Browsing by Author "Faria, Helena"
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- Dwarf cavendish as a source of natural fibers in poly(propylene)-based compositesPublication . Faria, Helena; Cordeiro, Nereida; Belgacem, Mohamed Naceur; Dufresne, AlainComposite materials were prepared by com pounding and hot-pressing PP or MAPP and lignocellulosic fibers extracted from the rachis of Musa acuminate Colla var. Dwarf Cavendish banana tree. The fibers were used as raw filler or after a chemical treatment expected to remove most of the extractible compounds. The resulting materials were characterized using SEM, DSC, DMA, tensile tests and water sorption experiments. All results show that the main aspect involved in the interfacial adhesion between the polar filler and the non-polar matrix is the extraction of lignin and fatty substances. This results in higher values of the degree of crystallinity and crystallization temperature of the matrix, higher mechanical properties and lower water sensitivity. Scanning electron micrograph showing the cross section of the lignocellulosic filler obtained from rachis of banana tree: (a) raw, and (b) extracted fibers.
- Surface modification of banana-based lignocellulose fibresPublication . Cordeiro, Nereida; Oliveira, Lúcia; Faria, Helena; Belgacem, Mohamed Naceur; Moura, João C. V. P.Lignocellulosic raw materials were isolated from rachis of Musa acuminata Colla var. cavendish and characterised before and after chemical modification. The rachis was submitted to different mechanical treatments, milling and defibration, resulting in rachis powder and rachis fi bers, respectively. The chemical composition of these two samples was established and it was shown that rachis fibres exhibited higher polysaccharide and lignin contents and lower amounts of ash and extractives components, as compared with the rachis powder. The effects of solvent extrac tion, alkali treatment and chemical modification using phenyl isocyanate, maleic anhydride, alkenyl succinic anhydride and alkyl ketone dimer as grafting agents were studied. The materials were characterized in terms of chemical structure by ATR–FT-IR and 13C-CP-MAS-NMR spectroscopy, morphology by scanning electron microscopy and surface energies by inverse gas chromatography and contact angle measurements. The surface energy of these materials was found to be very close to other similar lignocellulosic materials. Finally, the water absorption of these materials before and after treatment was ascertained. The modified fibres showed considerable changes in ATR–FT-IR and 13C-CP-MAS-NMR spectra and surface properties, providing very convincing evidence that chemical grafting had occurred.