Postprocessing method-induced mechanical properties of carbon fiber-reinforced thermoplastic composites

Abstract

Promising carbon fiber-reinforced thermoplastic (CF/polyetherketoneketone (PEKK)) composites were fabricated by the state-of-the-art technology known as “Automated Fiber Placement.” The mechanical properties of CF/PEKK were evaluated for four different postprocessing methods: in situ consolidation, annealing, vacuum bag only (VBO), and hot press (HP). The evaluation was performed by narrowing down the relevant processing parameters (temperature and layup speed). Furthermore, the void content and crystallinity of CF/PEKK were measured to determine the effect of these postprocessing processes. The HP process resulted in the best quality with the highest interlaminar shear strength, highest crystallinity degree, and lowest void content. The second most effective method was VBO, and annealing also realized an improvement compared with in situ consolidation. The correlation between the postprocessing method and the void content and crystallinity degree was also discussed.

A rational study on the hydrothermal aging of AFP manufactured CF/polyetherketoneketone composites with in situ consolidation supported by acoustic emission inspection

“…16 The void contents of CF/PEKK composites manufactured via in situ consolidation and secondary hot press methods were reported to be 6% and 0.30%-0.43%, respectively. 1 Although in this study, a lower compaction force (300 N) is employed in comparison to the typically applied compaction forces (1000 N) for the in situ consolidation, CF/PEKK composite laminates with relatively lower void volume content (average 5%) have been manufactured successfully.…”

“…Carbon fiber reinforced high-performance thermoplastic composites can be regarded as a very competitive alternative to their thermoset based counterparts due to their following important attributes; high toughness, damage tolerance, unlimited storage life without any need for cold storage, recyclability, high chemical/solvent resistance, and relatively easier processability as they do not entail complex chemical reaction or curing process. [1][2][3][4] Moreover, thermoplastics can readily lend themselves to automated manufacturing processes such as AFP. In the thermoplastic AFP lay-up process, thermoplastic impregnated tows (towpreg)/slit tapes are laid upon a substrate while being locally heated to its melting temperature and concurrently consolidated with the aid of a compaction roller.…”

“…Nevertheless, these secondary processes increase the processing time and cost and disturb the automation of manufacturing, and therefore, need to be eliminated by employing an in situ consolidation with AFP lay-up only on the condition that successful consolidation is achievable. 5 Albeit the practicality of the in situ consolidation process, it can give rise to an unacceptable level of void contents and poor interlayer bonding quality for the aerospace composites, 1 knowing that these voids can facilitate damage formation and propagation and, in turn, decrease the mechanical performance of the composite part, especially under harsh service conditions.…”

Consolidation of continuous-carbon-fiber-reinforced PAEK composites: a review

“…On-going research aims at developing ATP both for lay-up and "insitu" consolidation, which would actually be the most interesting solution in terms of productivity [15,18,58,59]. However, the current technological state-of-the-art does not produce yet composites with the same consolidation quality as those obtained by press or autoclave [60]. Adapted from [37].…”

Effect of processing parameters on properties of printed and consolidated thermoplastic composites

“…These publications give a good overview of the emergence of new techniques and the development of 3D printing applied to composite materials. Hoang 11 presented a process for manufacturing continuous carbon fibre and PEKK panel. This process consists of a preforming step with an Automated Fibre Placement (AFP).…”