PSI - Issue 13

Mark Kopietz et al. / Procedia Structural Integrity 13 (2018) 143–148 Kopietz et al. / Structural Integrity Procedia 00 (2018) 000 – 000

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5

of the 2P composites exhibited clearly strong adhesion of the polymer on the fibers with partially polymer -covered fibers (Fig. 3, right). Thus, qualitative SEM analysis confirmed the mechanical investigations regarding ILSS and fiber/matrix adhesion, respectively.

-5 -4 -3 -2 -1 0 1 2 3 4 5 Mass difference  m [%]

0 1 2 3 4 5 Mass difference  m [%]

Matrix

3P 2P-15ELO 2P-15ELO-1WE3110

Media

1N HCl 1N NaOH

-5 -4 -3 -2 -1

Matrix

3P 2P-15ELO 2P-15ELO-1WE3110

0 15 30 45 60 75

0 15 30 45 60 75

Time t [d]

Time t [d]

Fig. 2. Progress of mass difference Δ m of ILSS samples while stored in deionized water (H 2 O, left) and acid and alkaline solutions (HCl/NaOH, right), respectively, compared to non-stored samples (Air)

Fig. 3 . Scanning electron microscopy of composites’ morphologies of 3P (left) and 2P (right) GFRP, respectively, with magnification x5000

Conclusion

It was shown that composites made of reference 3P Resin® possess a lower ILSS and worse fiber/matrix adhesion than the innovative composites containing 2P resins. These investigations were further successfully confirmed by SEM analysis. The ILSS of 2P composites could be even further enhanced by a surfactant. It is important to mention that 2P composites undergo a post-curing process to reach the maximum ILSS. Due to media contact the ILSS of the composites was generally decreased over time. However, no general principle could be found how each media affects each matrix. Gravimetric tests showed that 3P composites inherently exhibit mass loss over time, independent from the storage media. They exhibit an unfavorable diffusion of chemically non-bonded organic phosphates into the media. In case of water storage, the 2P composites absorb only a small amount of water what is further improved due to the presence of the surfactant. Their storage in aggressive acid and alkaline solutions resulted in minor mass loss, which indicated slight degradation effects.