30 October 2014
ABOUT DSM IN AUTOMOTIVE/TRANSPORTATION
DETAILS
says a combination of two of its most innovative
thermoplastics technologies has resulted in
high performance pressure vessels
that are ideally suited for use as lightweight fuel tanks
for automobiles running on
compressed natural gas (CNG) or hydrogen.
With a solution for both
the inner liner and the outer tape reinforcement,
DSM is able to reduce the weight of the tank by up to 70%.
Hydrogen and natural gas
are claiming their place in the field of cost-effective and
low carbon-footprint fuels for use in automobiles.
Countries with major natural gas reserves
are looking at the advantages of using
CNG as an alternative fuel which
reduces the CO2emission by 15%
compared to current solutions in petrol or diesel.
Type IV pressure vessels
are based on plastics and continuous fiber reinforcements,
unlike Type I, II and III pressure vessels,
which contain metal components.
DSM demonstrated a tank with
a liner blow molded in its Akulon Fuel Lock,
a polyamide 6-based engineering plastic
with very high barrier to hydrocarbons,
at the Fakuma plastics processing exhibition
in Friedrichshafen, Germany, in mid-October.
The tank can be wrapped in a tape based on
thermoset or thermoplastic resins,
including its EcoPaXX® polyamide 410.
A traditional steel tank of 40L weighs around 60 kg,
while a composite ‘Type IV’ tank with Akulon® Fuel Lock liner
can weigh down to 20 kg.
Every 10 kg removed from a vehicle translates roughly
into a reduction in CO2 emissions from
the vehicle on the road of one gram per km.
Liner material for the CNG tank
Akulon Fuel Lock contains an additive formulation
that further improves the already strong gas barrier of polyamide 6,
and also provides it with extremely high impact resistance
at low temperatures (down to -60°C).
The permeation of HDPE liners is too high to
allow the installation of composite Type IV tanks
incorporating such liners inside a vehicle.
However, Akulon Fuel Lock liner material reduces
emissions by a factor of at least 150
compared to HDPE and therefore enables
the use of Type IV tanks inside the car.
The Akulon Fuel Lock portfolio has been expanded
with a grade that is suitable for
blow molding of liners for large pressure vessels
for heavy duty vehicles such as buses and trucks.
It is normally difficult to make large blow moldings
in polyamide 6, owing to the polymer’s relatively
low melt strength, but this grade has sufficient melt strength
to create a stable parison for tanks beyond
a length of 2m, enabling high precision
in control of the wall thickness.
Tape material for CNG tank
In current Type IV pressure vessels,
the tape reinforcement comprises either
glass or carbon fibers in a thermosetting polymer,
such as an epoxy or unsaturated polyester.
DSM is cooperating in the development of next-generation
Type V pressure vessels.
These are made by winding a tape, developed by DSM,
of continuous fiber reinforced with a thermoplastic,
such as the company’s EcoPaXX polyamide 410,
or another grade of Akulon.
Type V pressure vessels
weigh around 70% less than steel tanks and
can be lighter than Type IV pressure vessels too.
They are more durable than steel,
they have better chemical resistance (no corrosion),
and they are also fully recyclable.
EcoPaXX has the additional advantage that
it has a zero carbon footprint from cradle to gate,
owing to the fact that the polymer is
made entirely from renewable resources.
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