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16 PRoJeCt HoUse sYsteMs InteGRAtIon
e-sPInnInG
Fine dust doesn’t stand a chance
One of the technical highlights from the Project House
Systems Integration is a new generation of polymer-based
filter materials that can be used to separate fine dust from the
waste gases of such installations as incinerators or cement
plants. In cooperation with external machine manufacturers,
this electrospinning process, as it is called, has been developed
for the highly temperature-resistant Polyimide P84 all
the way to the pilot production scale. The secret to this
material is fibers with a diameter significantly below one
micrometer: In purely mathematical terms, a purchase order
of one gram of polymer yields a fiber length of about 5,000
kilometers. This creates an extremely finely woven filter
medium.
In electrospinning, a P84 solution is set in an electrical
field under high voltage. When a certain electrical field
strength is reached, the dosing electrode forms a “fiber jet”
in the direction of the counter electrode. The solvent evaporates
and a fine fleece forms on a substrate in front of the
counter electrode. The fibers are then stuck together and
fixed on a stable support fabric. In close cooperation with
the Performance Polymers Business Unit, the developers in
the project house have created the basis for optimizing the
filtration properties of the fiber material with an eye toward
their end application. The newly acquired electrospinning
plant in the project house even allows small-scale internal
pilot production at Evonik Industries. This, in turn, will
enable researchers to evaluate the ability of other polymers
to be spun in this same way.
elements39 Issue 2|2012
A close-meshed
filter medium for
the deposition
of fine particles,
produced by electrospinning
333 But the key to commercial success for these composites
is cost-efficient mass production. This was a
special focus of the project, and there was a surprising
result: There is not just one economical process
but a number of processes that provide the best cost
efficiency, depending on the component and piece
count.
Micromagnets in new
applications
VP MAGSILICA® are highly versatile magnetic particles.
The brownish powder consists of ultrafine iron
oxides embedded in a dense silicon dioxide matrix.
Through induction, VP MAGSILICA® can be heated
to over 500 °C in a few seconds without stirring. So
the push of a button, for example, can generate local
heat, such as that required by chemical crosslinking
reactions, which can be accelerated significantly by
the heat supply. These applications were investigated
in the Bonding on Demand project.
Here, project house employees worked with
equipment manufacturers and the Inorganic Materials
Business Unit to develop new expertise in the inductive
heating of plastics and adhesives, and build a
complete application technology. With the help of
mobile induction units, potential customers conducted
pilot tests in production and addressed a number
of issues: How do we work VP MAGSILICA® into
an adhesive or a rubber? How should we construct
and design the induction apparatus? How do we
achieve the best heat input?
One of the big potential applications for VP MAG-
SILICA® is the crosslinking (vulcanization) of rubber
profiles. In this process, the powder is added in small
concentrations to the rubber formulation and heated
immediately after extrusion, thereby vulcanizing the
rubber. It became clear that the mechanical properties
of the hardened profiles are comparable to conventionally
vulcanized rubbers.
Even modern insulating glass panes can be bonded
faster and easier with the superparamagnetic powder.
Normally, the double panes of modern windows
are placed and bonded together in the edge region by
an aluminum spacer. In order to fulfill the requirements
of the upcoming thermal insulation regulation,
the aluminum will be omitted as a thermal bridge. In
cooperation with a hotmelt adhesive manufacturer,
the project house has developed a mounting process
by which the aluminum spacer can be replaced by
plastic.
Three years of work in the Project House Systems
Integration have been crowned with success: At the
end of the third year, all nine projects are still alive
and continue to look promising. Seven of the nine
projects have already been sent back to the par ti -