2001 Fiscal Year Final Research Report Summary
Evaluation of charging characteristics of polymeric powders by thermally stimulated current spectroscopy
| Project/Area Number |
11650058
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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 |
Applied physics, general
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| Research Institution | Keio University |
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Principal Investigator |
IKEZAKI Kazuo Keio University, Science and Technology, Applied Physics and Physico-Informatics, professor, 理工学部・物理情報工学科, 教授 (50051462)
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| Project Period (FY) |
1999 – 2001
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| Keywords | thermally stimulated current / charging characteristics / polymer / powder / toner / electrostatic powder coating / thermosetting / charge control additive |
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| Research Abstract |
We proposed a method for correcting the open-TSC error induced by thermal change in thickness of sample powder layers during TSC measurement. For application of this proposed method to polymeric powders we developed an equipment for measuring the thickness change of sample powder compactions. Two kinds of sample container were also developed in response to the characteristics of sample powders. The proposed correcting-method of TSC of powder-formed polymers was applied to the following 3 systems, using a newly developed sample molding technique and above-mentioned containers of powder samples:
(1) From the results of TSC spectra of powder paints stored at high temperatures, it was confirmed that lowering in charge stability of these powder paints appeared before blocking generation of the powders. It was also shown that progress in cure reaction of powder paints could be evaluated by TSC method.
(2) Electrical characteristics and crystalline structure of a quaternary ammonium salt charge
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control additive were examined. As a result, irreversible transition of the crystalline structure and remarkable increase in the electrical conductivity of the additive was observed when it was heat-treated at temperatures higher than 162 ℃. TSC spectra of a pseudo-toner containing this charge control additive showed that the additive was more effective to contact and triboelectrification than corona electrification. Triboelectrification between toner and carrier was also studied using a newly developed carrier dropping method" which can be used under two different conditions: electrically isolated and unisolated conditions. It was also found that the proposed method was useful for examining the mechanism of functional recovery in charging sites of carriers.
(3) TSC spectra of cryogenically pulverized polypropylene powders have one broad TSC band peaked around 110℃ in a temperature range above room temperature, unlike the case of film samples of polypropylene This broad TSC band was assigned to a band relating with crystalline defects introduced during pulverization. An irreversible crystalline structural change (α_1 to α_2) was also observed for polypropylene powders heat-treated above 150℃. Less
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