Pusat Pengajian Kejuruteraan Bahan dan Sumber Mineral - Tesis
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- PublicationProperties of epoxy composite for solder mask application: effect of inorganic fillers and hyperbranched polyester polyol(2024-08-01)William, Lim Yung LingHigh packing density of electronic components in printed circuit boards (PCBs) inevitably raised the risk of thermo-mechanical damages during PCB assembly process. As solder mask (SM) is the PCB’s outermost layer, thermal and mechanical properties of SM become increasingly vital. This study aims to improve the properties of SM by investigating the addition of inorganic fillers, hyperbranched polyester polyol (HBP-OH) toughening agent and silane coupling agents. Firstly, commercial SM was characterized and the results were used as benchmarking for comparison. In this study, different types and loadings of fillers (talc, BaSO4, SiO2 and BN at 5 and 15 wt%), HBP-OH toughening agent (10-40 wt%) and silane coupling agent (APTES and GPTMS at 3, 5 and 10 wt%) were mixed with epoxy using ultrasonication method. The samples were characterized based on tensile and thermal properties as well as pull off strength. Results unveiled that the commercial SM consists of BaSO4 filler and epoxy acrylate. Among different filler types, 15 wt% SiO2-filled epoxy showed higher tensile strength and modulus, storage modulus and glass transition temperature (Tg) with improvement of 11.6%, 16.2%, 8.8% and 1.7 ˚ C, respectively, compared to neat epoxy. Inclusion of 20 wt% HBP-OH into 15 wt% SiO2/epoxy results in enhancements of elongation at break (EB) and thermal decomposition temperature (Td). Among silane-added composites, the addition of 5 wt% APTES showed the best tensile strength and modulus, EB, and pull off strength, increasing by 5.58 MPa, 0.98 GPa, 0.235%, and 43.4%, respectively, compared to untreated sample. Overall, 5 wt% APTES/20HBP-OH/15SiO2/epoxy composite is the most recommended composition for SM application due to their superior tensile properties and pull off strength.
- PublicationDevelopment of ZnO nanorods on supporting substrates for photocatalyst applications(2024-02)Siti Nor Qurratu Aini binti Abd AzizZinc Oxide (ZnO) nanorods based photocatalyst suffers from performance deterioration over time due to loss of ZnO nanorods in the particle form. In addition, a low cost and rapid synthesis technique is needed for mass production of ZnO nanorods particularly on supporting substrate. In this work, ZnO nanorods (particle and nanorods immobilisation on substrate) were successfully synthesized by solution precipitation technique and direct heating (DH), respectively. The results were confirmed by X-ray Diffraction Spectroscopy (XRD) and X-ray Photoelectron Spectroscopy (XPS) analysis. The small IUV/IVis ratio in Room Temperature Photoluminescence (RTPL) analyses indicate that the ZnO contained crystal defects such as oxygen interstitial, zinc vacancy or oxygen vacancy. The ZnO nanorods demonstrated photodegradation of RhB dye under exposure of UV irradiation, and selectively removal on Cu2+ ions and Ag+ ions. The photodegradation of Rhodamine-B (RhB) dye complied to 1st order kinetic reaction. The scavenger study indicated that OH● free radicals and O2●- free radicals were the dominant species that actively involved in the photodegradation of RhB dye. The ZnO particles demonstrated the highest photodegradation efficiency (PE%) (72%), but deteriorated in the cyclic test. ZnO nanorods immobilised on PET fibre demonstrated decrease in PE% was attributed to reduction of surface area as the ZnO nanorods were stacked on each other. The PE% of ZnO nanorods grown on kanthal wires/meshes were the lowest. This was because of smaller catalyst loading was used in the photocatalytic test. In term of its reusability, ZnO nanorods grown on kanthal wires/meshes were the best. The selection of polymeric flexible substrate or rigid substrate depends on the usage point in the wastewater treatment. Lastly, DH technique is successfully developed to synthesise ZnO nanorods in short duration (15 min), consuming low electrical power (≤0.060 kWh). It is a potential synthesis technique that can be upscale for larger substrate size and mass production of ZnO nanorods for the fabrication of wastewater treatment module.
- PublicationPreparation and characterization of inner self-healing rubber filled ground tyre rubber tape for puncture proof application(2024-06-01)Mimi Syahira, MasraffA self-healing natural rubber (NR) based on reversible metal-thiolate ionic networks was successfuy fabricated. Recycled tire rubber was added to the self- healing rubber compound with the aim of improving the healing properties of the rubber tape and promoting the sustainable development of rubber products. Different types of recycled tyre rubber (rubber shred (RS), rubber dust 30 mesh (RD30) and rubber dust 40 mesh (RD40)) were assessed in order to achieve optimal content of recycled tyre rubbers for efficient self-healing performance. The results revealed that self-healing rubber with 10 phr, RD40 showed 90% recovery from puncture damage for nail diameter below 3.4 mm. Subsequently, the effect of plasticizer was investigated to improve the dispersion of RD40 within the self-healing rubber matrix. The amount of plasticizer was varied at three different levels (3, 6 and 9 phr). It was found that addition of 9 phr plasticizer enable 100% recovery of puncture damage for nail diameter below 3.4 mm and 85-95% recovery for nail diameter of 4.0 mm. RD40 was also selectively modified by grafting with acrylic acid which contributed to additional formation of ionic cluster and enhanced rearrangement and reformation of reversible metal ioniic bonding between natural rubber and RD40 particles. The results showed 100% puncture recovery for smaller nail diameter and notorious increased in healing efficiency up to 90-97% for 4.0 mm nail diameter. This promising result open path for development of puncture-proof self-healing tyre.
