# Quality Analysis of Bonded Joints in the Renovation of Plastic Automotive Parts
## 3 Results
### Assessment of the Impact Strength of Bonded Joints
#### 3.3.2 Impact Strength Evaluation of Bonded Joints after Exposure to a 20% Salt Solution  
After exposure of the specimens to the saline solution, the bonded joints were impact stressed. The measured values of the impact strength of the bonded joints for the different types of adhesives are shown in Table 19 and graphically processed in Figure 14. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Adhesive Type** & **Bond Failure** \\ \hline MEGABOND 2000 & & \\ Adhesive thickness 0.1 mm & & \\ Bond failure: adhesive mixed & & \\ \hline CHS EPOXY 1200 & & \\ Adhesive thickness 0.1 mm & & \\ Bond failure: adhesive & & \\ \hline DINITROL 860 & & \\ Adhesive thickness 0.1 mm & & \\ Bond failure: adhesive & & \\ \hline DINITROL 860 & & \\ Adhesive thickness 0.1 mm & & \\ Bond failure: adhesive & & \\ \hline \hline \end{tabular}
\end{table} 
Table 19: Measured impact strength values for the specimens after exposure to a 20% salt solution. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Adhesive** & **Average Impact Strength** & **Average Impact Strength** \\
**Adhesive** & **[kg.cm\({}^{-1}\)]** & **[kg.cm\({}^{-1}\)]** \\  & **Curing Time** & **Salt Solution** \\ \hline Megabond 2000 & 32.16 & 3.2 \\ ChS EPOXY 1200 & 23.84 & 7.2 \\ DINITROL 860 & 15.68 & 6.7 \\ \hline \hline \end{tabular}
\end{table} 
Table 18: Fracture surface appearance after curing and SO\({}_{2}\) environment after impact test. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Adhesive Type** & **Bond Failure** \\ \hline MEGABOND 2000 & & \\ Adhesive thickness 0.1 mm & & \\ Bond failure: adhesive & & \\ ChS EPOXY 1200 & & \\ Adhesive thickness 0.1 mm & & \\ Bond failure: adhesive & & \\ \hline \hline \end{tabular}
\end{table} 
Table 20: Fracture surface appearance after exposure to a 20% salt solution. Figure 15: Impact strength comparison after exposure in atmospheric conditions for one year. A graphical comparison of the change in the impact strength of the joints after curing and after exposure under realistic atmospheric conditions for one year shows that only the MEGABOND 2000 type adhesive showed a decrease in impact strength, as it was a two-component adhesive (epoxy-acrylate). As it was a combination of atmospheric factors, some of them could have influenced the impact strength, such as diffusion of water into the adhesive layer, etc. ChS EPOXY 1200 and DINITROL 860 type adhesives are better able to withstand atmospheric conditions, as the impact strength of these two adhesives increased due to environmental influences. We suppose that curing of the adhesives has occurred. Table 22 shows the characteristic fracture surface appearances for different types of adhesives with 0.1 mm adhesive thickness. The appearance of the fracture surfaces was similar for all specimens bonded with the same type of adhesive of a given thickness. For the ChS EPOXY 1200 adhesive, an 80% adhesive and 20% cohesive failure could be observed. The other adhesive types showed adhesive failure. An overall assessment of the changes in impact strength after curing and after exposure to different environments for all three types of 0.1 mm thick adhesives is shown in Table 23, and their graphical representation is shown in Figure 16. \begin{table}
\begin{tabular}{l} \hline \hline
**Adhesive Type** & **Bond Failure** \\ \hline MEGABOND 2000 \\ Adhesive thickness 0.1 mm \\ Bond failure: adhesive mixed \\ \hline \hline \end{tabular}
\end{table} 
Table 22: Fracture surface appearance after exposure to atmospheric conditions for one year. The highest impact strength values were achieved by MEGABOND 2000 adhesive and the lowest by DINITROL 860 in curing time. Exposure of the joints to an environment with SO2 in the presence of total moisture condensation, as well as immersion in a 20% solution of industrial sprinkling salt, significantly reduced the impact strength values for all adhesives evaluated.