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

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Effect of styrene content on structure and properties of vulcanizates from natural rubber grafted with polystyrene

2025 , Nabil Hayeemasae , Siriwat Soontaranon , Zunaida Zakaria , Mohamad Syahmie Mohamad Rasidi , Abdulhakim Masa

Graft copolymer from natural rubber grafted with polystyrene (NR-g-PS) was prepared. Influences of polystyrene (PS) content grafted on the natural rubber (NR) were investigated. Prior to compounding and compression molding to vulcanizates, the graft copolymers were prepared by emulsion polymerization. Proton nuclear magnetic resonance confirmed the chemical structure of the graft copolymer as NR-g-PS. Grafting of PS onto NR improved the tensile modulus and tensile strength of the vulcanizate, whereas the elongation at break decreased, depending on the PS content. However, a drastic reduction of tensile strength and elongation at break were seen when the PS content was greater than 20%. Compared to ungrafted NR, the onset strain for deformation-induced crystallization of graft copolymers was reduced, while the crystallinity at a given strain was higher. The improved tensile properties and crystallization ability suggest interfacial interactions of NR and PS phases. Such interactions were also responsible for improved thermal stability of the graft copolymer, having the degradation temperature increased by 17–38°C over the ungrafted NR. The best balance in overall properties was achieved by NR/PS 90/10.

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Effect of Activating Agent on Porous Activated Carbon in Alginate Macrobeads for Removal of Remazol Red Dye

2024-06-07 , Zakir N.I.M. , Zunaida Zakaria , Hakimah Osman , Hafiza Shukor , Masa A.

Alginate macrobeads filled with porous activated carbon (PAC) treated using different types of chemical activating agents were prepared in this study. Rice husk ash (RHA) was treated using five types of chemicals, such as sodium hydroxide (NaOH), potassium hydroxide (KOH), zinc chloride (ZnCl2), hydrochloric acid (HCl) and citric acid, at a low temperature (~80°C) for 2 hours to produce PAC with high porosity and compared to the conventional process using furnace with a high processing temperature. A biopolymer, namely sodium alginate, was used to hold the PAC powder to produce an immobilized structure of PAC in macrobeads form. Adsorption of remazol red (RR) dye using macrobeads was measured using UV-spectrophotometer, while the morphology and composition of PAC were observed using scanning electron microscope (SEM) and energy dispersive X-ray (EDX), respectively. The functional groups of PAC were identified using attenuated total reflection Fourier transform infrared (ATR-FTIR). The results indicated that the alkali treated PAC successfully removed up to ~99% of the dye in 120 minutes, while the acid treated PAC could only remove ~30% the dye at the same time. This demonstrated that alkaline treatment produced PAC with higher porosity structure and the PAC produced using NaOH has high adsorption of RR dye.

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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 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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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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Recycled polyethylene terephthalate blends and composites: Impact of pet waste, engineering design, and their applications

2023-09-23 , Zunaida Zakaria , Hakimah Osman , Nor Azura Abdul Rahim , Munusamy Y. , Ismail H.

Polyethylene terephthalate (PET) is one of the major polymers produced and has been widely used in downstream industries, such as the production of textile fibers, packaging bottles, and films. The increased use of PET is associated with its excellent properties, which include thermal resistance, lightweight, high transparency, good impact, and relatively low cost. This indirectly contributes to a large amount of PET solid waste, which is detrimental to human life and exacerbates environmental issues. As a result, conversion to new PET blends and composites is an efficient method to recycle PET and reduce waste. While research in this area is ongoing and improving with the development of new materials for various applications, its commercialization has yet to begin. This chapter focuses on the designation of recycled PET and its performance as new blends and composites. Among the other topics discussed are PET waste sources, recycling methods, and applications, as well as the challenges of recycling PET and converting this solid waste into value-added products. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023.

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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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Recycled polyethylene blends and composites: Current trend, technology, and challenges

2023-09-23 , Munusamy Y. , Zunaida Zakaria , Ismail H. , Nor Azura Abdul Rahim

Thermoplastics being a modern material had provided significant contribution to human civilization. Polyethylene (PE) being the highest consumed thermoplastic is gaining more momentum in production for application in the field of automotive, electrical, and food packaging. Environmental issues with single-usage trend of PE products had catalyzed various initiative to recycle PE specially to produce recycle PE blends and composites. Even though various laboratory-based development been successfully carried out to produce recycled PE blends and composites but its commercialization is still at infancy. Thus, in this chapter the current PE recycling methods, products, and its applications are being discussed and the challenges faced by industry for full-scale adaption of findings in laboratories are highlighted. Critical analysis on the production and products of recycled PE blends and composites are reported to provide the reader with future trends for practical approach in PE recycling at industrial scale. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023.

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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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Swelling behavior and melt fracture of polypropylene-co-ethylene filled with sago starch extrudates by using twin screw extruder

2022-05-18 , Nor Azura Abdul Rahim , Huan G.T. , Jalilah Abd Jalil , Zunaida Zakaria , Jikan S.S.

Barus effect and melt distortion of an extrudate is the indication of viscoelastic nature of a polymer melt. Polypropylene-co-ethylene (PPcoE) filled with various amounts of sago starch were compounded using a co-rotating twin screw extruder and the extrudate blend swelling ratio and its appearance upon exiting the die at different screw speed and temperature were carefully analyzed. The Melt Flow Index (MFI) test and the morphology test using optical microscope (OM) were conducted to justify the obtained results. The addition of sago starch in PPcoE has significantly introduced a porous structure to the produced extrudates and the porosity became more obvious with the increasing amount of sago starch. Meanwhile, below 30 rpm screw speed, higher starch content generated lower extrudate swelling ratio. At constant screw speed of 30 rpm, a sign of flow instabilities occurred in the extrudate blends which can be directly evident from the captured OM image. In conclusion, the incorporation of sago starch in PPcoE has ultimately altered the melt strength of PPcoE which is concurrently reflected by the swelling behaviour and melt distortion of the blend.

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