Hakimah Osman
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Preferred name
Hakimah Osman
Official Name
Hakimah, Osman
Alternative Name
Osman, Hakimah
Osman, H.
Main Affiliation
Scopus Author ID
7005733143
Researcher ID
AAT-9920-2020

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Synthesis and Characterization of a Novel Nanosized Polyaniline

2023-12-01 , Banjar M.F. , Joynal Abedin F.N. , Fizal A.N.S. , Muhamad Sarih N. , Hossain M.S. , Hakimah Osman , Khalil N.A. , Ahmad Yahaya A.N. , Zulkifli M.

Polyaniline (PANI) is a conductive polymer easily converted into a conducting state. However, its limited mechanical properties have generated interest in fabricating PANI composites with other polymeric materials. In this study, a PANI–prevulcanized latex composite film was synthesized and fabricated in two phases following chronological steps. The first phase determined the following optimum parameters for synthesizing nanosized PANI, which were as follows: an initial molar ratio of 1, a stirring speed of 600 rpm, a synthesis temperature of 25 °C, purification via filtration, and washing using dopant acid, acetone, and distilled water. The use of a nonionic surfactant, Triton X-100, at 0.1% concentration favored PANI formation in a smaller particle size of approximately 600 nm and good dispersibility over seven days of observation compared to the use of anionic sodium dodecyl sulfate. Ultraviolet–visible spectroscopy (UV-Vis) showed that the PANI synthesized using a surfactant was in the emeraldine base form, as the washing process tends to decrease the doping level in the PANI backbone. Our scanning electron microscopy analysis showed that the optimized synthesis parameters produced colloidal PANI with an average particle size of 695 nm. This higher aspect ratio explained the higher conductivity of nanosized PANI compared to micron-sized PANI. Following the chronological steps to determine the optimal parameters produced a nanosized PANI powder. The nanosized PANI had higher conductivity than the micron-sized PANI because of its higher aspect ratio. When PANI is synthesized in smaller particle sizes, it has higher conductivity. Atomic force microscopy analysis showed that the current flow is higher across a 5 µm2 scanned area of nanosized PANI because it has a larger surface area. Thus, more sites for the current to flow through were present on the nanosized PANI particles.

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Plastics in Agricultural Mulch Film

2022-01-01 , Hakimah Osman

Mulching film in agriculture is the practice of covering the soil around plants to improve the growing conditions for the crop through control of weeds and insects, increase soil temperature, moisture retention, reduction of evaporation, prevention of soil erosion, less crop contamination, and improve germination rates. Historically natural mulches such as straw, compost, hay and wood chippings have been used but since 1950s paper and plastics mulching have been tried. Because of its poor wet strength and high price, paper has been found less effective and more costly than plastic, thus plastic mulch film is the primary choice. Most of plastic mulch films such polypropylene (PP), low-density polyethylene (LDPE), high-density polyethylene (HDPE), and poly(vinyl chloride) (PVC) are not biodegradable and are typically removed after each growing season. Recovery of these plastics from the soil is difficult and can affect successive crop yields while causing substantive cost to the environment and farmers. Due to increasingly stringent regulations regarding use of non-degradable plastic in agriculture they are likely to be phased out soon. In the past decades several classes of ‘biodegradable’ materials have been studied but most of these films are reported to be relatively weak in mechanical properties, not efficiently degradable and cost prohibitive compared to conventional plastic mulches. For instance, the standards for degradation in compost (ISO 17088, ASTM D6400) specify that at least 90% of the organic carbon need to be converted to CO2, leaving room for up to 10% of the organic carbon to remain. Because of changes to more stringent regulations, researchers worldwide are now putting extra effort into research on biodegradable polymers from renewable resources. Consequently, biodegradable plastic mulch (BPM) is now being considered as a potential and viable option for the agriculture application in the near future.

