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Polymer specifications' optimization for tailored applications is desirable for enhanced applicability. In this research, we have successfully prepared the PMMA/metal oxide (0.1 wt% CeO2, and TiO2) through a feasible casting method. The implications of the metal oxides incorporation were explored. XRD reveals the successful formation of the composites, with 20 nm crystallite size of both composites. FTIR reinforces the intended composite formation with significant bands allocation. Optical bandgaps for PMMA/CeO2 and PMMA/TiO2 are 2.91 and 3.15 eV for direct transitions, respectively. For indirect transitions, the bandgap is around 3.33 eV for both. Other optical parameters were calculated as real and imaginary dielectric constants. THz displays a linear manner with a somewhat more PMMA fixed band due to the inharmony of intermolecular vibration mode. Dielectric studies manifest polymer loss spectra with multiple non-Debye relaxation progressions β, and γ relaxations alongside MVS polarization for films containing CeO2 or TiO2. The synthesized nanocomposites indicated antibacterial influence against (S. aureus, and B. subtilis) as Gram-positive bacteria, and (E. coli, and K. pneumoniae) as Gram-negative bacteria, (C. albicans) (A. niger) as yeast and Fungi strains. The PC samples show a high impact against Gram-positive bacteria, yeast, and Fungi strains, while PT samples show a high impact against Gram-negative bacteria. [ABSTRACT FROM AUTHOR]

Nerve injuries and neurodegenerative disorders remain serious challenges due to the poor results of nerve cell regeneration. The most promising treatment for such injuries is treatments based on stimulating cells to grow and differentiate stem cells in that area into nerve cells, but there are obstacles in controlling the growth and differentiation into fully functional nerve cells and research is ongoing to overcome these obstacles. In this study, polymethyl methacrylate (PMMA) and its laser modified surfaces were used for cell culture and differentiation into neuron-like cells. In order to show the differentiation of PC12 cells into neuron-like cells, the expression levels of the neuronal markers Map2 and Synapsin-1 were examined. The results showed the growth of PC12 on raw PMMA was increased significantly compared to the control group and micrometric parallel grooves lead to a significant difference in cell growth compared to raw PMMA. Also, the simultaneous irradiation of laser to the cell cultured on PMMA caused more cell adhesion on the surface, faster growth and differentiation of PC12 into neuron-like cells. [ABSTRACT FROM AUTHOR]

Several studies have confirmed the antimicrobial effect of a mixture solution composed of hydrogen peroxide 3% and vinegar 4% (HPV) as a disinfectant solution used for Polymethylmethacrylate (PMMA) denture base. Immersing dentures in this solution may result in alterations to the physical characteristics of PMMA. This in vitro study was conducted to examine the effect of different immersion times of HPV on surface roughness of heat cure and computer-aided design/computer- aided manufacturing (CAD/CAM) PMMA. Material and methods: 60 PMMA samples were prepared and divided equally according to two different types of PMMA materials: a) heat cure (H) and b) computer-aided design/computer-aided manufacturing (CAD/CAM) (A) PMMA. Each type was subdivided into three groups (10 samples for each) according to immersion time in the HPV mixture prepared with a ratio of (1:1); the control group was not immersed (H0 and A0), the second group was immersed for 90 days (H1 and A1) and the last group for 180 days (H2 and A2). Each group was examined before and after two immersion times with surface roughness measured by a portable roughness tester. The collected data were analyzed using Shapiro-Wilk for normality test and statistically analyzed with Two-way ANOVA. The data were considered statistically significant when P≤ 0.05. Results: statical analysis shows the highest surface roughness mean value was observed for the heat cure PMMA group (0.141). Statistical analysis showed no significant changes in the two immersion times (90, and 180 days) for both materials. Conclusions: The study concluded that HPV could be used as an alternative disinfectant solution for heat and CAD/CAM PMMA without promoting deleterious effects on surface roughness. [ABSTRACT FROM AUTHOR]

Polymeric sheets of poly(methyl methacrylate) loaded with organic dye with various amounts of metal oxide nanopowder are promising alternatives to traditional inorganic materials, as they have similar mechanical properties to flexible substrates with relatively high refractive index that can be used in flexible optical/optoelectronic devices. Polymeric sheets of poly(methyl methacrylate) loaded with boron subphthalocyanine chloride with various amounts of cerium(IV)-zirconium(IV) oxide nanopowder were fabricated. Fourier transform infrared spectroscopy and X-ray diffraction techniques were used to examine and analyse the structure of the fabricated polymer sheets. Introducing organic dye and nanofiller in the polymer molecular chains matrix does not change the infrared characteristic transmission peaks. The X-ray diffraction spectra of the polymeric sheets have an amorphous nature. Characterized by spectroscopic measurements (fluorescence, transmittance, and reflectance), the optical properties such as the optical energy gap, emission bands, and refractive index of the fabricated polymer sheets were explored. By controlling the concentration of boron subphthalocyanine chloride and cerium(IV)-zirconium(IV) oxide nanopowder, energy gaps and the refractive indexes of the fabricated polymer sheets can be controlled. The poly(methyl methacrylate) loaded with boron subphthalocyanine chloride with 20 mg cerium(IV)-zirconium(IV) oxide nanopowder showed optical energy gap transitions at 4.79, 2.66 eV, and 2.08 eV, it has the highest PL intensity with a strong emission band at 413 nm, and also it has the highest refractive index. Finally, the obtained experimental results showed that the prepared polymer systems can be considered promising flexible polymer sheets for optics, and photonics devices. [ABSTRACT FROM AUTHOR]

