Firuz Zainuddin

Sol Gel Synthesis and In Vitro Evaluation of Apatite Forming Ability of Silica-Based Composite Glass in SBF

In this study, xerogel glass based on SiO-CaO-PO4 was synthesized by a low temperature acid catalysed sol-gel route. The in vitro evaluation of apatite forming ability for the glass was conducted in simulated body fluid (SBF) solution as the glasses were immersed for duration of 1, 7, 24 hours and 7 days. The XRD analysis showed that the glass formed semi-crystalline structure when sintered at 1000oC and consisted of Ca2O7P2 and Ca2O4Si phases. Image captured using FESEM showed the apatite-like structures were eventually formed on the glass top surface in small numbers after the glass immersed in SBF for only an hour. The numbers of the apatite structures were continuously grown with the increase period of immersion time. The apatite structure mostly covered on top of the glass surface after 24 hours of immersion and continuously growth into bone-like apatite structure when immersed for 7 days in the SBF. The apatite layer formed on the surface of the glass was confirmed as crystalline structure of hydroxyl-carbonate-apatite (HCA) as revealed by the complimentary results of EDS, XRD and FTIR analysis.

Treatment Method for Dispersion of Carbon Nanotubes: A Review

Polymer nanocomposites have a great interest because of special properties of carbon nanotubes (CNTs) as excellent for mechanical, chemical, electrical and thermal properties. CNTs are categorized as single walled nanotubes (SWCNTs) and multi walled nanotubes (MWCNTs). The largest challenge is how to achieve uniform distribution of CNTs within the polymer matrix due to CNTs tend to agglomerated because of their hydrophobic nature. The resulted from CNTs bundles or aggregates reduced the mechanical performance of the final polymer nanocomposites. The surface of the CNTs must be modifiy to reduce the hydrophobicity and improved the interfacial adhesion to a bulk polymer. This paper reviewed the two (2) treatments of CNTs such as physical methods and chemical methods to obtain a better dispersion and enhance the CNTs properties in polymer nanocomposites.

The Influence of Sodium Bicarbonate Loading as Blowing Agent on the Properties of Epoxy Foam

This research studied the effect of sodium bicarbonate content on the properties of epoxy. Sodium bicarbonate (SB) was used as foaming agent to improve the properties of thermosetting epoxy resin. The samples of epoxy foam were produced using mixing method. Sodium bicarbonate was selected as blowing agent by reason of the environmental friendly and low cost concern. Mechanical, physical and morphology properties were done. Sodium bicarbonate content was varied at 5, 10, 15, 20 and 25 part per hundred (phr), respectively. It can be highlighted that the optimum content of the SB was selected at 15 phr and it gave the moderate porosity percentage (%), and moderate value in mechanical and density properties, higher SB content exhibited lower flexural properties.

Preparation and Characterization of Macro Porous Glass-Ceramics as Bioactive Scaffold Material

Bioactive glass and glass-ceramics have a huge interest in biomedical application due to their high biocompatibility and bioactive property. In this study, macro porous glass-ceramic based on 51.26% SiO2 - 36.56% CaO - 11.83% P2O5 and 42.11% SiO2 - 18.42% CaO - 29.82% Na2O - 9.65% P2O5 (in mol%) were prepared via sol-gel synthesis and powder sintering method. Sodium nitrate was used as the precursor for sodium oxide (Na2O) composition in the sol-gel glass. Effect of sodium nitrate addition on the sintered glass (glass-ceramic) properties were studied. The stabilized gel-glasses obtained were compacted into pellets and sintered at 1000 °C for 3 hours. It was found that, Na-contained glass-ceramic (Na-GC) crystallized at 71.5% due to increase in sodium-related crystalline phases. Na-GC showed 72.98% of apparent porosity and densified at 27.02% with macro porous structure with pore sizes in the range of 22.4 μm to 302 μm. The macro porous structure of Na-GC was obtained due to the foaming effect occurred during sintering. Flux effect occurred during sintering also resulted in relatively high compressive strength of Na-GC at 21.53 MPa. The macro porous Na-GC also proved to be bioactive as apatite-like structures were deposited on its surface after immersed into SBF solution for 14 days. The prepared macro porous Na-GC has high potential to be used as a scaffold material in biomedical application due to combination of suitable macro-pore size range, bioactive and has sufficient mechanical strength.

Sol Gel Synthesis and Preparation of Macroporous Glass: Effect of Sodium Nitrate Addition

The aim of this study is to prepare gel glasses derived via acid catalyst sol-gel method based on SiO2-CaO-P2O5 and SiO2-CaO-Na2O-P2O5. The synthesized gel glass powder was compacted into pellets and sintered at 1000 °C for 3 hours. The initial characteristics and sintered properties for both glasses then were analyzed. It was found that, the addition of sodium nitrate in the glass leads to foaming effect which occurred during sintering process. Thus, enables the formation of macroporous structure and expansion in thickness experienced by the glass. The pore size was approximately 300 μm by varying the sodium to calcium composition, whereas glass without sodium content only contained nanopores. The fluxing effect that occurred during sintering also caused vitrified bodies which reduced the glass porosity percentage. Glass with sodium content formed sodium related phases such as Na5.27Ca3(Si6O18) which increased the glass crystallinity. From this study, it shows by addition of sodium nitrate into the glass composition, macroporous glasses can be produced which potentially being used as a scaffold material.

