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Polymer Synthesis & Manufacturing Systems
Frank Crossman and Robert Milligan
Overview
From our current knowledge of the chemical makeup of the Mars regolith and
atmosphere, we develop a sequence of chemical processes that produce
sufficient quantities of chemical precursor and reagent stocks to
(1)allow the synthesis of some important polymers for construction of a small
permanent settlement in a two- Earth year time period and
(2) provide the chemical industry infrastructure necessary to replicate that
settlement in subsequent two-year cycles in arithmetic increments of settlers
every two years.
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Scope
We describe the synthesis & manufacture of three polymers which represent
three uses of structural polymers on Mars:
•polyethylene for piping and a variety of general storage containers. A pellet
extruder and die system will be used to produce piping and joints, blown
bottles, and other structural shapes from extruded sheet and assembled by
thermal welding.
•polyester to provide a matrix for glass fiber reinforced composites used for
habitat module construction. Glass reinforced polyester matrix composites will
be used where structural strength is critical such as in the habitat pressure
vessels. The cylindrical pressure vessel structures will be fabricated in a wet
filament winding machine and the polyester matrix will be cross-link cured at
room temperature.
•epoxy for use as a structural adhesive for metal, glass, and composite joints.
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Challenges in Polymer Manufacture on Mars
… Imagine awaking in your bed one morning to discover that all man-made
polymers in your daily life had disappeared. You have no sheets, no toothbrush,
no computer, no microwave, no phone. You might have some cotton
undergarments remaining…
… Now imagine that you awakened in a world where oil is non-existent as well.
Now you have no oil power, no gas heat, and no petroleum chemical stocks from
which most chemicals and polymers are derived.
… The challenge is to synthesize and manufacture polymers from scratch using
available in-situ minerals and gases on Mars with chemical processing
equipment that is sized to the Mars Homestead needs.
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Sizing the Chemical Plant
Phase 2 Design studies have estimated the quantity
materials needed to build a habitat sufficient to
house 12 settlers.
• 115 tonnes of fiber glass polyester composite,
• 46 tonnes of polyethylene
• 5 tonnes of epoxy adhesive
These materials are produced during a 400 day period
at average daily production rates of
• 70 kg/day - Unsaturated polyester resin and
styrene for crosslinked polyester
• 116 kg/day - Polyethylene
• 12 kg/day - Epoxy
The size of the chemical reactor to produce 45 kg of
unsaturated polyester resin (a viscous liquid) in a
one batch a day process is
Volume = mass/density = 45/1.2 = 0.038 cubic meters
or 9.4 gallons
Conclusion: The chemical plant needed to produce
these quantities is more than laboratory scale but
less than that of many pilot plants on Earth.
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F. Crossman and R. Milligan
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Pdc Machines, Inc.
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To Polymers working forward
from known Mars resources
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The known in-situ Mars resources that we start with are small in number and rely on the existence of a
chemical processing capability already established on Mars to produce the bare necessities of life
including methane for fuel and oxygen to breathe.
The 12 chemical building blocks are:
• CO2 (carbon dioxide) and N2 (nitrogen) from the atmosphere of Mars
• H2O (water), NaCl (salt), and hydrated CaSO4 (gypsum), silica, alumina,
magnesia from the regolith of Mars
• CO (carbon monoxide), CH4 (methane) from the making* of methane fuel
• H2 (hydrogen) and O2 (oxygen) from the electrolysis* of water to obtain oxygen
* (see R. Zubrin, The Case for Mars, 1996)
All the rest of the required chemicals and polymers are derived from this short
list of pre-existing chemicals.
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The end products
Case 1: Polyethylene flake + remelted/formed
= Polyethylene thermoplastic
Case 2: Bisphenol A + Epichlorohydrin + Diamine accelerator
= Crosslinked Epoxy Adhesive
Case 3: Glass fiber + Unsaturated Polyester Resin + Styrene + Peroxide initiator
= Glass Fiber Reinforced, Crosslinked Polyester Composite
For this presentation we’ll detail the materials needed for the third case- glass
fiber reinforced composites for pressure vessels.
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Working backward from crosslinked polyester
• Unsaturated Polyester Resin (1) which is derived from
Maleic anhydride (2) which is derived from
butane (3) (& O2 & VPO catalyst) which is derived from
butene (4) (& H2 & Raney Ni catalyst) which is derived from
methanol (5) (& Zeolite catalyst) which is derived from
CO, H2, CO2
and
Ethylene glycol (6) is which derived from
oxirane (7) (& steam) is which derived from
ethylene (8) (& Ag and Al2O3 catalysts) which is derived from
methanol
• Styrene (9) which is derived from
ethylbenzene (10) (& Fe catalyst) which is derived from
benzene (11) (& Zeolite catalyst) which is derived from
CO2, O2, H2, H2O
and
Aug-6-05
ethylene (12) which is derived from
methanol
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Working backward to the basic 12 chemicals
And as the reaction initiator
• Methyl ethyl ketone peroxide (13) which is derived from
2-butanone (14) which is derived from
2-butanol (15) which is derived from
butene
and
hydrogen peroxide(16) which is derived from
sulfuric acid (17) which is derived from
SO2 (18) (& O2, H2O & Vanadium dioxide catalyst) which is derived from
Gypsum thermal decomposition
and
HCl (19) which is derived from
sulfuric acid
and
NaCl
.