In this work, we study the combinational effects of UV irradiation, functionalized graphene (FG) sheets, and organic solvents on the crack evolution in PMMA/FG composites. The UV irradiation leads to the scission of polymer chains in the PMMA/FG composites with the FG sheets hindering the scission of polymer chains. The evolutions of surface cracks and the pre-formed crack in the PMMA/FG composites depend on the diffusion of organic solvents. The increase of Hansen solubility distance (HSD) with the solvent follows the order of cyclohexanol, 2EA, and 1-butanol sequence. The solvent with a smaller HSD diffuses faster in polymer, producing larger tensile stress to cause the nucleation and growth of cracks. The density of surface cracks and the length of the pre-formed crack decrease with increasing the FG fraction and HSD and increase with increasing the UV dose. The activation energy and heat of mixing for the growth of surface cracks increase with the FG fraction and HSD and decrease with increasing the UV dose. The activation energy for the growth of the pre-formed crack increases with increasing the FG fraction and HSD and decreases with increasing the UV dose. The activation energy for the inculcation period of the growth of the pre-formed crack has an opposite trend to the activation energy for the growth of the pre-formed crack versus the FG fraction, HSD, and UV dose. The experimental results show that the evolutions of surface cracks and the pre-formed crack follow the scaling law describing the diffusion of organic solvents in solids. [ABSTRACT FROM AUTHOR]

A macromolecule viz; poly (p-phenylene azomethine) (PPAM) has been synthesized by a novel methodology for utilization in opto-electronic devices. The developed PPAM has been comprehensively characterized by using UV-Visible and FTIR techniques. X-ray studies affirmed the crystalline nature of PPAM, while UV-visible absorption spectroscopy, in DMSO, confirmed the extensive conjugation; with promising optical properties. Thermal stability was evaluated through thermogravimetric analysis. The computational analysis of PPAM was also implemented to complement the experimental observations. To explore practical applications, a homogenous film was successfully developed from PPAM with a minor quantity (0.25wt%) of poly(methyl methacrylate) PMMA. The resulting film was characterized for thermal stability, morphological features, and optical behaviour. The findings underscore the potential of PPAM as a versatile material with tunable properties, opening avenues for innovative applications in the realm of optical science. [ABSTRACT FROM AUTHOR]

This research article focused on the blending of poly(lactic acid)/poly(methyl methacrylate) (PLA/PMMA) polymer materials to overcome PLA's inherent weaknesses, such as low glass transition temperature, brittleness, and lack of melt strength. Consolidated feasible characteristic investigations, such as mechanical, thermal, and aging behavior, were carried out for PLA/PMMA blended polymer materials. Initially, the miscibility of PLA/PMMA blend filaments was prepared at various blend ratios (91/9, 82/18, and 73/27) and samples were printed by fused deposition modeling (FDM). Differential scanning calorimetry (DSC) and Fourier infrared spectroscopy (FTIR) analysis have been utilized to evaluate the glass transition temperature (Tg) and intermolecular interaction, respectively, on blended polymer materials. Experimental tensile, compression, and flexural strength testing were performed on neat polymers and blended polymer composites. Compared to neat PLA materials, blended composites had 13.24% and 19.07% higher flexural and compression strengths. Besides, the interfacial interaction of neat and blended polymers has been done using dynamic mechanical analysis (DMA). Furthermore, Tg, storage modulus, and aging behavior of blended polymer materials have significantly improved over neat PLA materials. Altogether, the development of PMMA/PLA blends as sustainable biomaterials for dental applications aligns with environmental concerns and the need for biocompatible materials in dentistry. Highlights: Blending of PLA and PMMA helps mitigate the inherent constraints of PLA.Blended composites exhibited greater compressive and flexural strengths.Better glass transition temperature and intermolecular interaction.Excellent thermal stability and water aging imply viable dental biomaterials. [ABSTRACT FROM AUTHOR]

A simple solution casting technique was used to formulate films of polyvinylidenefluoride‐co‐hexafluoropropylene, polymethylmethacrylate, and Ti3AlC2 MAX phase polymer nanocomposites (PPT) with different filler content. The functional groups present in the PPT films were studied using the Fourier transform infrared spectroscopy and the nature of crystallinity was observed using X‐ray diffraction technique. The morphology of the films was studied by scanning electron microscopy. The thermal analysis was done using the thermogravimetric analysis and differential thermogravimetry analysis. The tensile behavior of the prepared films was studied from the stress‐strain graphs. The ultraviolet–visible spectra revealed their optical characteristics. The dielectric parameters of the polymer blend and nanocomposite films like dielectric constant, loss tangent, AC conductivity, and complex impedance spectroscopy with corresponding equivalent circuits were studied. A comparative study of the above parameters was done for both the polymer blend and nanocomposites to find out the advancement in the properties of the prepared nanocomposite compared with the polymer blend. The nanocomposite film having 3 wt% of Ti3AlC2 MAX phase filler loading exhibited the best properties among all the nanocomposites. The enhanced dielectric properties of the nanocomposites with mechanical and thermal resistance can be used for real‐time efficient energy storage applications. [ABSTRACT FROM AUTHOR]

Abstract Background Polymethylmethacrylate (PMMA) bone cement is used in orthopedics and dentistry to get primary fixation to bone but doesn’t provide a mechanically and biologically stable bone interface. Therefore, there was a great demand to improve the properties of the PMMA bone cement to reduce its clinical usage limitations and enhance its success rate. Recent studies demonstrated that the addition of halloysite nanotubes (HNTs) to a polymeric-based material can improve its mechanical and thermal characteristics. Objectives The purpose of the study is to assess the compressive strength, flexural strength, maximum temperature, and setting time of traditional PMMA bone cements that have been manually blended with 7 wt% HNT fillers. Methods PMMA powder and monomer liquid were combined to create the control group, the reinforced group was made by mixing the PMMA powder with 7 wt% HNT fillers before liquid mixing. Chemical characterization of the HNT fillers was employed by X-ray fluorescence (XRF). The morphological examination of the cements was done using a scanning electron microscope (SEM). Analytical measurements were made for the compressive strength, flexural strength, maximum temperature, and setting time. Utilizing independent sample t-tests, the data was statistically assessed to compare mean values (p

