From lab to production,
providing a window into the process
Where the charge mass is in grams, ρ is the melt density in g/cc and MFR is the anticipated 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 anticipated MFR of 3.5 at 230 C, using the melt density of 0.738 from the above table, the estimated charge
mass would be:
3.6*0.738+0.60*3.5=4.76g
In our lab, we have found that 4.6 grams is a good charge for a 3.5MFR 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.
Barrel Charge Size in Grams
Melt Density->
MFR g/10 min
0.75 g/cc
1.0 g/cc
1.2 g/cc
0.1
2.7
3.6
4.4
0.2
2.8
3.7
4.4
0.5
3.0
3.9
4.6
1
3.3
4.2
4.9
2
3.9
4.8
5.5
3
4.5
5.4
6.1
4
5.1
6.0
6.7
5
5.7
6.6
7.3
6
6.3
7.2
7.9
7
6.9
7.8
8.5
8
Plug
8.4
9.1
9
Plug
9.0
9.7
10
Plug
9.6
10.3
11
Plug
Plug
10.9
12
Plug
Plug
11.5
13
Plug
Plug
Plug
P/N:974179
Rev: 0918 ECO: 49667
www.dynisco.com