Effect of Kenaf Fiber on Morphology and Mechanical Properties of Rigid Polyurethane Foam Composite

In this work polyurethane foam composites were prepared by using kenaf core fiber as filler at different percentages. Polyurethane foam acts as the matrix and was prepared by using palm oil based polyol and isocyanate with ratio of 1:1.1. From the results obtained, composites filled with kenaf core fiber showed lower mechanical properties i.e modulus and compression strength, up to 85% decrease. However the addition of kenaf core fiber decreases the rise time of the polyurethane foam composites. SEM micrograph analysis showed the evidence of irregular cell shape with the presence of kenaf core fiber. The percentage of kenaf core fiber plays crucial role in determining the composites properties.

Polyurethane foam with multi walled carbon nanotubes/magnesium hybrid filler

The purpose of this paper is to investigate the effect of multiwalled carbon nanotubes (MWCNTs)/magnesium (Mg) hybrid filler in polyurethane (PU) foams with different weight percentages (0.5 wt.% to 3.0 wt.%). The PU/MWCNTs/Mg foam composites were formed by reaction of based palm oil polyol (POP) with methylene diphenyl diisocyanate (MDI) with ratio 1:1.1 by weight. The foam properties were evaluated in density, morphology and compressive strength. The addition of 2.5 wt.% hybrid filler showed the higher density in 59.72 kg/m3 and thus contribute to the highest compressive strength at 1.76 MPa. The morphology show cell in closed structure and addition hybrid filler showed uneven structure.

Synthesis of sol-gel derived glass powder and in vitro bioactivity property tested in simulated body fluid

The objective of this study is to determine the apatite forming ability of sol-gel derived glass based on chemical composition 50%(SiO2)-40%(CaO)-10%(PO4) by examine the reacted sample surface after soaking in simulated body fluid (SBF). The glass was synthesized via an acid catalyzed low temperature sol-gel route, dried, crushed and uniaxial pressed into pellets before finally heated at 600°C to maintain the amorphous nature and to obtain stabilized glass pellets. The bioactivity test of the glass was carried out in vitro by soaking the pellets into simulated body fluid (SBF) for various times up to 14 days. It was revealed that apatite-like structures were rapidly formed on the surface of the glass showed by the glass surface was totally covered with these crystallized apatite within the first 24 hours of immersion. The formation of crystallized carbonated apatite (HCA) was proved within the first 24 hours of immersion via XRD, FTIR and FE-SEM analysis method. Increased in immersion time period to 14 da...

Synthesis of 60 (wt.)%SiO2-40 (wt.)%CaO Sol-Gel Derived Glass-Ceramic and In Vitro Bioactivity Assessment in SBF Solution

The objective of this study is to determine the bioactive property of compacted and crystallized glass-ceramic based on 60 (wt.)%SiO2-40 (wt.)%CaO by immersion in simulated body fluid (SBF) for various times. The powder of this phosphate-free glasses based on binary SiO2-CaO system was synthesized via an acid catalyzed sol-gel route prior to powder compaction for the bioactivity assessment. The main chemical precursors used for synthesis the glass powder were tetraethylorthosilicate (TEOS) and calcium nitrate tetrahydrate reagent whereas nitric acid was used as the catalyst during the sol-gel process. The obtained hydrogels were dried, heat treated and grounded into powders before being pressed into rounded shape compacts. The initial compacted glass then sintered at 1000°C for 4 hours in typical muffle furnace to obtain crystallized glass-ceramic phase. Precipitation of apatite structures on the glass-ceramic surface were observed by immersion of the compacted pellets into SBF solution from one to 21 days. All the test results obtained from X-Ray Diffraction (XRD), Fourier Transform-Infrared (FT-IR), Field Emission-Scanning Electron Microscopy (FE-SEM) and Energy Dispersive Spectroscopy (EDS) indicates that the sintered glass-ceramic showed an actively bioactivity property. Precipitation of apatite was detected on the surface of the compacted glass-ceramic within the first 24 hours after being immersed in SBF. The development of apatite structures were continuously increased and progressively growth into coral-like structure and has particularly found to crystallize into carbonated apatite (HCA) layer after 14 days of immersion in SBF.

Compression Characterization of Polyurethane Foams with Different Formulations of Polyol and MDI

Rigid polyurethane (PU) foams were prepared with palm oil based polyols (POP) and methylene diphenyl diisocyanate (MDI) in order to archieve rigid formulations. The effect of the different amount of MDI (1 wt.%, 1.1 wt.% and 2 wt.%) were studied in density, compressive strength and energy absorption. It was found that the higher compressive strength of the PU foams showed at 1.604 MPa whereas the amount of MDI increased to 1.1 wt. %. The increased amount of MDI to 2 wt.% showed the higher value in density (0.0531 kg/m3) and energy absorption with 46.490 J for 70 % displacement.