Ahmad Faiza Mohd

Effect of silver (Ag) substitution nano-hydroxyapatite synthesis by microwave processing

Synthetic hydroxyapatite, (HA, Ca10(PO4)6(OH)2), is an attractive and widely utilized bio-ceramic material for orthopedic and dental implants because of its close resemblance of native tooth and bone crystal structure. This HA can be used in bio-implants as well as drug delivery application due to the unique properties of HA. Biomaterials synthesized from the natural species like mussel shells have additional benefits such as high purity, less expensive and high bio compatibility. In this project, a mussel shells were extracted to produce calcium oxide (CaO) sample. The efficient temperature to produced CaO is 1000 °C in 90 minutes. The different contents of silver (0.5AgHA – 6AgHA) are prepared to check the extent of silver substitution for calcium in the HA. Then the mixtures of silver nitrate and CaO are subjected into microwave for 900 W in 30 minutes. The AgHA powder samples were characterized by X-ray diffraction (XRD) technique and also scanning electron microscope (SEM). From SEM analysed, AgHA particles had shown the shape likes needle morphology. In addition, the particles showed high tendency to agglomerate and not dependent on the amount of silver content. From XRD analysed, the samples with Ag content ≥ 0.3 shows the Ag peak clearly at 2θ∼38.2 °. The crystalline size of AgHA from microwave processing is around 14.96 nm – 23.03 nm and does not effected by contents of silver.

Epoxidation of palm oil catalyzed by titanium-grafted silica catalyst

Epoxidation reaction is an important reaction in organic synthesis because the formed epoxides are intermediates that can be converted to a variety of products. Catalytic palm oil epoxidation using titanium-grafted silica, hydrogen peroxide, and peroxoformic acid was carried out at 60 °C in a fixed batch reactor. Titanium-grafted silica with different percentages of silica content was prepared through sol-gel hydrolysis and was utilized in epoxidation of palm oil. Titanium-grafted silica particles and Epoxidized palm oil were characterized by techniques such as Fourier Transform Infrared Spectroscopy (FTIR), Field Emission Scanning Electron Microscope (FESEM) and Nuclear Magnetic Resonance (NMR). The TiOSi bonds were detected at 960 cm-1 in Ti-Si 0.5 and exhibited highest yield of epoxidized palm oil (EPO) in the epoxidation process which is 84% conversion of unsaturation in palm oil to epoxy groups. New peaks observed in the range of δ 2.4 ppm to 3.6 ppm in the NMR spectrum of EPO belong to protons of the epoxy cyclic ring group, CH-O-CH confirming successful epoxidation of palm oil using the prepared catalyst.

Nanopolyaniline as immobilization template for signal enhancement of surface plasmon resonance biosensor - A preliminary study

A technique for the enhancement of Surface Plasmon Resonance (SPR) signal for sensing biomolecular interactions is described. Polyaniline (PANI) of particle size in the range of 1 to 15 nm was synthesized and used as the template for the immobilization of protein molecules. Biomolecular interactions of unbound and PANI-bound proteins with antibody molecules were SPR-monitored using a model system comprising of Bovine Serum Albumin (BSA) and anti BSA. A 7-fold increased in the signal was recorded from interactions of the PANI-bound BSA with anti BSA compared to the interactions of its unbound counterpart. This preliminary observation provides new avenue in immunosensor technology for improving the detection sensitivity of SPR biosensor; and thereby increasing the lower detection limit of biomolecules.

Effect of Epoxidized Oil on Tensile and Tear Strength of NR Vulcanizate and its Comparison with Aromatic Oil NR Vulcanizates

Epoxidized oil (EO) is a sustainable oil that can be obtained form edible or non-edible naturals oil. The incorporation of epoxidized oil can increase the green component in rubber compound. It can contributes to worldwide technology specially in green tyre manufacturing. Epoxidized oil has the potential to replace aromatic oil (AO) to rubber and polymer industry. The effect of incorporation of EO and AO into natural rubber vulcanizates (NR) was studied via tensile and tear strength tests according to ISO 31-1977 and ISO 6133, respectively. Tensile strength of AO value showed greather value compared to EO. Gradual increases of elongation were observed form both AO and EO. Both moduli at 100% and 300% elongation, showed reductions as oil loading were increased. The tear strength results showed that tearing energy insignificantly increased with oil loading. EO compound was found to possess higher tearing energy compared to AO compound for most composition except for 15 pphr EO.

Cure characteristic and mechanical properties of natural rubber vulcanizates with digested rice husk ash (RHA)

Rice husk (RH) is a hard shell that protects the rice grain and can be found in abundance in all rice producing countries. Burning RH as fuel to generate energy would result in a waste product, rice husk ash (RHA). RHA contains approximately 90 – 98% of silica (SiO2), after undergoing a complete combustion process, which is the highest among other agricultural wastes. Silica is one of the commonly used fillers in natural rubber (NR). A chemical treatment for the RHA was developed to collect the silica, via a simple method consisting of alkaline extraction and acid precipitation. This method can produce finer and visually whiter RHA powder. The effects of the chemical treatment on the particle size and surface area of the silica particles were measured. The precipitated silica was then incorporated into NR, using a laboratory-size two-roll mill. For comparison, commercial silica was used as a control. The cure characteristics and mechanical properties of the vulcanizates were evaluated. It was found that the chemical treatment (digestion and precipitation) on RHA has resulted in a significant decrease in its particle size and increase in its specific surface area. However, the mechanical properties of the vulcanizates produced from the treated RHA were lower than that of the commercial silica.Rice husk (RH) is a hard shell that protects the rice grain and can be found in abundance in all rice producing countries. Burning RH as fuel to generate energy would result in a waste product, rice husk ash (RHA). RHA contains approximately 90 – 98% of silica (SiO2), after undergoing a complete combustion process, which is the highest among other agricultural wastes. Silica is one of the commonly used fillers in natural rubber (NR). A chemical treatment for the RHA was developed to collect the silica, via a simple method consisting of alkaline extraction and acid precipitation. This method can produce finer and visually whiter RHA powder. The effects of the chemical treatment on the particle size and surface area of the silica particles were measured. The precipitated silica was then incorporated into NR, using a laboratory-size two-roll mill. For comparison, commercial silica was used as a control. The cure characteristics and mechanical properties of the vulcanizates were evaluated. It was found that t...

