Investigation of surface properties of physico-chemically modified natural fibres using inverse gas chromatography

Inverse gas chromatography (IGC) is a suitable method to determine surface energy of natural fibres when compared to wetting techniques. In the present study, the surface properties of raw and modified lignocellulosic fibres have been investigated by IGC. The fibres chosen for the study were flax, hemp, kenaf, agave, agave hybrid, sisal and pineapple. The treatments used were 4% NaOH and 2% zein. The uniqueness of zein treatment is that it is bio-based and therefore maintains the biodegradable character of the natural fibres. Fourier transform infrared spectroscopy (FTIR) and environmental scanning electron microscope (ESEM) were also performed to characterize the surface changes in fibres. The surface properties of fibres are influenced by the chemical composition, crystallinity and morphology of the fibres. Bast fibres exhibited higher surface dispersive energy than leaf fibres. The raw fibres have a predominant basic character, whereas the alkaline treatment makes the fibres more acidic. Both alkaline and zein treatments decrease the dispersive surface energy and the specific free energy of adsorption.

Research highlights▶ γSD was found to be dependent on chemical composition, crystallinity and morphology. ▶ Natural fibres were found to have a predominant basic character. ▶ The alkaline treated fibres change the acid-base properties to a Lewis acid surface. ▶ Chemical treatments decrease the specific and dispersive interaction active sites.