Photoacoustic study of PET films and fibers dyed in supercritical CO2 reactor

Abstract

Photoacoustic (PA) spectroscopy was applied to study the dyeing process in poly(ethylene terephthalate) films and fibers when supercritical (SC) pressure of CO2 is used. The samples were prepared according to a factorial design having four variables in two levels. They were dyed in red or blue. Following the PA intensity as a variable of response, it was applied an algorithm to take into account the effects of the dyeing variable. The results show that treatment and time were the more influent for blue dyed films and fibers. In contrast, time and temperature were more effective for red films. Depth penetration of the red dye shows saturation near 60 μm with a characteristic time of 30 min. Overall, the results presented CO2 pressure as the less effective variable and the SC–CO2 dyeing method being more effective if compared to conventional bath.