In-plane moisture variations and the effect on out-of plane deformation and paper properties

Background
Modern papermaking is a highly automated and advanced process. In the beginning of the process, a dilute suspension consisting of approx. 1% fibres and 99% water is distributed evenly on a permeable wire running up to 100 km/h. This means that approx 100 kg of water has to be removed to manufacture 1 kg of paper. It is of vital importance for the properties of the final paper that the water is removed in a uniform way. In-plane variation in moisture content may have negative effects on the strength and visual appearance of the paper. It has e.g. been shown that small scale variations in in-plane moisture content may result in out-of-plane deformation (cockling).

Project description
The goal whit this project is to make a detailed lab-scale investigation of in-plane moisture variations and the effect on out-of-plane deformation and paper properties (strength and optical). The project will include the design of model experiments where a controlled amount of moisture is added to handsheets. The out-of-plane behavior during drying will be studied for different in-plane straining conditions. The out-of-plane deformation can be studied under both static and dynamic conditions using available stereoscopic imaging equipment. The findings will, if time permits, be compared to moisture variations observed on commercial paper machines (measured using a novel approach based on high-speed infrared thermography).

Time plan and required background
The work is planned to last 20 weeks, starting August/September 2010, and will be performed at Innventia in Stockholm. The project is suitable for 2 persons. The candidates should preferably be final year students in a suitable M.Sc program, e.g. mechanical engineering, applied physics, chemical engineering or equivalent. Applicants should have an interest in practical laboratory work as the project involves the design of model experiments.

Contact
Fredrik Rosén
[email protected]
08-6767334

To apply, please send:
–Motivational letter/email
– CV