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Facile study on molar ratio and the significance of particle effect in polymerization of polyaniline

2024-03-28 , Banjar M.F. , Suphi H.D. , Sarizan M.I. , Yaacob S. , Rahman A.S.A. , Khalil N.A. , Sapawe N. , Hakimah Osman , Jaswan Singh M.S.A. , Dulaimi A. , Zulkifli M.

The synthesis of polyaniline in varied conditions or parameters produce different outcomes in term of morphologies and particle size. Well defined theory that clearly illustrate complete morphology spectrum remains scarce. Chemical oxidative polymerization of polyaniline (PANI) to be compounded in prevulcanised latex (PVL) film was produced throughout this work. PANI was prepared using aniline in hydrochloric acidic solution (HCl) with the presence of ammonium persulphate (APS) as the oxidizing agent and sodium dodecyl sulphate (SDS) as surfactant. This work proposes an outcome to reveal the significance of different molar ratio of aniline to oxidant at equimolar (0.2: 0.2 M) and non-equimolar (0.3: 0.1 M) with respect to different preparation process yielded different particle size of polymerized PANI. Analysis of microscopy images and particle size analysis (sonicated and unsonicated) reveal that all samples were highly flocculated with particle size of equimolar ranging between 10.0 to 152.45 µm and non-equimolar with 15.0 to 130.0 µm. After sonication applied, the population of smaller particle increased notably. Both ratio of aniline to oxidant formulation yields flocculated particle and quite consistently similar particle size. Microscopy images are present to support the findings.

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Effect of blowing agent on compression and morphological properties of natural rubber latex foam

2020-09-21 , Syahrin S.M. , Zunaida Zakaria , Hakimah Osman , Syarifah Nuraqmar Syed Mahamud

Sodium bicarbonate (NaHCO3) was used as a blowing agent in natural rubber latex foam (NRLF) in this study. At fixed vulcanization temperature and time in an air-circulating oven, the NRLF was prepared via the Dunlop method by whipping until frothing and adding NaHCO3 in latex compounds with different loading (i.e., 0, 3, 9 and 12 phr). An alternative formulation for the inclusion of NaHCO3 in NRLF was used. The effect of different blowing agent loading on the physical characteristics of NRFL such as relative foam density was investigated. Observation of cell diameter was performed using an optical microscope (OM). The result of NRLF's compression strength was also evaluated, which correlated with the foam's physical characteristics. The relative foam density was increased with an increase in the amount of NaHCO3. However, the average cell diameter was shown to decrease as the loading of the blowing agent increased. The outcomes of the NRLF's compression strength were also enhanced as the loading of the blowing agent increased following the physical characteristics of the foam respectively.

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Evaluation and Enhancement of Polylactic Acid Biodegradability in Soil by Blending with Chitosan

2023-06-01 , Nor Helya Iman Kamaludin , Ismail H. , Rusli A. , Sam Sung Ting , Hakimah Osman

This study highlights the soil burial degradation of polylactic acid/chitosan (PLA/Cs) biocomposites prepared by the melt compounding technique. The effect of various Cs loadings (2.5, 5, 7.5, 10 parts per hundred parts of polymer (php)) and soil burial periods (0, 2, 6, 12 months) on visual observation, weight loss, changes in functional groups, as well as tensile, thermal, and morphological properties were analyzed. The PLA/Cs biocomposites became brittle and showed more fragmentation with increasing Cs content and buried time. The result correlates with a remarkable increase in weight loss percentage of about ~ 192%, with Cs addition from 2.5 to 10 php at the end of soil degradation. Besides, a decrement in peak intensity at 1751 cm−1 and 1087 − 1027 cm−1 after 12 months signifies the breakdown of PLA ester bonds due to the hydrolytic degradation. This correlates to a significant drop of 60% and 55% in tensile strength and elongation at break, respectively, in the 2.5 php sample, whilst further Cs addition resulted in the broken of the biocomposites at the end of the soil degradation. Yet, no significant difference was observed in the tensile modulus. A consistent stiffness in the biocomposite suggests the degradation occurs in the amorphous region and leaves the crystalline part. This is proven by the 70% increment in crystallinity degree in all samples after 12 months of soil burial. Moreover, surface morphology showed numerous and extended crack formations. It proposes a notable deterioration effect of the biocomposite due to biodegradation. The hydrophilicity of Cs enhances water-polymer interaction, thereby accelerating the biodegradation of polymer components. Therefore, Cs could be a good candidate for facilitating PLA biodegradation in the natural soil environment.

