Isolation And Characterization Of Cellulose Nanocrystals From Oil Palm Trunk
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Date
2016-09
Authors
Lamaming, Junidah
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Abstract
This study investigated the properties of cellulose nanocrystal (CNC) isolated
from oil palm trunk (Elaeis guineensis) (OPT). Six types of CNCs were extracted from
OPT using two different methods. Four types of CNCs were derived from the OPT as
a whole that is CNCs from raw and water treated and also from separated parenchyma
and vascular bundle of OPT using chemo-mechanical followed by sulfuric acid
hydrolysis. Two more types of CNC with and without water pre-hydrolysis were
prepared by soda pulping followed by ozone bleaching and hydrolyzed with
hydrochloric acid. Physical and chemical properties, thermal behaviour, and also
crystallinity index of all obtained CNCs were determined using scanning electron
microscopy (SEM), transmission electron microscopy (TEM), zeta potential,
elemental analyzer, fourier transform infrared (FTIR), thermogravimetric analysis
(TGA) and X-ray diffraction (XRD), respectively. The results showed individual fiber
of rod-shape particle with a nano-sized average diameter and length in all cellulose
nanocrystals produced. The FTIR spectra indicated that the peaks attributed to lignin
and hemicelluloses were absent after chemical and pulping treatment and seems that
both components were completely removed from the samples after acid hydrolysis.
Thermogravimetric analysis displayed that the thermal stability in all materials
increased after acid hydrolysis. The TGA curves showed that both cellulose
nanocrystals from parenchyma and vascular bundle have good thermal stability with
higher values observed for parenchyma compared with vascular bundle cellulose
nanocrystals. Even though sulfur content giving a stable CNC suspensions, however,
it was affecting the yield and the onset temperature of the CNCs isolated using sulfuric
acid due to the negative charged of sulfate group. The XRD analysis showed that
crystallinity increased after acid hydrolysis indicating the crystalline nature of the
isolated nanocrystals for all samples. Cellulose nanocrystals isolated using ozone
bleaching and hydrochloric acid hydrolysis showing the highest crystallinity that is 75 %
even though cellulose degradation occurs in the ozone bleaching stage. Cellulose
nanocrystals isolated using soda pulping followed by ozone bleaching and hydrolyzed
with hydrochloric acid showed greater properties in terms of dimensions, thermal and
crystallinity as compared to the cellulose nanocrystals isolated using chemomechanical
followed by sulfuric acid hydrolysis. Further works were carried out to
produce bio-nanocomposite films. The chosen cellulose nanocrystals were
incorporated with polyvinyl alcohol (PVA) with solvent casting technique. The PVA
films reinforced with several cellulose nanocrystals contents (0, 1, 3, and 5 wt %) were
casted and were evaluated for their mechanical and physical properties. The result
displayed excellent compatibility between matrix (PVA) and reinforcement (CNC)
which is responsible for the increasing in mechanical properties of PVA/CNC films.
Thermal stability increased with the incorporation of the CNC into PVA matrix. From
the FTIR spectra and XRD analysis, the incorporation of CNC did not have an effect
on the crystallinity of the PVA matrix. The results showed a good mechanical, physical
and thermal properties of the PVA/CNC bio-nanocomposite films.
Description
Keywords
The properties of cellulose nanocrystal (CNC) isolated , from oil palm trunk (Elaeis guineensis) (OPT).