CD Laboratory for Surface Chemical and Physical Fundamentals of Paper Strength

The chemical and physical fundamentals of the fibre-fibre bond in paper are being researched. A deeper understanding of this bond will enable the creation of stronger paper and thus also new areas of application for paper.

Paper consists of a network of cellulose fibres. The strength of the individual fibres together with the bond between the fibres (fibre-fibre bond) determine the strength of the paper. Relatively much is already known about the characteristics of the individual fibres, but little is known about the fibre-fibre bond. For this reason, the main chemical and physical aspects that determine this bond are investigated here.

An important point here is the chemistry of the fibre surface, which is investigated using special spectroscopic methods such as Fourier transform infrared spectroscopy. Another aspect is the contact surfaces of the bonded fibres. The spatial shape (morphology) of this bonding surface, but also of the fibre itself and the fibre braid, is analysed using a microscopic imaging method. For this purpose, a fibre braid is cast in synthetic resin and cut into micrometre-thick slices. Following the microscopic analysis of the individual slices, the spatial conditions are reconstructed by computer-aided composition of the individual images.

An atomic force microscope at the University of Leoben allows mechanical scanning and visualisation of the fibre surface. The actual strength of the fibre-fibre bond is also determined there. The morphology of fibre fracture surfaces in the nanometre range is also analysed.

The new findings will make it possible to develop a model for paper strength. This will have a fundamental influence on the understanding of paper strength. Its application in paper production will make it possible to strengthen the fibre-fibre bond and thus create stronger papers. This will open up new application possibilities, particularly for the packaging industry.