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Author Topic: Produce a low-freezing rocket fuel  (Read 15972 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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Enthalpy

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Re: Produce a low-freezing rocket fuel
« Reply #33 on: May 16, 2018, 11:56:28 AM »

Easy precursors of farnesane make most of the oil of Ocotea caparrapi.

Citing Palomino et al
http://www.academia.edu/11238744/Caparratriene_an_Active_Sesquiterpene_Hydrocarbon_from_Ocotea_caparrapi
incisions in the large Colombian tree secrete oil comprising mostly nerolidol, together with caparrapi oxide, and the diol and triol analogues of nerolidol, plus a bit of caparratriene.

It is my hope that indistinct dehydration of the mixture provides hydrocarbons with the proper skeleton, whose hydrogenation gives mainly farnesane with a nice mix of stereoisomers - or hydrogenate first or in several steps. The intermediate alkene may also grow longer chains easily, preferred for flash point and lubrification. Beware caparratriene is a cell growth inhibitor.

Palomino et al got their >100g sample from the market in Caparrapi. Incisions in trees make latex for cheap, Ocotea caparrapi oil hopefully too. Competing against Kerosene and Diesel oil is presently uncertain, but hydraulic fluid, transformer oil, cooling oil seem easy markets, Mars and Moon landers obviously.

Marc Schaefer, aka Enthalpy
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Enthalpy

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Re: Produce a low-freezing rocket fuel
« Reply #34 on: May 17, 2018, 05:50:26 AM »

Trying to compare the production of Ocotea caparrapi oil with latex, without reliable sources...

The tree is banal in a part of Colombia. Producing its oil resembles more an individual and occasional activity exploiting isolated uncultivated trees.

One Ocotea caparrapi seems to produce as much per year as one hevea, need more area but far less work. Selection and optimization would improve the yield. Automation looks feasible.

Latex sells for 1.5usd/kg presently. Prior to heavy investments, farnesane a few times more expensive would not replace aeroplane and car fuels, but address easily all other markets.

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As an early alternative to start an activity, farnesol sells for some 30usd/kg on Alibaba. It's nearly nerolidol, with one double bond and the hydroxyl elsewhere. Cheap enough for Mars landers and others.

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Looks like Amyris, who initially wanted to fly aeroplanes with farnesane produced by bacteria, have good readings
https://www.energy.gov/sites/prod/files/2014/11/f19/x_velasco_biomass_2014.pdf
page 6: lubricants, transformer oil, hydraulic oil.

Together with partners, they flew airliners with farnesane, kudos. As a costly demonstration, but this is already admirable.
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