The utilization of polymethyl methacrylate (PMMA) bone cement is employed for the purpose of stabilizing fractured vertebral bodies. The existence of a mechanical imbalance in hard polymethylmethacrylate (PMMA) bone cement has the potential to increase the likelihood of a fracture occurring in the neighbouring vertebral body. In order to reduce potential difficulties, the primary goal of this study is to investigate the potential benefits of increasing PMMA bone cement's bioactivity and lowering its elastic modulus. The incorporation of a 10% volume fraction of hyaluronic acid (HyA) and polyethylene glycol (PEG) into the bone cement led to an improvement in the bioactivity and decreasing of elastic modulus of polymethylmethacrylate (PMMA). The integration of HyPE gel phase presents several advantages over pure PMMA bone cement, including enhanced setting parameters, improved degradability, and increased biocompatibility. The gel phase is additionally accountable for a reduction in the elastic modulus of polymethylmethacrylate (PMMA) bone cement. In addition, the existence of a porous structure that arises from the degradation of the HyPE gel phase delivers a significant amount of room, thereby enhancing the process of bone regeneration when implanted in the femur of rabbits. The utilization of HyPE in PMMA has been shown through comprehensive µ-CT analysis to enhance bone formation, thereby promoting osteointegration at the implantation site. Furthermore, the histological analysis demonstrated the existence of osteogenic activity in the PMMA polyethylene glycol supplemented with 10% HyA and 10% PEG after a 2-month period subsequent to implantation. [ABSTRACT FROM AUTHOR]

Background: Polymethylmethacrylate (PMMA) bone cement is used in orthopedics and dentistry to get primary fixation to bone but doesn't provide a mechanically and biologically stable bone interface. Therefore, there was a great demand to improve the properties of the PMMA bone cement to reduce its clinical usage limitations and enhance its success rate. Recent studies demonstrated that the addition of halloysite nanotubes (HNTs) to a polymeric-based material can improve its mechanical and thermal characteristics. Objectives: The purpose of the study is to assess the compressive strength, flexural strength, maximum temperature, and setting time of traditional PMMA bone cements that have been manually blended with 7 wt% HNT fillers. Methods: PMMA powder and monomer liquid were combined to create the control group, the reinforced group was made by mixing the PMMA powder with 7 wt% HNT fillers before liquid mixing. Chemical characterization of the HNT fillers was employed by X-ray fluorescence (XRF). The morphological examination of the cements was done using a scanning electron microscope (SEM). Analytical measurements were made for the compressive strength, flexural strength, maximum temperature, and setting time. Utilizing independent sample t-tests, the data was statistically assessed to compare mean values (p < 0.05). Results: The findings demonstrated that the novel reinforced PMMA-based bone cement with 7 wt% HNT fillers showed higher mean compressive strength values (93 MPa) and higher flexural strength (72 MPa). and lower maximum temperature values (34.8 °C) than the conventional PMMA bone cement control group, which was (76 MPa), (51 MPa), and (40 °C), respectively (P < 0.05). While there was no significant difference in the setting time between the control and the modified groups. Conclusion: The novel PMMA-based bone cement with the addition of 7 wt% HNTs can effectively be used in orthopedic and dental applications, as they have the potential to enhance the compressive and flexural strength and reduce the maximum temperatures. [ABSTRACT FROM AUTHOR]

The paper presents a study of the luminescence properties in the visible spectral range of poly(methyl methacrylate) (PMMA) doped with organic dye-methyl red and CdSe quantum dots. The emission spectra of polymer-doped composite structures were investigated and compared with pure PMMA. Optical characterisation was carried out, focused on the measurement and analysis of excitation and luminescence spectra. Comparison of the spectroscopic characteristics of the developed materials allowed comparing the effect of doping on the luminescence properties of the obtained materials and considering their potential application as luminescent materials in fibre optic sensors. [ABSTRACT FROM AUTHOR]

3D printing of thermoplastics through local melting and deposition via material extrusion additive manufacturing provides a simple route to the near net‐shape manufacture of complex objects. However, the mechanical properties resulting from these 3D printed structures tend to be inferior when compared to traditionally manufactured thermoplastics. These unfavorable characteristics are generally attributed to the structure of the interface between printed roads. Here, we illustrate how the molecular mass distribution for a model thermoplastic, poly(methyl methacrylate) (PMMA), can be tuned to enhance the Young's modulus of 3D printed plastics. Engineering the molecular mass distribution alters the entanglement density, which controls the strength of the PMMA in the solid state and the chain diffusion in the melt. Increasing the low molecular mass tail increases Young's modulus and ultimate tensile strength of the printed parts. These changes in mechanical properties are comparable to more complex routes previously reported involving new chemistry or nanoparticles to enhance the mechanical performance of 3D printed thermoplastics. Controlling the molecular mass distribution provides a simple route to improve the performance in 3D printing of thermoplastics that can be as effective as more complex approaches. [ABSTRACT FROM AUTHOR]

The usage of plastic and its decomposition products leads to their ubiquitous distribution, resulting in their uptake by all living beings, including humans. Polymethylmethacrylate (PMMA) is known as a biocompatible polymer and is used widely in medicine and dentistry, although recent findings have shown its induction of oxidative stress within cells. Worryingly, hardly any data exist investigating the uptake of PMMA particles by cells, the potential effects of these particles on cells and cell signaling pathways and their contributing factors. We assessed the uptake of PMMA beads via confocal microscopy after their incubation with HEK293, A549 and MRC5 cells. Through cell staining, we localized multiple PMMA beads within the cytosol of cells. No alterations regarding cell growth, cell morphology or cell division were found, implying no short-term toxicity towards human cells. Using a cAMP response element binding protein (CREB)-mediated reporter assay, we assessed whether internalized PMMA nanobeads alter cell signaling pathways after stimulation of the cells. CREB was chosen as a well-described transcription factor involved in various cellular processes. Our data led to the assumption that PMMA nano- and microbeads are internalized via endocytosis and end up in lysosomes within the cell cytosol. We concluded that differences regarding the surface composition of the PMMA nanobeads affect their potential to alter cell signaling. These findings emphasize the key role the surface composition plays regarding microplastics and their risks for human health, whereas the usage of medical-grade PMMA remains safe. [ABSTRACT FROM AUTHOR]

