IIRC it's a technique also employed for gelatine processing in capsule
manufacture for drugs. I vaguely recall gelatine has quite a narrow window
of temperature where it will stay liquid - around 60deg C or thereabouts; so
a heating jacket is employed using steam, but due to the lower temperature,
its pressure is reduced to near vacuum to ensure boiling and uniform steam
dispersion throughout the heating jacket.
Speaking of vacuums, you can also utilise a partial or full vacuum to
increase the safety margin of propellant processing utilising elevated
temperatures ie. it's much harder to ignite propellants under vacuum
conditions.
Troy
-----Original Message-----On
From: arocket-bounce@xxxxxxxxxxxxx [mailto:arocket-bounce@xxxxxxxxxxxxx]
Behalf Of Henry Spencercan
Sent: Thursday, 9 July 2020 7:19 AM
To: Arocket List <arocket@xxxxxxxxxxxxx>
Subject: [AR] Re: Amateur thermoplastic binder solids
On Wed, 8 Jul 2020, William Claybaugh wrote:
My sources say AP ignites a little above 400 degrees F so a binder
that forms a low viscosity fluid at around the BP of water will in
theory work fine if there is no possibility of hot spots.
If you can find something that works *at* the boiling point of water, you
use steam heat (with a steam source that heats the water, not thefilling
steam) to ensure it just can't go any hotter.
(This technique is, or was -- my info may be out of date -- widespread for
munitions with TNT, which is a fairly-stable liquid at 100degC.distance
That helpful property is one reason why TNT became so popular.)
If I were going in that direction I would want to automate the mixing
rather than stand over an open pot of hot binder, AP, and Al, stirring.
If one must pre-fix fuel and oxidizer :-), especially hot, doing it from a
makes a whole lot of sense.
Henry