- PublicationDevelopment of rubber compound with bio-based oil and enhanced performance for green tyre tread application(2024-04-01)Nur Raihan, MohamedThe purpose of this research is to create an environmentally friendly pre-cured tyre tread liner compound using a ternary rubber blend of natural rubber (NR), butadiene rubber (BR), and solution styrene butadiene rubber (SSBR) filled with hybrid fillers of carbon black and silica. Prototype tyre tread liners were manufactured as the end-product and went for a trial run on the road using a single-axle 10,000 tonnes lorry provided by rubber manufacturer Eversafe Rubber Works Sdn. Bhd. A few studies have been performed, starting with developing new formulations by the alterations on blend and fillers compositions. The blend composition of NR/BR/SSBR (60/30/10) was used as the reference, which rubber manufacturers use to produce the all-season tyre. A design of new formulations for NR/BR/SSBR, 65/30/5 and 70/25/5, was proposed based on the existing blend composition. The 5-10 phr of additional NR has slightly increased tyre tread performance. The blend composition of 65/30/5 showed comparable results with lower wear resistance than the control sample, 60/30/10. Interestingly, the 70/25/5 composition displayed higher tensile strength. In the case of hybrid fillers, the compound with a CB/Silica ratio of 20/48 showed higher tear strength and M300%. Noting that filler compositions with a CB/Silica ratio of 12/56 produce an outstanding ratio for the wear resistance and skid resistance compared to control compound together with 28/40, additional increases in CB and decreases in silica loading can improve filler dispersion, as shown by the Payne effect. Further, the study focused on fully substituting bio-based oils in the compounds to replace the common practice of petroleum-based mineral oil. There are four bio-based oil proposed namely coconut oil (CO), sunflower oil (SFO), soybean oil (SBO) and Epoxidized Palm Oil (EPO). Among the proposed bio-based oil, EPO is selected due to its great value of skid resistance and a slight reduction in rolling resistance. In addition, EPO is considered the main natural resource in Malaysia and is readily commercialised by local industry. By altering the EPO content, the mechanical properties of the rubber compound, such as wear resistance, tensile strength, and hardness, were improved. Finally, the prototype tyre tread liner was successfully produced based on the specific formulation and labelled PT-1 (Prototype 1) and PT-2 (Prototype 2). PT-1 showed promising mechanical properties in tensile strength, tear strength and abrasion resistance. Similar mechanical properties are enhanced for PT-2 but with a slight reduction in abrasion resistance. According to the dynamic mechanical properties, both prototype tyres (PT-1 and PT-2) offered superior properties, with PT-1 obtaining a lower rolling resistance while PT-2 showed a slightly increased skid resistance. PT-1 and PT-2 also have better retention in tensile characteristics after being subjected to thermal ageing, which increases the compounds’ thermal stability. Promisingly, the initial tire tread liner prototype demonstrates a notable rise in the utilization of environmentally friendly raw materials, that comes from natural rubber, silica, processing aid, and EPO, with percentages of 66% (in PT-2 tyre formulation) and 70% (in PT-1 tyre formulation), respectively. This stands in contrast to the control sample, which only utilized 51% of green raw materials. This substantial increase in the incorporation of green materials significantly enhances the tire tread liner's overall sustainability and ecological footprint.
- PublicationDevelopment of thermochromic films of polylactic acid (pla)-based smart materials(2024-09-01)Chan, Qi-HuaThermochromic materials respond to temperature changes by changing colour. As polylactic acid (PLA) is inherently non-thermochromic, commercial pigments were incorporated to impart thermochromism onto PLA. However, a high amount of fillers may cause agglomeration and poor dispersion. Plasticisers can be used to counteract the issue of poor dispersion. Moreover, blending transparent PLA with an opaque polymer may affect the colour of the thermochromic samples produced. In the first part of this study, thermochromic PLA with varying pigment content (0-3 wt.%) were produced using extrusion. In the second part, polyethylene glycol (PEG) plasticisers with different molecular weight (1400, 2500, 6000) were added to thermochromic PLA to improve the pigment dispersion. In the third part, thermochromic PLA was blended with the naturally opaque poly(butylene adipate-co-terephthalate) (PBAT) at different weight ratios (100/0, 70/30, 50/50, 30/70, 0/100). The thermochromic performance was assessed through visual observation and colorimetric analysis while the material properties were studied through tensile test, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Thermochromic PLA with 2 wt.% pigments recorded the highest total colour difference (ΔE) while that with 3 wt.% pigments exhibited clear colour changes and superior mechanical properties but the pigment dispersion was poor. Thus, PEG plasticisers were added, and it was found that the thermochromic performance and pigment distribution were successfully enhanced by PEG6000. The elongation at break also increased greatly. In addition, blending PBAT with thermochromic PLA generally improved the observability of thermochromic colour transition. The mechanical properties was also found to be tuneable with respect to the PLA/PBAT blend ratio, making thermochromic PLA/PBAT suitable for a wide range of applications such as packaging and medical devices.