Polyvinyl chloride (PVC) and polymethyl methacrylate (PMMA) have been used as polymeric matrices for the synthesis of polymeric nanocomposite films that incorporate titanium oxide nanoparticles (TiO 2 NPs) and graphite nanoplatelets (GNPs) as nanofillers. Based on TEM studies, TiO 2 nanoparticles have a tetragonal anatase phase, ranging in size from 15 to 60 nm, whereas GNPs have a nanoplatelet-like shape, varying in thickness from 10 to 20 nm. XRD analysis shows that PVC/PMMA polymer nanocomposite samples have less crystallinity when added with TiO 2 NPs and GNPs. Infrared Fourier analysis (FT-IR) indicated a complex interaction between the PVC/PMMA blend and both GNPs and TiO 2 NPs. The UV/visible spectrum of the PVC/PMMA blend showed two absorbance peaks at 279 and 223 nm which may result from the n→π* and π→π* transitions. Moreover, optical bandgaps were reduced for both indirect and direct transitions when TiO 2 NPs and GNPs were added. AC electrical conductivity and dielectric properties of the samples were measured at room temperature. Results indicated a significant increase in conductivity after filling from 2.6 x 10−14 S/cm for pure PVC/PMMA to 7.3 x 10−6 S/cm for PVC/PMMA-TiO 2 /GNPs nanocomposite. In addition, high nanoparticle concentrations lead to higher composite dielectric loss and dielectric constants. These findings suggest the possibility of using the prepared nanocomposites in capacitive energy storage and optoelectronic devices. [ABSTRACT FROM AUTHOR]

Orthodontic acrylic resin is used in the construction of orthodontic appliances. It lacks antimicrobial properties and is prone to microbial infection. So, the infection associated with it can be reduced via modification of orthodontic acrylic resin with nanoparticles (NPs) incorporation. The study directed to evaluate the antifungal properties of modified orthodontic acrylic resin incorporated with magnesium oxide (MgO)-NPs and silver (Ag)-NPs. NPs were mixed with polymethylmethacrylate (PMMA) in ethanol-assisted mixing method. Disc samples (10 mm in diameter and 2 mm thick) of PMMA-MgO, PMMA-Ag nanocomposites and PMMA alone (as control) were prepared. Then, C. albicans was isolated and identified clinically through taking swabs from acrylic denture base orthodontic appliances, cultured on a Sabouraud Dextrose Agar medium, followed by transferring on HiCrome™ candida Differential agar which is a selective and differential medium to distinguish distinct Candida species. The polymerase chain reaction was performed and the amplicon was separated by 2% gel electrophoresis and then visualized by ethidium bromide. DNA sequencing was performed on the sample at Sanger sequencing/ ABI 3500. Antifungal activity of PMMA-MgO and PMMA-Ag (1%, 3% and 5% of NPs) was conducted through disc diffusion assay and colony forming unit counts. The result showed a decrease in the number of adhered Candida albicans (C. albicans) of all concentrations of both nanocomposite and the decrease was statistically significant (P<0.05) in all experimental groups except MgO-NPs 1% and 3%. Increasing the concentration of NPs was associated with decrease in the adhered C. albicans. It was concluded that PMMA-MgO and PMMA-Ag nanocomposites showed anti-adherence activities against clinically isolated C. albicans in concentration dependent manner. [ABSTRACT FROM AUTHOR]

Purpose: To compare the shear bond strength between polyetheretherketone (PEEK) and heat activated polymethylmethacrylate (PMMA) resin after laser treatment. Materials and Methods: A total of 128 PEEK discs were fabricated (10 mm diameter and 2 mm thickness) and allocated into two groups. Group 1 was subjected to surface treatment followed by thermal cycling for 5000 cycles and group 2 was subjected to surface treatment followed by thermal cycling for 10,000 cycles. Each group was further subdivided into four subgroups (n = 16) which were: no surface treatment; primer treatment; acid etching; and laser surface treatment. PEEK was then bonded with PMMA resin using the conventional flasking technique. The shear bond strength was evaluated using a universal testing machine with a crosshead speed of 1 mm/min. Statistical analysis was done using one‐way ANOVA for comparing within groups, followed by Tukey HSD test. Student's T‐test was done to evaluate between the two groups. Results: In group 1, the highest shear bond strength was exhibited by the laser group (19.08 ± 0.16 MPa) followed by the acid etch group (14.84 ± 0.23 MPa), and the primer group (6.43 ± 0.20 MPa), while the least shear bond strength was observed in the no surface treatment group (4.98 ± 0.34 MPa) which was found to be significant (p < 0.05). In group 2, the highest shear bond strength was observed in the laser group (18.21 ± 0.23 MPa) followed by the acid etch group (13.77 ± 0.48 MPa), and the primer group (6.04 ± 0.11 MPa), while the least shear bond strength was observed in no surface treatment group (4.35 ± 0.21 MPa) which was found to be significant (p < 0.05). Conclusion: The shear bond strength between PEEK and PMMA resin was highest for specimens that were surface treated with laser and followed by specimens treated with acid etching, primer application, and without surface treatment, respectively. Increasing thermal cycling from 5000 cycles to 10,000 cycles also reduced the bond strength. [ABSTRACT FROM AUTHOR]

