JEC COMPOSITES MAGAZINE - Issue #98 - July/August 2015 - 43

tanks

Natural gas tanks take the pressure with
high-performance thermoplastics

By
tim vorAge,
globAl inCubAtor mAnAger
dsm engineering plAstiCs

A combination of two of DSM's 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, the
company is able to reduce the weight of the tank by up to 70%.
set or thermoplastic resins, including the
EcoPaXX® polyamide 410.

Liner material
Akulon Fuel Lock contains an additive formulation that further improves the already
strong gas barrier properties 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, the 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 moulding of liners for large
pressure vessels for heavy duty vehicles such
as buses and trucks. It is normally difficult to
make large blow mouldings 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 2 m, enabling high precision control of the wall thickness.

Focus
"In the process developed by Covess for making Type V pressure vessels, you can balance weight,
performance, and economics by using glass, carbon or even hybrid fibres," says Tony Vanswijgenhoven, Director of Covess, a specialist in advanced thermoplastic composite vessels for a wide
range of applications, who is working closely with DSM. "Whatever choice you make, it always
works out lighter than the existing comparable type IV tanks."

Automobile natural gas tanks take the pressure
with composites in DSM high-performance
thermoplastics

Tape reinforcement
In current Type IV pressure vessels, the tape
reinforcement comprises either glass or carbon fibres in a thermosetting polymer, such
as an epoxy or unsaturated polyester. The
company is cooperating in the development
of next-generation Type V pressure vessels.
These are made by winding a tape, developed
by DSM, of continuous fibre 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, have better
chemical resistance (no corrosion), and
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. n
More information:

No98 July - August 2015 /

www.dsm.com/automotive
www.akulon.com
www.ecopaxx.com

Feature Automotive

ydrogen 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 CO2 emissions by 15%
compared to current solutions using petrol
or diesel fuel. A traditional steel tank of 40
l weighs around 60 kg, while a composite
'Type IV' tank with an 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.
Type IV pressure vessels are based on plastics and continuous fibre reinforcements,
unlike Type I, II and III pressure vessels,
which contain metal components. DSM
presented a tank with a liner blow moulded
in its Akulon Fuel Lock, a polyamide
6-based engineering plastic with very high
hydrocarbon barrier properties. The tank
can be wrapped in a tape based on thermo-

jec composites magazine 43

http://www.dsm.com/automotive http://www.akulon.com http://www.ecopaxx.com

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #98 - July/August 2015