1996 Fiscal Year Final Research Report Summary
Where are the surface charges vanishing? -the decay by two-dimensional observation-
| Project/Area Number |
07805003
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
表面界面物性
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| Research Institution | Nagoya Institute of Technology |
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Principal Investigator |
HORI Yasuro Faculty of Engineering, Nagoya Institute of Technology Associate Professor, 工学部, 助教授 (90024348)
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| Project Period (FY) |
1995 – 1996
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| Keywords | electrostatics / polymer surface / contact charging / charge distribution / decay mechanism |
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| Research Abstract |
An apparatus of measuring the two-dimensional distribution of surface charges has been constructed with a sample-holder on a rotary disk. All the system are controlled by an on-line computer. This system has employed a new type of electric induction electrometer which introduces a rather low input impedance (10 G OMEGA) to a MOS FET operational amplifier. This low input impedance avoids an electric charge-up on a probe by the bias current from the operational amplifier, and assures the repeating measurements with a short interval. The disk with the sample-holder is rotating at a speed of 1 round/sec. The probe electrode with 0.1 mm diameter is mounted within the 0.3 mm diameter aperture of the center of earthed guard electrode, and set at a distance of 0.3 mm from the surface of sample polymer on the disk. This probe can move along the radial direction. Within 1 min, the observation can be completed for the two-dimensional distribution of surface charges on the area of 1 cm^2 at a precision of 0.2 mm.
Using the above mentioned apparatus, the following three results were obtained for the surface charges on polymers.
(1) For the PMMA film, it has been observed that the surface charges spread along the surface of polymer. Conduction along the surface is the major mechanism for the decay of charges.
(2) The negative charges on PP film and on PE,are very stable and more than 70% of charges survive after 8h from charging. The charges are standing at the same position, and the discharge into air is the main mechanism of decay.
(3) A part of PP film surface was roughed with sandpaper. Contact charging with mercury on the roughed surface and on the smooth surface was simultaneously performed. It has been found that there is no surface charges on the roughed plane.
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