Poly Methyl Methacrylate Nanocomposites Research Articles

Machine learning-driven analysis of dielectric response in polymethyl methacrylate nanocomposites reinforced with multi-walled carbon nanotubes

Machine learning-driven analysis of dielectric response in polymethyl methacrylate nanocomposites reinforced with multi-walled carbon nanotubes

Comparative analysis of machine learning techniques for predicting wear and friction properties of MWCNT reinforced PMMA nanocomposites

Polymer nanocomposites have received significant scientific and industrial attention due to the synergetic combination of features of a polymeric matrix and organic or inorganic nanofillers. While experiments have been essential for identifying and characterizing new materials, their high costs and limited trials have shifted the focus towards applying machine learning (ML) to predict nanocomposite properties. This study aims to establish a connection with the tribological performance of multi-walled carbon nanotubes (MWCNT) reinforced with polymethyl methacrylate (PMMA) nanocomposites through the comparison of ML techniques. The wear and friction characteristics of MWCNT-reinforced PMMA nanocomposites were predicted based on three input variables: material weight percentage, load weight, and track diameter. The features of nanocomposites were predicted using three different ensemble ML algorithms: random forest (RF), extra tree (ET), and gradient boosting machine (GBM). The dataset was utilized to train the proposed models in Python, followed by hyperparameter tuning to determine the best model for predicting target values. The results demonstrated that the GBM model outperformed the RF and ET models, with an R-squared of 0.99, RMSE of 0.62, and MAE of 0.18. The proposed models’ predictions of wear values were more precise than their friction values. These findings indicate that ML techniques, particularly the GBM model, can effectively predict the tribological properties of MWCNT-reinforced PMMA nanocomposites, potentially reducing the need for extensive experimental trials and contributing to advancements in nanocomposite material science.

A computational Finite Element Study for Optimizing the Biomedical Strength of MWCNT Reinforced Polymer Nanocomposites

Multi-walled carbon nanotubes (MWCNTs) are highly regarded for reinforcing polymeric nano biocomposites, like polymethylmethacrylate (PMMA), owing to their versatility across various biological applications such as such as dental crowns, artificial teeth and dentures. In this study micromechanical models were meticulously developed to evaluate PMMA matrices fortified with MWCNTs at varying weight percentages (0.1%, 0.5%, and 1.0%). The assessment was conducted using Finite Element Analysis (FEA) facilitated by ANSYS 2022 (Ansys, Inc., USA). Notably, the investigation focused on validating the tensile strength against experimental data, revealing the peak tensile strength at 0.5 wt% MWCNT. Moreover, models featuring isotropic filler orientations demonstrated remarkable alignment with experimental outcomes. Furthermore, the study delved into exploring the influence of diverse MWCNT filler diameters (ranging from 10 to 35 nm) on the tensile strength, indicating a direct correlation with increasing diameter. However, it was observed that the larger diameters tended to correlate with decreased compressive and flexural strength. These comprehensive findings underscore the promising potential of MWCNT reinforced PMMA nanocomposites in advancing biomedical research, where enhanced mechanical properties play a pivotal role.

Optical and UV Shielding Properties of Inorganic Nanoparticles Embedded in Polymethyl Methacrylate Nanocomposite Freestanding Films.

Polymethyl methacrylate (PMMA) is an interesting polymer employed in various applications due to its outstanding properties. However, its electrical and mechanical properties can be further improved by incorporating nanoparticles, and in particular, PMMA nanocomposite with nanoparticles provides various multifunctional properties. This work reports PMMA nanocomposite preparation and structural and optical characterizations incorporating carbon nanotubes (CNTs), TiO2 nanoparticles, and carbon quantum dots (CQDs). CNT/PMMA, TiO2/PMMA, and CQD/PMMA nanocomposite freestanding films were prepared using a simple solution method. Various properties of the prepared composite films were analyzed using scanning electron microscopy, X-ray diffraction, photoluminescence, Fourier transform infrared, and UV-Vis and Raman spectroscopy. Optical parameters and photocatalytic dye degradation for the films are reported, focusing on the properties of the materials. The CNT/PMMA, TiO2/PMMA, and CQD/PMMA films achieved, respectively, good electrical conductivity, photodegradation, and fluorescence compared with other composite films.

