The Melt Flow Properties of Poly(propylene)/Glass Bead Composites

Abstract

The effects of filler content and its surface treatment on the melt flow properties of A‐glass bead‐filled poly(propylene) (PP) composites have been investigated using a capillary rheometer at a wide apparent shear rate scope of 150 to 7 200 s–1 and a temperature range of 160 to 200°C. It was found that the melt shear flow obeyed roughly the power law. The melt shear viscosity (ηw) of the treated glass bead‐filled system with a silane coupling agent was somewhat higher than that of the raw glass bead‐filled system when both the systems were subjected to the same test conditions. The increase of the resistance to flow and flow satiability for the former system can be attributed to the improvement of the compatibility and interfacial adhesion between the filler and matrix as well as the dispersion of the filler in the matrix due to the surface treatment of the glass beads. The dependence of ηw on temperatures can be expressed with an Arrhenius relationship. The temperature sensitivity of ηw for the composite melts is greater than that of the unfilled PP. Furthermore, ηw increases obviously with the volume fraction (ϕf) of the fillers at lower shear rates, while the dependence of ηw on ϕf decreases with the increase of shear rates. This is attributable to the increase of the ability of relative movement between the filler and matrix melt at high extrusion rates.

A single‐mode rheological model for steady flows of polymer melts

“…Even if a is zero and the values of b , g , and η 0 are arbitrary in the model, the power law derived from eq. (18) is $\eta_s \sim {\mathop \gamma \limits^{\bullet}}^{ - {2 / 3}}$ at high shear rate, which also closes to experimental facts of polymer melts 17, 21, 28–30. Because the data of steady shear viscosity is easy to be obtained from the experiments, the parameters of this model are easy to be determined.…”

Melt flow properties of graphite nanoplatelets-filled polypropylene

“…Melt flow indexer, torque, capillary, and rotational rheometers are the main rheological characterization devices. Researchers have carried out studies on composite rheology for many years including various polymers as suspending fluid and materials such as calcium carbonate, 1,16–18 glass beads, 19,20 titanium (IV) oxide, 21 aluminum, 22 carbon black, 23,24 nanoclay, 25 and graphite 9,10,13,26 as filler. Various rheological characterization techniques have been applied to the polymer composites for different purposes in literature.…”

Melt flow behavior in capillary extrusion of nanosized calcium carbonate‐filled poly(L‐lactic acid) biocomposites

“…Melt shear viscosity and entry pressure losses are the major parameters for characterizing the melt flow behavior of polymeric materials and often required for the design of an extruder and a runner system of an injection‐mold tool. Recently, the authors [19–24] have investigated the viscoelastic properties of inorganic particulate‐filled polyolefin composites through a capillary rheometer in order to determine the flow mechanisms and optimum conditions for processing particulate polymer composites. They found pressure oscillation phenomenon and its critical conditions during capillary extrusion flow of carbon‐black‐filled nature rubber/butadiene rubber compounds [19], and the influence of the bead size and its distribution on the entry pressure drop and entry elongation stress during extrusion of low‐density polyethylene (LDPE)/glass bead (GB) composite melts is insignificant at low‐filler concentration [21].…”