Spectroscopic characterization of engineered lignocellulosic fibers with mono-substituted polysiloxane films

The present investigation relates to the changes of the chemical compositio n and chemical binding states of the component elements in the surfaces of two different lignocellulosic fibers during the pre-coating process. Both C -13 and Si-29 NMR spectroscopy studies provided information on chemical bon d formation between selective polysiloxanes and lignocellulosic materials. A thin film of siloxane was formed on the fiber surfaces and was found to b e bonded through single oxygen atoms. In addition, the thin film coating is characterized relative to substitution with functional groups such as fluo rine, thiol and amino groups. An X-ray photo-electron spectroscopy (XPS) st udy of the uncoated and coated surface of lignocellulosic fibers demonstrat ed that the relative oxygen contents and the existence ratios among the COO , C=O, C-O-C, C-OH, C-N, C-F and CS changed significantly with the pre-coat ing operation. In addition, it was revealed that lignocellulosic fiber prod uced by thermomechanical pulping (TMP) of a wood species reacted differentl y from a lignocellulosic fiber produced by refiner mechanical pulping (RMP) of a non-wood fiber. The changes in the composition ratios and binding ene rgies support the progress of following three phenomena on the surface of t he fiber during the impregnation and drying process: i.e. deposition of ult ra thin film of polysiloxanes, chemisorption of the deposited compound, the rapid reaction of selective polysiloxane with lignocellulose.