Post Consumer Polyolefin Recycling Property Degradation Fundamentals
Polyolefin property degradation stems from chain scission, oxidation, and contamination; managing property drift requires strict OIT, melt index, and blend controls.
Compounding Melt Pump
Meaning
Positive displacement gear pumps installed in extrusion lines ensure a stable and consistent melt delivery to the pelletizer or die. Plastic compounding operations utilize a compounding melt pump to isolate the molding or extrusion die from the pressure fluctuations generated by the primary extruder. This equipment handles high viscosity resin melts and maintains a uniform output.
By decoupling the mixing stage of the extruder from the high-pressure discharge stage, the system optimizes both compounding efficiency and throughput consistency.
Volumetric Flow
Intermeshing gears rotate to capture molten polymer and move it along the housing wall from the inlet to the outlet. In a compounding melt pump, this volumetric displacement delivers a precise quantity of material per revolution, regardless of upstream pressure changes. This mechanical action ensures a constant flow of polymer through the compounding system.
Pressure Stabilization
Extruder surges and shear heating are mitigated by splitting the pressurization task between the screw and the gear pump. The compounding melt pump takes over the high-pressure generation needed to force the polymer through the die. This allows the extruder to operate at lower pressures and temperatures, reducing resin degradation and energy use.
Pellet Uniformity
Pellet quality improves because the flow through the die is highly consistent. Using a compounding melt pump reduces variations in pellet size, which is critical for downstream injection molding. The stable output also allows for higher throughput during production runs.