Zunaida Zakaria
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Preferred name
Zunaida Zakaria
Official Name
Zunaida, Zakaria
Alternative Name
Zakaria, Zunaida
Zunaida, Z.
Zakaria, Z.
Main Affiliation
Scopus Author ID
57217205824
Researcher ID
M-6958-2019

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Development of porous epoxy micro-beads using ammonium bicarbonate through a single epoxy droplet in corn oil

2021-01-01 , Leemsuthep A. , Zunaida Zakaria , Tanrattanakul V. , Ramarad S. , Muniyadi M. , Jaruga T. , Munusamy Y. , Wnuk I. , Pietrusiewicz P.

This paper explored the effects of ammonium bicarbonate and different ratios of epoxy to polyamide on the formation of porous epoxy micro-beads through a single epoxy droplet. A single drop of a mixture, consisting of epoxy, polyamide, and ammonium bicarbonate, was dropped into heated corn oil at a temperature of 100 °C. An epoxy droplet was formed due to the immiscibility of the epoxy mixture and corn oil. The ammonium bicarbonate within this droplet underwent a decomposition reaction, while the epoxy and polyamide underwent a curing reaction, to form porous epoxy micro-beads. The result showed that the higher ammonium bicarbonate content in the porous, epoxy micro-beads increased the decomposition rate up to 11.52 × 10−3 cm3/s. In addition, a higher total volume of gas was generated when a higher ammonium bicarbonate content was de-composed. This led to the formation of porous epoxy micro-beads with a smaller particle size, lower specific gravity, and better thermal stability. At an epoxy to polyamide ratio of 10:6, many smaller micro-beads, with particle sizes ranging from 201 to 400 μm, were obtained at an ammonium bicar-bonate content of 10 phr. Moreover, the porous epoxy micro-beads with open pores were shown to have a low specific gravity of about 0.93 and high thermal stability at a high ammonium bicarbonate content. Based on the findings, it was concluded that porous epoxy micro-beads were successfully produced using a single epoxy droplet in heated corn oil, where their shape and particle size de-pended on the content of ammonium bicarbonate and the ratio of epoxy to polyamide used.

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Formation of porous epoxy micro-beads from a single droplet of epoxy-polyamide-ammonium bicarbonate at different temperatures

2021-06-01 , Leemsuthep A. , Zunaida Zakaria , Tanrattanakul V. , Lan D.N.U.

Process temperature greatly affects the decomposition behavior of a blowing agent, and changes the structure of the porous epoxy. This paper investigates the effect of processing temperature on the decomposition rate and volume of decomposing gases from ammonium bicarbonate as well as the properties of porous epoxy micro-bead through a single epoxy droplet. A single epoxy droplet (epoxy-polyamide-ammonium bicarbonate) was dropped into the corn oil heated at the temperatures of 80°C, 90°C and 100°C. This study found that by controlling the processing temperature, an epoxy foam bulk (80°C) or a number of porous epoxy micro-beads were fabricated (90°C and 100°C). Higher total volume of gas was generated which was 1142.86 cm3/g at 100°C, with lower viscosity of epoxy. Therefore, the initial epoxy droplet of 10:6 ratio burst into smaller micro-beads with dominant sizes in the range of 251-500 μm and porosity of 30%. From the perspective of epoxy polyamide ratios, the 10:10 ratio has porous epoxy micro-beads slightly larger than that of 10:6 ratio. This induced a decrease in porosity and an increase in specific gravity of micro-beads of 10:10 ratio.

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Effect of Different Foaming Temperature on Properties of NaHCO3 – Natural Rubber Latex Foam

2023-01-01 , Smail M.S. , Zunaida Zakaria , Hakimah Osman , Masa A. , Leemsuthep A.

High volatile fatty acid natural rubber latex foam (H-VFA NRLF) was prepared via the Dunlop process using sodium bicarbonate, NaHCO3 as the blowing agent. The influence of different foaming temperatures (140 ℃, 150 ℃, 160 ℃, 170 ℃, and 180 ℃) on relative foam density, average cell size, cell size distribution frequency and compression stress-strain of H-VFA NRLF were studied. The average cell sizes were related to the relative foam density of H-VFA NRLF. As the temperature increased, the relative foam density increased, and eventually the average cell size decreased due to high amount of gas generated by blowing agents simultaneously. Meanwhile, smaller cell sizes were distributed as the temperature increased. It was found that the optimum temperature for H-VFA NRLF was 150 ℃ due to the lowest relative foam density and significantly larger uniform cell size were produced. Thus, the lowest compression stress up to 60% of strain was found at 150 ℃ and increased with increasing temperature. The mechanical properties were correlated with the morphology and physical properties of the H-VFA NRLF, respectively.

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