Date of Award
Master of Science in Applied Physics - (M.S.)
John Francis Federici
N. M. Ravindra
Polymerized PCDA, otherwise known as pentacosadiynoic acid, due to its color changing response to high temperatures, has been used as a means of indicating whether the material has been exposed to high temperatures. Quick-Response codes or Q-R codes have been used as means of serialization due to their two-dimensional design, allowing for the embedding of larger amounts of information than their one-dimensional barcode predecessors.
Combining the colorimetric response of PCDA polymer with the information coding powers of Q-R codes, an improved version of the Q-R Code is made, which was used not only for serialization purposes, but as a means to provide visual indicators as to the temperature the item is exposed to. This can be used to quantize the quality of the product in question. These results are read out by an application which is adapted to an Apple smart phone.
Usage of purified PCDA in a chloroform solution shows to provide clearly printed Q-R codes which could be read by the application, which proves that the difference in color does not affect the capability of the code to be read. A comparison of the reflection of each color to the white paper background shows that the range of temperatures where the codes changes color is very large, spanning from 20% light reflected to 60% light reflected for the color red, 20% light reflected to 40% light reflected for green and 40% light reflected to 50% light reflected for blue. There is no obvious ratio of red, green, and blue that could be used in order to find a usable function of temperature versus color without use of more advanced analysis algorithms. The PCDA exhibits the onset of color changes around 50 to 55 degrees Celsius, while having a vigorous color change around 65 degrees Celsius, and finally reaches its maximum color change at 75 degrees Celsius for the water based ink. The PCDA shows color change for the chloroform-based ink at 65 degrees Celsius and steadily increases in the color red until around 85 degrees Celsius when a maximum is reached. The reflectivity spread for the chloroform-based ink is slightly less than the water-based, ranging for red ranging from 40%-70%. However, it gains spread in the blue and green ranging from 60%-90% and 45%-70%, respectively. The use of chloroform leads to the degradation of the inkjet nozzle head however, and careful selection of printing heads that does not degrade with the intended solvent should be exercised. While the water-based solution is shown to work, it requires many more layers to be printed to make the design as dark as the chloroform-based, as well as having a lighter shade of blue than the chloroform-based after UV treatment, which makes it unable to be read by the application, which is calibrated for the chloroform based ink.
Stavrou, Constantino, "Inkjet printing polymerized pcda as a means of serialization" (2017). Theses. 11.