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The use of collagen is the recent development in various medical fields. Huge quantities of hide and skin trimmings are generated during the leather processing are wasted or underutilized. Trimmings contain collagen which can be beneficially extracted and utilized for high value products. Poly methyl methacrylate based denture materials exhibit serious concerns such as high porosity, presence of residual monomer, shrinkage, distortion and high rate of deterioration of the materials. This study aims to incorporate extracted Type I collagen with polymer to obtain denture base and investigate its chemical and mechanical properties. The present research methodology also reduces the quantity of monomer and acrylic resin usage. The collagen was extracted from animal skin and hide trimmings which are otherwise disposed as wastes. This study investigated the effect of visco-elastic characteristics of resulted specimens and their transition temperature, mechanical properties, decomposition temperature and leachability. The collagen-based specimens have better tensile strength with high decomposition temperature compared to control specimens. Scanning Electron Microscopy analysis revealed that the experimental specimens was cohesive and homogeneous which explained the higher tensile and decomposition values. The study suggests that collagen cross-linked acrylic denture base exhibit better mechanical and thermal resistance properties when compared to control specimens. The study indicates that biomaterials are emerging as smart products of value in human health. [ABSTRACT FROM AUTHOR]

This study aims to elucidate the effect of non ethanol-assisted and ethanolassisted mixing methods and adding MgO-and Ag-nanoparticles (NPs) into PMMA on flexural strength, impact strength, microhardness (HV) and compressive strength. NPs (1%, 3% and 5% concentrations) were mixed with poly (methyl methacrylate) (PMMA) powder by either using ethanol as a solvent (ethanol-assisted) or without ethanol (non ethanol-assisted). A total of 91 specimens were examined. One- and Two-way ANOVA tests were used to find the effect of mixing methods and concentration of NPs on mechanical properties of PMMA. The results showed an increase of flexural strength for all NPs concentrations (except 1% MgO-NPs) and HV (5% both NPs) in ethanol-assisted groups compared to non ethanol-assisted group (p < 0.05). Furthermore, the combined effects of NPs and mixing methods revealed statistically significant increases in flexural strength and HV in ethanolassisted group (except in 1% and 3% MgO-NPs) compared to the control group. Meanwhile, no statistically significant differences were detected in impact strength and compressive strength between ethanol-assisted and non ethanolassisted groups (p > 0.05). The combined effects of NPs and mixing methods presented a statistically significant increase only in compressive strength of 5% of both NPs in ethanol-assisted group in comparison to the control group. Ethanolassisted mixing of MgO-NPs and Ag-NPs with PMMA showed an increase in the mechanical properties of flexural strength, HV and compressive strength compared to non ethanol-assisted, whereas no improvement in the impact strength property of PMMA was detected. Furthermore, synergetic effects of adding NPs and mixing methods were identified. [ABSTRACT FROM AUTHOR]

Polymethylmethacrylate (PMMA) has been irradiated by 365 nm UV wavelength at different exposition times in air and room temperature. The macromolecular modifications induced in the polymer have been investigated using attenuated total reflectance (ATR) coupled to Fourier transform infrared (FTIR) spectroscopy, UV-Visible spectroscopy, surface profiler, wetting ability, and electronic microscopy. The observed chemical, optical and morphological changes occurred as a consequence of the UV irradiation suggest that chain scissions are induced by the UV radiations, with reduction of the IR and visible transmittance, wetting ability and surface roughness. The study of the degradation of PMMA by different times of exposure to UV radiation is investigated with the aim of understanding the effects produced over time on optical devices such as intraocular lenses, optical fibres, protective screens, and instrumental lenses. [ABSTRACT FROM AUTHOR]

The production of functional parts, including those employed by the biomedical industry has been achieved a promising candidate in fused deposition modelling (FDM). The essential properties of these biomedical parts which manufactured by additive manufacturing as compared to some other conventional manufacturing processes depend on structural and process parameters rather than material properties alone. Regarding to the evaluation the flexural strength of medical-grade, polymethylmethacrylate (PMMA) has been received relatively very little investigation to date. PMMA is a biocompatible filament that be used in manufacturing of patient-specific implants such as dental prosthesis and orthopaedic implants. The proposed work explores the effect of three process parameters that vary with respect of three levels on the flexural strength. These levels can be specified by layer height (120, 200, 280 µm), infill density (40, 65, 90%) and skewing angle (0°, 45°, 90°) on the flexural strength of medical-grade PMMA. Maximum and minimum flexural strength that be obtained in this work about 93 and 57 MPa respectively. The analysis of variance (ANOVA) results shows that the most effective factor is the layer height followed by infill density. The flexural strength rises significantly with decreases layer height and the skewing angle is in zero direction. The process parameters have been optimized through utilizing of genetic algorithms. The optimal results that emerged based on genetic algorithm technique are approximately 276 µm as layer height, 46% infill density, and skewing angle 89°, which maximize the flexural strength to 97 MPa at crossover for ten generation. [ABSTRACT FROM AUTHOR]

MXenes, which have good reinforcing and toughening effects, can serve as excellent polymer additives. However, the mechanism whereby MXenes act has not been revealed. In this study, to understand the reinforcement effect of Tin+1Cn on polymethyl methacrylate (PMMA) from an atomistic perspective, we used molecular dynamics to conduct unidirectional tensile simulations of PMMA composites reinforced with monolayer Ti2C and Ti3C2 sheets. The results showed that Ti3C2 can more significantly improve the mechanical properties of the PMMA polymer than Ti2C, and the yield stress and Young's modulus of the Ti3C2/PMMA complexes were respectively 54.39% and 73.46% higher than the Ti2C/PMMA complexes. To further reveal the interaction mechanism between Tin+1Cn and PMMA, different separation speeds were used to simulate the pull‐out of Tin+1Cn from the PMMA matrix. The results showed that, in addition to the enhancement of interfacial strength by non‐bonding van der Waals forces, there were TiO and CTi bonds between Tin+1Cn and PMMA, which further increased the interfacial strength. Ti3C2 formed a denser interfacial region with PMMA, it could more effectively resist the formation and expansion of cracks. These findings may provide an important theoretical basis to design new type of MXene/polymer composites with excellent mechanical properties. Highlights: MXene greatly improved the mechanical properties of the PMMA matrix.Formation of chemical bonds improved connection between the MXene and PMMA.The addition of MXene slows down the rate of crack propagation in PMMA. [ABSTRACT FROM AUTHOR]