High Refractive Index Carbonized Polymer Dots Acting as Light Scattering Units in Nanocomposites for Full‐Screen Light Guide Plate

AbstractThe full‐screen mobile phone can be fabricated by integrating the camera beneath the screen, which needs the nanocomposite light guide plate (nano‐LGP) with exceptional transparency and light‐guiding properties simultaneously. Choosing an appropriate nanoparticle with a high refractive index and exceptional compatibility within the polymer matrix is crucial for producing the nano‐LGP. In this study, the high refractive index carbonized polymer dots (HRI‐CPDs) are synthesized through the solvothermal treatment, achieving a refractive index value of 1.7220 at 450 nm. Subsequently, the modified HRI‐CPDs (mHRI‐CPDs)/polymethyl methacrylate (PMMA) nanocomposites are fabricated by copolymerizing the mHRI‐CPDs with methyl methacrylate . Due to the high visible light transmittance and Rayleigh scattering characteristics when light passes through the nanocomposites, this kind of nanocomposites is suitable for serving as nano‐LGPs. The potential of carbonized polymer dots as light‐scattering unit is originally explored to improve surface illuminance and uniformity of nano‐LGPs. The best‐performing 4.3‐inch LGP with 1.0 wt.% doping content shows 15.8 times higher surface illuminance and 2.1 times higher uniformity than pure PMMA. This new type of LGP based on mHRI‐CPDs/PMMA nanocomposite holds tremendous promise in conjunction with advanced liquid crystal display technology.

Robust Strategy to Improve the Compatibility between Incorporated Upconversion Nanoparticles and the Bulk Transparent Polymer Matrix.

Traditional transparent polymer nanocomposites combined with functional fluorescent inorganic nanofillers are promising for many advanced optical applications. However, the aggregation of the incorporated functional nanoparticles results in light scattering and will decrease the transparency of nanocomposites, which will restrain the application of the transparent nanocomposites. Herein, a robust synthesis strategy was proposed to modify upconversion nanoparticles (UCNPs) with polymethyl methacrylate (PMMA) to form UCNP@PMMA core@shell nanocomposites though metal-free photoinduced surface-initiated atom transfer radical polymerization (photo-SI-ATRP), and thus, the dispersity of UCNP@PMMA and the interface compatibility between the surface of UCNPs and the bulk PMMA matrix was greatly improved. The obtained PMMA nanocomposites possess high transparency and show strong upconversion photoluminescence properties, which promises great opportunities for application in 3D display and related optoelectronic fields. This strategy could also be applied to fabricate other kinds of functional transparent polymer nanocomposites with inorganic nanoparticles uniformly dispersed.

Cytotoxicity Analysis for the Hydroxyl Functionalized MWCNT Reinforced PMMA Nanocomposites in Oral Squamous Carcinoma (KB) Cells.

In this particular research study, a unique three-dimensional mixing technique was used to incorporate multi-walled carbon nanotubes (MWCNTs) into polymethyl methacrylate (PMMA), and the KB cell line was used in the analysis of cytotoxicity, apoptosis detection, and cell viability using the MTT assay protocol. At low concentrations (0.001 to 0.1 g/mL), these results showed that the CNT did not seem to cause cell death or apoptosis directly. It increased lymphocyte-mediated cytotoxicity against KB cell lines. This was demonstrated by the fact that the CNT increased the time it took for KB cell lines to die. In the end, the unique three-dimensional mixing method solves problems such as clumping and uneven mixing that have been written about in the relevant literature. Phagocytic uptake of MWCNT-reinforced PMMA nanocomposite by KB cells leads to oxidative stress and apoptosis induction in a dose-dependent manner. The cytotoxicity of the generated composite and the ROS (reactive oxygen species) it produces may be controlled by adjusting the MWCNT loading. The conclusion that can be drawn from the studies to date is that it could be possible to treat some types of cancer using PMMA that has MWCNTs incorporated into it.

