Effects of gamma-ray irradiation on dielectric surface breakdown of polybutylene polymers

Abstract

Polymer materials are required to be used in radiation environments of space and nuclear power stations as insulation materials. For the use of polymer materials in such regions, it must be confirmed whether the electrical performance under radiation environments is different from that without radiation. This paper describes the effects of gamma-ray irradiation on dielectric breakdown of polybutylene naphthalate and terephthalate by applying a dc pulse voltage. Both the polybutylene naphthalate and polybutylene terephthalate were irradiated in air up to 100 kGy and then up to 1000 kGy with dose rate of 10 kGy/h by using a 60 Co gamma-source. The total dose of gamma-ray irradiation effects on the time to dielectric breakdown and the discharge quantity of discharge current were discussed. Obtained results show that with increasing the total dose of gamma-ray irradiation, the time to dielectric breakdown increased with polybutylene naphthalate, but decreased with polybutylene terephalate. With increasing the total dose of gamma-ray irradiation, the discharge quantity decreased with polybutylene naphthalate, but increased with polybutylene terephalate. The experimental results suggest that the chemical structure plays a main role in the result of the radiation reaction, which is related to cross-linking and degradation reactions. Dielectric properties are improved by the irradiation for polybutylene polymers which contain more combined phenyls in the main chain.

Effects of low pressure on tracking failure of printed circuit boards

“…The temperature was measured using a thermocouple and controlled over the range from 23 to 150 o C by a temperature controller. A pulse generator was applied to provide unipolar pulses for simulating voltage surges [13], with pulse width of 1 ms and voltage amplitude of 30 kV. The interval of repetitive pulses was in the range of 3 ms to 100 ms.…”

“…The sampling time of A/D converter used in this experiment was 10 µs. A time integral method was adopted to obtain the cumulative charge passing in the discharge currents [13]. …”

Mechanical properties and temperature stability of modified polybutylene terephthalate by beta rays

“…Although many research papers are written about radiation cross-linking of numerous of polymers [9,10,11], not so many research papers are written about irradiation of polybutylene terephthalate. A small amount of research which is written about radiation cross-linking of polybutylene terephthalate is written [12,13] but it does not examine mechanical properties and thermal resistance. These research papers study dielectric constant, thermal degradation and flames retardant additives [12], the effect of gamma irradiation on dielectric surface breakdown of PBT under reduced pressure [13].…”

“…A small amount of research which is written about radiation cross-linking of polybutylene terephthalate is written [12,13] but it does not examine mechanical properties and thermal resistance. These research papers study dielectric constant, thermal degradation and flames retardant additives [12], the effect of gamma irradiation on dielectric surface breakdown of PBT under reduced pressure [13].…”

Effects of atmospheric pressure on tracking failure of gamma-ray irradiated polymer insulating materials

“…The selection of the proper polymer dielectric for a desired application depends on the requirements and operating conditions of the system [1]. Voltage surges are known to be one of the factors leading to tracking failure [2], which often appear in lighting, switching and circuit breaker operation. Tracking failure is a dielectric breakdown phenomenon occurring on polymer surfaces comprising carbonized conductive paths.…”