Abstract
Dwarf-green coconut fibers were modified by alkali treatment and
characterized by scanning electron microscopy (SEM), X-ray diffraction
(XRD), Fourier transform infrared spectroscopy (FT-IR), as well as
thermogravimetric (TGA), mechanical, and dielectric analyses. Changes in
composition, structure, and morphology of the coconut fibers were
observed after sodium hydroxide treatments due to the removal of lignin,
hemicellulose, and other impurities. The XRD data were in agreement with
the morphological analysis, where the crystallinity fraction increased
with the concentration of alkali solution and fell off above 10%. The
infrared spectrometry showed the partial dissolution of hemicellulose,
lignin, and pectin, which was clearly identified by the band at 1736
cm(-1). Thermogravimetric analysis showed a double degradation process
for the untreated dwarf-green coconut fibers, while a single one was
observed after the pretreatment. The tensile properties showed an
increased elongation at break, modulus, and strength, and the dielectric
results showed a decrease of all parameters (permittivity, dielectric
loss, and conductivity), reflecting the reduced dipole and ion mobility
associated with the loss of amorphous components.
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