Enhancing the Interlaminar Fracture Toughness and AO Resistance of CFRPs by Using Phosphorus-Containing Polymer/PEC-K Bifunctional Film

Abstract

A new attempt to use a bifunctional interleaf for developing a novel structure–function-integrated composite with simultaneously improved interlaminar fracture toughness and atomic oxygen resistance was studied. The toughening mechanism and the atomic oxygen erosion property of the delaminated surfaces of the composites were examined. The bifunctional interleaf was prepared by blending a phosphorus-containing polymer and a thermoplastic polymer. After being interleaved, the mode I and mode II fracture toughness increased by 8.2% and 23.7% compared to the control sample, respectively. The toughness gains are much smaller than that of the only thermoplastic film-toughened composite because of the relative brittleness of the blend film. The atomic oxygen erosion rates of the mode I and mode II delamination surfaces decreased by 45.3% and 31.3% compared with the control, respectively. The carbon fibers on the irradiation surfaces are protected by a layer of phosphine oxide to prevent further erosion, and they were much less eroded, particularly for the mode I surface. In comparison, the erosion rates of the mode I and mode II surfaces of the toughened-only composite significantly increased by 83.6% and 107.2%, respectively, and the carbon fibers are seriously eroded.

Aging Effects on the Mechanical Performance of Carbon Fiber-Reinforced Composites

“…After interleaving Mode-I and Mode-II fractures, toughness improved by 8.2% and 23.7% compared to unmodified composite, respectively. Similarly, atomic oxygen erosion rates of Mode-I and II delamination surfaces decreased by 45.3% and 31.3% in comparison with unmodified composite, respectively [82].…”

“…Moreover, a 3-point bending test also exposed that the crack density in the aged composite is higher than in unaged composites [53]. It is assisted by degradation in the interlaminar region and hence proceeds towards delamination [82].…”

“…The polymer composite undergoes irreversible changes when exposed to UV rays [88,89]. In another case of filler addition, organophosphorous is blended with thermoplastic polymer to protect the composite from UV rays [82]. For UV protection, 5 wt% nanosilica and 15 wt% microsilica in a carbon-reinforced epoxy composite showed barrier properties.…”