JEC COMPOSITES MAGAZINE - Issue #84 - October 2013 - 50

P.U.
lent fibre/matrix bond, which contributes to the outstanding mechanical and
dynamic properties of the polyurethane
composite. Generally, the cured polyurethane infusion resin exhibits outstanding
tensile, compressive and flexural strength,
as well as excellent compressive modulus
of elasticity and tensile modulus of elasticity in the direction of and perpendicular
to the fibre. For example, in tensile tests
perpendicular to the fibre, epoxy resin fails
far earlier because it is relatively brittle, and
tears.
By contrast, the polyurethane resin is more
flexible and does not exhibit the brittle
fractures commonly seen during tensile
tests of epoxy resin (see Figure 1). Consequently, no premature laminate damage is
seen in similar load situations. The excellent long-term dynamic fatigue strength
of the polyurethane resin deserves special
mention. In fatigue tests in the direction
of the fibre based on DIN 50100 (Wöhler
tests), it proved far stronger and therefore

more stable in the long term than standard
epoxy resin - even after over a million load
cycles (see Figure 2).

Even suitable for very
long rotor blades
The excellent mechanical properties of
the polyurethane system, its low heat
generation during curing and the fact that
it barely shrinks while solidifying make it
easier to produce thick-walled and large
components. This means that the polyurethane resin can also be used to produce
very long rotor blades with ease.
State-of-the-art facilities are already in
place for the solvent-free production of rotor blades made of polyurethane infusion
resin. In cooperation with Bayer MaterialScience, HÜBERS Verfahrenstechnik
Maschinenbau GmbH (Bocholt, Germany) has developed and tailored a manufacturing technology that enables controlled
and therefore constant mould filling. Highlights of the technology include extremely

Fig. 3: Windpower station

careful degassing of raw materials and a
precise metering and mixing technology
that enables continuous, bubble-free and
demand-based mixing of the polyurethane
raw material components isocyanate and
polyol. This way, the polyurethane reaction resin always delivers the same quality
during the infusion process. This results in
a filling process with fixed, reproducible
fill times. The filling speed and pressure
can also be controlled during the infusion
process. n
More information:
www. bayer.com

Rocky waters call
for steady performers.

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With Maxguard™ gelcoats and AME™ and Aropol™ resins, Ashland is pushing marine
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spans, Ashland's suite of gelcoats and resins offers unparalleled choices for builders. For more
information on how Ashland can help you craft the finest boats, visit ashland.com or email
PMeuropesales@ashland.com.

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50 jec composites magazine / No84 October 2013

With good chemistry great things happen.™

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JEC COMPOSITES MAGAZINE - Issue #84 - October 2013

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