Yeah, Ray Goodson used to experiment with many of those binders including
PVC and their curing agents. He predicted his own death 25 years before he
died because of exposure to these chemicals,he said he would die in his
50's. He died at 52 of a horrible mutagenic cancer throughout his body. I
learned virtually everything I know about composite propellant, including
hands-on, from Ray. Formulating, vacuum mixing and casting,particle sizes
and distribution,chemistry,etc,etc. His 3,4&5" nozzleless rocket flights
are on line, Gary Rosenfield,Ray's colleague, owner of RCS published them.
Ken
On Fri, Jul 10, 2020 at 2:28 PM Anthony Cesaroni <anthony@xxxxxxxxxxx>
wrote:
Don’t forget about PVC Plastisol. ARC used it exclusively for the ARCAS
sounding rocket IIRC. It’s fussy about the precursor grade of PVC powder
used but it’s still available.
Anthony J. Cesaroni
President/CEO
Cesaroni Technology/Cesaroni Aerospace
http://www.cesaronitech.com/
(941) 360-3100 x1004 Sarasota
(905) 887-2370 x222 Toronto
*From:* arocket-bounce@xxxxxxxxxxxxx <arocket-bounce@xxxxxxxxxxxxx> *On
Behalf Of *William Claybaugh
*Sent:* Friday, July 10, 2020 3:24 PM
*To:* arocket@xxxxxxxxxxxxx
*Subject:* [AR] Re: Amateur thermoplastic binder solids
Ben:
The professional literature typically describes a mix of styrene and other
plastics, waxes, and or oils. (Anthony has a nice patent on one class of
thermoplastic binders.) The other obvious possibility is the thermoplastic
used for “run flat” bicycle tires which could even be obtained by remelting
used copes of same and does have some nice elastic properties.
Your comment about Mojave summers seems to me germane: an issue with these
binders is that they can become soft at high ambient temperatures and can
pass to a glass phase at relatively high lower temperatures. The other
issue is they tend toward a thicker melt layer than HTPB (which typically
has little or none) which can flow with the gas flow, increasing burning
rate.
I’m still thinking about it but I’m not yet ready to start building the
required GSE.
Bill
On Thu, Jul 9, 2020 at 6:13 PM Ben Brockert <wikkit@xxxxxxxxx> wrote:
Bill,
I googled around a bit but didn't find many plastics that are higher
than Mojave in summer temperature but lower than 100 C. PEG 8000 is
about as close as I got, https://amzn.to/2ZbzHNc
Melts at 160-165 deg F, sg 1.111. Have not put it into pypropep to see
what it does.
Independent of the "thermoplastic APCP" use case, it seems like an
interesting addition to try in KNSB motors. KNSB is melted and cast,
but is fairly brittle and stiff and can't generally be case bonded.
PEG is specifically used as an additive to other plastics to make them
more flexible. It is fairly water soluble, but then so is KN and SB so
it doesn't change that aspect of the motors.
Agreed that hands-off melting and casting seems like a good idea, but
from Troy it sounds like that is fairly well sorted out already.
On Wed, Jul 8, 2020 at 1:01 PM William Claybaugh <wclaybaugh2@xxxxxxxxx>
wrote:
then mix in Potassium Perchlorate so there is an existence proof that a
Ben:
The RRI (circa 1968) use to melt tar in an electrically heated pot and
“low” melting point binder can be mixed with oxidizer w/o ignition.
forms a low viscosity fluid at around the BP of water will in theory work
My sources say AP ignites a little above 400 degrees F so a binder that
fine if there is no possibility of hot spots.
rather than stand over an open pot of hot binder, AP, and Al, stirring. I
If I were going in that direction I would want to automate the mixing
would also expect that the casting process would require starting with a
heated motor / mandrel and then cooling it, presumably from bottom to top,
assuming a vertical pour. Again, I would not be willing to be standing
next to this setup during pour.
wrote:
I’m thinking of putting it on the to-do list but I’m cautious.
Bill
On Wed, Jul 8, 2020 at 12:36 PM Ben Brockert <wikkit@xxxxxxxxx> wrote:
In the "sugar" world where dry mixing and melting is common, they did
some basic sensitivity tests of putting the propellant on the skillet
or whatever and seeing how much excess heating it takes to set it off.
It turns out that it's usually quite a lot, though it's a proof test
that should be redone when things like catalysts are added.
I don't know how AP mixes compare for autoginition or decomposition
temperatures. But you can run the process with an inert oxidizer
stand-in, to look for hot spots and see how the viscosity works out at
a given dry proportion to melted.
Supposedly the big "hybrid" of doom has (or had) some oxidizer mixed
into the fuel grain to increase performance, so there's probably
someone out there who would really like to talk about casting a ton of
thermoplastic nylon with oxidizer.
On Wed, Jul 8, 2020 at 8:13 AM William Claybaugh <wclaybaugh2@xxxxxxxxx>
accept somewhat lower performance then a professional propellant, it
There are today plenty of “rubbery” thermoplastics available. If we
seems—in principle—that making and casting solid propellant using a
thermoplastic binder should be relatively simple, as previous RRI
experience w/ asphalt suggests.
sporty.
The problem for me has been figuring out a relatively safe process:
Dry mixing the ingredients and then melting seems—again, to me—too
breaking into pellets for later processing also seems safe up to the point
Dry mixing the Al and binder seems safe enough; melting that and
that AP is added.
mix dry fuel and oxidizer before melting?
Any thoughts as to how to cast a thermoplastic grain w/o having to
Bill