Papers by Keyword: FTIR

Abstract: This paper presents performance of blended geopolymer mortars prepared from fly ash (FA) and palm oil fuel ash (POFA). Both materials are used their Si and Al elements were activated by alkaline solution. The alkaline solution was prepared by mixing sodium silicate and sodium hydroxide. The optimum mix proportion of geopolymer mortar with FA:POFA mass ratio was 90:10. The ratio of sodium silicate solution to sodium hydroxide solution by mass was 2.5:1. The mass ratio of sand to blended ashes was 2.75:1. The mortar specimens were prepared using 5×5×5 cm cube and cured at room temperature (28oC) for 3 days before subsequently heat-cured at 110oC for 24 hours. The specimens were immersed in distilled water and peat water with pH 4-5 for 120 days. The compressive strength change, porosity, and sorptivity tests were taken. In general, the results shows there was a decrease in strength, an increase in porosity and sorptivity of the blended geopolymer mortars. Fourier Transform Infra Red (FTIR) test revealed that interaction of geopolymers mortar with the acidic peat water can also cause replacement of the exchangeable cations (Na, K) in polymers by hidrogen or hydronium ions. Formation of some new zeolitic phases in blended FA-POFA geopolymer mortar exposed to acidic peat water were observed.

Abstract: Infra-red spectroscopic (IR) analysis of the geopolymers provides information regarding gel chemistry, quantitative analysis, kinetics and effect of different activators on geopolymers. This review discusses the IR analysis of geopolymers and their starting materials. Different applications of IR spectroscopy, used in geopolymerization, are explored in detail. Future research questions regarding IR analysis of geopolymers are also discovered

Abstract: Fly ash is a pozzolanic material which is produced during coal combustion in thermal power plants. This paper investigates the suitability of Malaysian fly ash for geopolymer synthesis. Chemical composition analysis, particle size analysis, amorphous and crystalline phases present, bonding nature, and microstructural behavior are used to determine the suitability of fly ash for geopolymer synthesis. The results showed that fly ash contains silica, alumina, ferrous oxide, and calcium oxide in major proportions which are the main ingredients required for geopolymer synthesis. Higher portion of particles having size in the range of 1-15 µm. Fly ash contains quartz, mullite, and ferrite as the crystalline compounds while the major portion of fly ash is in amorphous form. The band due to asymmetric stretching vibration mode of Si-O-T appears at 1095 cm^-1 which is the main band used to follow geopolymer formation. Microstructure of fly ash shows that the higher portion of fly ash is in amorphous form while it contains cenospheres, magnetic spheres, carbon, and a large number of small particles. Malaysian fly ash is a suitable material for geopolymer and it can be used for geopolymer synthesis.

Abstract: This research works involves the production of microencapsulated phase change material (PCM) in which paraffin wax was used as the core components with sebacyol chloride (SC) and hexamathylene diamine (HMD) as the shell component. The microencapsulated PCM was characterized using Fourier Transform Infrared (FTIR) and scanning electron microscopy (SEM). Thermal energy storage capacity was measured by differential scanning calorimetry (DSC) while thermal conductivity was measured by thermal gravimetric analysis (TGA). The microencapsulated PCM were found to have a regular spherical shape with a size of 50µm while FTIR indicated that the microencapsulation process occurs due to the existence of alkyl group (C-H) and carbonyl group (C=O) in the spectra. DSC analysis shows that the paraffin start to melt at 47°C to 56°C with thermal energy storage capacity of 140.097 J/g and 114.766 J/g for sample A and sample B respectively. It was found that higher value of thermal energy storage resulting to lower thermal conductivity, which can be used as a thermal barrier in various applications.

Abstract: In a process of bioleaching of sulfides, the surface of target mineral is sometimes covered with intermediates and final products to interfere the extraction of metal. Understanding characterization and formation order of secondary minerals, which are responsible for passivation, is a key to resolve the passivation. In the present article, identification of secondary minerals and intermediates in a process of bioleaching of several sulfides by X-ray photoelectron spectroscopy, Raman spectroscopy, identification of jarosite group minerals using Raman spectroscopy, and expectation of formation order of secondary minerals by SEM-EDX and TEM observation are overviewed. Direct observation of a nanodomain by TEM provided a useful information on amorphous secondary minerals. In bioleaching of arsenic-bearing copper sulfides, which are expected to be a new target in the near future, a passivation model was proposed to keep maximizing Cu recovery and minimizing As solubilization, based on combination of solid characterization with aqueous observation.

