• The Journal of Advanced Prosthodontics
• /
• v.5 no.2
• /
• pp.75-83
• /
• 2013

PURPOSE. Maxillofacial silicone elastomer is usually colored intrinsically with color pigments to match skin colors. The purpose of this study was to investigate the color stability of a maxillofacial silicone elastomer, colored with a thermochromic, color changing pigment. MATERIALS AND METHODS. Disc-shaped maxillofacial silicone specimens were prepared and divided into 3 groups: a conventionally colored control group, one group additionally colored with 0.2 wt% thermochromic pigment, and one group with 0.6 wt% thermochromic pigment. Half of the surface of each specimen was covered with an aluminium foil. All of the specimens were exposed to UV radiation in 6 hour cycles over 46 days. In between the UV exposures, half of the specimens were stored in darkness, at room temperature, and the other half was stored in an incubator, at a humidity of 97% and a temperature of $+37^{\circ}C$. Color measurements were made with a spectrophotometer and registered according to the CIELAB $L^*a^*b^*$ color model system. The changes in $L^*$, $a^*$ and $b^*$ values during artificial aging were statistically analyzed by using paired samples t-test and repeated measures ANOVA. P-values <.05 were considered as statistically significant. RESULTS. The UV exposure resulted in visually noticeable and statistically significant color changes in the $L^*$, $a^*$ and $b^*$ values in both of the test groups containing thermochromic pigment. Storage in the incubator lead to statistically significant color changes in the $a^*$ and $b^*$ values of the specimens containing thermochromic pigment, compared to those stored at room temperature. CONCLUSION. The specimens containing thermochromic pigment were very sensitive to UV radiation, and the thermochromic pigment is not suitable, as such, to be used in maxillofacial prostheses.

• Journal of the Optical Society of Korea
• /
• v.17 no.2
• /
• pp.168-171
• /
• 2013

A reflective flexible display was fabricated by placing a thermochromic pigment on a polyethylene naphthalate (PEN) substrate coated with an indium tin oxide (ITO) film, and its thermo-optical characteristics were investigated. The reflective thermochromic display showed good image quality with a reflectance of approximately 65%. As a flexible display, the display showed reliability without damage to the image even after the display was bent strongly. The reflective display cell exhibits continuously the gray level according to the temperature controlled by applied voltage. This low cost display is expected be used in outdoor poster applications where information needs to be presented clearly.

• Journal of the Optical Society of Korea
• /
• v.17 no.5
• /
• pp.428-432
• /
• 2013

This research presents a flexible reflective thermochromic display (TCD) comprised of thermochromic pigments and a patterned indium tin oxide (ITO) film coated on a polyethylene naphthalate (PEN) substrate, and the display's thermo-optical characteristics. The display showed maximum red, green, and blue reflectances of 30%, 38%, and 29%, respectively. Furthermore, the display exhibited a continuous grey color when the temperature was changed continuously. As a flexible display, the display showed reliable thermo-optical performance without image damage even when highly bent. We expect the proposed TCD will be used in outdoor information display applications where low cost is a key factor.

• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.43 no.5
• /
• pp.11-16
• /
• 2011

This study was aimed to apply thermochromic and photochromic pigments to coating color and to develop a speciality functional coated layer. Two special pigments were added to a conventional coating color. The effects of the special pigments on coating color properties such as water rerention, low-shear viscosity were evaluated. Also the color changes of coated paper was observed under various circumstances. The results showed that the special pigments didn't influence the coating color properties. The coated paper with the special pigments showed four different colors, under various circumstances, implying that thermochromic and photochromic pigments can be used to produce a security paper.

• Textile Coloration and Finishing
• /
• v.30 no.1
• /
• pp.1-8
• /
• 2018

In the present study, three morpholine substituted crystal violet lactone (CVL) have been synthesized to monitor the thermochromic property. This work is explaining the role of substituent on the lactone ring. The methyl substituents induced greater chromic effects than the chloro substituents. Furthermore, the three-component mixtures that contained CVL, bisphenol-A, and methyl stearate were used to analyse the thermochromic effect of the CVLs as bulk samples with various temperature. The thermochromic properties of the CVLs were evaluated using solid-state UV-Vis and FT-IR spectroscopic techniques. Finally, one of the synthesized CVL has been successfully converted into the form of a test paper similar to pH paper for use as thermal indicators.

