Today's KNOWLEDGE Share : Compounding highly filled polyolefin compounds with mineral filler

Today's KNOWLEDGE Share

Compounding highly filled polyolefin compounds with mineral filler contents of 70-80% by weight requires careful management of air entrainment and venting in twin-screw extruders.


High free-volume extruders with a Do/Di ratio of 1.65 or higher support increased throughput while accommodating the low polymer content and reduced torque demands of these formulations.


Effective processing depends on controlled side-feeder operation and targeted venting strategies. Key practices include placing loss-in-weight feeders close to side-feeder hoppers with flexible sleeves to limit aeration, running side-feeder screws slowly to reduce air intake, and positioning back and front vents around axially open screw sections.


- Use wide kneading blocks with 30- or 60-degree staggering angles after side feeders to improve filler incorporation and prevent vent flooding.

- Adjust filler distribution across main feed and side feeders based on bulk density, moisture, and viscosity to avoid agglomeration.

- Install a melt pump rated for high-filler compounds to decouple pressure build-up from the die and reduce discharge temperature.


These steps address vent blocking and ensure homogeneous dispersion without altering the polymer matrix. https://lnkd.in/eB98dPnq


source : Plastics Technology


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