Yeoh Cheow Keat
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Preferred name
Yeoh Cheow Keat
Official Name
Cheow Keat, Yeoh
Alternative Name
Yeoh, C. K.
Yeoh, Cheow Keat
Yeoh, Cheow-Keat
Main Affiliation
Scopus Author ID
16231574200
Researcher ID
EGP-0633-2022

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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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The effect of liquid silicone rubber content on the properties of filled and unfilled natural rubber latex/liquid silicone rubber blend (NRL/LSR)

2022-05-18 , Ming C.W. , Teh Pei Leng , Jalilah Abd Jalil , Yeoh Cheow Keat , Lim J.H.

Polymer blend is known as the simplest method to obtain a new material by just blending two or more materials with suitable mixing technique. Most of the material engineers play their effort to improve the compatibility and miscibility of the blend components since this gives significant effect on the properties of the resulting materials. However, some of the creative engineers used the shortage of the immiscible blend material in the electronic application by inducing the double percolation with the aim to improve the electrical conductivity of the inherently insulating polymeric materials and at the same time conserve the attractive properties of the polymeric matrix. Herein, unfilled NRL/LSR and filled NRL/LSR with 7phr of GNP-SDS blend materials were prepared in order to investigate the effect of LSR content on the crosslink density, tensile properties, tear strength and electrical properties of the blend materials. It was found that the physical and mechanical properties of the materials declined with the increasing LSR content. Nevertheless, the modulus and the electrical properties of the filled NRL/LSR have been improved.

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Effect of dispersibility of graphene nanoplatelets on the properties of natural rubber latex composites using sodium dodecyl sulfate

2022-01-01 , Che W.M. , Teh Pei Leng , Yeoh Cheow Keat , Jalilah Abd Jalil , Lim Bee Ying , Rasidi M.S.M.

Natural rubber latex/graphene nanoplatelet (NRL/GNP) composites containing GNP-pristine and GNP-SDS were prepared by a simple mechanical mixing method. The main objective was to study the effect of dispersibility of GNP on the properties in NRL. X-ray diffraction confirmed the adsorption of sodium sulfate dodecyl (SDS) on the GNP surface. The results showed that high filler loading diminished the physical and mechanical properties of the composites but successfully endured to satisfy electrical conductivity to the NRL/GNP composites. Besides, the SDS surfactant-filled system demonstrated better physical, tensile, electrical, and thermal stability properties than the GNP-pristine. The intercalated and dispersed GNP-SDS increased the number of routes for stress and heat transfer to occur and facilitated the formation of conductive pathways as well, leading to the improvement of the properties as compared to NRL/GNP-pristine composites. However, as the GNP-SDS loading exceeded 5 phr, the GNP-SDS localized in the interstitial layer of NRL, restricted the formation of crosslinking, and interfered with the strain-induced crystallization ability of the composites.

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Effect of infill pattern on mechanical properties of 3D printed PLA and cPLA

2020-11-24 , Yeoh Cheow Keat , Cheah, Chee Son , Pushpanathan, Raguvaran , Song, Cheah Chie , Tan, Mei Ai , Teh Pei Leng

PLA are the most sustainable alternatives and can fit in a wide-range of applications of electronics, nonwoven fabrics and food packaging. With these PLA's adaptability and suitability in many techniques of production such as injection moulding, extrusion, and blow moulding, PLA has become high interest in the production process. Besides, PLA as a thermoplastic polyester that mostly obtained from renewable materials [1]. Infill patterns can affect the mechanical properties of 3D printed PLA and cPLA. PLA with zig zag infill pattern has higher tensile strength of 23.409 MPa compared to PLA with grid and concentric infill pattern. Meanwhile, cPLA with grid infill pattern has higher tensile strength of 30.5638 MPa compared to cPLA with concentric and zig zag infill pattern. By using the suitable infill pattern parameter, the 3D printed PLA and cPLA can have good mechanical properties and can be applied in packaging, pharmaceuticals, textiles, automotive, biomedical and tissue engineering. It has been widely investigated for biomedical applications due to its biodegradability and biocompatibility.

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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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