# Investigation of the Effect of Operational Factors on Conveyor Belt Mechanical Properties
## 4 Comparison of Results and Discussion
### Samples Exposed in the Thermal Shock Chamber
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Variable** & **Reference** & **KSZ A** & **KSZ B** & **KSZ C** & **KSZ D** \\ \hline Reference & 1.0000 & \(-0.8365\) & \(-0.9888\) & \(-0.5745\) & \(-0.8802\) \\ KSZ A & \(-0.8365\) & 1.0000 & 0.9089 & 0.0439 & 0.5942 \\ KSZ B & \(-0.9888\) & 0.9089 & 1.0000 & 0.4487 & 0.8329 \\ KSZ C & \(-0.5745\) & 0.0439 & 0.4487 & 1.0000 & 0.6383 \\ KSZ D & \(-0.8802\) & 0.5942 & 0.8329 & 0.6383 & 1.0000 \\ \hline \hline \end{tabular}
\end{table} 
Table 10: The correlation coefficient of tensile modulus obtained in various ageing variants under thermal shock conditions and in the reference condition (for significance coefficient \(p<0.05\)). \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Variable** & **Reference** & **KSZ A** & **KSZ B** & **KSZ C** & **KSZ D** \\ \hline Reference & 1.0000 & \(-0.4861\) & \(-0.7497\) & \(0.0655\) & \(-0.2703\) \\ KSZ A & \(-0.4861\) & 1.0000 & 0.6259 & 0.4191 & \(-0.5748\) \\ KSZ B & \(-0.7497\) & 0.6259 & 1.0000 & \(-0.3298\) & 0.0326 \\ KSZ C & \(0.0655\) & 0.4191 & \(-0.3298\) & 1.0000 & \(-0.7440\) \\ KSZ D & \(-0.2703\) & \(-0.5748\) & 0.0326 & \(-0.7440\) & 1.0000 \\ \hline \hline \end{tabular}
\end{table} 
Table 11: The correlation coefficient of tensile strength obtained in various ageing variants under thermal shock conditions and in the reference condition (for significance coefficient \(p<0.05\)). The following observations can be made based on the statistical results presented in Table 10:  
* in comparison to the correlation between the value of tensile modulus in the thermal shock conditions and the reference variant, the strongest correlation can be seen in the case of KSZ B; in this case, a strong negative correlation (the correlation coefficient is 0.9888) was observed for KSZ B and the reference variant. This means that an increase in the number of cycles (1200 cycle variant of thermal shock) leads to a decrease in the tensile modulus,
* in the majority of variants of ageing under the tested thermal shock conditions, the correlation or strong correlation between the value of the tensile modulus and the thermal shock conditions cannot be observed, although in some cases, some correlation (albeit not strong) can be seen; for example, this case is presented in the variant KSZ A and KSZ B (the correlation coefficient is 0.9089). The correlation or strong correlation between the value of the tensile strength and the thermal shock condition cannot be observed in the majority of ageing variants in the tested thermal shock conditions based on the correlation coefficient results of presented in Table 11.  
Temperature, humidity and thermal shock are some of the factors that degrade polymer materials. Degradation, as defined, is a process of structural change that can be the result of physical or chemical changes occurring in polymer materials under the influence of the long-term action of various external factors. It should be noted, however, that in some cases, in the first phase of degradation, the degradation agent improves specific properties of the material, especially mechanical strength. This is done by additional cross-linking of the material structure under the influence of, for example, heat. It is only during the further action of degradation factors that the properties deteriorate due to various processes, e.g., excessive cross-linking or molecular weight reduction.