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Impact of Mendong fiber–epoxy composite interface properties on electric field frequency exposure

2023-11-01 , Suryanto H. , Irawan Y.S. , Soenoko R. , Binoj J.S. , Azlin Fazlina Osman , Hakimah Osman , Maulana J. , Ali A.

This research investigates the effects of the frequency of the external electric field during the curing process on the interfacial properties of epoxy composites reinforced by Mendong fiber. Epoxy was used as a matrix with cycloaliphatic amine as a curing agent. The AC electric field by frequencies of 1, 2, and 3 kHz and strength of 750 V/cm were applied during the curing process. The functional groups, structure, interface properties, and morphology of treated epoxy were observed using Fourier-transform infrared, x-ray diffraction, scanning electron microscope, and pull-out test, respectively. The result indicates that after treatment with an electric field of 1 kHz, new peaks were observed in the epoxy diffractogram at the angle of 6.2° and 12.3°, change in morphology, the wettability properties of epoxy were increased and interface shear strength was improved. Increasing the frequency of electric fields results in more damage to the interface and subsequently reduces the shear strength at the interface. Highlights: Interface properties of the composite after curing in an electric field characterized. Exposure to electric field frequency during curing changed epoxy properties. Shear strength of Mendong fiber/epoxy varied post-exposure to the electric field.

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Comparison study: The effect of unmodified and modified graphene nano-platelets (GNP) on the mechanical, thermal, and electrical performance of different types of GNP-filled materials

2021-09-01 , Ka Wei K. , Teh Pei Leng , Yeoh Cheow Keat , Hakimah Osman , Sullivan M. , Voon Chun Hong , Lim Bee Ying , Mohamad Syahmie Mohamad Rasidi

Graphene nano-platelet (GNP) nano-fillers were successfully covalently functionalized with carboxylic and epoxide groups as proven by Fourier-transform infrared spectroscopy. This paper reports the effect of unmodified and modified GNP nano-fillers on the mechanical, thermal, and electrical performance of GNP-filled materials. The results show that the mechanical properties of GNP-filled materials were enhanced with a modified GNP nano-filler. Among the GNP-filled materials, the modified epoxy/NR/GNP compatibilized material shows higher flexural and toughness properties. The modified GNP nano-filler has reduced the thermal stability of the modified compatibilized material. This is because the oxygen-containing groups (C–O–C and –COOH) on the surfaces of modified GNP nano-fillers have lower thermal stability; which accelerates the thermal decomposition of the modified material. Modified compatibilized material shows higher electrical conductivity than the unmodified compatibilized material. X-ray diffraction results proved that d-spacing of modified GNP nano-fillers in modified compatibilized material was shortest when compared to unmodified GNP nano-fillers in unmodified compatibilized material, thus, allowing more electrons to travel at a faster rate through the conductive pathways.

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Physical and compressive stress of rice husk ash macroballoons in syntactic foam: Effect of rice husk ash layer

2024-04-01 , Zakir N.I.M. , Hasbullah S.Z. , Zakaria Z. , Hakimah Osman , Masa A.

