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ficantly smaller piece counts, they are produced in a
heat forming process. By the end of their first development
year, they had already received approval from
the German Federal Motor Transport Authority that
covers not only roof glazing but also rear and fixed
side windows. This meant that concrete projects with
customers could be started as early as the second year
of the project house. Various automobile manufacturers
are currently conducting street tests of the
first PLEXIGLAS® glazing in prototype vehicles.
In another project, the developers investigated
how a photovoltaic function might be integrated into
the roof glazing. The challenge for developers of
these power-supplying variants is that the PV cell and
polymer composite show different thermal expansion
coefficients. To ensure that the solar cells do not tear,
the researchers developed a sandwich structure, in
which the optically active cells are embedded in an
elastomer matrix that is decoupled from the exterior
PLEXIGLAS® composite layers. They have developed
three different processing techniques in all for manufacturing
such composites.
These composites, however, are flat PV semi-
finished products that still have to be formed into the
spherical shape of the roof glazing. The developers
have successfully advanced these to prototype status:
To make them operational, they produced prototypical
roofs for a standard subcompact car, including
A sandwich made of rOHACeLL® rigid foam and fiber composite top layers
is ideally suited to lightweight construction in the vehicle: this method of construction
allows a unique combination of low weight and maximum mechanical stability
PRoJeCt HoUse sYsteMs InteGRAtIon
roof glazing with integrated PV cells and transparent
roof glazing without PV integration. Evonik’s objective
is to gather practical experience with this demonstration
vehicle and, at the same time, convince
automobile manufacturers and potential customers
of the benefits of PLEXIGLAS® glazing solutions.
Transparent glazing:
The first prototypes have
already hit the streets
Evonik’s ROHACELL® rigid foam also makes a
big contribution to the lightweight construction in
the vehicle: In combination with high-strength cover
layers, it creates an extremely rigid composite that
finds potential applications in both the interior and
exterior. Concrete applications have been and are
now being tried out in numerous projects with
customers: From construction components with
rather simple requirements, such as rear seat backs,
all the way to structurally relevant components,
where ROHACELL® composites are far superior to
conservative construction methods when it comes to
energy absorption and stiffness.
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elements39 Issue 2|2012