Hazizan Md Akil

Polymethyl methacrylate (PMMA) is widely used in denture base fabrication; however, its relatively low flexural strength (FS) and durability limit long-term clinical performance. Reinforcing with nanofillers such as Halloysite nanotubes (HNTs) has emerged as a promising strategy to enhance the material's mechanical properties. This study aimed to evaluate the effect of different HNT loadings on the FS and surface hardness (VH) of PMMA denture base composites. PMMA composites were prepared using a heat-polymerised resin reinforced with treated HNTs at concentrations of 0, 1, 3, 5, 7, and 9 wt.%. To achieve uniform dispersion, the nanofillers were ultrasonically dispersed in methyl methacrylate before conventional polymerisation; the filler distribution and the effectiveness of silane functionalisation were examined through morphological and microchemical characterisation using scanning electron microscopy (SEM) coupled with energy-dispersive X-ray spectroscopy (EDX). Mechanical performance was assessed by determining FS via the three-point bending test, while VH was measured using the Vickers hardness method. Statistical analysis one-way Analysis of Variance (ANOVA) followed by Tukey’s post hoc test, with significance set at p < 0.05 was performed, confirming that incorporating silane-treated HNTs significantly affected both tested properties (p < 0.05), with the highest values for FS (98.1 MPa) and hardness (20.20 kg/mm ² ) observed at 5 wt% HNT loading, representing substantial improvements over unmodified PMMA. At higher concentrations (7-9 wt.%), a decline in properties was observed, attributed to nanoparticle agglomeration and reduced interfacial efficiency. HNT reinforcement effectively enhances the mechanical performance of PMMA denture base materials, with 5 wt.% identified as the optimal concentration. These findings support the potential application of HNT-reinforced PMMA to improve durability and clinical longevity of denture prostheses.

Natural fibre composites offer sustainability advantages but often suffer from limited structural reliability and thermal stability when used as single-fibre systems. In this study, vacuum-infused woven jute/epoxy and jute/glass hybrid epoxy laminates with 2-, 4-, and 6-ply architectures were fabricated and systematically evaluated to determine the combined effects of fibre hybridisation and ply architecture on thermo-mechanical performance. Tensile, flexural, impact, density, and thermogravimetric analyses were performed, while scanning electron microscopy and optical microscopy were used to examine fracture features and laminate morphology. Finite element analysis (FEA) was conducted to simulate stress distribution and deformation behaviour, and analysis of variance (two-way ANOVA) was used to determine the statistical significance of hybridisation and ply architecture. The results demonstrate that hybrid laminates significantly outperformed jute-only systems, with the 6-ply jute/glass configuration achieving tensile strength and modulus improvements of 22.6% and 283%, respectively, together with flexural strength and modulus enhancements of approximately 50% and 75%. Thermal analysis revealed delayed degradation onset and approximately fourfold higher residual char yield, confirming improved thermal resistance of the hybrid architectures, while microscopy revealed reduced fibre pull-out, improved fibre embedding, and more compact laminate structures. FEA predictions reproduced experimental mechanical responses with deviations between 2 – 14% and accurately captured stress localisation patterns consistent with observed failure modes, validating the numerical modelling framework. Overall, the results indicate that controlled hybridisation and ply architecture provide an effective route for improving the structural efficiency of vacuum-infused natural fibre composite laminates for lightweight engineering applications.

This paper presents a review that summarises research conducted over the past few decades on enhancing acrylic denture base resin, specifically focusing on the effects of fibre, filler, and nanofiller additions on the properties of poly (methyl methacrylate) (PMMA). The review incorporates scientific papers, abstracts, and studies published between 2015 and 2023, which explore the impact of additives, fibres, fillers, and reinforcement materials on PMMA. According to the reviewed studies, the addition of fillers, fibres, nanofillers, and hybrid reinforcement materials has been shown to enhance the properties of PMMA denture base material. However, it is important to note that most of these investigations were limited to in vitro experiments and did not thoroughly explore the bioactivity and clinical implications of the modified materials. Based on the findings of the review, it is concluded that there is no single ideal denture base material. However, the properties of PMMA can be improved through certain modifications, particularly the addition of silanised nanoparticles and the use of a hybrid reinforcement system. These modifications have shown promising results in enhancing the performance of PMMA as a denture base material.

