Nor Azura Abdul Rahim
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Preferred name
Nor Azura Abdul Rahim
Official Name
Nor Azura, Abdul Rahim
Alternative Name
Rahim, Nor Azura Abdul
Rahim, N. A. A.
Main Affiliation
Scopus Author ID
57203438760
Researcher ID
AAC-3346-2021

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Effect of zinc oxide suspension on the overall filler content of the PLA/ZnO composites and cPLA/ZnO composites

2023-01-01 , Tan M.A. , Yeoh Cheow Keat , Teh P.L. , Nor Azura Abdul Rahim , Song C.C. , Voon Chun Hong

This work aimed to study the effect of zinc oxide (ZnO) filler suspension on the mechanical, electrical, and thermal properties of polylactic acid (PLA)/ZnO and cPLA/ZnO. Fused deposition modelling, one of the additive manufacturing methods, was used to fabricate the PLA specimen. PLA was used as the main material in this project, and the ZnO suspension was added during the printing process. The speed of the dispenser (low speed = 1,000 rpm, medium speed = 1,400 rpm, and high speed = 1,800 rpm) was the parameter that was varied to control the filler content of the composite. All the samples underwent a tensile test to determine the mechanical properties, followed by the scanning electron microscopy (SEM) test to analyse the fracture surface properties of the tensile test. SEM observations showed the PLA samples' inherent smooth appearance, but the PLA/ZnO composite showed a rougher surface. PLA and cPLA composites showed an enhanced storage modulus but lower loss modulus than the pure samples. Because of the high thermal and electrical conductivity of carbon black and ZnO, cPLA composites had higher electrical and thermal conductivity than PLA composites.

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Effect of infill density with ZnO concentration on the mechanical properties of 3D printed PLA/ZnO composites

2022-05-18 , Tan M.A. , Yeoh Cheow Keat , Teh Pei Leng , Nor Azura Abdul Rahim , Song C.C. , Mansor N.S.S. , Lim J.H.

Polylactic acid (PLA) plastics are biodegradable materials manufactured from PLA resin by melt spinning and solvent spinning methods. PLA is widely applied in textile fabric, non-woven, masks and sanitary napkins applications due to excellent safety, environmental protection and good mechanical properties. The process of 3D printing is continuous and able to produce complex three-dimensional structures. PLA/ZnO composite samples were fabricated by a 3D printer. ZnO acts as filler in PLA/ZnO composites to obtain the excellent properties like specific tensile properties and density. However, ZnO agglomeration occurred at higher concentration when viewed via SEM. Printing parameters such as infill density, raster orientation and infill pattern can influence the mechanical properties of 3D samples as well. The objective of this paper is to determine the effect of infill density with different ZnO concentration on the mechanical properties of 3D printed PLA/ZnO composites. Tensile and density measurement were carried out to determine the mechanical properties of composites. The influence of 80%, 90%, 100% infill rate and ZnO concentration varied by 1 and 5 mol. As a result, higher infill rate (100%) and optimum filler concentration (1 mol ZnO) give the excellent properties thus can be used for future applications.

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The Effect of Solvents on the Preparation of Poly(9,9-Dioctylfluorene) Thin Films

2022-01-01 , Chew K.W. , Nor Azura Abdul Rahim , Teh Pei Leng , Abdul Hisam N.S.

The optoelectronic properties of Poly(9,9-dioctylfluorene) (PFO) are highly influenced by the existence of a well-defined chain extended “β-phase” conformational isomer. This study aims to evaluate the produced PFO films optical properties. Pristine PFO films and aggregated PFO films were fabricated by the solvent casting method. PFO was first dissolved in chloroform and toluene separately. Meanwhile, for aggregated film, different percentage of methanol (poor solvent) was added to the PFO solution to induce β-phase formation. UV-vis measurement and scanning electron microscopy were used to characterize the films. The results reveal that PFO was fully soluble in chloroform while moderately soluble in toluene. This result was further confirmed by micrograph; the PFO film prepared from chloroform exhibited glassy conformation. While for the aggregation system, the absorption spectra of β-phase becoming more intense as methanol content increase.

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The effect of coated calcium carbonate using stearic acid on the recovered carbon black masterbatch in low-density polyethylene composites

2023-01-01 , Leow V.J. , Teh Pei Leng , Yeoh C.K. , Nor Azura Abdul Rahim , Wong W.C. , Voon Chun Hong , Mohamed Rasidi M.S. , Lim Bee Ying

This research focuses on recycling rubber tire waste through pyrolysis to produce recovered carbon black (rCB). The rCB is combined with recycled low-density polyethylene (rLDPE), calcium carbonate (CaCO3), fatty acid, metallic stearate, and polyethylene (PE) wax to create an rCB masterbatch for household packaging. Surface modification of CaCO3 particles using stearic acid improves the compatibility with LDPE. The study investigates mechanical properties, morphology, melt flow index (MFI), X-ray diffraction, and thermogravimetric analysis in three systems: uncoated, coated, and a hybrid combination of coated and uncoated CaCO3 in LDPE/rCB masterbatch composites. The coated system demonstrates higher mechanical properties and improved compatibility between CaCO3 and LDPE. All three systems exhibit enhanced thermal stability and MFI compared to virgin LDPE, with the coated system showing the most significant improvement. The study showcases the potential of LDPE/rCB masterbatch composites for household packaging, with the coated system displaying the optimum performance across various characteristics.

