Poly(ethylene terephtalate) films modified with N,N-dimethylacrylamide: Incorporation of disperse dye

Poly(ethylene terephtalate), PET, can be modified with N,N-dimethylacrylami de to obtain a better incorporation of disperse dye (Disperse Blue 79). Min imal variations in the decomposition at 10% level, melting, and glass trans ition temperatures, show that the thermal stability of modified PET films d oes not change when compared to nonmodified PET. The atomic force images sh ow nanopeaks formation on the surface due to the modification. Modified PET films show a decrease in the contact angle and then, an increase in the su perficial tension measurements, when compared to the value of 37 +/- 1 dyne s.cm(-1) (nonmodified), with values liying in the range of 42-46 +/- 0.5 dy nes.cm(-1). The data obtained by photoacoustic spectroscopy (PAS) for dyed PET films show a dye peak at 580 nm. The data analysis of the peak area sho w that PET films modified with N,N-dimethylacrylamide for 15 min at 85 degr ees C, dyed for 6 h at 85 degrees C with a dye concentration of 0.333 g/L, incorporate three times more dye than the nonmodified films dyed in the sam e conditions. By the data obtained from PAS, it was possible to calculate t he depth profile of dyeing with values around 54 mu m. Factorial analyses s how that the dyeing time was the most important variable. The major amount of incorporated dye was obtained by the following combination of variables: temperature and time of modifier treatment were, respectively, 72.5 degree s C and 15 min; time and temperature of dyeing were, respectively, 90 degre es C and 195 min for a dye concentration of 0.133 g/L. (C) 2000 John Wiley & Sons, Inc.