| Budget Amount *help |
¥11,960,000 (Direct Cost: ¥9,200,000、Indirect Cost: ¥2,760,000)
Fiscal Year 2009: ¥2,210,000 (Direct Cost: ¥1,700,000、Indirect Cost: ¥510,000)
Fiscal Year 2008: ¥4,030,000 (Direct Cost: ¥3,100,000、Indirect Cost: ¥930,000)
Fiscal Year 2007: ¥5,720,000 (Direct Cost: ¥4,400,000、Indirect Cost: ¥1,320,000)
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| Research Abstract |
To understand basic electric properties of nano-sized magnesium oxide (MgO)/low-density polyethylene (LDPE) nanocomposite under voltage application, various properties were investigated. The main results are summarized below.
(1) Compared to that of the LDPE sample, the sample containing a MgO nanofiller (hereafter, called a nanocomposite) had a higher DC breakdown strength. The positive charge in nanocomposite increased as the average field increased up to 250kV/mm, and then decreased with the average field until the breakdown. The conduction current in the nanocomposite sample increased rapidly at the field bringing the decrease of the space charge. The local heating in nanocomposite sample was obverted just prior to the breakdown while their in the LDPE sample did not. From these results, The increase in the DC breakdown strength by the addition of a MgO nanofiller is probably due to the suppression effect of the conduction current determined by the space charge rather than the suppression effect of an electronic avalanche.
(2) The nanocomposite sample under an AC voltage also exhibited the excellent properties such as water tree retardation and electrical treeing retardation compeered to that of the LDPE sample as well as those under a DC voltage.
(3) A new method for assessing the diffusion coefficient using the conduction current was proposed. This method could bring the assessing the diffusion coefficient more easily and practically. This method also would lead to the estimation of the filler dispersion in the composite insulating materials.
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