The primary cell wall studied by dynamic 2D FT-IR:: Interaction among components in Norway spruce (Picea abies)

Knowledge on the interactions among the wood polymers, viz. cellulose, hemicellulose, pectin, lignin and protein, in the outer fibre wall layers is essential for understanding fibre separation in thermomechanical and chemithermomechanical pulping processes. For this reason, dynamic two-dimensional Fourier Transform Infra-Red (2D FT-IR) spectroscopy was applied to examine the interaction of these components in the primary cell wall of spruce fibres. Sheets made of an enriched primary cell wall material were used for studying the viscoelastic response to loading. The dynamic 2D correlation FT-IR spectra indicated the existence of strong interactions between lignin and protein, as well as among pectin, xyloglucan and cellulose, in the primary cell wall. This is in contrast to the picture for the secondary cell wall, in which cellulose-glucomannan and xylan-lignin interactions are prevailing.