M0726(2):LMFI Series 5000 Lab Melt Flow Indexer
11
English 02/2014
INTRODUCTION
A flow rate test is a measure of a polymer's mass flow rate (grams extruded in 10 minutes) using a
particular orifice under specified conditions of temperature and load. Machines that determine
flow rate are generally called Melt Indexers. Test methods by ISO, DIN, ASTM and others specify
heat chamber and piston tip diameter such that the shear stress on the polymer is the same in all
machines for a given load. In addition, material specification guidelines (by ISO, DIN, ASTM, GM
etc) may exist which give further constraints on how a particular type of material may be run.
The tests performed are those described by ASTM D1238 and ISO 1133-1, 1133-2. This manual
in no way supersedes either of these documents. The precision and accuracy of the test has been
determined by ASTM method D1238. Contributing to both precision and accuracy are operator
variances such as; packing technique, cleaning, cutting, weighing etc. With moisture sensitive
polymers, dryness can also play a major role, and time can be a factor with thermally unstable
polymers, so procedures must be identical. Dynisco Polymer Test Systems has found that
charging a consistent mass of material into the barrel (±0.1 grams) is the most critical factor in
getting precise data.
Several methods have been developed for running flow rate tests under D1238, with Methods A
(mass of material over time) and B (volume of material over time) being the basic of all methods.
Method A is simply the collection of extrudate over time, while Methods B, C and D are the
measurement of time for the flow of a fixed volume of polymer. All but Method A require an
encoder to measure distance traveled to detemine volume of material extruded during the test.
Method A
Method A
-- the test is completely manual and is sometimes called
the "cut-and-weigh" method. Measurement in g/10min.
Method A/B
Method A/B
-- this employs a digital encoder. In order to run a
method B test, an A/B test MUST be run first to determine the
polymer's melt density. This test takes both A-type and B-type
results to determine melt density. Measurement in g/cc.
Method B
Method B
can be conducted only if material melt density is known as
is determined by an A/B type test. This is a "no-cuts" test that is the
most convenient for busy laboratories. Measurement in cc/10min.
Method C
Method C
can be conducted only if material melt density is known as
is determined by an A/B type test. This is also
known as the “half
die” method. A half-length die is used and is generally used for
testing high flow rate polymers. This is a "no-cuts" test that is the
most convenient for busy laboratories. Measurement in cc/10min.
Method D
Method D
can be conducted only if material melt density is known as
is determined by an A/B type test. This is also known as a FRR
(Flow Rate Ratio) test. It uses two weights with the same charge
of material to determine the materials FRR. The FRR is the ratio of
the average flow rate of the material under higher load to the
average flow rate of the material under lower load. This is a "no-
cuts" test that is the most convenient for busy laboratories.
Measurement is unit-less ratio.
