It's something I've never worried much about. The MW of a typical HTPB molecule
is in the thousands and when you react it with (say) a typical diisocyanate,
it's only the very ends (hydroxyl) of each molecule that are affected ie. none
of the bulk hydrocarbon chain that we generally are focusing on for our
thermochem.
Troy
-----Original Message-----
From: arocket-bounce@xxxxxxxxxxxxx [mailto:arocket-bounce@xxxxxxxxxxxxx] On
Behalf Of James Padfield
Sent: Friday, 30 March 2018 8:50 PM
To: Arocket@xxxxxxxxxxxxx
Subject: [AR] Accounting for cured HTPB in ProPEP
How do you account for cured HTPB in ProPEP and similar thermodynamic
tools?
For example, let's say I have a composite propellant with a binder that uses
R45 HT at 5.70%, and this is cured with IPDI at 0.54%.
There are entires for R45 HT and IPDI of course, but in reality what is
present in
my cured propellant is 6.24% of a cured polyurethane.
I have just noticed that there is an entry in the PEPCODED.DAF file titled
"HTPB/CURATIVE" - is this a generic entry for cured HTPB?
G 475 HTPB/CURATIVE (JOS) 656C 978H 5N 13O 0 0 -498
.0329
Or does it not really matter and I am worrying about something that really
has
no significant effect on the outcome of the calculation?
Thanks,
James
