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Home  >  Journal list  >  Polymer Journal  >  Vol.22  No.10 (1990)  >  pp.875-882

Polymer Journal
<<Previous article Vol.22  No.10 (1990)   pp.875 - 882 Next article>>

Isothermal Imidization of an Aromatic Polyimide Precursor Studied by Fluorescence Spectroscopy

Masatoshi Hasegawa1), Hisae Arai2), Itaru Mita1) and Rikio Yokota3)
1) Research Center for Advanced Science and Technology, The University of Tokyo
2) Toho University
3) Institute of Space and Astronautical Science


ABSTRACT:  Isothermal imidization of an aromatic polyimide (PI) precursor, poly(amic acid) (PAA) derived from biphenyltetracarboxylic dianhydride (BPDA) and p-phenylene diamine (PDA) was studied in solution and the solid state using intermolecular charge-transfer (CT) fluorescence reflecting sensitively the degree of molecular aggregation of polyimides. Isothermal imidization was carried out in a hand-made furnace which makes possible to jump the temperatures of samples to the established reaction temperatures by inserting the samples into a slit in the temperature-controlled heating block. The degree of imidization (i) was determined by IR spectroscopy. When imidized at 110°C in solution (10 wt%), the fluorescence of the as-cast films reduced rapidly and became very weak at about 30% in conversion. In the solid state, as imidization proceeded, the fluorescence of the PAA reduced rapidly as well as in solution, and then the CT fluorescence of the PI increased. The relationship between the intensity and the conversion clearly shows that the fluorescence intensity at a same conversion depends strongly on the imidization temperature (Ti). For example, when imidized at 150°C the intensity increases only slightly as the reaction proceeds, while at higher Ti such as 230 or 270°C the intensity increases rapidly. This indicates that the degree of the molecular order in the PI formed on isothermal imidization depends strongly on Ti.


Keyword:
Polyimide/ Isothermal Imidization/ CT Fluorescence

Published online: April 06, 2005
© Copyright, 2005 by The Society of Polymer Science, Japan

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