Numerical & experimental assessment of mixed-modes (I/II) fracture of PMMA/hydroxyapatite nanocomposite

Nowadays, polymer-based nanocomposites widely used in biocompatible restorative materials and medical equipment and polymer-based nanocomposites are the most important of them. One of the most useful biocompatible polymers in this field is polymethyl methacrylate (PMMA). In this research, the experimental and numerical analysis of the fracture behaviors of PMMA nanocomposites that are reinforced with hydroxyapatite (HA) nanoparticles are investigated under pure mode I, pure mode II and mixed-mode (I/II) loading. For this purpose, notched semi-circular bend (SCB) specimens containing various Wt. % of HA nanoparticles and different notch angles were fabricated. Then, the mechanical properties of the specimens and the fracture toughness of the notched specimens were investigated. To evaluate the accuracy of nanomaterial distribution, scanning electron microscopy (SEM) images are analyzed and it was observed that at Wt. % of more than 1.5%, specimens with more cumulative masses of hydroxyapatite nanoparticles have more strength reduction. Also, to investigate the fracture behaviors of the produced specimens, the failure criteria of maximum tangential stress (MTS) and generalized maximum tangential stress (GMTS) were evaluated and it was observed that the GMTS criterion is more in line with the experimental results. In addition, the results showed that by increasing the Wt. % of HA nanoparticles from zero to 1% mass, the KIC value increased compared to the pure PMMA, whereas, by increasing this value to 1.5% mass, the fracture toughness decreased. Finally, the fracture initiation and propagation are evaluated using FEM and XFEM numerical methods and the values of stress intensity factors and crack growth path are predicted and compared with experimental values. The obtained numerical results are in good agreement with the experimental results.

Synthesis of semiconductors nanocomposites of polymethyl methacrylate and reduced graphene oxide by ultraviolet radiation

Polymeric nanocomposites of polymethylmethacrylate (PMMA) added with up to 20wt.% of graphene oxide (GO) were synthesized by the solvent evaporation technique and, for the first time, irradiated with ultraviolet radiation (UV-B) to reduce GO and obtain novel films of electrically semiconductive nanocomposites (PMMA-rGO). The exposition times to reduce the GO in these nanocomposites were 48 and 96 h. Chemical, physical, and electrical conductivity analyses were performed, and both GO and rGO added PMMA nanocomposites results were compared before and after UV-B radiation. Plain PMMA results were also compared as control. These results showed that the addition of GO flakes and its reduction (rGO) by UV-B radiation promoted better thermal stability and stiffness to the nanocomposites than to plain PMMA, as demonstrated by the thermogravimetric and differential scanning calorimetry analyses. High resolution scanning electron microscopy demonstrated well distributed rGO particles in the PMMA matrix. FTIR and Raman confirm the reduction process of GO after being UV-B rays irradiated. The colorimetric analyses showed that the GO and rGO flakes and the PMMA matrix presented an excellent superficial interaction. The results of electrical conductivity for the PMMA matrix (4.50 × 10−9 S/m) and the nanocomposites with 2 wt. % GO (1.21 × 10−9 S/m) revealed an insulating behavior, whcich decreases for an addition of 20 wt.% GO. The electrical conductivity displayed a significant improvement with UV-B radiation, such that with 20 wt.% rGO exposed to 48 and 96 h of UV-B radiation, the PMMA-rGO nanocomposites became semiconductor.

Facile functionalization of YVO4:Eu3+: From nanoparticles to luminescent PMMA nanocomposites for radiation detectors

YVO4:Eu3+ is a luminescent material that has been widely used in cathode ray tubes and plasma display panels. Nowadays, different applications are being explored. Fiber-optic Dosimetry (FOD) is an alternative to traditional dosimetry systems for radiotherapy treatments. Although some published results have demonstrated the potential of using YVO4:Eu3+ as nanometer powder for FOD systems, none of them tend to improve its tissue equivalence, a significant limitation. One possible solution could be to disperse the NPs in a tissue-equivalent polymer matrix, like Poly Methyl Methacrylate (PMMA). Consequently, YVO4:Eu3+/PMMA nanocomposites were developed using NPs synthesized according to a combustion method previously reported. This work focuses on studying two different NPs functionalization strategies. One of them involves the synthesis of a SiO2 shell and a posterior treatment with Oleic Acid (OA). The other involves the use of a silane (3-(Trimethoxysilyl)propyl methacrylate, TMSPM) as a coupling agent. Both strategies allow the surface modification of NPs. The study of luminescence properties of NPs showed no significant changes between both functionalized NPs related to Eu3+ spectrum characteristic peaks. However, YVO4:Eu3+@TMSPM has better performance (the reduction in YVO4:Eu3+@TMSPM is about 15%, while in YVO4:Eu3+@SiO2@OA is 62%). On the other hand, functionalized nanoparticles were used to develop polymeric nanocomposites (PNCs) by in situ polymerization of Methyl Methacrylate using a cyclic triperoxide as initiator. Functionalized NPs were characterized by Fourier Transform Infrared Spectroscopy, Transmission Electron Microscopy, Dynamic Light Scattering, Thermogravimetric Analysis, and luminescence measurements. Films were obtained by dissolution of the PNCs, and their luminescent properties were also studied. Results indicate that although the strategy that involves the silica shell plus OA is better in terms of cover density, the TMSPM promotes a better dispersion on the polymer matrix.

