On the resistance of PEKK to degradation during multiple recycling cycles for additive manufacturing
Year: 2026
Type: article
Abstract: The recyclability of high-performance poly(ether ketone ketone) (PEKK) is critical for sustainable additive manufacturing and future in-space resource utilization. This study systematically examines the thermal, mechanical, and chemical stability of PEKK subjected to multiple recycling loops to elucidate its degradation mechanisms. Thermogravimetric analysis revealed negligible (< 1 %) mass loss after 5 h of isothermal exposure below 450 °C, confirming excellent thermal resistance under extrusion and printing conditions. Cyclic differential scanning calorimetry up to 380 °C showed stable melting and crystallization behavior across six thermal cycles, indicating that molecular mobility and crystallization kinetics remain unaffected by repeated processing. Tensile, flexural, and dynamic mechanical analyses demonstrated that mechanical integrity was preserved after three complete recycling sequences involving shredding, pulverization, extrusion, and reprinting. Fourier transform infrared spectroscopy detected no new carbonyl or hydroxyl bands, excluding oxidative chain scission, while X-ray fluorescence revealed only trace (< 0.5 wt %) metallic contamination. Scanning electron microscopy of fracture surfaces confirmed well-fused interlayer morphology and minimal porosity evolution. Collectively, these results demonstrate that PEKK maintains its molecular and microstructural integrity during repeated thermal-mechanical cycles, highlighting its exceptional thermal-oxidative stability and suitability for circular, high-performance, and extended-lifetime polymer applications.
Authors: F. Malekpour, M. Hojjati
Language: English
Subfield: Automotive Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $4,190
OpenAlex ID: W7124904847