Pusat Pengajian Kejuruteraan Bahan dan Sumber Mineral - Tesis
Browse
Recent Submissions
Now showing 1 - 5 of 444
- PublicationInvestigation of halloysite nanotubes reinforcement in self-healing natural rubber composites.(2025-03)Abdul RehmanFormulating rubbers with both self-healing abilities and excellent mechanical performance poses a significant challenge, as optimizing one property often comes at the expense of the other. The self-healing performance of rubbers relies on a flexible and dynamically reversible cross-linked network. In contrast, mechanical strength is influenced by the rigidity and stability of this network, creating a delicate balance. This research aimed to investigate the reinforcement effect of halloysite nanotubes (HNTs) on the self-healing performance of natural rubber (NR) composites based on metal thiolate ionic networks. The initial work involved characterization of raw halloysite particles which emphasis on particle size, shape, structure and chemical composition, and characterization of self-healing behavior of unfilled natural rubber. The unfilled self-healing NR showed excellent self-healing performance (98.5%) however, the tensile strength was low at ∼1.2 MPa. The halloysite nanotubes reinforced self-healing NR composites were prepared using conventional rubber processing. Materials were compounded using internal mixer and two-roll mill and subsequently vulcanized by compression moulding. The self-healing rubber composites were thoroughly examined and characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), universal testing machine (UTM), dynamic mechanical analysis (DMA), Anton Paar rheometer, and compression set testing. The results revealed that, addition of 8 phr HNTs in the self-healing NR was found to be an optimum reinforcement to the better tensile performance of 4.12 MPa with 89.8% healing efficiency. Furthermore, the surface modification of halloysite nanotubes with acrylic acid (AA) was carried out to improve the compatibility between halloysite and natural rubber, since the major disadvantage of halloysite is poor compatibility with the non-polar rubber. The strategy was to reduce the surface hydroxyl groups on the HNTs and enhanced the interfacial adhesion between filler and rubber. Additionally, AA treatment on HNTs generates massive Zn2+ salt bonding between zinc thiolate grafted NR and carboxylic (COOH) groups of treated HNTs which enable electrostatic interaction and allows additional reversible ionic networks. It was found that the self healing rubber composites filled with 6% (AA) treated HNTs increased tensile strength to 5.56 MPa (increased by 34.9%) with 98.9% healing efficiency (increased by 10.1%) compared to untreated HNTs filled self-healing NR composites. Finally, the thermal stability and flame retardancy of self-healing rubber composites were investigated using thermal constants analyzer, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), flammability test, and limiting oxygen index (LOI) measurements. Altogether, the results revealed that the addition of HNTs into self healing NR nanocomposites enhanced 17.5% of their thermal conductivity, 19% of thermal stability, 27.7% of LOI, and 29% reduction in burn rate compared to the unfilled self-healing NR. A two-phase Lewis–Nielsen model was also utilized to simulate efficiency of the thermal conductivity of self-healing natural rubber containing halloysite nanotubes. The utilization of halloysite nanotubes as a reinforcement in self-healing natural rubber is promising for rubber products that experience high temperature environments especially for seals and gaskets.
- PublicationPreparation And Properties Of Polypropylene / Waste Tyre Dust / Short Glass Fibre (Pp/Wtd/Sgf) Composites(2014-05)Zainal, ZuriatiPolypropylene/ waste tyre dust/ short glass fibre (PP/WTD/SGF) composites were melt-mixed in an internal mixer at 180 oC and 50 rpm rotor speed. Four series of composites with various compositions were prepared using WTD of 250-500 μm and at different 5, 10, 15 and 20 php SGF loading. Characterization was done to determine the properties of the composites and thus to study the effects of SGF loading, the incorporation of silane coupling agent, γ-aminopropyltrimethoxysilane (γ-APS) and dynamic vulcanization (DV), the hybridization of SGF with carbon black (CB) and silica on processing characteristics, mechanical properties, morphology, swelling resistance and thermal properties of the composites.
- 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.