Fabrication of Cross-Linked PMMA/SnO2 Nanocomposites for Highly Efficient Removal of Chromium (III) from Wastewater.

In recent times, developments in polymer application properties have required the design of different polymer structures more than ever. Cross-linked polymers (CPs) could be considered a good candidate material for potential applications when used in conjunction with nanoparticles. Cross-linked polymethyl methacrylate nanocomposites are considered to be one of the most commonly polymeric adsorbents due to their varied and simple modification methods. A new class of C-PMMA/SnO2(a–d) nanocomposites have been fabricated as surface-selective adsorbents of Cr (III) with a good yield and different loading of SnO2 nanoparticles. The morphology, molecular structures, and thermal stability of the new cross-linked polymers were examined using a Scanning electron microscope (SEM), the Fourier Transform Infrared method (FTIR), X-ray diffraction (XRD), and Thermogravimetric Analysis (TGA). The adsorption study of C-PMMA/SnO2 was investigated, and an efficient level of adsorption for Cr (III) cations was detected. To evaluate the potential for the new polymers to be used as adsorbents against Cr (III) ions, the contact time, the initial concentration of Cr (III), and the effects of pH were studied. The introduction of SnO2 into the polymer network enhanced the efficiency of the adsorption of heavy metals. The C-PMMA/SnO2 is highly efficient at removing Cr (III) ions in wastewater samples at pH 6 for one hour. The adsorption study demonstrated that the adsorption capacity of C-PMMA/SnO2c for Cr (III) was 1.76 mg /g, and its adsorption isotherm agreed with the Langmuir adsorption model.

Evaluation of thermal properties of different shaped BiOCl dispersed PMMA nanocomposites

The Ellipsoid-like and Flower-like Bismuth Oxychloride (BiOCl) 3D hierarchical nanostructures (HNs) successfully synthesized via Solvothermal and Sol-gel method. The synthesized nanostructures then introduced into Polymethylmethacrylate (PMMA) via in-situ polymerization in order to develop a polymer based nanocomposite of thickness50 μm. To examine the development of these nanocomposites a comparative study on the distribution of two different shape and sized BiOCl incorporated PMMA carried out to study the various properties including poor heat resistant, brittleness and crystallinity. SEM and XRD results confirmed the less crystallite size of BiOCl-ellipsoid than BiOCl-flower with better distribution with the PMMA. The ability of polymer chain to penetrate into interlayer space of BiOCl gives rise to nanocomposites with intercalated and exfoliated structures. These structures showed high thermal and structural stability inferred the potential application of this material in energy storage and photocatalysis.

Highly flexible and stable memristive devices based on hexagonal boron-nitride nanosheets: Polymethyl methacrylate nanocomposites

The current-voltage results for nonvolatile memristive devices based on hexagonal boron-nitride nanosheets:polymethyl methacrylate nanocomposites exhibit the characteristics of write-once-read-many-times in the voltage range from −3 to 3 V. The electrical characteristics remain unchanged even the devices are under highly bended states. After the devices had finished the “writing” process, they could be read more than 500 times under both flat and bending conditions. Both the high and the low resistance states could be maintained at almost constant levels for more than 1.5 × 10 4 s, and the ON/OFF ratio of the devices remained about 10 3 . After more than 2 × 10 3 bendings, the electrical properties of the devices remained almost the same. • Memristive devices based on h-BN NSs:PMMA nanocomposite demonstrated nonvolatile write-once-read-many-times memristive characteristics. • The current ON/OFF ratio of the devices was about 1 × 10 3 , and the retention time were more than 1.5 × 10 4 s. • The devices had excellent stability and excellent flexibility. • The operating mechanisms of the devices were explained using band diagrams and fitting the I–V curves. • The I–V curves for devices with different h-BN NS concentrations were analyzed.

