Pusat Pengajian Kejuruteraan Bahan dan Sumber Mineral - Monograf

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Effect of molecular structures and concentration of hardener on thermal characteristics of epoxy underfill
(2024-08-02)
Nor Rashikin Binti Abd Khalid
The reliability and performance of electronic packaging is greatly dependant on the underfill material. The underfill material operate as a barrier to keep out environmental elements like moisture, pollutants, and mechanical harm. On the other hand, variables like curing temperature and molecular structure could have an impact on the curing rate of the underfill materials which determines its qualities and performance. In this work, the effect of different molecular structures (i.e. linear and aromatic) and anhydride hardener’s concentration (i.e. 1.0 and 1.5 weight ratio) of the underfill materials on the thermal behaviour were compared, characterised and studied in anhydride-epoxy curing system. The chemical, physical, and thermal properties of the underfill material were evaluated using Fourier-transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), hardness test, and optical image. It could be observed that all epoxy underfills in this study were completely cured by the disappearance of peaks at 1848 – 1774 cm-1 and 887 cm-1 in the FTIR spectrum that correspond to the anhydride and epoxy respectively. From the DSC and TGA analyses, it was found that the molecular structure (i.e. aromatic and linear) contributes to the thermal stability and flexibility of the epoxy underfill in the DSC. The glass transition temperature (Tg) could be observed at -2oC for EPM (Epoxy-Polyethylene Glycol-Maleic Anhydride) and none in the EHM (Epoxy-Hydroquinone-Maleic Anhydride) for the temperature range of 25 to -40 oC. This is due to the linear molecular structure that contributing to the easier chain segment movement between the crosslinks while the aromatic restricted the chain movement thus increasing the Tg. Moreover, hardness studies indicate that aromatic structure (EHM) is harder than linear structure (EPM). This is further supported by the optical picture, which indicates that EPM is more flexible than EHM. Additionally, it has been determined by DSC, TGA, and hardness tests that the presence of aromatic and linear structures would affect the thermal and physical performance.
Effect of different chain extender on the properties of self-healing polyurethane
(2024-08-01)
Putri Hani Syafiqah Binti Ismail @ Ismil
Self-healing polyurethane is a type of polymer that can repair damage such as scratches. It can restore its original properties without external intervention and can enhances the durability and lifespan of materials. This research is to investigate the development and characterization of self-healing polyurethane. By optimize the synthesis process to achieve good mechanical properties. Various concentrations (in mmol) of hexamethylene diisocyanate (HDI) and methylene dicyclohexyl diisocyanate (HMDI) were used to study their effects on the mechanical properties and self-healing efficiency of polyurethane. Then, the polyurethane was characterized and tested to evaluate their properties by using tensile test, self-healing efficiency, optical microscope, FTIR and WCA. The self-healing polyurethane demonstrated improved mechanical properties compared to conventional polyurethane coatings. The PU were able to autonomously repair micro-cracks and minor damages, thereby extending their lifespan and maintaining performance over time. The study revealed that PU-HMDI samples exhibited higher tensile strength, better self-healing efficiency, and greater hydrophobicity compared to PU-HDI samples, with optimal performance observed at 1.25 mmol HMDI content. The optimized PU exhibit good tensile strength and making them suitable for various industrial applications, including automotive, aerospace, and construction.
