Yeoh, Cheow Keat, Assoc. Prof. Ir. Dr.
http://dspace.unimap.edu.my:80/xmlui/handle/123456789/34030
This page provides access to scholarly publications by UniMAP Faculty members and researchers.2024-03-29T13:52:37ZThe properties of epoxy resin coated silica fillers composites
http://dspace.unimap.edu.my:80/xmlui/handle/123456789/34482
The properties of epoxy resin coated silica fillers composites
Teh, Pei Leng, Dr.; Mariatti, Mustapha; Hazizan, Md Akil; Yeoh, Cheow Keat, Dr.; Seetharamu, Kankanhally N.; Amir Nur Rashid, Wagiman; Beh, Keh Shin
Epoxy resin coated silica fillers composites with high percentage of filler loading, such as 80 to 95 vol.% are able to be produced by a mechanical mixing technique. The advantages of high filler loading of theses materials are noted from the thermal and flexural modulus. Apparently, the materials exhibit low coefficient of thermal expansion (CTE) at as low as or below 10 ppm/°C and high flexural modulus of above 20 GPa. In general, these promising characteristics fulfill the requirement to be used as substrate materials in electronic packaging applications.
Link to publisher's homepage at http://www.sciencedirect.com/
2007-05-01T00:00:00ZEffect of acetic acid as catalyst on the properties of epoxy foam
http://dspace.unimap.edu.my:80/xmlui/handle/123456789/34468
Effect of acetic acid as catalyst on the properties of epoxy foam
W. N. F, Wan Hamad; Teh, Pei Leng, Dr.; Yeoh, Cheow Keat, Dr.
In this study, the effect of acetic acid used as catalyst in promoting the decomposition rate of blowing agent (sodium bicarbonate) in epoxy foam was done. Hard epoxy foam was produced using mechanical mixing technique. Epoxy foam has been tested with adding acetic acid at 5 phr and different content of sodium bicarbonate which are 0, 5, 10, 15, and 20 phr, respectively. The effect of acetic acid on the viscosity, density, mechanical properties, and dielectric constant has been studied. The results were compared between with and without acetic acid in the system. Viscosity reading was increased with increasing the content of sodium bicarbonate due to the rapid production of bubbles that created porosity in the structure of epoxy foam. The addition of acetic acid is able to reduce the dielectric constant. In overall, the density, flexural strength and modulus dropped for the epoxy foam with acetic acid as compared to that of without acetic acid.
Link to publisher's homepage at http://www.tandfonline.com/
2013-01-01T00:00:00ZThe properties of recycled copper filled epoxy/unsaturated polyester composites
http://dspace.unimap.edu.my:80/xmlui/handle/123456789/34451
The properties of recycled copper filled epoxy/unsaturated polyester composites
Phua, J. L.; The, Peter L.; Supri, Abdul Ghani; Yeoh, Cheow Keat, Dr.; Ishak, S. N.
A blend system between two different thermoset polymer, epoxy and unsaturated polyester at ratio 80/20 weight percentage (wt. %) with 10, 20, 30 and 40 volume percentage (vol. %) of recycled copper powder as conductive filler was investigated. The conductive polymer blend composites were undergone some characterization and testing which include flexural properties, hardness, thermal stability, electrical properties and scanning electron microscopy (SEM). The flexural strength of the unfilled system decreased as increasing of the recycled copper powder content. With the increase of recycled copper, from 0 vol.% to 40 vol.%, a total 350% of increment in flexural modulus was observed. The thermal stability of the blend polymer increased with the filler loading, from 140°C to 300°C, which was the 5% weight loss onset degradation temperature. The electrical conductivity properties of the blend composite shown the percolation threshold at 30 - 40 vol.% of recycled copper powder filler content, where the conductive blend composites change from insulator to conductor.
Link to publisher's homepage at http://www.ttp.net/
2013-01-01T00:00:00ZThe effect of particle size on the electrical and thermal properties of recycled copper filled polyester composites
http://dspace.unimap.edu.my:80/xmlui/handle/123456789/34438
The effect of particle size on the electrical and thermal properties of recycled copper filled polyester composites
Pargi, M. N. F.; Chong, Y. T.; Teh, Pei Leng; Yeoh, Cheow Keat, Dr.
Due to high product value and some related environmental issues, recycled copper was used as filler in polyester system. The waste copper was collected from the milling machine. The effects of particle size distribution of recycled copper on properties of the polyester composites were studied based on the thermal stability, coefficient of thermal expansion (CTE), electrical conductivity and hardness. It was found that addition of recycled copper has improved the thermal stability of polyester. Incorporation of recycled copper has also decreased the CTE of the composites. From the aspect of different particle size distribution, monomodal distribution shows the most stabilised thermal behaviour with the highest degradation temperature of 314.41°C. However, insignificant effects of particle size distribution on the CTE values were found. In terms of electrical properties, recycled copper filled composites with average particle size of 16 µm exhibited the highest conductivity owing to better continuity provided by coarse particles. Meanwhile, composite with monomodal distribution has shown the highest hardness value due to more rapid collision of the particles and it distributes the stresses more effectively.
Link to publisher's homepage at http://www.inderscience.com/
2013-01-01T00:00:00Z