Synthesis, characterization and nonlinear optical properties of polylactide and PMMA based azophloxine nanocomposites for optical limiting applications

The widespread usage of harmful pulsed laser sources emitting brief but intense radiations implies to search for appropriate and convenient forms of protection. Nonlinear optical nanomaterials can serve this purpose when properly embedded in a solid medium, resulting in nanocomposite passive optical limiting filters.This article focuses on the optical limiting behavior of a series of polymer-dye nonlinear nanocomposites, for which we combined azophloxine, a red azo dye, with two polymer hosts, namely polymethyl methacrylate (PMMA) and polylactide (PLA). In this work, optical filters were produced by chemical synthesis from the bulk. Their linear absorption and transmittance were measured by UV–VIS-NIR spectrophotometry and their thermal examination was done via TGA measurements. The optical limiting properties were characterized using an appropriate custom-made optical setup and the nonlinear absorption coefficients and refractive indices were measured by the Z-scan method. Optical measurements in the nonlinear regime were performed at the wavelength of 1064 nm with nanosecond pulses at a low pulse repetition rate. The nonlinear optical properties resulting from energy dependent transmittance assessments reveal that the dye concentration is of major relevance regarding the PMMA nanocomposites, and to a lesser extend for the PLA based systems. The PLA synthesis concept described in this study offers an easy way to directly attach the dye covalently to the polymer chain. The originality and novelty of this synthesis technique is to be pointed out since it has never been mentioned elsewhere to date. For the various types of nanocomposites investigated, significant differences in the optical limiting response were observed. For instance, it is averred that a significantly higher optical limiting effect results in the systems with the less azo dye concentration and the best optical limiting performance corresponding to a laser protection level of OD = 3.3 was measured for the PLA based system. Besides, the PMMA nanocomposite system exhibits an optical limiting level of OD = 1.9. A molecular model claiming for the dye aggregation in the PMMA nanocomposites is discussed. Two different absorption regimes responsible for the optical limiting action have been identified to be reverse saturable (RSA) – excited state absorption (ESA) on the one hand and multi-photons absorption (MPA) on the other hand. By means of transmittance investigations in an open Z-scan configuration, one could observe the sudden and remarkable changeover from a saturable absorption (SA) regime to a reverse saturable absorption one for high azo dye loads in PMMA. Such transition from SA to RSA has been basically revealed for materials and experimental conditions close to or centered on the resonance of absorption (i.e. around 532 nm). To the author’s knowledge, a study in off-resonant conditions (i.e. 1064 nm) was never reported elsewhere to date. Also tracked out by open Z-scan measurements, significantly higher nonlinear absorption coefficients βresulted for the PLA based systems. Similar experiments in a close aperture Z-scan scheme revealed nonlinear refractive indexes in the order of n2=-2.0X10-15cm2/W for the PMMA nanocomposites and n2=-3.0X10-15cm2/W for the PLA nanocomposites.

Optimization of the Mechanical Properties and the Cytocompatibility for the PMMA Nanocomposites Reinforced with the Hydroxyapatite Nanofibers and the Magnesium Phosphate Nanosheets.