Preparation of titania from carbosulfidation of malaysian ilmenite with catalyst
(2024-08-01)
Poh Xi Er
Titanium dioxide (TiO2) essential for various industrial applications. Global demand for TiO2 was projected to increase annually. Thus, attention needs to be paid to ilmenite, which is abundance in nature, as the reserves of high purity source, rutile was depleting rapidly. However, Malaysian ilmenite contains high impurities. The research aims to study how varying temperatures, reaction times, and the concentration of NaCl affect the carbosulfidation process, described in the form of extent of reduction (R) and the degree of sulfidization (Xs). The morphological, and compositional properties was investigated to identify the formation of titanium oxide phases and removal of Fe. The research was conducted at different combination of parameters, done by DOE. DOE was carried out by using 2k factorial design to define the optimum parameters. Phase analysis was performed using XRD and SEM to identify surface morphology and elemental composition by EDX and XRF. From DOE results, the R was the highest at condition with 0.017 mol NaCl, 1100°C and 3 hours at 72.71 % (sample 8), while at 0.017 mol NaCl, 900 °C and 1 hours, the Xs was the highest (52.70%) in sample 5. The results showed the increase in NaCl concentration resulted in a higher R and Xs. Increasing in temperature and reaction time led to a higher R, significantly favoured the formation of titanium oxide compounds, with higher total of TiO2, and Ti6O11 phases formation in XRD result. However, the Xs decreased with longer reaction times, highlighting a limit to the sulfidation process's efficiency. XRD and SEM further confirmed the formation of key phases such as FeS2, TiO2, and Ti6O11 in cubic structure. The novelty of this research lies in its comprehensive investigation of the carbosulfidation process for extracting titanium oxides from Malaysian ilmenite while removing Fe as FeS2, by exploring the synergistic effects of both processes.
Dependency of filler loading on the epoxy underfill performance for electronic packaging application
(2024-08-01)
Phang Wei Jie
The performance of epoxy underfill in electronic packaging is dependent on the loading of fillers, which significantly impacts various properties essential by for the reliability and efficiency of electronic components. The aim of this project is to study the effect of filler loading on the flow rate, viscosity and thermal properties of epoxy underfill for electronic packaging application. The epoxy is mixed with the hardener, maleic anhydride and polyethylene glycol with the ratio of 1:1:1 and cured at 120 °C for 24 hours. The filler loading of fumed silica with nano sized was set at 0%, 1% and 2% which according to the total weight of the epoxy mixture. The uncured and cured epoxy underfill were studied in term of viscosity, flowrate, spectroscopic analysis, and thermal behaviour. The Fourier Transform Infrared (FTIR) analysis was conducted to compare the curing behaviour and chemical structure of uncured epoxy sample with cured epoxy sample. Meanwhile the Differential Scanning Calorimetry (DSC), Thermogravimetry Analysis (TGA), and Thermomechanical Analysis (TMA) were performed to investigate the thermal behaviour of epoxy underfill. It was found that, the viscosity of epoxy mixture increased with the increasing of fumed silica loading and in turn flow rate under glass slide decreased. It also found that the increasing fumed silica loading increased the thermal stability of epoxy and decrease the thermal expansion of epoxy which are important criteria for electronic packaging application. These findings suggest that while higher filler content may enhance certain thermal properties, it poses challenges for the electronic packaging application process due to reduced flowability.
Development of direct heating method for the synthesis of cobalt oxide nanowalls
(2024-08-01)
Ooi Chia Wen
In this research, cobalt-based nanomaterials were synthesized using the direct heating (DH) method. Cobalt oxide (Co3O4) is a black compound with a band gap ranging from approximately 1.48 eV to 2.19 eV. Traditional synthesis methods for Co3O4 nanomaterials, such as as the sol-gel method, hydrothermal method, green synthesis, and microwave-assisted method, typically involve high energy consumption and long processing times. The DH method was developed to synthesize Co3O4 nanomaterials on kanthal wire, offering a more energy-efficient and time-efficient alternative. Synthesis parameters, including the type of precursors, heating power, and heating duration, were systematically investigated to identify the optimal conditions for Co3O4 nanomaterial formation. Characterization techniques, such as XRD, FESEM, Raman spectroscopy, and UV-Vis spectroscopy, were employed to analyse the synthesized nanomaterials. XRD analysis confirmed that the as-grown nanomaterials were cobalt-based, specifically Co3O4, with an average particle size of 2104.29 nm ± 509.72 nm as determined by FESEM. The optimal synthesis parameters were using C4H6CoO4·4H2O precursor, a heating power of 30 W, and a heating duration of 20 min. The Co3O4 nanomaterials synthesized under these conditions exhibited a specific capacitance of 193.45 F/g. Additionally, the band gap of the synthesized Co3O4 nanowalls was in the range of 1.81 eV to 2.11 eV. However, the photodegradation efficiency of the Co3O4 nanowalls for methylene blue dye was relatively low, at 5.56%.

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