FIBER STRUCTURE DEVELOPMENT IN HIGH-SPEED MELT-SPINNING OF COPOLYESTERS - POLY(ETHYLENE TEREPHTHALATE-CO-1,4-CYCLOHEXYLENE DIMETHYLENE TEREPHTHALATE)

High-speed melt spinning of poly(ethylene terephthalate) (PET), poly(1 ,4-cyclohexylene dimethylene terephthalate) (PCT) and ET/CT copolyeste rs were performed and the structure and properties of as-spun fibers w ere investigated. Molecular orientation increased with an increase in the take-up velocity, and orientation-induced crystallization of PET a nd PCT started at similar to 4.5 and 3.5 km/min. With the addition of CT component to PET, and ET to PCT, the onset of crystallization shift ed to higher velocities. In as-spun fibers of the copolymer of ET/CT = 66/34 mol%, which is known as an amorphous copolyester, the crystalli zation was not observed even at the attained highest take-up velocity, 6 km/min. On the other hand, crystallization of these fibers occurred on annealing suggesting that although the incorporation of copolymer component suppresses the crystallization, the molecular orientation en hances the crystallization of copolymer systems as in the cases of hom opolymers.