Mild Two-Step Thermochemical Recovery of Clean Glass Fibers from Wind-Blade GFRP

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Science

Background:

• End-of-life wind turbine blades pose a growing waste management issue.
• Current recycling methods for glass fiber-reinforced polymer (GFRP) composites offer limited value recovery.
• Low-energy, high-purity glass fiber recovery from GFRP remains an underexplored area.

Purpose of the Study:

• To investigate a mild, two-step thermochemical process for recovering clean glass fibers from GFRP.
• To determine if minimal isothermal dwell times are sufficient for complete matrix removal.
• To quantify the energy efficiency and material recovery value of the proposed method.

Main Methods:

• Utilized epoxy-based GFRP from wind turbine blades.
• Employed a step-batch reactor with thermogravimetric analysis (TGA)-based thermodynamic mapping.
• Applied a two-step process: short pyrolysis (425 °C) followed by mild oxidation (475 °C) with controlled dwell times (0-30 min).
• Used model-free kinetics and machine learning to analyze activation energy.

Main Results:

• A process of 0 minutes pyrolysis at 425 °C followed by 15 minutes oxidation at 475 °C yielded clean, white glass fibers.
• Recovered fibers retained 76% of original tensile strength and 88% of Young's modulus.
• Activation energy for the process was quantified between 120-180 kJ mol⁻¹.

Conclusions:

• The developed thermochemical sequence enables energy-efficient recycling of GFRP.
• This method offers a viable pathway for recovering high-quality glass fibers from wind turbine blades.
• Findings can guide the design of future industrial-scale thermochemical recycling systems.