# 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  
A comparison of the results obtained for the samples tested in the thermal shock chamber with the application of a varying number of cycles is shown in Figure 17.  
Figure 17: Strength parameters of samples exposed in the thermal shock chamber. \begin{table}
\begin{tabular}{l c c c c c c c} \hline \hline
**Variable** & **Reference** & **KKA-30-20** & **KKA-20-20** & **KKB-10-80** & **KKB-30-80** & **KKB-80-80** & **KKC-30-50** \\ \hline Reference & 1.0000 & 0.3303 & 0.3102 & 0.7420 & 0.1880 & \(-\)0.7522 & 0.5233 \\ KKA-30-20 & 0.3303 & 1.0000 & 0.6964 & 0.4763 & \(-\)0.2325 & \(-\)0.2274 & 0.0000 \\ KKA-20-20 & 0.3102 & 0.6964 & 1.0000 & 0.6423 & \(-\)0.2495 & \(-\)0.6713 & \(-\)0.1515 \\ KKB-10-80 & 0.7420 & 0.4763 & 0.6423 & 1.0000 & \(-\)0.4603 & \(-\)0.6924 & \(-\)0.1561 \\ KKB-30-80 & 0.1880 & \(-\)0.2325 & \(-\)0.2495 & \(-\)0.4603 & 1.0000 & \(-\)0.2115 & 0.9190 \\ KKB-80-80 & \(-\)0.7522 & \(-\)0.2274 & \(-\)0.6713 & \(-\)0.6924 & \(-\)0.2115 & 1.0000 & \(-\)0.3596 \\ KKC-30-50 & 0.5233 & 0.0000 & \(-\)0.1515 & \(-\)0.1561 & 0.9190 & \(-\)0.3596 & 1.0000 \\ \hline \hline \end{tabular}
\end{table} 
Table 9: The correlation coefficient of the tensile strength obtained under various ageing variants and in the reference condition (for significance coefficient \(p<0.05\)). The results (Figure 17) demonstrate that the tensile modulus is similar in the majority of the tested cases. Only when the samples were exposed to 1200 cycles, did this lead to the lowest value of E being achieved, amounting to 367 MPa, which is 90% of the highest tensile modulus obtained for variant IV (1800 cycles and 500 cycles). In other cases, the difference is about 3%. It can, therefore, be observed that the number of curing cycles does not affect the tensile modulus of the tested materials. Nonetheless, compared to the reference samples (i.e., those that were not exposed to varying temperature), the exposure to thermal shock led to a decrease in E by 8%, 14%, 8% and 5%, respectively. In other words, the test samples exposed to thermal shock had lower properties (tensile modulus) compared to the reference samples. Analyzing the results, it can also be observed that the tensile strength results do not differ much in terms of the number of curing cycles of the samples in the thermal shock chamber. The maximum tensile strength is 54 MPa, and the lowest is 51.7 MPa, which is a difference of over 4%. However, one can see that tensile strength tends to decrease with the increasing number of curing cycles of the samples in the thermal shock chamber, particularly when compared to the tensile strength of the reference samples. It was observed that the tensile strength of the reference samples was higher than that of the samples exposed to thermal shocks. Although the differences were not significant, the above-mentioned trend could be observed. Concerning the yield strength, a trend can be observed whereby the yield strength decreases with increasing numbers of cycles of the samples exposed in the thermal shock chamber. The difference between the highest and the lowest yield strength is 3.6 MPa, which amounts to almost 20% of the maximum value. The highest yield strength, 18.1 MPa, was obtained for the ageing of the samples in the climatic chamber for 600 cycles (\(-20\)\({}^{\circ}\)C/+\(60\)\({}^{\circ}\)C) (253-333 K), while the lowest was obtained for KSZ D (1800 + 500 cycles). Comparing these results with those of the reference samples, it can be observed that the yield strength of the samples exposed to a reduced number of cycles was lower, while the yield strength of the test samples is lower than that of the reference samples with increasing numbers of cycles. The correlation coefficient results of the tensile modulus for the samples subjected to ageing under different thermal shock conditions and for reference samples are presented in Table 10, and in Table 11 the results refer to the tensile strength.