The objective of this study is to investigate the effect of the rice husk ash (RHA) layer on the physical and compression properties of macroballoons in syntactic foam. The epoxy mixture was used to coat the surfaces of the expanded polystyrene (EPS) beads template, and the beads were rolled on the RHA and left at room temperature to produce E1RHAM macroballoon. The procedure was repeated to produce the second layer (E2RHAM) and third layer (E3RHAM) of the RHA macroballoon. The macroballoons were then post-cured in the air-circulating oven to shrink the EPS beads to produce hollow structures. The macroballoons were embedded in the epoxy mixture to produce epoxy syntactic foam. The syntactic foams with E1RHAM, E2RHAM, and E3RHAM were characterized in terms of physical and compression properties, respectively. It was found that E2RHAM exhibited the highest compressive stress and compressive modulus followed by E1RHAM and E3RHAM. The wall thickness of E2RHAM is 1.405 mm followed by E1RHAM at 0.745 mm and E3RHAM at 1.0701 mm. E2RHAM also has compressive strength and compressive modulus at 37.5 MPa and 925.03 MPa respectively followed by E1RHAM at 25 MPa and 642.86 MPa, and E2RHAM at 16 MPa and 168.08 MPa.

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Extraction of silica content from the Cymbopogan citratus (lemon grass) and its performance as reinforcement for polymers

2017-07-21 , Nur Firdaus Mohamed Yusof , Hakimah Osman , Hendrik Simon Cornelis Metselaar , Rozyanty Rahman

Silica is widely used as sources for adsorption materials, medical additives and fillers in composite and rubber industries. The manufacturing process of commercial silica use in various industries is very expensive and energy extensive. Therefore, agricultural waste material such as lemon grass is seen as a potential alternative silica sources for replacement of commercial silica which is currently available in the industry. In this research, a simple method based on the acid leaching treatment with hydrochloric acid (HCl) was developed to produce purified silica from lemon grass, followed by thermal combustion at 600°C. Acid leaching temperatures of 33, 50, 80 and 110°C were used. The silica content, shape and texture of the lemon grass ash was characterized using scanning electron microcopy -energy-dispersive X-ray (SEM-EDX) analysis. The SEM analysis indicated the presence of tubular-shaped porous aggregates, spherical and fibrous shapes of untreated and treated lemon grass at 33°C to 110°C. The highest silica content recorded was 73.46% for lemon grass treated at the highest leaching temperature of 110°C. The thermal stability of lemon grass ash was examined by using a thermogravimetric analysis (TGA) instrument. The TGA analysis shows that the untreated and treated lemon grass ash start to decompose at lower temperature (90 to 100°C). Lemon grass treated at the highest leaching temperature 110°C exhibit the highest thermal stability.

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Effect of sulphur vulcanization system on physical, morphological and thermal properties of natural rubber latex foam

2022-05-18 , Mohammad Syahrin Smail , Zunaida Zakaria , Hakimah Osman , Syarifah Nuraqmar Syed Mahamud , Munusamy Y.

Recently, several research studies have been implemented using sodium bicarbonate (NaHCO3) as a blowing agent on rubber foams, yet none has been found in natural rubber latex foam (NRLF). The use of NaHCO3 as a blowing agent in NRLF prepared by the Dunlop process can potentially develop greener foaming processes and more environmentally friendly foam in the industry of latex foam. This novel method is designed to manage the reduction of harmful waste disposal associated typically in producing the NRLF product which is useful for industry purposes. Hence, this research is presented to investigate the physical properties of NRLF such as relative foam density, crosslink density, average cell diameter, and thermogravimetric analysis (TGA) based on the influences of different sulphur vulcanization systems via conventional vulcanization (CV) system and efficient vulcanization (EV) system. The relative density and crosslink density were increased with an increase in NaHCO3 concentration with the CV system exhibiting higher value than the EV system. For average cell diameter, the results showed a decrease in both systems with the EV system having higher value than the CV system. Thermal stability from the TGA results was also improved at higher NaHCO3 concentration and for the use of the CV system as a foaming approach, the CV system has higher thermal stability than the EV system.

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