Yarn-Based Aligned Recycled Carbon Fiber/PA11 Composites: Yarn Development, Coupon Characterization, Initial Structural Demonstration, and Screening Life-Cycle Assessment

@article{brauner2026yarnbased,
  title = {{Yarn-Based Aligned Recycled Carbon Fiber/PA11 Composites: Yarn Development, Coupon Characterization, Initial Structural Demonstration, and Screening Life-Cycle Assessment}},
  author = {Christian Brauner and Delal Arslan and Julian Kupski and Florian Givel and Mohammad Hajikazemi and Miriam Preinfalck and Stephan Baz and Götz T. Gresser and Jascha Schmied and Sebastian Bühler and Christian Braun},
  journal = {Polymers},
  year = {2026},
  month = oct,
  doi = {10.3390/polym18212658},
  url = {https://www.mdpi.com/2073-4360/18/21/2658},
  note = {CC BY 4.0},
}

TY  - JOUR
TI  - Yarn-Based Aligned Recycled Carbon Fiber/PA11 Composites: Yarn Development, Coupon Characterization, Initial Structural Demonstration, and Screening Life-Cycle Assessment
AU  - Christian Brauner
AU  - Delal Arslan
AU  - Julian Kupski
AU  - Florian Givel
AU  - Mohammad Hajikazemi
AU  - Miriam Preinfalck
AU  - Stephan Baz
AU  - Götz T. Gresser
AU  - Jascha Schmied
AU  - Sebastian Bühler
AU  - Christian Braun
PY  - 2026
DA  - 2026/10/27
JO  - Polymers
DO  - 10.3390/polym18212658
UR  - https://www.mdpi.com/2073-4360/18/21/2658
AB  - Re-aligned recycled carbon fiber (rCF) yarns provide a complementary architecture to aligned rCF tapes, enabling load-path-oriented reinforcement placement with potential for automated near-net-shape preforming and three-dimensional formability. This study investigates hybrid rCF/polyamide 11 (PA11) wrap yarns produced through roller carding, hollow-spindle wrap spinning, tailored fiber placement (TFP), and consolidation. Two rCF/PA11 yarn formulations with nominal fiber/matrix mass ratios of 72/28 and 80/20 were developed, yielding fiber volume fractions of 54.4 and 58.5 vol.%, respectively. Mechanical characterization focused on UD coupon testing under axial tensile, transverse tensile, and shear loading. For the rCF/PA11 72/28 and 80/20 formulations, longitudinal tensile testing yielded moduli of 57.8 ± 4.2 and 64.3 ± 6.3 GPa and strengths of 920 ± 41 and 815 ± 86 MPa, respectively. The 72/28 material additionally exhibited an in-plane shear modulus of 1.87 ± 0.03 GPa and shear strength of 48.7 ± 1.4 MPa. Relative to the previously reported aligned rCF/PA11 tape laminates at a comparable fiber volume content, albeit with distinct processing machinery, the 72/28 yarn laminate showed higher longitudinal modulus and longitudinal strength but substantially lower transverse and shear properties, suggesting a possible architectural trade-off associated with discrete yarn lanes, helical wrapping, and TFP preforming. A conrod-shaped preliminary structural benchmark manufactured from rCF/PA11 72/28 sustained 11.3 ± 0.5 kN at a mass of 23.0 ± 1.0 g, corresponding to a 71% higher specific load capacity than the aluminum reference. Proof-of-concept thermoforming of three double-curved shell demonstrators confirmed the capability of the yarn-based preforms to form complex three-dimensional geometries, although local fiber alignment defects highlighted the need for improved draping control. A screening life-cycle assessment estimated 0.42 kg CO2-eq per rCF/PA11 benchmark part, representing reductions of approximately 63% relative to the virgin-CF/PA12 stretch-broken yarn route and 52% relative to virgin-CF/epoxy routes. The results demonstrate the potential of rCF/PA11 wrap yarns as high-fiber-content textile intermediates for load-path-oriented TFP preforming and subsequent three-dimensional thermoforming.
SN  - 2073-4360
ER  -