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Online measurements for nanocellulose films and coatings

Reliable and accurate online quality measurements are needed when approaching large-scale conversion of nanocellulose films and coatings. Three different non-contact measurement technologies to measure coating thickness were evaluated and compared in a Master's thesis work. Optical confocal displacement sensing was found most suitable for the microfibrillated cellulose materials.

Abundant research efforts are being made towards enabling high-throughput processing of nanocellulosic materials into end-use products. Examples of such products are nanocellulosic thin-film structures, such as standalone films and coatings. Application areas include printed electronics, food packaging and biomedicine. Similar to any industrial process, quality control systems are required also for nanocellulose conversion.

In the Master's thesis of Aayush Kumar Jaiswal, different online measurement techniques that could be utilized in industrial process control of nanocellulose-based films and coatings were studied. The materials to be measured were microfibrillated cellulose (MFC) and cellulose nanofibrils (CNF) in dry and wet state.

The work dealt with non-contact thickness measurement of nanocellulose coatings applied on polypropylene film, polyether sulfone membrane and stainless steel belt. Three non-contact methods; NIR spectroscopy, IR thermography, and optical confocal displacement sensing (OCDS) were tested.

OCDS was found to be the most accurate technique for measuring the thickness of MFC films, with a root-mean-square error of 9.3% for wet films and 29.1% for dry films.

However, IR thermography produced the best results for CNF films, with an error of 26.1% and 13.2% for wet and dry films, respectively.

For more information, please contact

Ulla Forsström, Principal Scientist, +358 40 8202 191, ulla.forsstrom@vtt.fi

Master's thesis and Website

The thesis can be downloaded by clicking here.

NanoTextSurf project: http://www.nanotextsurf.eu/


An optical confocal displacement sensor is measuring the thickness of a nanocellulose film.


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