OBJECTIVE: To determine setting and temperature properties of diluted polymethyl methacrylate (PMMA) bone cement in vitro to assess utility for vocal fold augmentation in horses. SAMPLES: 4 dilutions of PMMA equivalent to volumes of 15 mL, 20 mL, 25 mL, and 30 mL PMMA powder (PMMAp) in 10 mL solvent. METHODS: For each volume PMMAp, setting times (tset), peak temperatures (Tmax), and times to peak temperature (tmax) were determined using a temperature data logger in a 4-mL volume of PMMA. Injectability was assessed in vitro by documenting the force required to inject 0.2 mL PMMA through an 18-gauge 3.5-inch spinal needle attached to a 6-mL syringe at 1-minute intervals. Working time (twork) was calculated from a linear regression of injectability. RESULTS: Peak temperatures increased with increasing volume of PMMAp: 56°C, 86°C, 99°C, and 101°C. Times for tset, twork, and tmax were inversely proportional to PMMA concentrations, resulting in tset of 23, 21, 17, and 14 minutes; twork of 22.75, 12.25, 7, and 4 minutes; and tmax of 28, 24, 19, and 16 minutes, respectively, for 15, 20, 25, and 30 mL PMMAp. Pairwise comparisons for all analyses were significant apart from Tmax for 25 and 30 mL PMMAp (P = .96) and twork for 20 and 25 mL PMMAp (P = .06). CLINICAL RELEVANCE: Decreasing the concentration of PMMA bone cement resulted in longer working times and setting times; however, peak temperatures did not differ between the 2 strongest concentrations. Further research is warranted to quantify diluted PMMA properties for in vivo use for vocal fold augmentation in horses. [ABSTRACT FROM AUTHOR]

Last years research in polymers registered an increase of interest regarding polymer mixtures aiming to obtain materials with properties of the mixed polymers. In this respect many studies are pointing the mixtures between a thermoset polymer and a thermoplastic polymer. It is known the fact that thermoplastic polymers are much more malleable than the thermoset ones and the goal is to obtain a mixture with the general properties of the thermoset polymer and with a machining ability proper to the thermoset polymer. The vitrimers are this type of polymers and, some of them, can be obtained by mixing polymers form the two categories. This study is about using solutions of two thermoset polymers to modify the basic properties of three epoxy resins. The results show that the presence of PMMA, respectively, PLA inside the epoxy resin matrix determines changes of the mechanical properties of the formed materials. Without analysing the adhesive properties of new materials is hard to decide about their value from the composites applications point of view. [ABSTRACT FROM AUTHOR]

Poly(methyl methacrylate) (PMMA) polymers, both undoped and doped with nickel-doped tin sulfide (Sn0.8Ni0.2S2) and with various weight percentages of carbon nanoparticles (CNPs), were prepared using casting techniques. The structure, elemental analysis, morphology, and optical features of the obtained polymers were investigated using x-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, energy-dispersive x-ray spectroscopy, fluorescence (FL), and diffuse reflectance spectroscopy. Investigations were conducted to determine how SnS2/Ni and/or carbon nanoparticle content affects the optical properties of PMMA, including its energy band gap, refractive index, dielectric constant, linear first-order susceptibility, nonlinear third-order susceptibility, and nonlinear refractive index. The direct and indirect optical band gaps for PMMA decreased from (4.99, 4.4) eV to (4.09, 2.28) eV upon doping with SnS2/Ni and 0.25 wt.% CNPs. The effect of SnS2/Ni and/or CNPs on the frequency dependence of the dielectric properties was investigated. The FL intensity can be controlled to a desired limit by adjusting the SnS2/Ni and CNP concentrations in PMMA blends for different applications in optical devices. The emitted colors from each sample were found using the CIE 1931 chromaticity diagram. [ABSTRACT FROM AUTHOR]

In the present work, sol–gel‐synthesized titanium oxide nanoparticles (TiO2 NPs) were added to polyvinyl chloride (PVC) and polymethyl methacrylate (PMMA) to create polymer nanocomposites (PNCs) samples. The preparation was carried out via the solution casting method. The synthesized TiO2 NPs have a tetragonal anatase phase and an average grain size of 15.7 nm. XRD analysis reveals that the TiO2 NPs' addition to PVC/PMMA causes a decrease in the crystallinity of PNCs films. Infrared Fourier analysis demonstrated the interplay/complexity between the PVC/PMMA blend and TiO2 NPs. The UV/visible spectrum of the PVC/PMMA blend showed two absorbance peaks at 278 and 208 nm, which may result from the n → π* and π → π* transitions. Also, optical bandgaps for indirect and direct allowed transitions decreased with increasing TiO2 NPs concentration. The samples' AC electrical conductivity and dielectric properties were measured at room temperature. As the TiO2 NPs content in the nanocomposite rises, a percolating network begins to emerge inside the composite, demonstrating that AC electrical conductivity obeys Jonscher's law. Additionally, it has been demonstrated that nanoparticle concentration leads to a higher composite dielectric loss and dielectric constant. These findings suggest the possibility of using the prepared nanocomposites in capacitive energy storage and optoelectronic devices. Highlights: PVC/PMMA‐TiO2 nanocomposites' films were fabricated via the solution casting method.Adding TiO2 NPs to PVC/PMMA reduces the crystallinity of the PNCs films.The allowed direct and indirect bandgaps decreased with rising TiO2 NPs content.AC conductivity, impedance, and dielectric characteristics were discussed.The findings indicate the use of prepared samples in optoelectronic devices. [ABSTRACT FROM AUTHOR]

