Surface modification of nanofibrillated cellulose films by atmospheric pressure dielectric barrier discharge

Abstract

A dielectric barrier discharge in a gas mixture of tetrafluoromethane (CF₄) and O₂ was used for tailoring the surface properties of nanofibrillated cellulose (NFC) films. The surface chemical composition of plasma-modified NFC was characterized by means of X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry, while surface morphology was illustrated by atomic force microscopy. Wettability was characterized through the static sessile drop method. The adhesion between NFC and polylactide (PLA) laminated films was tested by the double cantilever beam technique. As a result of atmospheric pressure plasma treatment, the water contact angle of NFC films increased and the values were comparable with those of PLA films. On the other hand, surface chemical characterization revealed inhomogeneity of the plasma treatment and limited improvement in adhesion between NFC and PLA films. Further research in this direction is required in order to enhance the uniformity of the plasma treatment results.

Keywords:

• adhesion
• compatibility
• contact angle
• hydrophobicity
• polylactide
• nanofibrillated cellulose
• surface roughness

Acknowledgments

The authors acknowledge the kind assistance of Mikael Ankerfors and Åsa Blademo at Innventia AB in producing and supplying the carboxymethylated NFC gel, as well as help from Professor Hans Nørgaard Hansen at the Department of Mechanical Engineering, Technical University of Denmark in making polymer extrusion facilities available for our use The research of István Siró was supported by the Danish Council for Independent Research, Technology and Production Sciences (Project grant: 274-08-0072).