Correlation Between Thermal Parameters and Morphology of Cross-Linked Polyethylene

This paper reveals a correlation between morphology and thermal parameters on cross-linked polyethylene (XLPE) cable with different insulating states. Several cables were selected to detect the physicochemical and thermal parameters of the XLPE. The results show that the cable ampacity is determined by the thermal parameters, which are deeply subjected to the morphology of the XLPE. The molecular chain and crystal structure of the XLPE have a close connection with the thermal resistivity. The physicochemical parameters of carbonyl index (<italic>CI</italic>) and unsaturated band index (<italic>UBI</italic>) from Fourier transform infrared spectrum (FTIR) and melting range (<inline-formula> <tex-math notation="LaTeX">$R_{m}$ </tex-math></inline-formula>) from differential scanning calorimetry (DSC) can be the indicator to evaluate the diversity of the thermal resistivity. The change of thermal capacity is governed by the crystal distribution of the XLPE. The physicochemical parameters of crystallinity (<inline-formula> <tex-math notation="LaTeX">$\chi$ </tex-math></inline-formula>) and lamellar thickness (<inline-formula> <tex-math notation="LaTeX">$L$ </tex-math></inline-formula>) from DSC can be the indicator to evaluate the change of the thermal capacity. In addition, FWHM of the crystallization peak <inline-formula> <tex-math notation="LaTeX">$\Delta W$ </tex-math></inline-formula>, crystalline rate index (<inline-formula> <tex-math notation="LaTeX">$T_{0}$ </tex-math></inline-formula>-<inline-formula> <tex-math notation="LaTeX">$T_{\mathrm {P}}$ </tex-math></inline-formula>) and cross-linking degree (<inline-formula> <tex-math notation="LaTeX">$G$ </tex-math></inline-formula>) can also be the indicator of the thermal parameters. Finally, this paper proposes a more accurate on-line monitoring method for electric power industry by detecting thermal parameters to diagnose the operating cables in the practical application.