Recycling Continuous Glass Fibre-Reinforced Polyamide 6 Laminates via Compression Moulding

Area of Science:

• Materials Science
• Polymer Engineering
• Sustainable Manufacturing

Background:

• End-of-life continuous glass fibre-reinforced polyamide 6 (cGF/PA6) composites often degrade during conventional recycling (shredding, milling, injection moulding) due to reduced fibre length.
• This leads to diminished mechanical properties in recycled materials, limiting their application.

Purpose of the Study:

• To investigate the thermomechanical reprocessing of cGF/PA6 laminates using compression moulding.
• To evaluate the impact of compression moulding on fibre length preservation, matrix crystallinity, thermomechanical properties, and flexural performance.
• To compare the effectiveness of reprocessing at temperatures below and above the melting point of PA6, considering different sizing agents.

Main Methods:

• Two types of cGF/APA6 laminates (with reactive (RS) and non-reactive (nRS) sizing agents) were reprocessed via compression moulding at 180 °C and 230 °C.
• Analysis included matrix crystallinity, thermomechanical properties (Tg), microstructure, and flexural performance testing.
• Microstructural analysis focused on fibre-matrix adhesion post-reprocessing.

Main Results:

• Reprocessing at both 180 °C and 230 °C improved matrix crystallinity and retained desirable α-crystalline phases, elevating the glass transition temperature (Tg).
• Flexural performance was maintained at 180 °C for both laminate types.
• Reprocessing at 230 °C resulted in a ~20% flexural strength improvement for the RS laminate, with retained fibre-matrix adhesion observed microscopically.

Conclusions:

• Compression moulding is a viable recycling method for cGF/APA6 laminates, preserving fibre length and enhancing material properties.
• Reprocessing temperature significantly influences the mechanical outcome, with higher temperatures potentially boosting performance, especially for laminates with reactive sizing agents.
• This approach offers a sustainable alternative to conventional recycling, maintaining high performance in recycled composites.