Physical and mechanical properties of compounded hydroxylated natural rubber

In this study, oil resistance properties, tensile strength and hardness properties of compounded hydroxylated Natural rubber (OONR) were evaluated. Oil and oxidation natural rubber (OONR) exhibited shorter cure time compared to the SMR-L and EPDM and recorded better crosslinks density. The performance of OONR clearly dominated the unmodified NR in terms of swelling to hydrocarbon oils and non-polar solvents. The OONR also depicted an increasing trend in hardness compared to the unmodified NR. However, the tensile strength of OONR vulcanizate was drastically decreased compared to SMR-L and EPDM compounded rubber.

Thermal properties of hydroxylated natural rubber from in-situ hydroxylation process

A thermal property of hydroxylation of natural latex has been studied in this research. The effect of the hydroxylation conversion of the double bond to hydroxyl functionality of natural rubber in one pot solution using in-situ method. It was studied at different duration; 10, 20, 30, 40 and 50 hours of reaction. A mechanism for the hydroxylation of the natural rubber was also proposed. The result shows the optimum conversions of double bond to hydroxyl functionality was recorded highest at 40 hours and remain constant although the reaction was continued until 50hrs. Fourier Transform (FT) Raman spectroscopy was used to analyze the conversion. −1HNMR was used to confirm the formation of hydroxyl to support the peak from FT Raman spectra. Differential Scanning Calorimetric analysis was used to analyze the glass transition temperature (Tg) of modified and unmodified natural rubber. The result showed lower Tg in modified natural rubber compared to the unmodified natural rubber. On the other hand, the onset o...

Thermal Energy Storage of Polyester Fabric Coated with Paraffin Liquid as Microencapsulated Phase Change Material (PCM)

This research work involves the production of microencapsulated phase change material (PCM) in which paraffin liquid was used as the core component with two different concentrations of sebacyol chloride(SC) of 0.17 mol (Sample A) and 0.18 mol (Sample B) and hexamathylene diamine (HMD) (0.2) to make polyamide shell components. The microencapsulated PCM was characterized using Fourier Transform Infrared (FTIR) and Scanning Electron Microscopy (SEM). The thermal energy storage capacity was measured by Differential Scanning Calorimetry (DSC). The FTIR indicated that the microencapsulation process occurs due to the existence of alkyl group (C–H) and carbonyl group (C=O) in the spectra. DSC analysis shows that the paraffin started to melt at 20–30 °C with thermal energy storage capacity 0.06342 and 0.07925 J/g for Sample A and Sample B respectively. The results obtained show that the concentration of shell component affects the thermal energy storage of paraffin liquid.

Blending of polyvulcanize natural rubber

Natural rubber (NR) latex is widely used in the manufacture of thin film barrier products such as gloves and condom. However, due to its low Tg, film casted from NR latex is soft and tacky, and needed to be strengthened to produced high performance products. Films of prevulcanized natural rubber latex (PVNR) blended with nanosized copolymer of n-butyl acrylate/butyl methacrylate (BA/BMA) were prepared at three different ratios of acrylate copolymer: PVNR. The tensile strength and elongation at break of films prepared decreased with increasing ratios of acrylate copolymer:PVNR. FESEM images showed the occurrence of agglomeration of the acrylate copolymers with PVNR molecules. The degree of agglomeration of the blended molecules increased with percentages of copolymer added. The decrease in the tensile strength and elongation at break may due to the agglomeration of the blended molecules suggesting poor dispersion and/or destabilization of PVNR molecules.

The Effect of Glycidyl Silane as Coupling Agent in Intumescent Flame Retardant System

The effect of different carbonizing agents; ethylene glycol, glycerol, and pentaerythritol to the char formation were studied in this research. After burning process, formulation with ethylene glycol, glycerol, and pentaerythritol showed chars thickness of 10 mm, 32 mm, and 45 mm. The chars’ strength at peak force was recorded at 3.20 N, 7.75 N, and 9.48 N while the burning rate of each sample were 5.23 x 10-4 mm/s, 4.20 x10-4 mm/s, and 6.24 x10-4 mm/s respectively. Formulation with glycerol as carbonizing agent showed the lowest burning rate as compared to the other formulations. Additional formulation with glycidyl silane as coupling agent in glycerol formulation was also studied. The formation of chemical bonding between silane, glycerol, and epoxy glycerol was confirmed by Fourier Transform Infrared (FTIR) absorption peak at 767.25 cm-1. The burning rate was 1.44 x 10-5 mm/s after silane treatment. Thermal degradation of the silane-treated resin started at 220°C as measured by thermogravimetric analysis (TGA).