Acrylic bone cement, which primarily consists of polymethyl methacrylate (PMMA), is widely used in orthopaedics, dentistry, and particularly in joint arthroplasty surgery. However, bone cements (BCs) have several limitations, including low mechanical properties, bioactivity issues, and high heat generation during polymerization. In recent years, there has been significant interest in studying the development of mechanical, thermal, and antibacterial properties of bone cement. In this study, ZnO nanostructures modified CFs were added to PMMA BCs at concentrations ranging from 0.10 wt% to 1.00 wt%, and the mechanical and thermal properties of the novel PMMA composite BCs were investigated. The novel composite materials were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy, and Fourier-transform infrared spectroscopy (FTIR). Mechanical tests including compression and 4-point bending were performed on the composite structures, along with thermogravimetric analysis (TGA). The results revealed that the composite cement containing 0.25 wt% ZnO/CFs reinforcement agent exhibited the best mechanical properties and thermal stability. The flexural strength of the 0.25 wt% ZnO/CFs reinforced PMMA composite BCs increased by 78.9%, while the compression strength increased by 277.4% compared to the control group. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate and compare the fracture resistance of a temporary three-unit fixed dental prosthesis (FDP) made of a new polymeric material obtained by an additive technique (3DPP) using a computer-aided design and manufacturing (CAD/CAM) system, comparing the prosthesis to the respective outcomes of temporary polymethylmethacrylate (PMMA) FDPs obtained by a subtractive technique (milling). Methods: Three-unit FDPs were 3D printed using a polymeric material (n = 20) or milled using polymethylmethacrylate (n = 20). After thermocycling at 5000 cycles at extreme temperatures of 5 °C and 55 °C in distilled water, each specimen was subjected to a compression test on a universal testing machine at a rate of 0.5 mm/min until failure occurred, recording the value in newtons (N). Results: There were statistically significant differences (p-value < 0.005) between the PMMA material (2104.7 N; SD = 178.97 N) and 3DPP (1000.8 N; SD = 196.4 N). Conclusions: The fracture resistance of the PDFs manufactured from milled PMMA showed higher values for fracture resistance. However, the resistance of the 3DPP showed acceptable values under mechanical load; this notable advance in the resistance of printed materials consolidates them as an important alternative to use in interim indirect restorations. [ABSTRACT FROM AUTHOR]

In the recent years, composite polymers have been widely involved in a large scale of sensitive applications such as biomedical, remote healthcare, electronic devices, smart industry 4.0, and so on. This is due to their numerous advantages in terms of high precision measurement, mechanical and electrical strengths, and affordable cost, witnessed by various recent researches. Moreover, and to meet their environment installation conditions, polymers are usually reinforced by a protective layer, thoroughly produced by various resistant materials such as carbon fibers (CF). In that context, our present work aims to analyze and compare the temperature effect and the mechanical stress on the fiber-matrix interface damage for the three reinforced polymers: CF/poly ether ether keton (PEEK), CF/poly methyl methacrylate (PMMA), and CF/poly phenylene sulfide (PPS). The obtained results by a genetic approach and a non-linear acoustic technique obviously depict that for the three composite materials, and above 137°C, the interface damage increases very swiftly. In addition, the fiber-matrix interface adhesion of CF/PEEK shows better response compared to the other interfaces CF/PMMA and CF/PPS, this conclusion was confirmed by Aucher where he found in his study that the ductility of the resin and the strong fibre/matrix adhesion, especially in the case of CF/PEEK, is better compared to CF/PMMA and CF/PPS. Results obtained by our present study are intended to complete those already found in the field of the reinforced polymers designed for the aforementioned engineering applications. [ABSTRACT FROM AUTHOR]

Even before considering their introduction into the mouth, the choice of materials for the optimization of the prosthesis depends on specific parameters such as their biocompatibility, solidity, resistance, and longevity. In the first part of this two-part review, we approach the various mechanical characteristics that affect this choice, which are closely related to the manufacturing process. Among the materials currently available, it is mainly polymers that are suitable for this use in this field. Historically, the most widely used polymer has been polymethyl methacrylate (PMMA), but more recently, polyamides (nylon) and polyether ether ketone (PEEK) have provided interesting advantages. The incorporation of certain molecules into these polymers will lead to modifications aimed at improving the mechanical properties of the prosthetic bases. In the second part of the review, the safety aspects of prostheses in the oral ecosystem (fragility of the undercuts of soft/hard tissues, neutral pH of saliva, and stability of the microbiota) are addressed. The microbial colonization of the prosthesis, in relation to the composition of the material used and its surface conditions (roughness, hydrophilicity), is of primary importance. Whatever the material and manufacturing process chosen, the coating or finishes dependent on the surface condition remain essential (polishing, non-stick coating) for limiting microbial colonization. The objective of this narrative review is to compile an inventory of the mechanical and physical properties as well as the clinical conditions likely to guide the choice between polymers for the base of removable prostheses. [ABSTRACT FROM AUTHOR]

Background: New materials for overdenture base construction were evolved. Thus, more clinical trials are needed to validate these materials. Objective: This study aimed to compare the difference between CAD/CAM‐milled poly methyl methacrylate (PMMA), poly ether ether ketone (PEEK) and conventional mandibular implant‐assisted overdentures regarding patient satisfaction and oral health‐related quality of life (OHRQL). Methods: This randomised, crossover, clinical study included 18 completely edentulous subjects rehabilitated with three mandibular implant‐assisted overdentures with three different denture base materials opposing a maxillary single denture. These materials were as follows: CAD/CAM‐milled PMMA, CAD/CAM‐milled PEEK and conventional PMMA. Every participant first received each mandibular overdenture in a random manner. After 6 months of each overdenture use, patient satisfaction and oral health‐related quality of life were assessed using visual analogue scale (VAS) and Oral Health Impact Profile (OHIP‐EDENT‐19), respectively, and then crossover to other groups was done. The same was repeated to the last group. Comparison of VAS and OHIP‐EDENT‐19 between groups was done using Kruskal–Wallis test followed by Bonferroni test. Results: Regarding all the VAS items, there were statistically significant higher scores for CAD/CAM‐milled PMMA and PEEK than conventional PMMA base except for speech, aesthetic and smell. Regarding OHIP‐EDENT‐19, many items revealed statistically lower problem scores for CAD/CAM‐milled PMMA, and CAD/CAM‐milled PEEK than conventional PMMA base except psychological discomfort, psychological disability and social disability. Conclusion: Within the limit of this study, CAD/CAM‐milled PMMA and CAD/CAM‐milled PEEK were recommended as implant‐assisted overdenture bases as it revealed higher patient satisfaction and better oral health‐related quality of life in comparison with conventional PMMA implant‐assisted overdenture. [ABSTRACT FROM AUTHOR]

