermal stability, and flame retardancy of these novel resins.

Main Methods:

• Pyrolysis of WPCB-NMF at various temperatures (300-500 °C) to optimize oil yield and phenolic content, with 400 °C being optimal.
• Synthesis of phenolic resins using recycled pyrolysis oil, pure phenol, and formaldehyde at varying ratios.
• Comprehensive characterization including GC-MS, FTIR, mechanical testing (tensile, impact), thermal stability analysis, and limiting oxygen index (LOI) for flame retardancy.

Main Results:

• Pyrolysis at 400 °C yielded the highest amount of recycled pyrolysis oil with significant phenolic content.
• Resins synthesized with up to 40 wt% recycled pyrolysis oil maintained over 82% of tensile properties and 87% of impact resistance compared to virgin resins.
• The limiting oxygen index (LOI) reached 27.0% for resins with 100% recycled oil, indicating flame retardant properties.

Conclusions:

• Recycled pyrolysis oil from WPCBs is a viable feedstock for producing high-performance, flame-retardant phenolic resins.
• This approach offers a sustainable route for e-waste valorization and circular material innovation.
• The developed resins demonstrate potential for applications requiring thermosets with enhanced safety and environmental profiles.