Nanocomposites de polycétone aliphatique renforcées au graphène : Vers une alternative durable aux polyamides

Abstract

Aliphatic polyketone (PK) is an emerging engineering polymer exhibiting competitive mechanical and barrier properties compared with conventional engineering polymers such as polyamide 66 (PA66), while offering a lower environmental footprint. However, its moderate thermal stability during compounding and the difficulty associated with its melt processing limit its use in technical applications. In this context, the incorporation of graphene nanoplatelets appears to be a promising strategy. Owing to their remarkable thermal, lubricating, and mechanical properties, these nanocarbon fillers can act as multifunctional additives capable of simultaneously improving the processability, thermal stability, and mechanical performance of neat PK and PK/glass fibers composites. The objective of this work is to evaluate the potential of graphene to enhance the processability as well as the thermal, mechanical, and thermomechanical properties of commercial PK and glass fiber (GF) reinforced PK composites. To this end, two grades of few-layer graphene (FLG), named FLG1 and FLG2 and differing in their specific surface area, were separately incorporated into the PK matrix through melt compounding to prepare PK/FLG nanocomposites. Subsequently, hybrid PK/FLG/GF composites were also developed to combine the reinforcing effects of both graphene and glass fibers. The thermal, mechanical, and thermomechanical properties of the prepared materials were investigated using thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), as well as tensile and flexural mechanical tests. The results show that the addition of graphene improves the processability of PK, particularly through a reduction in the mixing torque during melt mixing. Furthermore, an improvement in thermal stability at high temperatures was observed, suggesting a promising potential of graphene for enhancing the fire resistance performance of the composites. The crystallization behaviour study indicates that graphene acts as a nucleating agent, modifying the crystallization kinetics of PK while restricting the segmental mobility of macromolecular chains at the PK/graphene interface. This latter effect, confirmed by DMA analysis, is more pronounced for the highest surface area FLG2 grade, indicating a stronger interfacial interaction with the polymer matrix. From a mechanical standpoint, the nanocomposites exhibit a noticeable increase in stiffness and strength, especially under flexural deformation and in the presence of FLG2 grade. For instance, the incorporation of FLG2 leads to a progressive increase in Young’s modulus, reaching approximately 27% at 5 wt% FLG2 while the maximum increase in flexural modulus and strength were respectively 61% and 41%, at 1% FLG2. Finally, the simultaneous incorporation of low FLG contents in the range 0.5 to 1 wt% and 15 to 30 wt% GF leads to a synergistic effect, resulting in increased stiffness and strength, especially in the flexural mode, and attributed to better interaction at the interface PK/GF in the presence of FLG. It was seen that the incorporation of 0.5 to 1 wt% FLG2 could substitute at least 5 wt% GF in the hybrid composites while maintaining equivalent or better mechanical performance. These results demonstrate that graphene is an effective multifunctional additive for optimizing the performance of PK and its glass fibers reinforced composites while maintaining its potential as a sustainable engineering polymer.

Date	28 Aug 2026
Original language	French
Awarding Institution	École de technologie supérieure
Supervisor	Emna Helal (Supervisor)