Characterization of fiber wall surface structure of chemically modified TMP fibers from Norway spruce

Effects of chemical treatments on micro and nano scale surface structure of 1st stage TMP latewood fibers from Norway spruce were investigated. The chemicals applied were buffered sodium oxalate and hydrochloric acid. The outer as well as the inner fiber wall layers of the untreated and chemically treated fibers were separately analyzed by light microscopy, Atomic Force Microscopy (AFM) and Field-Emission Scanning Electron Microscopy (FE-SEM). The applied characterization methods allow to demonstrate the effect of different treatments on the fiber surface structure, both visually and quantitatively. The outer fiber wall areas (ML/P) appeared as intact bands surrounding the fiber and they were clearly rougher than areas of exposed inner fiber wall (S2). The roughness of the outer fiber wall areas increased most in the sodium oxalate treatment. The results indicated formation of more surface pores on the exposed S2 fiber wall areas than on the corresponding outer fiber wall areas as a result of the chemical treatments. The hydrochloric acid treatment seemed to increase most the surface porosity of the S2 wall areas.