Dichroism of poly(ethylene terephthalate)‐disperse dye system

摘要

AbstractAs an approach to the basic study on the orientation behavior of amorphous region, the dichroic orientation factor,D, of poly(ethylene terephthalate), PET, fiber or film dyed with disperse dyes was investigated in relation to Δn, birefringence of the crystalline and amorphous regions, and Δna, birefringence of the amorphous region. It was found thatDversus Δnplot belonged to a linear relationship passing through the origin but breaking slightly toward theDaxis at Δn≃ 0.14, whileDversus Δnaplot was expressed by a straight line passing similarly through the origin but with no break.D0, the value ofDat the ideal parallel orientation, was obtained by extrapolating the latter plot of the samples stretched with no relaxation: 1.00 and 0.73 for the PET–C.I. Disperse Yellow 7 and PET–C.I. Disperse Red 17 systems respectively. When the sample had been relaxed, theDversus Δnawas also linear; however,D0's obtained were smaller than the above mentioned respective values. Even in these casesDfor Disperse Yellow 7 versus the correspondingDfor Disperse Red 17 belonged to a linear relationship with the slop 1:0.73.As the result it was concluded that the transition moment of molecule of C.I. Disperse Yellow 7 coincided with the molecular axis and the dye molecule combined parallel to PET chain, while as to C.I. Disperse Red 17 any definite conclusion could not be determined. However, in the both cases the mode of combination of dye molecules with PET is definite and kept unchanged during stretching