Thermally conditioned aerospace‐grade carbon fiber reinforced polyether ketone ketone composites: Structure, impact response, and thermomechanical performance

Abstract

Carbon fiber‐reinforced high‐performance thermoplastic composites have recently become an efficient alternative for aerospace engineering applications. However, the temperature sensitivity of semi‐crystalline carbon fiber/polyether‐ketone‐ketone (CF/PEKK) polymers revealed the necessity of investigating their performance in service conditions. This study aims to evaluate the effect of extreme service conditions on thermomechanical performance and fracture characteristics of CF/PEKK composite laminates. For this, aerospace‐grade composite laminates were manufactured with the automated fiber placement process and were exposed to extreme service temperatures of −50°C (Conditioned I), 180°C (Conditioned II), and initially 180°C following −50°C (Conditioned III), simulating critical service temperature ranges in aerospace applications. According to impact tests, the energy absorbance of CF/PEKK composites decreased in all thermal conditioning scenarios by up to 25%. Additionally, Conditioned I samples represented relatively low glass transition temperature and degree of crystallinity compared to the control samples; however, Conditioned II and Conditioned III samples exhibited an opposite behavior. Dynamic mechanical analysis (DMA) investigations revealed a 13% reduction in the storage modulus for all thermal conditionings. While CF/PEKK composites represented ductile/brittle behavior at room temperature and high/low conditioning temperatures, their brittleness increased at −50°C, and the structure became ductile at 180°C. This study confirms that DMA is a powerful tool for determining the glass transition temperature for fiber‐reinforced composites with higher sensitivity and accuracy than DSC.

An experimental implication of long‐term hot‐wet‐aged carbon fiber/polyether ketone ketone composites: The impact of automated fiber placement process parameters and process‐induced defects

“…In general, the aging of aerospace-grade composites is affected by a variety of parameters, (i) moisture content and exposure time, (ii) temperature and environmental conditions (UV radiation, and harsh chemicals), (iii) material properties, and (iv) the manufacturing process (process parameters, process-induced defects). 5 With the increasing use of thermoplastic composites in primary structural parts of an aircraft, advanced manufacturing techniques have become necessary for producing large and complex geometry parts in a shorter period with low-cost, high accuracy, and production quality. 6,7 Advanced manufacturing technologies mainly include automated and robotic processes like automated tape laying and automated fiber placement (AFP).…”

Role of the inter‐ply microstructure in the consolidation quality of high‐performance thermoplastic composites

“…[1][2][3] Among other thermoplastics commonly used in the aerospace industry, glassy polyetherimide (PEI), and polyethersulfide (PES) or semi-crystalline polyphenilsulfide (PES), 4 polyaryletherketones (PAEK) are natural candidates for structural applications due to the wide temperature range at which they can be used, their (relative) ease of processability, high chemical, thermomechanical and oxidative resistance as well as good impact properties. 3,5,6 Polyetheretherketone (PEEK), whose structure consists in the repetition of two ether groups and one ketone has been the most studied and used PAEK so far. 3,7 The presence of ether groups leads to lower melting temperature (hence make them easier to process than other polymers of the same family, such as polyetherketone (PEK)).…”

“…High‐performance thermoplastic composites, that is, thermoplastics reinforced by a high volume fraction (~ 60 vol%) of continuous CF, gain interest over more well‐known thermoset‐based ones especially for aerospace applications because of their possibility to be welded or recycled 1–3 . Among other thermoplastics commonly used in the aerospace industry, glassy polyetherimide (PEI), and polyethersulfide (PES) or semi‐crystalline polyphenilsulfide (PES), 4 polyaryletherketones (PAEK) are natural candidates for structural applications due to the wide temperature range at which they can be used, their (relative) ease of processability, high chemical, thermomechanical and oxidative resistance as well as good impact properties 3,5,6 . Polyetheretherketone (PEEK), whose structure consists in the repetition of two ether groups and one ketone has been the most studied and used PAEK so far 3,7 .…”

Comparative analysis of thermoplastic and thermoset adhesives performance and the influence on failure analysis in jointed elium‐based composite structures

“…1 Therefore, designers and engineers prefer thermoplastics and a wide spectrum of industries are moving toward thermoplastic composites to make more robust, fuel-efficient, and lighter structures. [2][3][4][5][6] However, since they are available in pellet or film form, they must be melted at high temperatures for the injection molding process. Elium ® , an acrylic-based thermoplastic resin, is a liquid methyl methacrylate thermoplastic resin solution that can enable liquid molding and curing at room temperature.…”