• Journal of the Korean Ceramic Society
• /
• v.35 no.1
• /
• pp.11-16
• /
• 1998

$VO_2$ thin films have been prepared on borosilicate glass substrate using alkoxide method to characterize the effects of fabricating factors on thermochromic performance. The gel films formed by spin coating were converted to $V_2O_5$ phase during oxidizing heat-tratment and the $VO_2$ phase were formed by reducing heat-treatement. The thermochromic switching properties of $VO_2$ thin films are strongly affected by the crystal phase and microstructure and those could be controlled by reducing heat-treatment conditions. The ther-mochromic switching characteristics of $VO_2$ thin films synthesized were measured at IR (2.5$\mu\textrm{m}$) as the transition temperature of $63^{\circ}C$ the transition width of $3.6^{\circ}C$and the maximum and minimum transmittance of 84% and 14% respectively.

• Journal of the Korea Convergence Society
• /
• v.12 no.11
• /
• pp.291-299
• /
• 2021

Recently, due to environmental problems caused by densification and high rise of urban areas, interests in air flow is increasing and appropriate shape and layout design of buildings is required. Therefore, in this study, we intend to propose an experimental method that can observe the air flow around a building using thermochromic pigment. Thermochromic pigments have limitations in observing precise temperature changes due to the characteristic that the color changes only with respect to a specific temperature, but they have the advantages of easy configuration of experimental equipment and short time required for experiments. In this study, the air flow tendencies around a building was examined by performing CFD analysis for a simple model and then compared with the thermochromic experiment results in order to review the usefulness of the proposed experimental method. As a result of the experiment, it was possible to observe the formation of separated flow and vortex region generated by buildings using the charateristics of thermochromic pigment and it was confirmed that the proposed method can be useful for buildings design and urban city planning.

• Fire Science and Engineering
• /
• v.22 no.5
• /
• pp.61-66
• /
• 2008

In this research, gel compounds containing thermochromic ingredients were manufactured and evaluated to prevent the transition hazards of fire and explosion, which they are one of the methods for detecting abnormal conditions caused by overheating of special materials early. And also, compounds of viscoelastic and brushing types were manufactured as the kind and content of raw materials, and manufacturing process to enlarge the application for overheat-detecting targets. Test methods were conducted as chromism test, viscosity profile, starting time of thermochromism, and FT-IR analysis. Thermochromic gel materials exhibit chromism properties that can detect abnormal conditions effectively, and then they are possible to various applications.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.24 no.2
• /
• pp.188-194
• /
• 2000

Thermochromic liquid crystal reflect a unique color at even temperature. Therefore, they have been successfully applied to non-intrusive heat transfer research. Hue capturing method is widely used in the quantitative measurement from the TLC image. However it is affected by several measurement conditions. The distances of camera and light source have little influence on the color, but the value of hue is seriously affected by the measurement angle. In this study, the hue capturing method is improved by considering the effect of measurement angle. This improved calibration method can diminish the misreading of temperature caused by curvature of test surface.

• Applied Chemistry for Engineering
• /
• v.26 no.4
• /
• pp.427-431
• /
• 2015

In this study, vanadium dioxide ($VO_2$) powder well known as a thermochromic material was prepared from $V_2O_5$ powder and oxalic acid dihydrate by hydrothermal and calcination process at various conditions. The chemical bonding and crystal structures in addition to thermal property of samples were determined using FE-SEM, XRD, XPS, and DSC. Also, spectroscopic and thermochromic properties of film samples were analyzed by UV-Vis-NIR spectroscopy after the thin film was prepared from the sol dispersed with the size of below 50 nm by the ball-milling of powder sample. With increasing the calcination temperature, the phase transition temperature of samples increased from $40^{\circ}C$ to $70^{\circ}C$ due to the increase of particle size.