A discussion on properties of white powders yielded during package dyeing of polyester yarns

Modern analytical technologies such as FTIR spectroscopy,1H NMR,thermal analysis (DSC),gel permeation chromatography (GPC) in combination with conventional dissolving experiment were used to carry out a systematic study on the properties of white powders yielded during package dyeing of polyester yarns.The chemical composition,stereo structure,and crystalline properties were investigated.The results of dissolving experiment show that the white powders can be dissolved in chloroform,but not in carbon tetrachloride and ethyl ether.The results of thermal analysis reveal that the melting temperature of the white powders is around 319 ℃,not around 265 ℃ as normal PET.The results of FTIR and 1H NMR study further deduce that the main composition of the white powders is cyclictrimer of polyethylene terephthalate oligomers.