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.
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The properties of cellulose nanocrystal (CNC) isolated , from oil palm trunk (Elaeis guineensis) (OPT).
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