## 3 Results
[56] observed that the water absorption of an epoxy resin is considerable higher when immersed into deionized water than salt water, but this difference increases much more for composites due to water diffusion and capillary diffusion along the fibre-matrix interface debonding. On the other hand, when the matrix is filled with cork powder, exposure to all hostile solutions promoted lower maximum impact loads than those observed for the same conditions but in laminates with pure resin. In fact, cork is impermeable to liquids and practically impermeable to gases, thanks to the suberin and cerin present in the composition of cork cells [23; 57; 58]. In this context, cork powder acts as an impermeable agent and the diffusion that occurs between the cork/matrix interface is slower due to the longer and tortuous path caused by the presence of cork particles. Figure 5 shows the effect of exposure to hostile solutions in relation to maximum displacement. Once again, each result was divided by the respective value obtained with the control specimens (no immersion in any solution). Contrary to what was observed in Figure 4, in this case, carbon laminates with neat resin are more sensitive to harsh environments regarding the maximum displacement obtained. This is because they were more degraded by the hostile solutions than those that incorporate cork. As expected by what was previously reported and justified by the open literature, in general, the maximum displacement increases when the samples are exposed to different environments and this tendency is to increase with the exposure time, which agrees with the studies published [24; 44; 45]. The average results and respective standard deviations are shown in Table 5. According to this table, and contrary to what was observed for the maximum impact load, the maximum displacement is higher for laminates with matrix filled with cork powder than for composites with neat resin. On the other hand, Table 6 shows that the highest increase was observed for laminates with neat resin. For example, the highest increase of the maximum displacement is observed for laminates immersed into seawater at 60 \({}^{\circ}\)C (30.3% for neat laminates and 3.4% for laminates with cork), followed by immersion into NaOH (27.3% for neat laminates and 14.8% for laminates with cork) and HCl (24.2% for neat laminates and 8.0% for laminates with cork). This agrees with the studies developed by [PERSON] et al. [24; 44], where the effect of the NaOH solution, compared to the HCl solution, promotes the highest maximum displacement. It is also noted that the hydrochloric acid promotes worse results compared to sulfuric acid. Similar to what was previously reported, the exposure time proved to be determinant in the degradation of mechanical properties, and, in this case, it promoted higher values of maximum displacement. This parameter is crucial to favour the penetration and reaction that occurs between solutions and composite constituents, especially in terms of matrix cracking and degradation of the fibre-matrix interface strength [26; 46; 47]. However, for laminates with matrix filled by cork powder, and when subjected to compression during \begin{table}
\begin{tabular}{c c c} \hline \hline
**Solutions** & **Matrix with Cork Powder (\%)** & **Neat Resin (\%)** \\ \hline Diesel & 9.1 & 18.2 \\ Sulphuric acid (H\({}_{2}\)SO\({}_{4}\)) & 4.5 & 21.2 \\ Hydrochloric acid (HCI) & 8.0 & 24.2 \\ Sodium hydroxide (NaOH) & 14.8 & 27.3 \\ Distilled water & 13.6 & 19.7 \\ Sea water at room temperature & 2.3 & 16.7 \\ Sea water at 60 \({}^{\circ}\)C & 3.4 & 30.3 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Difference in the maximum displacement obtained for 30 days of immersion into different harsh solutions compared to non-immersed specimens.