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Author Topic: Produce a low-freezing rocket fuel  (Read 12052 times)

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wildfyr

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Re: Produce a low-freezing rocket fuel
« Reply #30 on: July 17, 2017, 03:53:24 AM »

https://en.wikipedia.org/wiki/Polysilane#Properties

It appears they are sensitive to UV as a small caveat, and while the wikipedia article isnt explicit, they seem to be solids. Are you thinking more towards the small molecule angle for this? I'm a polymer chemist so my mind goes straight to polymers due to their processability and generally superior mechanical properties.
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Enthalpy

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Re: Produce a low-freezing rocket fuel
« Reply #31 on: July 17, 2017, 03:55:33 AM »

If the low melting point of siloxanes, tetramethylsilane and hopefully silicon-containing alkanes results from the ease of rotation at Si-O and Si-C bonds, making the deformed molecules hard to stack orderly, then much void must remain between the molecules and disappear at high pressure.

This would give silicon-containing alkanes a bulk modulus as low as, or maybe lower than, silicones - the reference materials for low bulk modulus (big volume compressibility).

A low bulk modulus would be a drawback as a (aeroplane) hydraulic fluid, but an advantage in volumic springs, where a piston compresses a liquid or solid which is often silicone oil up to now, or in windows and lenses for underwater acoustics which use polymethylpentene (PMP) presently.

A solid silicon-containing alkane could hopefully result from disubstituted silane and a diene.

Marc Schaefer, aka Enthalpy
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Enthalpy

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Re: Produce a low-freezing rocket fuel
« Reply #32 on: July 17, 2017, 04:53:02 AM »

https://en.wikipedia.org/wiki/Polysilane#Properties
It appears they are sensitive to UV as a small caveat, and while the wikipedia article isnt explicit, they seem to be solids. Are you thinking more towards the small molecule angle for this? I'm a polymer chemist so my mind goes straight to polymers due to their processability and generally superior mechanical properties.

I have obviously nothing against polymers nor polysilane. Wiki tells implicitly that the polymers are solids: crystalline to amorphous, and so on.

My initial thoughts were about a few silicon atoms where the alkane is branched, but if a polysilane has good properties, it's just fine. UV are present in some applications only.

Dimethyldichlorosilane is widely available as the precursor to polydimethylsiloxane but it said to cost a bit. Silane is hopefully cheaper. That said, some uses accept more expensive compounds: vacuum grease, computer coolant, underwater acoustics, volumic springs and others.
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