Carbon-implanted ultra-high molecular-weight polyethylene studied by a pulsed slow-positron beam

Djourelov, N.; He, Chunqing; Suzuki, Takenori; Ito, Yasuo; Velitchkova, K.; Hamada, E.; Kondo, Kenjiro

doi:10.1016/s0168-583x(03)01750-6

Cited by 5 publications

(1 citation statement)

References 26 publications

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“…For the virgin silicone rubber, shown in Figure , the

S

value is low at the surface, and then grows to a maximum as

E_{+}

increases to 1.4 keV. The low

S

parameter for low positron energy (near sample surface) of silicone rubber is ascribed to the low fraction of Ps formation and annihilating in the subsurface of the sample, caused by the backscattering and back diffusion of low‐energy positrons . As the incident energy continually increases, ranging from 1.4 keV to 12 keV, the

S

parameter has an obvious decrease.…”

Section: Resultsmentioning

confidence: 93%

Investigation of the surface microstructure evolution of silicone rubber during corona discharge via slow positron beam and electrochemical impedance spectroscopy

Wang

Zhou

et al. 2019

Plasma Processes & Polymers

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Silicone rubber is the outer dielectric material of the composite insulator used in high‐voltage transmission lines. A study of the microstructure evolution during corona discharge could provide a new understanding of catastrophic fracture in composite insulators. In this paper, the corona degradation process of silicone rubber is divided into three stages based on the data obtained by slow positron beam and electrochemical impedance spectroscopy. In stage I, the S parameter decreases slightly in the low‐energy range, suggesting a crosslinking process in the polymeric “skin,” and the silicone rubber holds its high value of resistance, Rpore. In stage II, the organic sample surface is gradually transformed into an inorganic one. Further cracking of the surface layer contributes to a dramatic increase in the sample porosity. At the beginning of water immersion, the Bode phase angle remains approximately goodbreakinfix−50∘ at low frequency, and a diffusion‐dependent Warburg impedance is observed. In stage III, a massive number of polar groups and inorganic particles are generated and the sample fails to repel water. The increase in the sample porosity is the main factor that leads to an ingress of water and failure of the material, while the generated polar groups are the secondary factor.

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“…For the virgin silicone rubber, shown in Figure , the