Flexural Behavior and Fracture Mechanisms of Short Carbon Fiber Reinforced Polyether-Ether-Ketone Composites at Various Ambient Temperatures

Abstract

In this study, the flexural behavior and fracture mechanisms of short carbon fiber reinforced polyether-ether-ketone (SCFR/PEEK) composites at various ambient temperatures were investigated. First, the crystallinity and glass transition temperature (Tg) of PEEK and SCFR/PEEK were analyzed by differential scanning calorimetry analysis and dynamic mechanical analysis tests, respectively. The addition of SCFs increases the Tg but does not change the crystallinity of the PEEK matrix. Then, the three-point flexural tests of PEEK and SCFR/PEEK were performed over the temperature range of 20 to 235 °C, and the temperature-dependencies of the flexural properties of PEEK and SCFR/PEEK were discussed in detail. Finally, the microstructure of SCFR/PEEK was observed using a digital microscope and scanning electron microscope. The results show that the tension crack occurs first, and the crack extends upward leading to the shear crack and compression crack at room temperature. The fracture of SCFR/PEEK is mainly due to the extraction and rupture of SCFs. At high temperatures (above Tg), the tension crack and compression crack both occur, and the strong ductility of the matrix prevents the generation of shear crack. The fracture of SCFR/PEEK is mainly due to the rotation and extraction of SCFs, while the SCFs rupture plays a minor role.

Formability and Failure Mechanisms of Woven CF/PEEK Composite Sheet in Solid-State Thermoforming

“…Figure 9 shows the SEM images of the fracture surfaces of woven CF/PEEK composites after flexural testing under different conditions. The microscopic failure of FRP composites is generally due to matrix fracture and fiber/matrix debonding [30,31]. As shown in Figure 9a, the fracture exhibits the weak ductile fracture of the matrix and a small amount of fiber/matrix debonding when the temperature is 165 °C, which indicates relatively weak toughness and strong interfacial force.…”

“…The increase in ambient temperature softens the PEEK matrix [7,32], increasing the ductility of matrix while attenuating the interaction of fiber/matrix [30,31]. When the temperature is in the range of 165–235 °C, the matrix exhibits weak toughness and stronger interaction of the fiber/matrix (see Figure 9a,b).…”

Surface Modification of Staple Carbon Fiber by Dopamine to Reinforce Natural Latex Composite

“…Physical and Mechanical Properties. The hardness of the rubber vulcanizate was evaluated using Shore Hardmeter (LX-A, Shanghai Liuling Instrument Factory, Shanghai, China) according to ISO 7619-2: 2004, three points were measured for each sample and the final result produced the median [6]. The tensile and tear properties of the vulcanized rubber were tested using a universal testing machine (TS 2005 b, GOTECH TESTING MACHINES CO., Ltd., Taichung, Taiwan) at a drawing rate of 500 mm/min according to the standards ISO 37: 2005 and ISO 34-1: 2004, respectively [20].…”

“…Carbon fiber (CF) is formed by the thermal conversion of organic fibers, and has a high strength, high modulus, high thermal conductivity, chemical corrosion resistance and other excellent properties [1,2]. At present, CF-reinforced rubber composites (CFRC) have been widely used in aerospace, military, national defense, automobile and other fields due to their excellent properties [3][4][5][6]. A good interface between the CF and the rubber matrix is significantly difficult to obtain, and this plays a crucial role in preparing high-performance CFRC.…”

Thermally stable and high impact toughness chopped PI fiber-reinforced PEEK composites

“…Therefore, PEEK has been widely used for aerospace applications, electronic technology, medical industry, machinery manufacturing, and the nuclear industry. 13 –18…”