Commercial poly methyl methacrylate (PMMA)-based cement is currently used in the field of orthopedics. However, it suffers from lack of bioactivity, mechanical weakness, and monomer toxicity. In this study, a PMMA-based cement nanocomposite reinforced with hydroxyapatite (HA) nanofibers and two-dimensional (2D) magnesium phosphate MgP nanosheets was synthesized and optimized in terms of mechanical property and cytocompatibility. The HA nanofibers and the MgP nanosheets were synthesized using a hydrothermal homogeneous precipitation method and tuning the crystallization of the sodium-magnesium-phosphate ternary system, respectively. Compressive strength and MTT assay tests were conducted to evaluate the mechanical property and the cytocompatibility of the PMMA-HA-MgP nanocomposites prepared at different ratios of HA and MgP. To optimize the developed nanocomposites, the standard response surface methodology (RSM) design known as the central composite design (CCD) was employed. Two regression models generated by CCD were analyzed and compared with the experimental results, and good agreement was observed. Statistical analysis revealed the significance of both factors, namely, the HA nanofibers and the MgP nanosheets, in improving the compressive strength and cell viability of the PMMA-MgP-HA nanocomposite. Finally, it was demonstrated that the HA nanofibers of 7.5% wt and the MgP nanosheets of 6.12% wt result in the PMMA-HA-MgP nanocomposite with the optimum compressive strength and cell viability.

Mechanical and Tribological Performance of Self-Cured Poly Methyl Methacrylate Reinforced by Alumina Nanowires and Zirconia Nanoparticles for Denture Applications

Polymethyl methacrylate (PMMA) is one of the common widely accepted biomaterials in prosthetic dentistry due to its acceptable advantages, since 1937. In the present work, PMMA reinforced with Al2O3 nanowires (Al2O3 NWs) and ZrO2 nanoparticles (ZrO2 NPs) were fabricated by a self-curing method. Mechanical and tribological tests were conducted to study the effect of nanofillers on the mechanical and tribological performance of PMMA nanocomposites. Compression and microhardness tests, as mechanical tests, were accomplished to estimate the elastic modulus and microhardness number of the present nanocomposites. Also, tribological properties of unfilled PMMA and its nanocomposites were realized by pin-on-disk tester under dry sliding conditions. Wear test was conducted at room temperature under applied loads of 10, 20, 30, 40, and 50 N at a constant sliding speed and distance of 1.256 m/s and 226 m, respectively to study wear rate and coefficient of friction (COF) of the nanocomposites. Experimental results revealed that the elastic modulus, microhardness, wear rate, and COF were enhanced with increasing nanofiller content up to 0.5 and 0.7 wt. % of Al2O3 NWs and ZrO2 NPs, respectively. Also, wear rate increased with increasing applied loads up to 50 N, while COF decreased with increasing applied loads up to 40 N. Finally, specimens� worn surfaces were examined and imaged using scanning electron microscope (SEM).

Optical linearity and nonlinearity, structural morphology of TiO2-doped PMMA/FTO polymeric nanocomposite films: Laser power attenuation

This current study suggests a novel optical nanocomposite polymethyl methacrylate (PMMA) with titanium oxide (TiO2) nanoparticles at different concentrations, synthesizing an effective, unexpansive spin coating technique. Adding to that, using both the X-ray diffraction (XRD) method and Fourier transform infrared (FTIR) spectroscopy were very beneficial to study the consistent changes of grain size and strain in nanoscale for the combination of TiO2 nanoparticles in the host PMMA matrix. The topological structure images were observed by atomic force microscopy (AFM), and it was in good agreement with XRD analysis. Both linear and nonlinear optical parameters of the prepared TiO2/PMMA/FTO films were carried out using a VU-Vis-NIR spectrophotometer. Optimized reduction of the optical direct energy bandgap to around ∼ 3.35 eV and indirect bandgap to about 2.37 eV was determined. The obtained results illustrated under study, leading to promising technological applications. Such high structure stability, large dielectric constant, reduced optical bandgap, as well as higher nonlinear optical properties, concluded that the nano-TiO2 powder mix with PMMA can enhance the morphology and optical properties of the host PMMA polymer and that the uniform prepared TiO2 /PMMA nanocomposites are excellent candidates to be used in different applied optoelectronic devices.

Effects of defects on the interfacial shear characteristics between graphene and poly (methyl methacrylate)

AbstractPullout simulations were conducted to investigate the interfacial shear properties between defective graphene (DGr) and polymethyl methacrylate (PMMA) through molecular dynamics simulations with ReaxFF reactive force fields. The effects of number of defects (Stone‐Wales [SW] and double‐vacancy [DV] defects) were investigated. Our results showed that these two types of defects can obviously enhance the interfacial shear strengths of DGr /PMMA nanocomposites. And the DV defects have a greater contribution to the interfacial shear strength enhancement compared to the SW defects. Analysis of the morphology of DGr indicated that surface roughness, which was induced by defects, plays an important role in enhancing the interfacial shear strength at the interface between the DGr and PMMA. Moreover, the effects of chemical functionalization at the defect sites were also investigated. We observed that the CO bonds of functional groups (hydroxyls) at defect sites inclined from the datum plane (z = 0 plane) of the graphene sheet. The inclination of CO bonds, which weakened the mechanical interlocking between functional graphene and PMMA matrix, differently influenced by the DV defect and SW defect.

