DennyDevHE77
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Processing of plastisol compositions
There are a number of explosives (plastisol-plastigel) on a heat-curing base. The filler is usually ammonium perchlorate + RDX + aluminum. The binder
is usually a mixture of nitroesters (for example, a mixture of 70% diethylene glycol dinitrate and 30% triethylene glycol dinitrate) and polyacrylic
polymer (Vitan, or copolymer of methylacrylate and acrylic acid). These explosives are said to be easily recyclable back into
components. But I wondered, how? Solvents hardly take them. Acrylic polymers seem to be soluble only in alcohols, and then a little. Or do
these explosives become malleable again when reheated?
Does anyone know anything about this subject?
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dettoo456
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I am not sure about the compositions you mentioned, but I know for lots of plastics, the active EM can be extracted by destruction/depolymerization of
the polymer by mixing in dilute HCl or NH3, filtration, then solvent extraction. But if there are liquid and metal components like DEGDN and Al, the
process would be much more difficult.
There are thermoplastic-based energetic mixtures though, and yes they are flowable or at least moldable when hot. TPU is used with HMX in this way.
And an acrylate called HYTEMP is also used with HMX - I think that one can be injection molded.
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4-Stroke
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A quote from the Encyclopedia of Explosives and Related Items (Volume 2):
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b) Plastisol propellants are made of approx. 75% Ammonium Perchlorate and 25% of a mixture in equal parts of finely divided polyvinyl chloride and
non-soluble plasticizer. The mixt solidifies when heated.
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Note that it says propellants. Almost all references for plastisol in the book (all of the volumes) refer to it as a propellant, not an explosive.
Volume 3 defines plastisol as:
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Commercial Plastisol: According to definition given in Ref 2, a plastisol is a liquid dispersion of finely divided resin in a plasticizer. It is
usually 100% solid with no volatiles; when volatile content exceeds 5% of the total wt. it is called organosol. When the plastisol is heated, the
plasticizer solvates the resin particles, and the mass gels. With continued application of heat the mass fuses to become a conventional thermoplastic
material.
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Many of the plastisol compositions also contain/are based on nitrocellulose. Although I don't remember reading a single reference to plastisol as an
explosive, its ability to detonate (and the impact sensitivity) was noted several times. Not a single time, however, did I ever read that it is easy
to recycle back into components. Do you mind saying where you found that info? Because now I am curious myself 
Also just as dettoo456 said, it seems like many thermoplastic-based explosives can become moldable when heated, and "plastisol" (at least as defined
by the book) seems to be a thermoplastic too, so I think that it is quite likely that "plastisol" (at least some types of it) will become moldable
when heated.
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DennyDevHE77
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Yes, they were originally rocket fuel, not explosives.
In 1957, American sailors decided to test how their rocket fuel would react to an explosion. They wanted to make sure that ballistic missiles were
safe for submarines. So, they were testing, and one rocket engine filled with plastisol fuel exploded. The explosion was so wild that the guys
realized: this fuel is a great thing for explosives in torpedoes. Especially at that time it was established that the old explosive (H-6) in MK-46
torpedoes was not powerful enough to cope with the new Soviet submarines. That's how the new plastisol explosive composition PBXN-103 came to be: 40%
ammonium perchlorate, 27% aluminum, 23% trimethylolethanthrinitrate, 6% modified nitrocellulose, 2.5% triethylene glycoldinitrate, 1.3%
ethylcentralite and 0.2% resorcinol. The detonation velocity is 5900 m/s and the density is 1.89 g/cm³. However, the persistence and most importantly
the detonation capability of PBXN-103 was not particularly good. At least that's what the military decided. Therefore, PBXN-105 was invented later. By
composition PBXN-105 is a modified fuel of “Polaris” missile - a mixture of ammonium perchlorate, aluminum, RDX, mixture of nitroesters and
polyurethane polymer (i.e. like most plastisols nowadays). This new compound was used to fill MK-48 torpedoes. It was found to be much more resistant
to shock and temperature than the old H-6 mixture, but the military decided that this was not a significant advantage, against the background of much
greater efficiency in naval munitions. This effectiveness was the reason for its adoption.
And here's the book where I got the information that they're easily recyclable. (here is the link: https://vdocuments.mx/-2012-55844f60af0c2.html?page=189). Actually, the italicized translation below is from the same book.
"A continuation of the evolution of plastisol rocket fuels, widely used in the USA in the 50s and 60s of the 20th century, were explosives based
on a plastisol type binder that does not contain crosslinking agents: unlike thermoplastic explosives, plastisol explosives are processed at normal
temperatures, and cured when heated. Curing occurs due to the swelling of the polymer in the plasticizer – the transformation of plastisol into
plastigel. i.e. An already cured polymer swells in the plasticizer to form a rubber-like material. They are characterized by increased propellant
ability and low shock wave sensitivity, in addition, they are easily recycled back into components. Plastisol compositions are
characterized by low porosity and they can be used to form charges of complex configuration.
American plastisol formulations were introduced in the early 70s of the 20th century, their binder consisted of plastisol nitrocellulose and
nitroesters such as trimethylolethantrinitrate and butantrioltrinitrate. In recent years, there has been a trend in the United States to move away
from plastisol compositions for low-sensitivity explosives using energy-intensive plasticizers and binders, which are described above. This transition
is due not to the best energy characteristics of the latter, but to the possibility of mastering new expensive materials and increasing production
safety.
The first USSR plastisol compositions (80s of the 20th century – OFK, OFA, FP, OFP) as a binder contained a polyacrylic polymer with a plasticizer
of the FC type (FEFO), subsequently FC was replaced by cheaper and less toxic nitroesters. New compositions the OLD, OLA, LP, OLP series used in
modern USSR ammunition (mainly high-explosive and high-explosive fragmentation), contain a mixture of LD-70 nitroesters as a binder (it consists of
70% diethylene glycol dinitrate and 30% triethylene glycol dinitrate) and a polyacrylic polymer (for example, vitane), and as fillers may contain HMX,
RDX (including phlegmatized ones), aluminum and ammonium perchlorate. Heat-resistant versions of the formulations contain an additive of
diphenylamine. Polyacrylic polymer, unlike nitrocellulose, is inert a binder, however, it has better thermal and mechanical properties. It is also
much cheaper than plastisol nitrocellulose, which requires a large amount of solvents for its manufacture"
[Edited on 8-5-2024 by DennyDevHE77]
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