Browsing by Author "Pothan, Laly A."
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- Assessment of the changes in the cellulosic surface of micro and nano banana fibres due to saponin treatmentPublication . Cordeiro, Nereida; Faria, Marisa; Abraham, Eldho; Pothan, Laly A.The effect of saponin on the surface properties of banana fibres was studied by Inverse Gas Chromatography (IGC). Parameters including the dispersive component of the surface energy, surface heterogeneity, surface area, as well as acid-base surface properties were determined for saponin modified banana micro and nanofibres. These parameters show a more extensive saponin coating on the nanofibres with a network formation which is explained by the higher reactivity of nanofibres due to the higher surface energy, specific interaction and higher surface area presented by the nanofibres. The energetic profile indicates that both micro and nanofibres coated with saponin interact with the same, or similar, energy active sites. Saponin treatment reduces considerably the surface area of the fibres, with the consequent decrease in the monolayer capacity. The interaction with the polar probes clearly indicates that saponin treatment creates new polar active sites for specific interactions in both samples. However, the treatment increases predominately the basicity of the fibre surface with more relevance to the nanofibres. This behaviour will lead to better polymer/fibre interaction during composite preparation.
- Surface modification of banana fibers using organosilanes: an IGC insightPublication . Alonso, Emanuel; Pothan, Laly A.; Ferreira, Artur; Cordeiro, NereidaBanana fibers are an agricultural waste material with a great exploitation potential due to their cellulose-rich content. Raw banana fibers (RBF) were treated with 3-aminopropyltriethoxy silane and glycidoxypropyltrimethoxy silane to improve the inherent limitations of banana fibers, namely its poor cell adhesion. The fibers’ modification was evaluated by inverse gas chromatography (IGC). Similar cs d values were observed between the RBF and silane-treated fibers (39–41 mJ/m2 ), which indicates similar reactivity towards apolar probes. However, the decrease in the entropic parameter indicates the silane covalent bonding with the cellulose chains making a stiffer structure. Organosilane grafting was confirmed by an increased basic character in the silane-treated fibers (Kb/Ka from 1.03 to 2.81). The surface morphology also changed towards higher contact area (SBET increases 6.7 times) and porosity (Dp increases up to 67%). Both morphological and functional group reactivity changes suggest that the organosilane treatment offers new opportunities for these fibers to be used as adsorbents for proteins as well as to cell adhesion. Therefore, IGC proved a simple and viable technique in the characterization of silane-treated fibers.
- Utilization of various lignocellulosic biomass for the production of nanocellulose: a comparative studyPublication . Deepa, B.; Abraham, Eldho; Cordeiro, Nereida; Mozetic, Miran; Mathew, Aji P.; Oksman, Kristiina; Faria, Marisa; Thomas, Sabu; Pothan, Laly A.Nanocellulose was successfully extracted from five different lignocellulosic biomass sources viz. banana rachis, sisal, kapok, pineapple leaf and coir using a combination of chemical treatments such as alkaline treatment, bleaching and acid hydrolysis. The shape, size and surface properties of the nanocellulose generally depend on the source and hydrolysis conditions. A comparative study of the fundamental properties of raw material, bleached and nanocellulose was carried out by means of Fourier transform infrared spectroscopy, scanning electron microscopy, atomic force microscopy, transmission electron microscopy, birefringence, X-ray diffraction, inverse gas chromatography and thermogravimetric analysis. Through the characterization of the nanocellulose obtained from different sources, the isolated nanocellulose showed an average diameter in the range of 10–25 nm, high crystallinity, high thermal stability and a great potential to be used with acid coupling agents due to a predominantly basic surface. This work provides an insight into the effective utilization of a variety of plant biomass as a potential source for nanocellulose extraction.