Hysteresis in nitrogen adsorption isotherms on copper phthalocyanine pigments

The adsorption isotherms of nitrogen on copper phthalocyanine pigments often reveal hysteresis both at high and at low relative pressures. Two broad categories of hysteresis can be distinguished: in one category, the hysteresis loop broadens at relative pressures above 0.4, and in the other it broad...

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Bibliographic Details
Published in:Colloids and surfaces 1991-10, Vol.58 (4), p.401-407
Main Author: Mather, Robert R.
Format: Article
Language:English
Subjects:
Chemistry
Exact sciences and technology
General and physical chemistry
Solid-gas interface
Surface physical chemistry
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Summary:The adsorption isotherms of nitrogen on copper phthalocyanine pigments often reveal hysteresis both at high and at low relative pressures. Two broad categories of hysteresis can be distinguished: in one category, the hysteresis loop broadens at relative pressures above 0.4, and in the other it broadens towards lower pressures. An example is given of how the change from the first to the second category may occur when a copper phthalocyanine pigment is treated with an organic liquid. It is concluded that the first category of hysteresis is associated with pigment crystals aggregated into closely packed structures, whereas the second indicates more loosely packed aggregate structures.
ISSN:0166-6622
1873-4340
DOI:10.1016/0166-6622(91)80218-D