T. Toda et al., AMORPHOUS STRUCTURE CHANGES IN POLY(ETHYLENE-TEREPHTHALATE) INDUCED BY ANNEALING UNDER DRY AND WET CONDITIONS AND ITS DYE UPTAKE PROPERTIES, Polymer, 38(21), 1997, pp. 5463-5469
The amorphous structure changes in poly(ethylene terephthalate) (PET)
induced by annealing under dry and wet conditions were discussed in te
rms of amorphous density (rho(a)) and dye uptake properties. The rho(a
) value of PET decreased with increasing annealing temperature, but it
conversely increased at annealing temperatures above 210 degrees C fo
r the dry treatment and above 170 degrees C for the wet treatment. Wit
h decreasing rho(a) from 1.35 to 1.31 g cm(-3), the conformation of am
orphous molecules changed from the gauche to trans form. The rho(a) va
lue conversely increased on annealing at higher temperatures; however,
the dye exhaustion continuously increased. The ratio of the absorbanc
e of the alpha band to that of the beta band of the basic dye crystal
violet (alpha/beta ratio), indicating the degree of dye aggregation, i
n PET decreased with a decrease in rho(a). The degree of dye aggregati
on further increased when rho(a) conversely increased on high temperat
ure annealing. These results suggested that the free volume content of
PET increased as a result of conformational change from the gauche to
trans form in amorphous molecules with increasing annealing temperatu
re, and finally the increased free volume converted to microvoids arou
nd 1.31 g cm(-3) of rho(a). The dye exhaustion increased with increasi
ng annealing temperature according to microvoid formation. (C) 1997 El
sevier Science Ltd.