CF/PEEK

Figure 4.105. Neat CF PEEK examples of tensile strength retention (%) versus temperature (°C)...

Ishikawa, T., Sugimoto, S. Matsushima, M. and Hayashi, Y. (1995). Some experimental findings in compression-afler-impact (CAI) tests of CF/PEEK (APC-2) and conventional CF/Epoxy flat plates... 

CF/PEEK carbon fiber-reinforced polyetheretherketone PEVA pHEMA polyethylene-co-vinyl acetate poly(2-hydroxyethyl methacrylate)... 

Figure 13.5 WAXS trace of CF/PEEK. Source Reprinted with permission from Cogswell FN, Thermoplastic Aromatic Composites, Butterworth-Heinemann, Oxford, 1992. Copyright 1995, Taylor Francis...

Vybron Composites manufacture profiles by pultrusion/pulforming using CF/PPS for air compressor blades and guitar neck, CF/nylon with a braided exterior for orthopedic end uses and CF/PEEK for aerospace profiles. 

The hybrid effect in rheology means that the addition of macroscopic fibers and LCPs increase and decrease the melt viscosity of the whole material system, respectively. The apparent viscosity and torque for processing of CF/PES, CF/PEEK, and GE/PC reinforced plastics are high due to the existence of these macroscopic fibers in the melt. The addition of LCPs decreases the apparent viscosity and torque significantly, which favors the processing of in situ hybrid composites. The improvement of the processibility is very important for advanced engineering plastics, such as PES and PEEK. 

Gibson and coworkers [2] emphasized that the preheating section of their thermoplastic pultrusion process was of crucial importance to a successful operation. Besides the results achieved with CF/PEEK tapes, these authors presented a wide range of interlaminar shear strength (ILSS) data for pultrudates from glass fiber (GF)/polyamide 12 (PA12) tapes. 

Steinberg EL, Rath E, Shlaifer A, Chechik O, Maman E, Salai M. Carbon fiber reinforced PEEK Optima-A composite material biomechanical properties and wear/debris characteristics of CF-PEEK composites for orthopedic trauma implants. J Mech Behav Biomed Mater 2013 17 221-8. 

Naghipour P, Bartsch M, Voggenreiter H (2011) Simulation and experimental validation of mixed mode delamination in multidirectional CF/PEEK laminates imder fatigue loading. International Journal of Solids and Structures, 48,1070-1081. 

Fully consolidated fibers are used for winding of high performance components, for example bearing systems (Rg. 7.17) based on CF/PEEK. ... 

The fracture surfaces were investigated by scanning electron microscopy (SEM) to establish the mechanisms associated with toughness reduction [1315-1317]. The CF/PEEK fracture surfaces... 

Figure 3.484. Fracture energy plotted against crack tip displacement rate in CF/ PEEK and CF/Epoxy [1315-1317] (a) log-log scale for mode I (b) log-log scale for mode II.

A schematic illustration of the principal micromechanism of energy absorption in CF/Epoxy and CF/PEEK materials is shown in Figure 3.485. The succession of events that take place is the following 1) crack bringing by fibres of fibre bundles, resulting in 2) fibre fracture 3) formation of the fracture surface of the main crack 4) formation of the side cracks and 5) plastic deformation and/or microcracking of the matrix around the fibres. 

Figure 3.487. Slowly opened mode I crack (in situ) in CF/PEEK (dashed circle marks the approximate size of the damage zone around the crack tip [1317],...

Figure 3.488. Very slowly opened mode I crack in CF/PEEK, giving evidence for significant deformation around the main crack.

Figure 3.492 shows details of the damage mechanisms ahead of a mod II crack of CF/PEEK composite. Under the action of shear stress ahead of the crack tip, tensile cracks form in the matrix at 45°. In the regions within the damage zone where the stress intensity is highest, i.e. very close to the crack top, these cracks extend completely between fibre/matrix interface and open up. Finally, the material separation between the cracks leads to the full development of the hackled mode II fracture surface. The damage zone in CF/PEEK under low velocity/mode II conditions is extended over four to six fibre layers. 

Figure 3.493 displays the mode II crack top zone for CF/Epoxy composite. At very higher magnification it is observed that crack formation is similar to that observed in CF/PEEK composite. A significantly smaller damage zone is observed in the more brittle CF/... 

Figure 3.491. Higher magnifications of the damage zone ahead of a mode II crack in CF/PEEK fa) 0.25 mm ahead tbt 0.12 mm ahead (c) 0.06 mm ahead [1317].

Figure 3.495. Examples of fibre breakages on fracture surfaces, (a) CF/PEEK, mode I (unstable propagation region), and (b) CF/epoxy, mode II (unstable propagation region) [1317],...

Beehag, A. and Ye, L. (1996) Role cooling pressure on interlaminar fracture properties of commingled CF/PEEK composites. Composites Part A, 27A, 175-182. 

Diao, X., Ye, L, and Mai, Y.-W. (1997) Fatigue behavior of CF/PEEK composite laminates mode from commingled prepreg. Part I experimental studies. Composites Part A, 28A, 739 747. 

Ye, L. and Friedrich, K. (1997) Processing of CF/PEEK thermoplastic composites from flexible preforms. Adv. Compos. Mater., 6 (2), 83-97. 

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