Rheological behavior of EVOH

A series of studies on the rheological behavior of EVOH melt were carried on,so as to provide the optimal spinning parameters to prepare the PET/EVOH sheath-core fiber.The experimental results showed that EVOH belongs to the pseudo plasticity liquid,the non-Newton exponent is less than 1 and the apparent viscosity decreases with the increasing of the temperature or the shear rate.The non-Newton exponent of EVOH is 0.712 when extrusion spinning is carried out at the temperature of 240℃,which is closer to the Newton liquid as compared with spinning at the temperature of 250 and 260℃.The activation energy of EVOH is between 400 and 500 J/mol when spinning performed at 240,250 and 260℃,which increases with the increasing of the shear rate.