Papers by Author: Siti Hasnawati Jamal

Abstract: Nitrogen content is a paramount significance in predicting nitrocellulose. Nitrocellulose with high nitrogen content (>12.5%) can be used for propellant, while low nitrogen content (<12.5%) can be applied for the production of ink, paint and leather finishes. In this preliminary study, the effect of mole ratio of sulphuric acid to nitric acid, reaction temperature and time towards nitrogen content in nitrocellulose was investigated. Nitrocellulose was synthesized using nata de coco as bacterial cellulose source via nitration method. Nitrocellulose with percentage of nitrogen content of 11.74% to 12.75% was obtained when 2 to 4 mole ratio of sulphuric to nitric acid was used with operating temperature and time ranging 20°C to 40°C and 20 minutes to 40 minutes respectively. Analysis of Fourier transform infrared (FTIR) displayed the reduction of hydroxyl group in nitrocellulose proving that several hydroxyl group in cellulose was successfully replaced by nitryl group. Other characterizations such as elemental analyser, X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) were evaluated to support the result.

Abstract: Cellulose nitrate has attracted great interest amongst researchers due to its uses in wide range of products including paint and gun propellant. Therefore, this work focuses on the synthesis of cellulose nitrate from two different sources of cellulose; plant and bacterial, in order to obtain high percentage of nitrogen content hence suitable for propellant application. The synthesis of cellulose nitrate was carried out via nitration method using nata de coco and kapok (Ceiba pentadra L) as a raw materials of cellulose. The samples were then characterized by elemental analysis, fourier transform infrared (FTIR) spectroscopy, x-ray diffraction and surface electron morphology (SEM). FTIR analysis showed the presence of NO₂ groups in both nitrocellulose proving that nitrocellulose was successfully synthesized by nitration method even though it was produced from different sources of cellulose. It is also showed nitrocellulose with high percentage of nitrogen content was obtained from bacterial cellulose, 12.69% rather than plant cellulose.

Abstract: A simple, low cost and rapid analytical method for determination of HCl concentration after being treated with cellulose and cellulose nanofibers (CNF) is developed. This method is based on color intensity after the HCl solution is doped with sodium iodide (NaI). The color of HCl solution changes from colorless to yellow. The intensity of the color is measured by UV – Visible spectroscopy. The UV-Visible spectra of 0.15 M HCl treated with cellulose and cellulose nanofibers is reduced from its initial concentration. The CNF absorption capacity is higher as compared to cellulose. FT-IR analysis showed that there is interaction between C-H group from the CNF backboned and chloride ion from HCl solution.

Abstract: Current world events have made several countries as a target for terrorism. Chemical weapon such as nuclear weapon is commonly referred as a weapon of mass destruction. Organophosphorus (OP) compounds have long been used as pesticides and developed into warfare nerve agents such as tabun, soman, sarin, and VX. They are highly toxic and considered to be the most dangerous chemical weapons. Development on the protection material against OP compounds has gained interest among researcher. Nanocellulose has shown a great potential for high-performance filtration material due to its interesting characteristics such as high adsorption capacity, large surface area, high strength, renewable, chemical inertness, and versatile surface chemistry. Therefore, the evaluation of the chemical interaction between nanocellulose and organophosphorus is important. The analyses of fourier-transform infrared spectroscopy (FT-IR), ultraviolet-visible (UV-Vis), and elemental analysis were carried out in this study. It was found that the nanocellulose is capable to adsorb OP compound by forming the hydrogen bonding. The adsorption rate was increased as the nanocellulose concentration increased. This is the initial step to discover the potential of nanocellulose to be used in military protection mask.

Abstract: Understanding molecular electronics is critical in advance of organic devices. Intermolecular interaction between copper phthalocyanine (CuPc) and multi-walled carbon nanotubes (MWCNT) was studied using infrared spectroscopy and confocal Raman microscope. The organics were prepared using solution processing method at ambient atmosphere. The infrared spectrum showed the signal from the lower wavenumber was largely dominated by broad absorption and the lacking of ‘fingerprints’ peaks provided no information on the MWCNT. Raman absorption spectra under normal (λ = 532 nm) and resonant (λ = 633 nm) were obtained to tackle the disadvantages in the former method. Fingerprint peaks of CuPc in frequency of 600 - 1600 cm^-1 emerged under both excitation wavelengths. New 480 cm^-1, 1100 cm^-1 and 1300 cm^-1 peaks were found in resonant spectra. There were no strong evidence of presence and interaction between CuPc and MWCNT detected in these measurements possibly due to overlapping vibrational states between the two compounds and insufficient quantity of MWCNT in the sample.

Abstract: Multi walled carbon nanotubes (MWCNTs) were synthesized using floating catalyst-chemical vapor deposition (FC-CVD) with ferrocene and benzene as catalyst and carbon source, respectively. Argon was used as a purging gas while hydrogen was used as a carrier gas. Hydrogen flow rate, reaction time and reactor temperature were varied to obtain high yield and purity of MWCNTs. The morphology and microstructures of MWCNTs produced were studied using Scanning Electron Microscopy (SEM). It was found that the maximum yield and purity of MWCNTs were produced at hydrogen flow rate of 300 ml/min with reactor temperature of 900°C and reaction time 45 minutes. It was observed that the MWCNTs are film-like, randomly oriented and in some cases entangled with uniform diameter.