Abstract: Pure cement mortar and concrete possess disadvantages such as brittleness, low bonding or adhesion strength, low tensile strength, large drying shrinkage, low chemical resistance. In order to overcome these disadvantages, polymer concrete is used as a construction material in Singapore as the properties of polymer-modified (or polymer cement) mortar and concrete are superior to conventional cement mortar. In Singapore, new products or technologies can be found through distributers, agents, etc. Singapore is able to afford and try high quality products to maintain the quality of a building and structure. The importance of applying polymer to protect, repair, coat and strengthen concrete structures in Singapore have grown in the last two decades. To ensure and maintain the standards of construction and building quality, polymer concrete are used extensively in new developments in Singapore. In this paper, the mechanical properties and its corresponding testing methods for several types of polymer concrete used in Singapore are discussed. These products include mortar used to repair concrete spalling, acrylic polymer cementitious coating, waterproofing membrane, epoxy mortars and grouts, fibre reinforced plastic (FRP) and epoxy resin. In addition, the specifications for the above products used in Singapore’s Housing Development Board (HDB) are discussed in the paper as it’s a requirement for suppliers to test their products in accredited laboratories before it can be used.

Abstract: Polymers are commonly used in concrete materials. The type and concentration of polymer are important information for stakeholders, because they have a critical impact on the properties of concrete materials. Therefore, reliable and accurate information is highly desirable. To this end, Fourier Transform Infrared Spectroscopy (FTIR) and Thermogravimetric Analysis (TGA) are used to analyze polymer contents in construction materials. FTIR spectroscopy is a suitable technique to identify the polymer type using IR spectrum matching. Additionally, functional group information can be easily obtained from each peak. Attenuated Total Reflection (ATR) method can be used to measure extracted polymers from construction materials to obtain IR spectra, and match against the library database to identify the polymer materials. TGA is one of the common thermal analysis methods. It measures the weight loss or gain of sample due to chemical reactions such as vaporization, decomposition and oxidation as a function of temperature. In this paper, we will discuss development of reliable analytical methods with which mixtures of polymer, fine aggregate and cement with different percentages of polymer content were prepared and evaluated.

Abstract: High quality micro sheet rhombohedral graphite crystals were synthesized by Hummer method using compounds of MWCNT, K₂S₂O₈ and P₂O₅. The growth mechanisms were discussed by finite element simulation. The synthetic sheet rhombohedral graphite crystals showed a higher growth rate in radial direction than that in axial direction. Raman spectrum and Fourier transform infrared spectrum indicated that synthesized sheet rhombohedral Graphite had fewer crystal lattice distortions with no impurities. Finite element simulations indicated that the solvent metal convection field in the radial direction was stronger than that in the axial direction. As prepared graphite powder was annealed at 1350 oC to obtain diamond nanoparticles. The as-prepared products were exposed to formaldehyde gas.

Abstract: The influence of silica modulus (Ms) on the compressive strength of alkali activated ultrafine palm oil fuel ash based mortar has been investigated. Two alkali activated mortar mixtures, S₁ and S₂ were prepared using sodium silicate (Na₂SiO₃) with initial silica moduli, Ms of 3.3 and 2, respectively. The Na₂SiO₃ was used in combination with sodium hydroxide (NaOH) with NaOH concentration of 10 M. The results indicate that the S₂ mortar mixture has higher strength than the S1 mortar mixture at all testing ages, with 28 day strength of 27.18 MPa and 32.8 MPa recorded by S₁ and S₂ mortar mixture, respectively. Hence, lower Ms leads to higher compressive strength. The higher compressive strength of S₂ is corroborated by the formation of more C-S-H as implied by the Fourier Transform Infra-red (FTIR) spectra analysis.

Abstract: Hydroxyapatite (HA) modified silica aerogel (SA) was synthesized based on 2 different techniques namely encapsulation and in-situ via aqueous colloidal sol-gel process. The structure of the synthesized HA modified SA have been studied using Fourier transform infrared (FTIR) spectroscopy. FTIR spectra of HA modified SA, derived from in-situ technique appear to be different from those of encapsulation technique and free HA, with the main difference lying in the phosphate bending absorbance. Results showed that the encapsulation technique preserved the native confirmation of HA in SA frameworks compared to in-situ technique. It confirms that the use of an aqueous sol-gel encapsulation route provides a promising approach for the stabilization of HA in SA networks.