Coating processes – Direct application of electrical – magnetic – wave – or... – Plasma
Patent
1992-12-23
1994-02-01
Pianalto, Bernard
Coating processes
Direct application of electrical, magnetic, wave, or...
Plasma
427569, 427222, 427296, B05D 306
Patent
active
052830861
ABSTRACT:
Surfaces of fine polystyrene (PS) and polymethyl methacrylate (PMMA) powders were modified by exposure to the downstream products of a nitrogen or oxygen microwave plasma. The effects of nitrogen and indium incorporation in the powder surface were studied with emphasis on variations in the triboelectric properties of the powder. X-ray photoelectron spectroscopy (XPS) was utilized to determine the changes in surface elemental composition. After nitrogen plasma treatment, the C 1s peak profiles suggested the formation of amines in the case of PS, and the formation of imines and amides in the case of PMMA. Oxygen plasma treatment suggested the formation of hydroxyl and carbonyl groups on the surfaces of both PS and PMMA. After treatment with a nitrogen or oxygen plasma, the charge-to-mass ratio (Q/M) of PS and PMMA powders in contact with carrier particles was measured using the cage blowoff method. The surface charge density (Q/A) was calculated from Q/M. The Q/A of nitrogen plasma-treated PS powder was seen to shift towards positive charge with small increases in the nitrogen concentration. The Q/A of oxygen plasma treated PS powder initially shifted toward negative charge, but changed towards positive charge with higher oxygen concentrations. Plasma-treated PMMA powder showed a different behaviour and the variation of Q/A on PMMA was much less than that of PS. Results suggest that triboelectrification of the polymer powder may be related to changes in the electrical surface states, and that nitrogen may act as a group V dopant within the PS surface.
Castle George S. P.
Foerch Renate
Kodama Jun
McIntyre N. Stewart
Armstrong R. Craig
Fujitsu Limited
I.C.S.T., The Institute For Chemical Science and Technology
Pianalto Bernard
The University of Western Ontario
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