Bond strength and bond mechanism of injection over‐molded woven carbon fiber/PEEK‐short carbon fiber/PEEK composite components

Abstract

A weak interface is formed between injected plastic and substrate during the injection over‐molding process. This study investigated the effects of mold temperature and melt temperature on the bond strength of injection over‐molded components, which were produced by injecting short carbon fiber reinforced polyether‐ether‐ketone (SCF/PEEK) onto the surface of woven carbon fiber reinforced PEEK (WCF/PEEK) laminate substrate. The results show that the interfacial laminar shear strength (ILSS) increases significantly from 15.8 to 50.0 MPa as the mold temperature raises from 190 to 260°C. The ILSS increases first and then decreases with melt temperature raises from 380 to 420°C, achieving a maximum value of 44.4 MPa at 410°C melt temperature. Crystallinity analysis and microscopic observations indicate different bonding modes are formed at the interface. The matrix tangling appears in the matrix enrichment area, interlocking, and tangling appear in the pits and weak tangling and cracks occur on the fiber surface. The mold temperature affects the ILSS by changing the crystallization property and the connection mode in the interface, while the melt temperature affects the ILSS by changing the area of the matrix entanglement. The relationship between the process conditions—interfacial microstructure—interfacial mechanical performance was discussed.

Study on the Overmolding Process of Carbon-Fiber-Reinforced Poly (Aryl Ether Ketone) (PAEK)/Poly (Ether Ether Ketone) (PEEK) Thermoplastic Composites

“…Higher mold temperature increased the interface temperature between PEEK resin and PAEK and increased the blending time before curing, which was beneficial to the fusing process of the resin. When the interface temperature is higher than the melting temperature of PAEK, the resin eutectic layer is formed at the interface [ 30 ], which improves the interfacial bonding strength.…”

Fabrication of continuous carbon fiber reinforced polypropylene composites by injection compression molding with self‐resistance electric heating

“…[15][16][17] For overmolded thermoplastic composites, although hybrid components with comprehensive mechanical properties can be obtained via injection, there are disadvantages of lower interface strength and more process steps. [18][19][20] With regard to this phenomenon, some scholars tried to fabricate continuous fiber reinforced thermoplastics by injection molding process. Solorza-Nicolas et al [21] proposed to obtain woven glass fiber reinforced polycarbonate composites by injection compression molding technique, simulated the behavior of the polymer during the filling process, and studied the fiber orientation distortion with different laying modes.…”

“…[ 15–17 ] For overmolded thermoplastic composites, although hybrid components with comprehensive mechanical properties can be obtained via injection, there are disadvantages of lower interface strength and more process steps. [ 18–20 ]…”