Technology Guide Principles – Applications – Trends - hhimawan

Standard foam Nanofoam
pore size > 100 µm
100 µm
200µm
therm. conduct. > 30 mW/Km
pore size > 0.5 µm
0.1µm
500nm
therm. conduct. < 15 mW/Km
� Functional principle of nanoporous foams: Standard foams
have a pore size of 100 μm, which corresponds to 10 cells per
millimetre. Nanofoams have a drastically reduced pore size of less
than 0.5 μm, which corresponds to 2000 cells per millimetre. In
nanofoams, the number molecules per cell is so low that the
molecules do not “see” or transfer energy to each other. As a consequence,
insulation efficiency is greatly improved. Source: BASF
about by microencapsulated heat storers that use paraffin
wax. This material acts as a thermal buffer: during
the day, the wax heats up and liquefies, absorbing
large amounts of energy. During the night, when the
outside temperatures fall, the wax solidifies, releasing
the energy. The amount of energy stored and the temperature
at which the phase transitions occur depend
greatly on the material. The length of the hydrocarbon
molecule is the determining factor in paraffin waxes:
paraffin with a chain length of 16 carbon atoms melts
at about 20 °C, while chains with 18 atoms need 28 °C.
Melting points between 6–60 °C can therefore be selected
by choosing a different chain length. The challenge
is to integrate the melting wax safely into building
materials like wall plaster, mortar or gypsum
boards. The process is called microencapsulation: tiny
droplets of wax are enclosed in a virtually indestructible
polymer capsule that can withstand even drilling
and sawing.
Prospects
5 Polymers will continue to stimulate future development
trends in a number of industries, including
automotive, packaging, construction and
electrical sectors. They will increasingly supplant
classical engineering materials, such as metals, as
temperature
5
5
5
sensible
phase transition
temperature
latent
latent heat
new properties (e. g. conductivity) are successfully
introduced. Strong growth is particularly foreseen
in medical and electronics applications, especially
in connection with nanosized structures.
Manufacturing plastics as bulk material will give
way to custom designing of plastics for specific applications.
A growing understanding of the effects of the su-
pramolecular structures – and combining physical
findings and phenomena with chemistry and biology
– will open up a new range of applications for
polymers in the years ahead.
The combination of polymers and specific na-
noscale structures will produce materials that play
a key role in solving problems that must be faced in
the years ahead, including resource conservation,
reduction of energy consumption and generating
power.
Prof. Dr. Franz Brandstetter
Dr. Jens Assmann
BASF AG, Ludwigshafen
sensible
sensible
heat flow
� Latent heat is the amount of energy required by a substance
when passing from one phase to the other – for example from ice
to water or from water to steam. It is called latent, because it is not
apparent in the form of temperature differences. This is why a
melting ice cube removes large amounts of heat from the surrounding
liquid and keeps a long drink cool for a prolonged period
even in summer. Because melting 1 kg of ice at 0 °C requires a
whopping 330 kJ – the same amount of energy could heat the
cold water to about 80 °C. Right: The sun heats the room. At a
temperature of 26 °C, the wax begins to melt and absorbs the excess
heat. The wax is microencapsulated in a high­strength acrylic
polymer shell and these capsules are embedded in a matrix of
gypsum. Source: BASF
Internet
5
www.e­polymers.org
5 µm
5 http://plc.cwru.edu/tutorial/
enhanced/files/polymers/
apps/apps.htm
5 www.cem.msu.edu/~reusch/
VirtualText/polymers.htm
5 http://openlearn.open.
ac.uk/mod/resource/view.
php?id=196651&direct=1
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