Evaluation of Equivalent Flexural Strength for Complete Removable Dentures Made of Zirconia-Impregnated PMMA Nanocomposites.

High-impact (HI) polymethyl methacrylate (PMMA), obtained from modification of conventional PMMA, is commonly used in prosthodontics as a denture base material for improved impact resistance. However, it suffers from poor flexural strength properties. The aim of this study was to investigate the flexural strength of complete removable dentures made of HI heat-polymerised PMMA resin reinforced with zirconia nanoparticles at two different concentrations. The effect of fatigue loading on the flexural strength behaviour of the dentures was also investigated. A total of 30 denture specimens were fabricated from PMMA with different concentrations of zirconia nanoparticles: 0 (control), 3, and 5 wt.%. Ten specimens in each group were divided into two subgroups, with five specimens in each, to conduct both flexural strength and fatigue loading test of each of the subgroups. Fatigue loading was applied on the dentures using a mastication simulator and equivalent flexural strength was calculated with data from bending tests with and without fatigue cyclic loading. One-way analysis of variance (ANOVA) of the test data was conducted with the Bonferroni significant difference post-hoc test at a preset alpha value of 0.05. Paired t-test was employed to identify any difference between the specimens with and without the application of fatigue loading. The fractured surface of the denture specimens was examined with a scanning electron microscope (SEM). The bending tests demonstrated that the mean equivalent flexural strength of reinforced HI PMMA denture specimens with 5 wt.% zirconia nanoparticles increased significantly (134.9 ± 13.9 MPa) compared to the control group (0 wt.%) (106.3 ± 21.3 MPa) without any fatigue loading. The mean strength of the dentures with PMMA +3 wt.% zirconia also increased, but not significantly. Although the mean strength of all specimen groups subjected to fatigue loading slightly decreased compared to that of the specimen groups without any fatigue cyclic loading, this was not statistically significant. Denture specimens made of HI heat-polymerised PMMA reinforced with 5 wt.% zirconia nanoparticles had significantly improved equivalent flexural strength compared to that made of pure PMMA when the specimens were not subjected to any prior fatigue cyclic loading. In addition, the application of fatigue cyclic loading did not significantly improve the equivalent flexural strengths of all denture specimen groups. Within the limitations of this study, it can be concluded that the use of zirconia-impregnated PMMA in the manufacture of dentures does not result in any significant improvement for clinical application.

Effects of nanobarium titanate on physical and mechanical properties of poly(methyl methacrylate) denture base nanocomposites

The aim of this study was to (1) fabricate polymethyl methacrylate (PMMA) nanocomposites having better mechanical strength, (2) investigate the effects of nanobarium titanate (NBT) loadings (1–9 wt%) on tensile and flexural properties, and (3) evaluate surface roughness and hardness of the PMMA nanocomposites. The NBT was treated using a titanate coupling agent. Density, polymerization shrinkage (PS), surface roughness, and hardness were investigated. Tensile and flexural properties of PMMA nanocomposites were also evaluated. The roughness values of PMMA nanocomposites were significantly lower than those values proposed as a reference for clinical use (<200 nm). Moreover, the flexural modulus of the NBT/PMMA nanocomposites increased with increasing filler loadings. A remarkable increase in the tensile modulus values of filled PMMA was also observed ( p < 0.001). In the case of higher filler content, tensile modulus remains unaffected by filler incorporation. The tensile and flexural strength improved with increasing concentration of NBT up to 5 wt% and then decreased by an additional amount of NBT introduced into the nanocomposite resin. However, the tensile and flexural strength values of NBT/PMMA nanocomposites were higher than the PMMA matrix ( p < 0.001). Such enhancements obtained with titanate-treated NBT could lead to the promotion of the dental composites’ longevity.