A study of the flow properties of glass fibre reinforced PBT in extrusion

摘要

The extrusion shaping process of polymer materials is a course of polymer deformation, molten flow and solidification shaping. The melt flow character is one of the important parameters of polymer process-ability; it is usually expressed by a viscosity or flow curve. In the present study, the end effect and the flow properties of glass fibre reinforced PBT melt POCAN B4235 during extrusion have been investigated by using a Rheovis 2100 capillary rheometer. It has been found that the suitable extrusion temperature range of the sample is 240 ∼ 250 °C. Within the apparent shear rate ranged from 50 to 1000 s-1, the flow properties of the sample melt do not obey the power law. The relationship between the shear stress at the wall and the apparent shear rate is approximately linear. Under the lower extrusion temperature and apparent shear rate, the apparent shear viscosity of the sample melt has been found to be sensitive to the apparent shear rate. The dependence of the apparent shear viscosity on temperature does not agree with the Arrhenius equation. The entry effect of the sample melt is significant and the relationship between the entrance pressure drop and the apparent shear rate basically obeys the power law under the experimental conditions.