The demand for polymer-based nanocomposite-reinforced nanoporous materials is becoming essential in sustainable development studies. Integrating nanoporous materials such as Metal-Organic Frameworks (MOFs) in polymer matrices is essential for developing sustainable advanced materials. Combining MOFs and polymer matrices can produce a hybrid material with improved mechanical strength and stability relative to its constituents. This study aims to elucidate the effect of synthesised UiO-66 nanoparticles in a polyurethane (PU) matrix on the subsequent hybrid materials’ microstructural and mechanical properties. UiO-66 nanoparticles were synthesised at 120°C, 130°C, and 140°C. The nanoparticles and subsequent nanocomposite were characterised using X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), Brunauer-Emmett-Teller (BET), and Field Emission-Secondary Electron Microscopy (FE-SEM). The experimental findings indicate that the UiO-66 nanoparticles synthesised at 130°C exhibited a highly desirable crystal structure and effective adsorption properties, and the nanoparticles synthesised at this temperature were then used to reinforce PU, forming a polymer-MOF nanocomposite. The mechanical properties of the resulting nanocomposite were determined using tensile and nanoindentation tests. The UiO-66 nanoparticles were incorporated into PU matrices at various weight percentages (10 wt.%, 20 wt.%, 30 wt.%, and 40 wt.%) via the solution casting technique. The results indicated that 30 wt.% UiO-66 in the polymer nanocomposite exhibits the best mechanical properties, and loading the polymer nanocomposite beyond 30 wt.% is more likely to result in nanoparticle agglomeration and brittle behaviours

The research study focused on enhancing the mechanical characteristics of polymethyl methacrylate (PMMA) denture bases. PMMA is commonly used in dentistry due to its easy fabrication, cost-effectiveness, and favourable physical properties. However, its limitations include low wear resistance, hardness, and mechanical strength, making it less suitable for long-term dental applications. To address these limitations, the study employed a combination of hybrid nano-fillers, specifically HNTs (halloysite nanotubes) and MWCNTs (multi-walled carbon nanotubes), at varying loading levels to improve the mechanical characteristics of the PMMA composite. These nano-fillers underwent treatment by using a coupling agent to enhance their compatibility with PMMA. Key findings of the research include that introducing HNTs/MWCNTs into the PMMA matrix led to a substantial increase in flexural strength, with a significant improvement of 109.1 MPa compared to unfilled PMMA. This indicates that the composite material became more resistant to bending or deformation. There was a substantial rise in flexural modulus values, suggesting improved stiffness in the nanocomposite compared to unfilled PMMA. In addition, the tensile strength of the PMMA composite increased by 64.4 MPa with the addition of the hybrid nano-fillers, indicating enhanced resistance to stretching or pulling forces. The study found that the improvement in flexural and tensile strength was dependent on the concentration of MWCNTs. Increasing the MWCNT concentration up to 0.75 wt.% led to improved mechanical properties, but further increases resulted in a reduction in PMMA properties. Although there was a modest improvement in Vickers hardness (approximately 18.93 kg/mm ² ), the addition of HNTs/MWCNTs as hybrid nano-fillers effectively enhanced the properties of the PMMA nanocomposite. The study concludes that incorporating hybrid nano-fillers into PMMA could contribute to the longevity and durability of dental composites, addressing some of the material's inherent limitations. The specific combination and concentration of nano-fillers played a crucial role in determining the mechanical properties of the resulting nanocomposite.

Ultra-High Molecular Weight Polyethylene (UHMWPE) polymers have been used in biomedical applications due to its biocompatibility, durability, toughness and high wear resistance. To enhance the mechanical properties, various types of minerals are commonly utilized as fillers in UHMWPE. One of the minerals is dolomite, which has been recognized as a valuable mineral with versatile applications, particularly in the field of biomedical applications. This paper presents the tensile properties of UHMWPE composites that filled with dolomite and treated-dolomite at various filler loading (i.e., 1-5 wt.%). Nitric acid and diammonium phosphate were used to treat the dolomite. From the results, the peaks of the FTIR spectrum displays carbonate (CO3–2), phosphate (PO4–3) and hydroxyl (OH–) groups in the ct-dolomite powder sample while the XRD pattern reveals that using dolomite treated with 1M nitric acid resulted in the presence of calcium hydroxide phosphate (Ca10(PO4)5(OH)) and MgO. For tensile strength, UHMWPE/ct-dolomite composites show better tensile strength than the pure UHMWPE composites. Treated improve the dolomite filler and resulted in significantly better matrix-filler interfacial interactions and improve the properties.