High strength glass fiber / PEEK prepreg using slurry processing for structural application

The glass fiber / polyether ether ketone (GF / PEEK) prepregs were successfully prepared using both conventional hot melt (G-PEEK-M) and proposed slurry processing (G-PEEK-S) methods. The mechanical responses of the GF / PEEK prepreg were significantly improved compared to pure PEEK. The tensile strength and modulus of G-PEEK-S has increased by 71% and 83%, respectively, as compared to pure PEEK. Cross-sectional (edge view) scanning electron microscope (SEM) images clearly show that the PEEK polymer has impregnated the woven glass fibers, forming a strong interpenetrating network structure in the G-PEEK-S prepreg, which is categorically absent in G-PEEK-M. UV-vis and FTIR spectroscopy were employed to estimate the chemical interaction between glass fiber and PEEK polymer, and the XRD measurements was used to analysed the microstructural changes after the incorporation of the glass fiber in polymer matrix. The glass transition temperature (Tg), measured using dynamic mechanical analysis (DMA) by assessing the material’s response to an oscillatory force across a range of temperatures, has increased to 157 °C in G-PEEK-S, significantly higher than the Tg of pure PEEK (135 °C). The storage (Gʹ) and loss modulus (Gʺ) of the G-PEEK-S prepregs are 2020 MPa and 57.5 MPa, respectively, showing a 137% rise in Gʹ and a ⁓218% increase in Gʺ as compared to pure PEEK (Gʹ = 854 MPa, Gʺ = 18.1 MPa) at the same temperature (30 °C). Rheological analysis involves in the measurements of flow and deformation characteristics of materials under various conditions, such as different shear rates, temperatures, times and frequencies. The viscosities of PEEK, G-PEEK-M, and G-PEEK-S are found to be 5.1 × 10³, 19.6 × 10³, and 30.4 × 10³ Pa.s, respectively, showing no significant change in viscosity for GF/PEEK prepregs over time, while a gradual reduction was observed in pure PEEK.