Volume 3, Issue 8 (September 2006)
Effects of Particle Size and Shear Rate on Melt Flow Properties During Capillary Extrusion of Glass Bead-Filled LDPE Composites
The melt flow properties of a low-density polyethylene (LDPE) filled with glass brads (GB) were measured at 150°C by means a capillary rheometer to identify the effects of the particle size and extrusion rate on the melt flow behavior in the present paper. The volume fraction of the glass beads was 8.4 %. The surface of the particles had been treated with a silane-coupling agent and the diameter range was from 4 μm to 180 μm. The results showed that the entry pressure drop was a component function of apparent shear rate and the melt shear flow approximately obeyed the power law. The melt shear viscosity decreased roughly linearly with an increase of the wall shear stress, and it varied slightly with an addition of the bead diameter under various shear stress levels. Namely, the influence of the bead size on the melt flow properties of the LDPE/GB composites was insignificant at lower concentration of the fine spheres. This might be attributed to the relatively weak interfacial adhesion between the particles and the matrix due to the smooth spherical surface of the beads.