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Sanna Siljander: Ecological electrical conductivity from the combination of nanocellulose and carbon nanotubes

Tampere University
LocationHervanta Campus, Festia building, auditorium FA032 Pieni Sali 1 (Korkeakoulunkatu 8, Tampere)
Date4.11.2022 10.00–14.00
Entrance feeFree of charge
For the first time, foam forming has been used to make a three-dimensional heating element from a cellulose-based composite material providing comfort heat. The bio-based, intelligent heating element is the work of M.Sc. Sanna Siljander. In her dissertation, Siljander studied nanocellulose-carbon nanotube nanocomposites on which the innovation is based on.

Known as Salmiakki, the heating element was designed and manufactured in collaboration between researchers from the University of Tampere, Aalto University and VTT. Further processing of the innovation utilized techniques familiar from composite manufacturing. The embossed heating elements were implemented in the Liune intermediate door within the Pyörre house and presented to the general public at the Lohja Housing Fair 2021.

Neither innovation would have seen the light of day if there had not been systematic research on carbon nanotube dispersions and nanocellulose carbon nanotube nanocomposites. Sanna Siljander's dissertation “Nanoarchitectonics of nanocellulose — carbon nanotube composites: from dispersion to functional structures” is based on these studies.

– Nanoarchitectonics is a concept that combines several fields of research and technologies, including materials science, nanotechnology, and chemistry. When working with nanomaterials such as nanocellulose and carbon nanotubes, this interdisciplinary combination is utilized to help overcome the challenges that arise, explains Siljander.

Study helped reduce chemicals in manufacturing nanocomposites

In her doctoral thesis, Sanna Siljander studied two-, three- and four-component systems and identified parameters that influence interactions between nanomaterials. She also studied how the properties of the nanocomposite being manufactured can still be modified even after manufacturing.

– My goal was to use only the minimum amount of materials, chemicals and energy in the manufacture of composites, Siljander says.

She succeeded in greatly limiting the number of chemicals used in the research by selecting chemical types and quantities so that nanocomposites would have optimal functionality.

– In addition, I used chemicals in a dual role when processing composites and this further reduced the amount of chemicals needed. The need for energy also decreased as I successfully combined work steps in composite processing and optimized parameters, she says.

The pivotal discovery of the PhD research relies on the mutual size differences between materials when nanocellulose and carbon nanotubes are combined. This finding has not been previously reported in the literature.

– Generally, nanocellulose is processed to the smallest size range possible, but I found this to be disadvantageous when pursuing good electrical conductivity for a combination of nanocellulose and carbon nanotubes, she notes.

Sanna Siljander holds the unofficial world record for electrical conductivity for nanocellulose carbon nanotube nanocomposite.

Sanna Siljander's dissertation in the field of Materials Engineering, M.Sc. (Tech.) Nanoarchitectonics of nanocellulose — carbon nanotube composites: from dispersion to functional structures will be publicly inspected at Tampere University Faculty of Technology and Natural Sciences on Friday 4.11.2022 at 12 o'clock at the Hervanta campus, in the hall of the Festia building FA032 Pieni Sali 1 (Korkeakoulunkatu 8, Tampere). Opponents will be Professor Kristiina Oksman of Luleå University of Technology and Professor Eero Kontturi from Aalto University. The custos is Professor Jyrki Vuorinen from Tampere University.

The doctoral dissertation is available online.