No abstract

No abstract

No abstract

A study has been made of the electrokinetic charging of polymers during capillary extrusion. The levels of charge in the extruded polymer are significant ( w 10-4 C m-3) and depend on the polymer impurity, capillary material, and on the temperature and rate of extrusion. The charging is believed to be due to the separation of the double layer formed at the capillary/polymer interface, and gives rise to the well-known phenomenon of streaming current. A theory is developed for the streaming current generated by a liquid undergoing laminar flow in short tubes. By replacing the parabolic velocity profile with the more general velocity profile applicable to polymer flow, the theory is extended and satisfactorily explains the experimental results. If the polymer resistivity decreases below 10'0 Q m, the theory requires modification to account for the relaxation of extruded charge back to the capillary. This process leads to the appearance of a maximum in the charging characteristics. From the characteristics an estimate of the polymer resistivity can be made, and this is found to be in reasonable agreement with the low-field DC resistivity of the polymer measured at the temperature of extrusion.

No abstract

No abstract

No abstract

No abstract