Sourcing Polypropylene Homopolymer Grades for Thin Wall Packaging Applications
Sourcing thin-wall PP homopolymer demands qualifying melt flow rates above 60 g/10 min while auditing peroxide residues to protect mechanical impact.
Pneumatic Transfer Streamer
Meaning
Elongated polymer filaments form when resin pellets rub against the internal walls of high-velocity air-conveying lines. A pneumatic transfer streamer, often called angel hair, is a byproduct of friction that creates heat and melts a thin layer of the plastic. These strands can break off and accumulate in the material handling system.
They represent a contamination risk and a maintenance burden for the production facility.
Ribbon Formation
Sliding contact between the pellet and the pipe wall generates localized temperatures that exceed the melting point of the resin. This creates a pneumatic transfer streamer that can be several inches or even feet in length. The problem is more severe in long pipe runs with many bends, where the pellets are frequently pushed against the outer radius.
Soft polymers like polyethylene are more susceptible to this type of degradation than harder materials.
System Clogging
Accumulation of these thin fibers can block the filters, bends and rotary valves of the conveying system. When a pneumatic transfer streamer bundle becomes large enough, it restricts the airflow and slows down the material transfer rate. This can lead to the starving of an extruder or moulding machine, causing a production halt.
Cleaning these blockages often requires a complete shutdown of the handling line.
Mitigation Strategy
Reducing the velocity of the conveying air is the most effective way to prevent the formation of these defects. Specialized pipe coatings or roughened internal surfaces can also be used to disrupt the sliding motion and prevent the buildup of a pneumatic transfer streamer. Some systems include de-dusting units that pull the strands out of the material stream before they reach the machine hopper.
Regular inspection of the conveying lines ensures that the system is operating within the parameters that minimize friction. Velocity control is the primary defense against internal pipe fouling.