Dynisco 4001, Руководство пользователя

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Charge Weight
The Amount of Sample
ASTM gives a recommendation of how much material to put in the
barrel to perform a test. However, by determining the proper charge and
controlling it from run to run. Testing can be made easier and more
reproducible. The distance from the top of the die to the first scribe mark is
about 5 cm. Filling the barrel up to the first scribe mark is the minimum charge
needed to run a test. During the 6 minute melt time some material flows out of
the die so a larger charge is needed. The best situation would be if one added
just enough material, so that, during the melt time, the plunger slowly falls and
is just above the first scribe mark when the 6 minute melt time has expired. In
this way the required 6 minute melt time is satisfied and there is no excessive
waiting before the first cut is made (or timing flag starts in method B). A
conservative estimate for charge weight can be calculated if an approximate
melt flow rate and melt density for the material are known by using the
following formula:
Charge Mass
 
3 6

0 6
. . * MFR
Where the charge mass is in grams,

is the melt density in g/cc and MFR is the
melt flow rate in the typical units of g/10 min. This equation will tend to slightly
overestimate the charge needed. For a Polypropylene with an expected MFR of
3.5 at 230 C getting the melt density of 0.738 from the above table the
estimated charge mass would be:
3 6 0 . *
738
.
0 6 . 3 * 5 . 4 76 .
 
In our lab we found 4.6 grams is a good charge for a 3.5 Polypropylene sample.
The equation overestimates the charge since is assumes flow from the instant the
material is packed into the barrel. The following table shows an estimate of
charge weight in GRAMS based on anticipated MFR (g/10 min.) and melt
density (g/cc). Where the word PLUG appears indicates you cannot put
enough material into the barrel such that after 6 minutes there would be enough
left to test, the barrel must have a flow plug inserted at the base of the die to
keep the material from escaping.
Series 4000 Melt Indexer Operation Manual Charge Weight

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