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IX CONGRESO NACIONAL DEL COLOR. ALICANTE 2010
The three applied TC inks have similar round-shaped pigments (Figure 5). They lose their
colour during heating and regain it during cooling. The discolouration occurs at smaller
temperatures that the colouration (Fig. 6). It shows that the colour of a TC sample does not
depend only on temperature, but also on thermal history. The system has memory – the output is
not possible to be predicted without the path that it followed before the current state. This
phenomenon is called hysteresis. The activation temperature (TA), specified by producer, do not
mean a special point of the TC colour change. The degree of reversibility of TC colour change
depends on the highest temperature applied at heating. The effect was evaluated by total colour
difference between the same sample at starting heating and after finishing cooling at the same
temperature.
Figure 5. Photomicrograph of the black TC sample
in the dark field.
CONCLUSIONS
L*
90
80
70
60
50
40
red
blue
black
T A
15 20 25 30 35
Temperature ( 0 C)
Advanced application of chromogenic materials is feasible after careful colorimetric
characterization. The two electrochromic and thermochromic examples were shown here.
ACKNOWLEDGEMENTS
I express my sincere thanks to dr. Urša Opara Krašovec, Mojca Friškovec, Rahela Kulčar
and Nina Hauptman for working together in this research.
REFERENCES
Figure 6. Temperature dependence of the
CIELAB L* values of the three TC samples at
heating (solid signs) and cooling (open signs).
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by a switchable window”, J. Opt. Soc. Am. A, 22, 3, 416-423 (2005).
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modulated by an electrochromic switchable device”, Color Res. Appl. 34, 4,321-329 (2009).
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Limited; 2008).
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[6] Commision Internationale de l’Eclaraige (CIE), Colorimetry, Publication CIE 15:2004 (CIE: Vienna, 2004).
[7] Commision Internationale de l’Eclaraige (CIE), Method of measuring and specifying color rendering properties
of light sources, Publication CIE 13.3:1995 (CIE: Vienna, 1995)
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