1.25" diameter, 40:1 L/D,
Segmented Single Screw Extruder for Gas
The single screw extrusion foaming apparatus consists of a
1.25" diameter segmented single screw
extruder, volumetric resin metering feeder, gas/liquid injection system and
die. To monitor the temperature, pressure and the gas flow rate, transducers
were placed at strategic locations and the process variables are recorded. A
data acquisition system and digital computer are used to display the
variables in real time.
The transducers are connected to
fifteen bit accurate digital to analog converters. The converters are connected
to the serial port of an IBM digital computer. The visual graphical interface
and related computer coding was developed at
PPI. The picture shows the computer monitor displaying independent and
dependent variables as function of time.
The picture shows the 10" wide flat sheet die
being used to extrude PET foam at a density of 0.2 g/cc. This foam was
produced using reactor modified PET and carbon dioxide gas. A three roll
stack takeoff, equipped with constant temperature controller, was also used.
Similar experiments were conducted using
argon and nitrogen as physical blowing agents.
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