Pang Zhiyi, Li Yi, Zhang Yiyi
Faculty of Intelligent Manufacturing, Nanning University, Nanning 530200, China.
School of Mechanical and Electrical Engineering, Liuzhou Vocational & Technical College, Liuzhou 545000, China.
Polymers (Basel). 2023 Feb 28;15(5):1217. doi: 10.3390/polym15051217.
The ethylene propylene diene monomer (EPDM) is utilized in high voltage direct current (HVDC) cable accessories due to its exceptional insulation properties. The microscopic reactions and space charge characteristics of EPDM under electric fields are studied using density functional theory. The results indicate that as the electric field intensity increases, the total energy decreases while the dipole moment and polarizability increase, leading to a decrease in the stability of EPDM. The molecular chain elongates under the stretching effect of the electric field and the stability of the geometric structure decreases, resulting in a decline in its mechanical and electrical properties. With increased electric field intensity, the energy gap of the front orbital decreases, and its conductivity improves. Additionally, the active site of the molecular chain reaction shifts, leading to different degrees of hole trap and electron trap energy level distribution in the area where the front track of the molecular chain is located, making EPDM more susceptible to trapping free electrons or injecting charge. When the electric field intensity reaches 0.0255 a.u., the EPDM molecular structure is destroyed, and its infrared spectrum undergoes significant changes. These findings provide a basis for future modification technology, and theoretical support for high voltage experiments.
三元乙丙橡胶（EPDM）因其卓越的绝缘性能而被用于高压直流（HVDC）电缆附件中。利用密度泛函理论研究了EPDM在电场作用下的微观反应和空间电荷特性。结果表明，随着电场强度的增加，总能量降低，而偶极矩和极化率增加，导致EPDM的稳定性下降。分子链在电场的拉伸作用下伸长，几何结构的稳定性降低，导致其机械性能和电气性能下降。随着电场强度的增加，前线轨道的能隙减小，其电导率提高。此外，分子链反应的活性位点发生移动，导致分子链前线轨道所在区域出现不同程度的空穴陷阱和电子陷阱能级分布，使EPDM更容易捕获自由电子或注入电荷。当电场强度达到0.0255 a.u.时，EPDM分子结构被破坏，其红外光谱发生显著变化。这些发现为未来的改性技术提供了依据，也为高压实验提供了理论支持。
