Study on the Rheological Properties of Poly(trimethylene terephthalate) Melt in Uniaxial Extension

The Theological properties of poly(trimethylene terephthalate) melt in uniaxial extension were studied by using capillary rheometer. The results showed that the extensional viscosity decreased with increasing the extensional stress, which b ecame more obvious with increasing the molecular weight of PIT melt. With increa sing the molecular weight of PTT melt, the extensional strain rate affected sign ificantly the extensional viscosity of melt. The extensional stress increased an d the extensional viscosity decreased with increasing the extensional strain rat e, which might easily form the draw resonance in melt-spinning processing of PTT melt. It was very important to decrease spinneret draft in melt-spinning proces sing of PTT melt in order to decrease draw resonance and improve the spinnabilit y.