Abstract:
This thesis aimed to study the development of humidity-sensitive films from oleic acid-modified poly (vinyl alcohol) (P*) and Tung oil (T). P* were prepared by the reaction between poly (vinyl alcohol) and oleic acid at 1, 3 and 5 pph. The weight ratios of P*: T were varied at 97:3, 95:5 and 90:10. The resulting products were then crosslinked by irradiation and redox system. Cobalt chloride as a desiccant was also added. The received films were characterized by Fourier Transform Infrared Spectroscopy (FT-IR). Swelling, solid remains, moisture uptake (50-95 %RH), and initial contact angle were also measured. The resistance at different moisture conditions was investigated by 4-point probe resistivity measurements. It was found that the increase the ratios of oleic acid or Tung oil to PVA caused the increase in the water resistance but the decrease in moisture uptake properties and resistance. The results from contact angle test using distilled water showed the initial contact angle of the films in the range between 75-90o, indicating good water resistance properties of the films. The effects of the addition of CoCl2 into the films was found that the increased moisture uptake and resistance was decreased. The circuit including LED and films was found that LED can responded for all films at 75 and 95 %RH excepted for P5*90T10 (LED responded only at 95 %RH). Only P1*97T3Co films can make the LED responded at low %RH. As a result, the prepared films showed different humidity sensitive properties Which can be applied for humidity sensitive.