Fabrication and Characterisation of Aligned Discontinuous Carbon Fibre Reinforced Thermoplastics as Feedstock Material for Fused Filament Fabrication

Abstract

In this work, aligned discontinuous fibre composite (ADFRC) tapes were developed and investigated as precursors for a novel 3D printing filament. ADFRCs have the potential to achieve mechanical performance comparable to continuous fibre reinforced composites, given sufficient fibre length and high level of alignment, and avoid many of the manufacturing difficulties associated with continuous fibres, e.g., wrinkling, bridging and corner radii constraints. Their potential use for fused filament fabrication (FFF) techniques was investigated here. An extensive down-selection process of thermoplastic matrices was performed, as matrix properties significantly impact both the processing and performance of the filament. This resulted in four candidate polymers (ABS, PLA, Nylon, PETG) which were used to manufacture ADFRC tapes with a Vf of 12.5% using the high performance discontinuous fibre (HiPerDiF) technology and an in-house developed continuous consolidation module. Tensile stiffness and strength up to 30 GPa and 400 MPa respectively were recorded, showing that a discontinuous fibre filament has the potential to compete with continuous fibre filaments.

Fused Deposition Modelling of Fibre Reinforced Polymer Composites: A Parametric Review

“…Among those materials, the most common thermoplastic used in FDM is PLA because of its low processing temperature, low shrinkage, and relatively high mechanical performance to cost ratio. Another "generic use" thermoplastic is ABS that has better thermal conductivity than PLA, but its high viscosity hinders the fusion of the printed raster and leads to porosity in the structure [43,70]. Different classes of polyamide (e.g., PA6, PA12, PA66, etc.…”

“…It can be implied that the optimum thermoplastic in term of manufacturability and mechanical performance is PLA which shows relatively high mechanical performance and high printability with good visual quality, although it has a low heat resistance leading to some issues in high-temperature applications and warping on the printing bed. Another full review of the possible thermoplastics used for highly aligned discontinuous fibre thermoplastic composite FDM technology can be found in Blok et al [70] study. This trade-off study considered several parameters, including process temperature, moulding temperature, cost, glass transition temperature, coefficient thermal expansion, thermal conductivity, shrinkage, printing ability, interfacial properties with carbon fibre, specific heat capacity, density, crystallinity, and strength.…”

“…(a) Six polymers for 3D printer benchmarks according to a study from 3D Matter [72]; (b) sensitivity study of different thermoplastics for producing highly aligned discontinuous fibre thermoplastic 3D printing filament. Reproduced from Blok et al [70], with permission from MDPI AG.…”

Natural Fibres as a Sustainable Reinforcement Constituent in Aligned Discontinuous Polymer Composites Produced by the HiPerDiF Method

“…The alignment of fibres in ADFRC can be examined by analysing fibre orientation using optical microscopy and ellipse fitting of the cross-sections of fibres in ADFRC [ 31 ]. However, because of the inherent characteristics of natural fibres, i.e., non-perfectly circular cross-section, their alignment in ADNFRC cannot be determined by using basic characterisation techniques.…”

“… ( a ) An example of the HiPerDiF (carbon fibre) preform sandwiched between two polymeric films before consolidation process ( b ) Prepregging process. Figures were taken from [ 31 ]. …”