So…a total of 19 chemicals derived from the 12 basic chemicals have been identified for the
production of crosslinked polyester on Mars.
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Summary: all polymer precursor chemicals
8 inorganic chemicals
Sodium hydroxide
Chlorine
Sulfur dioxide
Sulfuric acid
Hydrogen chloride
Ammonia
Nitric acid
Hydrogen peroxide
Proceeding in a similar fashion with the backward derivation of polyethylene
and epoxy to the 12 basic chemicals, we discover that we need a total of
• 8 inorganic chemicals produced on Mars
• 30 organic polymer precursor chemicals produced on Mars
• 15 recoverable catalysts imported initially from Earth in small quantity
30 Organic polymer precursor chemicals
Methanol
Ethene
Propene
n-Butene
Ethylene oxide
Glycol
Acrolein
Allyl alcohol
Glycerol
Acetic Acid
3-Chloropropene
Glycerol dichlorohydrin
Calcium hydroxide
Epichlorohydrin
Butane
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Maleic Anhydride
2-Butanol
2-Butanone
MEKPO
Benzene
Cyclohexane
Ethylbenzene
Styrene
Cumene
Phenol
Acetone
Bisphenol A
1,3-Dinitrobenzene
1,3 Diaminobenzene
1-butene
F. Crossman and R. Milligan
15 Imported Catalysts
Cu
ZnO
Zeolite
Ag
Au
Vanadium oxide
Ru
Pt
Ir(CO)2,I2
Raney Nickel
VPO
Mo
CuCl
Ion exchange resin
Ti based Ziegler catalyst
9
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The analysis of each chemical reaction and the sequencing of these reactions has been carried to the
level of detail shown on this slide and the next.
CH3COCH3
1-10 atm., O2 [Cumene Hydro
Cumene
(2-Phenylpropane) 82 - 90oC,
-peroxide CHP]
radical initiator Ca. 30%
To 8.
60-70oC
H+,H20
Phenol
Vacuum distill unreacted cumene
Weak caustic scrub to remove phenol, acids
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Aliphatic Organic Synthesis Sequence*
* Patent Pending
Ag
3a.
CH2-CH2
O
oxirane
CH2=CH2
ethene
H2O
3b.
HOCH2CH2OH
ethylene glycol
To ethylbenzene 4.
To polyethylene 1.
To cumene 6.
H2
CO2 + CO
1.
MTO
CH3OH
methanol
2.
CH3CH=CH2
propene
HOCH2CH=CH2
2-propenol
4a.
Cl2
5a.
CH2ClCH=CH2
3-chloropropene
H2O2
4b.
HCl
HOCH2CHOHCH2OH
HOAc
glycerol
4c.
Cl2, H2O
CaO 5b.
As co-reactant for LDPE
H2
CH3CH2CH=CH2
+
CH3CH=CHCH3
1 and 2-butenes
7a.
ClCH2CHOHCH2Cl
6.
glycerol dichlorohydrin
CH3CH2CH2CH3
butane
H2O, H2SO4
Cu D
CH3CH2CHOHCH3
8a.
8b.
2-butanol
As solvent for polyethylene 1.
O
O=C
C=O
7/2O2, 400 - 480oC
CH=CH
0.3 - 0.4 Mpa
maleic anhydride
CH3CH2COCH3
2-butanone, MEK
H2S2O8
8c.
CaO
CH2-CHCH2Cl
O
epichlorohydrin
CH3CH2 CH3
HOOCOOCOOH
CH3 CH2CH3
MEKPO dimer
CO
CH3COOH
9.
Acetic acid
CO, O2
CH3OCOOCH3
CuCl, 130oC, 2000kPa
Dimethyl Carbonate
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Manufacturing the glass fiber
Glass fiber is the least energy intensive fiber to produce on Mars.
Three main types of fiber glass
1.
C glass (uncommon) used in corrosive environments. It is a soda-lime-borosilicate
composition
2.
E glass used in printed circuit boards. Has the greatest number of components.
3.
S glass used in aerospace for its high strength and resistance to moisture. It has the highest
strength and modulus of all these fibers and it is the simplest composition of only silica,
alumina, and magnesia or simply magnesium aluminosilicate
Glass
type
E
Silica Alumina Calcium Magnesia Boron Soda Calcium other
SiO2 Al2O3
oxide
MgO
oxide Na2O fluoride minor
CaO
B2O3
CaF2
oxides
54
14
20.5
.5
8
1
1
1
S
64
25
C
66
4
10
13
3
5
.3
1
8.5
1.3
Since we want the strongest fiber, and it is the simplest composition using compounds
that we know exist on Mars, we will make S glass fiber.
