Polymer Synthesis

1
Polymer Synthesis Manufacturing SystemsFrank
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. 

2
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.

3
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.
4
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.

Pdc Machines, Inc.
5
To Polymers working forward from known Mars
resources

• 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.
6
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 well detail the materials
needed for the third case- glass fiber reinforced
composites for pressure vessels.
7
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 ethylene (12) which is derived from
• methanol

8
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

.
Soa total of 19 chemicals derived from the 12
basic chemicals have been identified for the
production of crosslinked polyester on Mars.
9
Summary all polymer precursor chemicals
8 inorganic chemicals

• 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

15 Imported Catalysts
30 Organic polymer precursor chemicals
10
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.
11
Aliphatic Organic Synthesis Sequence
Patent Pending
12
Manufacturing the glass fiber

• Glass fiber is the least energy intensive fiber
  to produce on Mars.
• Three main types of fiber glass
• C glass (uncommon) used in corrosive
  environments. It is a soda-lime-borosilicate
  composition
• E glass used in printed circuit boards. Has the
  greatest number of components.
• 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

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.
13
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

14
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

15
Manufacturing Methods for Composites

• Using pressure and elevated temperature to aid
  infiltration of matrix around fibers
• Autoclave Cure - Best properties, but requires
  massive pressure vessel/oven
• 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
• Filament winding
• Open Mold processes
• Sprayup
• Hand layup

We will use filament winding and sprayup
16
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
17
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.
18
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
19
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 todays 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.
20
Next Step Design the Chemical Plant

• 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

21
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 Homestead 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 Homestead
  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.