Purging gels
Vol. 19, #2, June 1992
When high viscosity, particularly crosslinked resin gels have collected in low velocity areas of the melt stream and continue to show up in the extrusion product on a periodic basis, a very effective blend can be used to purge these persistent devils from the system:
Dry blend 47 1/2% 1 MI LLDPE, 47 1/2% 0.5 MI HDPE and 5% stearic acid (flake or powder) and enough to run 1/2 hour at 50 60% maximum rate. Repeat without stearic acid and then again with 2 MI LDPE.
Provide face and arm protection to operators as this technique tends to cause splitting and popping from die.
See also
Gels 1
Gels 2
Gels 3
Gel identification
Purge - closed vent
Removing gels