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Effect of combination printing parameter (infill density and raster angle) on the mechanical and electrical properties of 3D printed PLA/ZnO and cPLA/ZnO composites

2022-04-01 , Tan M.A. , Yeoh C.K. , Teh P.L. , Nor Azura Abdul Rahim , Song C.C. , Mansor N.S.S.

3D printed polylactic acid (PLA) composites reinforced with zinc oxide (ZnO) were successfully fabricated by attaching a ZnO dispenser beside a MendelMax RepRap Printer. Mechanical and electrical testings were performed to characterize the properties of PLA/ZnO and cPLA/ZnO composites. PLA polymer filament is a biodegradable material with the same strength and modulus as other plastic materials. This work emphasizes the effects of printing parameters (infill density and raster angle) on the mechanical properties and electrical conductivity of PLA/ZnO composites. The combination of 100% infill density and 0° raster angle resulted in a substantial increase in the tensile strength and Young's modulus, but reduction in break elongation. As the infill density increased and shifted from 90° to 0° raster angle, the storage modulus was enhanced but the damping factor declined. Scanning electron microscope images proved ZnO was dispersed in the PLA matrix. Optical measurements showed a large air gap across the 35% compared to the 100% infill density. Conductive PLA composites (cPLA/ZnO) enhanced electrical conductivity when increasing infill density compared to PLA composites. Therefore, optimizing printing parameters could help manufacturers provide superior quality structure and cPLA composites for electrical and electronic applications due to good electrical conductivity.

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Thermal Degradation of Photoluminescence Poly(9,9-dioctylfluorene) Solvent-Tuned Aggregate Films

2022-04-01 , Chew K.W. , Nor Azura Abdul Rahim , Teh Pei Leng , Abdul Hisam N.S. , Alias S.S.

The progression of the green emission spectrum during the decomposition of polyfluorenes (PFs) has impeded the development and commercialization of the materials. Herein, we constructed a solvent-tuned aggregated PFO film with the aim of retarding the material’s thermal degradation behavior which causes a significant decline in optical properties as a result of phase transformation. The tuning of the aggregate amount and distribution was executed by applying a poor alcohol-based solvent in chloroform. It emerges that at a lower boiling point methanol evaporates quickly, limiting the aggregate propagation in the film which gives rise to a more transparent film. Furthermore, because of the modulated β-phase conformation, the absorption spectra of PFO films were red-shifted and broadened. The increase in methanol percentage also led to a rise in β-phase percentage. As for the thermal degradation reactions, both pristine and aggregated PFO films exhibited apparent changes in the UV-Vis spectra and PL spectra. In addition, a 97:3 (chloroform:methanol) aggregated PFO film showed a more defined emission spectrum, which demonstrates that the existence of β-phase is able to suppress the unwanted green emission.

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Enhanced luminescence stability and oxidation–reduction potential of polyfluorene for organic electronics: a review

2024-06-01 , Chew K.W. , Nor Azura Abdul Rahim , Teh P.L. , Osman A.F.

In pursuing sustainable technologies, organic electronic-based materials have witnessed remarkable progress, with polyfluorene (PF) among the blue light-emitting polymers garnering significant attention. PF, renowned for its remarkable light absorption and exceptional optoelectronic properties, exhibits great potential for various applications including display technologies, solar cells, lasers and transistors. Nonetheless, the diverse phases in PF significantly affect the performance of optoelectronic devices, predominantly due to the coexistence of different conformations in thin films, while promising, PF confronts hurdles related to stability and degradation during operation, leading to spectral changes and colour purity issue. Since the early 1990s, various studies have been devoted by researchers to determine the chemical changes in the PF chain and its functional groups after being subjected to different types of degradation with the aim of controlling and retarding the decomposition process. Another alternative strategy is to promote the formation of β-phase in PF, which is characterised by well-ordered conformation. This review aims to provide a comprehensive overview of PF degradation behaviour, modes and mechanisms. Various approaches to delay and suppress PF degradation are discussed. Meanwhile, the role of the β-phase in suppressing PF degradation and enhancing optoelectronic applications has also been highlighted. Thus, scientists are diligently attempting to enhance the formation and stability of the β-phase to improve the performance of optoelectronic applications.

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The influence of liquid silicone rubber on the properties of polyurethane elastomer/liquid silicone rubber/graphene nanoplatelets stretchable conductive materials

2022-11-01 , Heng C.W. , Teh Pei Leng , Nor Azura Abdul Rahim , Yeoh C.K.

This work reports the influence of liquid silicone rubber (LSR) as a secondary matrix in the polyurethane elastomer (PUE)/LSR/graphene nanoplatelets (GnPs) stretchable conductive materials. PUE was prepared by mixing with diphenylmethane-4,4-diisocyanate (MDI) and 1,4 butanediol (BDO). The content of LSR varied from 0 to 50 vol.% at fixed 1.0 vol.% of graphene nanoplatelets (GnPs) as a conductive filler. Liquid silicone rubber was used as the secondary immiscible phase to localize GnPs into a path in the primary phase in order to obtain higher electrical conductivity value. The tensile strength of the PUE/LSR/GnPs decreased with increasing LSR content, while the tear strength shows the optimum value at 10 vol.% of LSR. The incorporation of 20 vol.% of silicone rubber has proven to enhance the thermal stability of the blends.

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