Interphase engineering in carbon fiber/epoxy composites: Rate sensitivity of interfacial shear strength and interfacial fracture toughness

Abstract

Designing the interface in polymer composites is fundamentally a challenging task. Here, we demonstrate a strategy to engineer the interphase microstructure in carbon fiber/epoxy composites (CFRPs) using carbon nanotubes (CNTs). The incorporation of CNT modifies the interfacial mechanics and interfacial chemistry in conventional CFRPs by creating concentrated, dispersed and mixed type interphase. Therefore, a detailed study is warranted to establish the interfacial microstructure‐property relationship in CNT modified CFRPs. Experimental results show that the relative improvement in interfacial shear strength (IFSS) and interfacial fracture toughness (Gic) depends on the microstructure of interphase. It is shown that simultaneous improvement in IFSS and Gic is possible with certain types of microstructural designs. Moreover, it is observed that IFSS and Gic are not constant material parameters but both of them show a power‐law type dependence on the applied loading rate. The range of rate sensitivity parameters as a function of interphase type suggests that while concentrated and mixed interphase is more suited to maintain the interfacial integrity, dispersed interphase is beneficial for energy dissipating applications of CFRPs. In addition, IFSS and Gic exhibit negative rate sensitivity for certain cases. Finally, it is shown that interphase designing using CNT is an excellent tool to accurately tailor the average interfacial properties of CFRP in a broad range of 16‐79 MPa and 100‐453 J m−2 for IFSS and Gic, respectively.

Improving the interface of carbon‐fibre‐reinforced poly(ether‐ether‐ketone) composites with fibre surface coating: a review

“…PEEK has high viscosity and poor wettability with CF. Based on the principle of ‘similar compatibility’, the CF/PEEK composite interface can be modified by coating the fibre surface with a sizing agent 24 . The compatibility between CF and resin and the interface chemical bonding between CF and resin can be increased, thereby improving the interface performance of the composites 25–27 …”

A review of recent progress in improving the fracture toughness of epoxy‐based composites using carbonaceous nanofillers

“…Therefore, the challenge to toughen EPs has been the subject of extensive research for years. [ 15–21 ] Generally speaking, the main strategy used to enhance the fracture resistance of EPs is to add a second phase, which precipitates during the curing process and makes a multi‐phase morphology able to initiate various toughening mechanisms during the growth of cracks. [ 22 ]…”

Effects of incorporating ZnO nanowires on the moisture absorption and mechanical properties of composites

“…To be effective, these materials were usually deposited onto the fabrics through techniques like electrophoretic deposition, spray coating, chemical vapor deposition (CVD). [23][24][25][26][27] For example, hybrid fabric composites with CNTs deposited through CVD process showed 69% improvement in interlaminar shear strength (ILSS). [23] Godara et al used CNT/sizing together to improve the ILSS by 90% in glass/epoxy composites.…”