Conductive And Water Dispersible Nanocomposite Prepared From Polyaniline And Polypyrrole Based On Oil Palm Empty Fruit Bunch Nanocrystalline Cellulose
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Date
2015-10
Authors
AHMED AL-DULAIMI, AHMED ABDULKAREEM
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Abstract
Nanocrystalline cellulose (NCC) was isolated from oil palm empty fruit bunch totally chlorine free pulp (OPEFB-TCF) via sulfuric acid hydrolysis and ultrasonic treatment. The effects of acid concentration and hydrolysis time on the NCC properties were investigated. Characterization of OPEFB-NCC was carried out using TEM, SEM, FTIR, CP/MAS 13C-NMR, XRD, zeta potential, and TGA. The results shown that the optimum acid concentration for sulfuric acid hydrolysis of OPEFB-TCF pulp is 58%. The optimal hydrolysis time was 80 min, resulting in the removal of most of the amorphous region as indicated by the ‘leveling off’ of the NCC dimensions (length 150 nm and diameter 6.5 nm); furthermore, there was no significant loss of crystallinity at this point. The presence of a 1200 cm-1 shoulder peak in the FTIR spectrum of OPEFB-NCC indicates the presence of a sulfate group that was acquired during hydrolysis. In addition, the MAS 13C-NMR analysis suggests that the cellulose pulp underwent structural changes during hydrolysis, indicating that most of the amorphous region had been removed. There is also a strong possibility that sulfonation not only occurred on the C6, but also on C2, C3 and C5. OPEFB-NCC isolated over shorter hydrolysis times was more stable thermally; however, the char fraction decreased with hydrolysis time despite having a higher zeta potential. The influence of reaction time on the NCC surface charge
was investigated using zeta potential measurement. Zeta potential measurement showed that the surface negative charge significantly increases with increasing reaction time. Water-dispersible polyaniline (PANI) and polypyrrole (PPY) were successfully synthesized by the chemical oxidation reaction of ammonium persulfate (APS) as an oxidant in an aqueous suspension of OPEFB-NCC. These conductive polymers were characterized using TEM, SEM, FTIR, XRD, TGA, thermal conductivity and cyclic voltammetry analysis. The electron microscopy results revealed that the new nanocomposite exhibits notable alteration in its morphology from nanospheres to nanofibers due to the presence of the nanocrystalline cellulose. The FTIR test detects the entire corresponding bands, hence proving that there exists a composite between the two materials. The XRD result of PANI-NCC shows significant improvement in the composite due to the presence nanocrystalline cellulose that was added during the polymerization process. Thermal stability spectra all show the main peaks for both components and also the subsequent new thermal properties of the composite. The cyclic voltammetry test proved the electrochemical activity for the CPs nanocomposites via redox activities. Thin layers of PANI-NCC and PPY-NCC were successfully deposited on the surface of paper substrate without any chemical binder or surface modification. Electrical and mechanical properties were investigated under different pH values, the latter controlled by adding proper amounts of hydrochloric acids (HCl) to the nanocomposite solution. Electrical conductivity shows significant improvement associated with the decreasing of pH value. Mechanical properties of the conductive paper showed remarkable results with an increase of the amount of dopant in terms of tensile strength and elongation at the break.
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Conductive And Water Dispersible Nanocomposite Prepared From Polyaniline , And Polypyrrole Based On Oil Palm Empty Fruit Bunch Nanocrystalline Cellulose