TP-1/S2-G sample, as shown in Fig. 36.20. Compared with the interfacial debonding in the S2 glass fiber-reinforced epoxy composite EP-1/6781S as shown in Fig. 36.17, less intensity, smaller debonding gaps and no matrix cracking were observed in S2-glass reinforced PEEK composite TP-1/S2-G. This was mainly attributed to the good HPHT hot-wet resistance and small water absorption and moisture diffusion rate of the semi-crystalline thermoplastic PEEK matrix [5]. However, in the case of TP-1/S2-G laminate system, even though the water diffusion through the PEEK matrix is slow, the water can also transport along the fiber/resin interface, and the rate of water penetration along the fiber can be much faster than through the resin phase [20]. This can cause further debonding of the glass-fiber/resin interface and the glass fiber surface corrosion. Additional studies were conducted with the chopped E-glass and carbon fiber (~0.8 mm in length) filled PEEK composite molding compounds, Victrex 450GL30 and 450CA30, respectively. These two thermoplastic molding compounds and their standard tensile test specimens were compounded and molded by the same manufacturer with the same grade of PEEK resin and the same process. In these short fiber-reinforced molding compounds, the fiber/resin interfacial bonding strength and its hot-wet resistant capability are more critical in control of the mechanical properties and hot-wet resistant capability of the composite materials than those in the continuous fiber-reinforced composite materials. These studies further confirmed very Fig. 36.20 Micrograph ( 800) of a cross-section surface of a TP-1/S2-G laminate sample in the asreceived condition Fig. 36.19 Micrograph ( 1000) of a cross-section surface of a TP-1/AS4 laminate sample after exposure in 3% NaCl brine at 177 C, 34.5 MPa for 240 h 306 Y. Yuan et al.
RkJQdWJsaXNoZXIy MTMzNzEzMQ==