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Homogenizing the glass composition
The first steps • homogenizing the glass composition and
• controlling the outflow temperature so that the viscosity of the drawn glass is constant
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Drawing the glass fiber
Next steps:
• Pulling fibers from the melt
• drawing them down from 1 mm to
10.0E-6 m, a reduction ratio of 100
• Organosilane coatings are applied
to protect the filament surfaces and
also to promote better wetting and
bonding between the glass filaments
and the thermosetting resin during
the filament winding process.
• taking them up as a single strand on
the forming winder or to fiber
chopper
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Manufacturing Methods for Composites
Using pressure and elevated temperature to aid infiltration of matrix around fibers
1.
Autoclave Cure - Best properties, but requires massive pressure vessel/oven
2.
VARTM (vacuum assisted resin transfer molding) - Uses woven dry fiber preforms and a
massive weaving machine to create them. Best properties for very large structures (a/c wings)
uses the pressure differential of 1 atm on Earth to pull the resin into a preform of fibers. But on
Mars the ambient pressure differential will be ~1/2 bar or less.
Low pressure and low temperature cure processes include:
1.
Filament winding
2.
Open Mold processes
•
Sprayup
•
Hand layup
We will use filament winding and sprayup
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Filament winding the pressure vessel modules
A Filament Winder is
like a lathe with a long
“cutting arm”
that adds material
(fiber and resin)
instead of removing
material
The composites
filament winding area
may have to be ~30 m
high to accommodate
vertical winding of
Homestead modules
A large crane is
required to support the
mass and to maneuver
it from vertical to
horizontal
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Sprayup Method for low pressure chambers
This method of building up a 15% chopped fiber
reinforced structure could have real value for the
internal walls of low pressure underground chambers.
It is a fast and non-labor intensive method of providing a
seal.
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Polyethylene Part Manufacture
• Polyethylene can be synthesized in three steps: (1) methane to (2) ethylene to (3) polyethylene pellets or
flake.
• As a thermoplastic it can be remelted and re-extruded as sheet, piping, bottles. Extrusion machines and
dies are complex and will need to be imported from Earth initially.
• PE is limited to use at low temperatures due to creep/viscoelastic deformation.
• It is chemically resistant to the point of being difficult to bond to other parts except by welding or by
mechanical joining.
Extrusion product lines are compact
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Conclusions
• We have analyzed the requirements to establish a chemical processing and polymer
manufacturing plant on Mars capable of producing, over a period of 400 days, 166 tonnes of
glass reinforced polyester composites for pressurized habitats, polyethylene piping and sheet,
and a quantity of epoxy adhesive for general structural bonding use.
• The route to polymer precursor formulation uses syntheses that do not rely on a petroleum
precursor, the basis for much of today’s chemical industry.
• Based on literature and patent searches, we have established the reaction sequence and
conditions (temperature, pressure, catalyst, reactants, products) to produce the polymer end
products.
• In the process we have also established the production of a range of organic and inorganic
chemicals and reagents that have other uses such as in the extraction and refining of metals
and ceramics from the Mars regolith.
The authors want to express their gratitude to Mark Homnick, Bruce Mackenzie,
and Joseph Palaia the founders of the Mars Foundation, without whose support and
encouragement this project would not have been undertaken.
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Next Step: Design the Chemical Plant
Reaction Pressure vs Temperature Scatter Plot
100
KAAP Ammonia Process
90
80
Methanol process
Pressure bar
70
60
HDPE and LLDPE
50
40
ethylbenzene
30
20
Styrene
10
Gypsum to SO2
Benzene
0
0
200
400
600
800
1000
1200
1400
Temperature deg C
• Plant design will use several batch reactors that operate in different T,P ranges
• Most reactions occur at less than 550 deg C and 5 bar
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The Next Step
The next step requires a chemical engineering plant design that is unique to Mars.
• The reaction products must be stored and/or fed as reactants to the next reaction sequence.
• Reaction chambers should be designed for production of several different chemical products that share
similar reaction temperature and pressure conditions.
• The reaction sequences must be prototyped to establish the reaction kinetics - optimum temperature &
pressure conditions, catalyst type, and the yield of each reaction. While many individual chemical
processes on Earth are licensable, they are designed for very large automated, continuous production
in facilities that occupy hundred of acres. It is not evident that the Mars facility can take advantage of
this prior art.
• The Mars Settlement chemical processing plant will involve a total plant size that is on the order of a
small pilot plant on Earth.
• Like most pilot plants The Mars Settlement chemical processing plant will likely use batch rather than
automated, continuous processing of chemicals, and this must be accomplished in a way that will not
be human labor intensive. It will of necessity require robotic support and automated sensing and
control equipment.
The Mars Foundation is soliciting the help of a Chemical Engineering group
at a university or research institute.
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