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The Constrained Groove Pressing (CGP) on annealed Al5083 (Al5083-O) alloy sheets by means of Polymethyl Methacrylate (PMMA) polymer is investigated in this research. Input parameters include Traverse Speed (1, 2, and 3 mm/min), Pass Number (1, 2, 3, and 4), and Lubricants (Grease, Oil, and without lubricants). Reciprocally, output parameters consist of Nanostructure (SEM and EBSD images), Hardness (HV), and Mechanical Properties – Impact Strength (kJ/m2), Tensile Strength (MPa), Young's Modulus (MPa), and Elongation (%). Revealed by the results, the impact strength is gradually improved in the 1st, 2nd, 3rd, and 4th passes by respectively adding oil and grease, compared to the state of using no lubricant. The impact strength results demonstrated that the addition of grease has a significant effect on the impact strength of composite samples. In order to build a high-quality product through the CGP process, it is very important for the mechanical properties to be based on the input parameters. In CGP processes, the Continuous Dynamic Recrystallization (CDRX) is considered as the ultrafine-grained mechanism. To predict the grain size evolution and the plastic deformation rate, the combination of Finite Element (FE) method and the ETMB model is utilized. Indicating the high generalizability and reliability as compared to other modeling methods, both the experimental test results and the ETMB model data, which have a higher degree of accuracy, are presented. [ABSTRACT FROM AUTHOR]

Giant Cell tumors (GCT) are benign tumors with aggressive characteristics and the potential to metastasize. These are seldom lethal benign bone tumors but are associated with massive local bony architecture distraction making their treatment difficult, especially if found in peri-articular locations. Several long bone giant cell tumor (GCT) cases have been reported. We report a unique treatment of distal femur GCT in a 19-year-old in a resource-limited setup whose initial presentation was following a pathologic fracture. We used a staged surgical protocol. In the first stage, distal femur resection and implantation of poly methyl methacrylate (PMMA) cement spacer for induced membrane formation was done, followed by SIGN nail and non-vascularized fibula strut graft. There was adequate healing and no recurrence was noted during the two-year follow-up. [ABSTRACT FROM AUTHOR]

Introduction: Sacroplasty is a minimally invasive treatment option for severe pain due to sacral insufficiency fracture. Cement leakage is a known risk of sacroplasty. Despite the elevated risk to the L5 nerve root and lumbosacral trunk from cement leakage anterior to the sacral ala, there are no reports regarding surgical management of this complication. Technical Note: We describe an anterior retroperitoneal transpsoas approach to the sacral ala to remove cement leakage causing acute L5 radiculopathy in a 57-year-old gentleman who had undergone sacroplasty for sacral insufficiency fracture (Denis zone 1). The approach provides rapid and excellent visualization of the sacral ala without manipulation of the iliac vessels. Conclusions: We recommend that surgery be considered in a timely fashion, to utilize neuromonitoring, and that surgeons be aware of the considerable variability of the neurologic structures that will be encountered, which is described in this technical note.

Recently, the studies on lightweighting have gained significant importance due to requirements such as energy efficiency and sustainability. Polymer materials are a group of materials that are frequently used for this purpose. This study investigated the effects of laser power, cutting speed and focal point on the kerf width, which are the most effective process parameters in laser cutting of Polymethylmethacrylate, a low-cost polymer material, using Response Surface Methodology and ANOVA. The results obtained from the data analysis show that the kerf width is seriously affected by the focal point depth as well as the speed and power. [ABSTRACT FROM AUTHOR]

This study aims to examine the impact of the direct and indirect mixing techniques on the dispersion and homogeneity of magnesium oxide (MgO) and silver (Ag) nanoparticles (NPs) mixed with polymethylmethacrylate (PMMA). NPs were mixed with PMMA powder directly (non-ethanol-assisted) and indirectly (ethanol-assisted) with the aid of ethanol as solvent. X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), and scanning electron microscope (SEM) were used to evaluate the dispersion and homogeneity of MgO and Ag NPs within the PMMA-NPs nanocomposite matrix. Prepared discs of PMMA-MgO and PMMA-Ag nanocomposite were analyzed for dispersion and agglomeration by Stereo microscope. XRD showed that the average crystallite size of NPs within PMMA-NP nanocomposite powder was smaller in the case of ethanol-assisted mixing compared to non-ethanol-assisted mixing. Furthermore, EDX and SEM revealed good dispersion and homogeneity of both NPs on PMMA particles with ethanol-assisted mixing compared to the non-ethanol-assisted one. Again, the PMMA-MgO and PMMA-Ag nanocomposite discs were found to have better dispersion and no agglomeration with ethanol-assisted mixing when compared to the non-ethanol-assisted mixing technique. Ethanol-assisted mixing of MgO and Ag NPs with PMMA powder obtained better dispersion, better homogeneity, and no agglomeration of NPs within the PMMA-NP matrix. [ABSTRACT FROM AUTHOR]

Background: The most widely used substance in the fabrication of dental prosthesis is poly (methyl methacrylate), or PMMA, and the development of biofilm is frequently associated with its use. To enhance the mechanical properties of heat-polymerized PMMA, this study prepared PMMA/gold nanoparticles (AuNps). The occlusal vertical dimension and tooth movement were examined in the current study. The occlusal vertical dimension was assessed using an electronic digital calliper measuring device, and tooth movement was measured using a CAD Star digital scanner. Results: Tooth movement and occlusal vertical dimension of a PMMA/gold nanoparticles (AuNps) were decreased for all groups containing AuNps. Statistical analysis was performed by means of the SPSS 16 software package. Conclusions: Incorporation of AuNps into heat- polymerized PMMA resin led to increase dimensional stability of complete denture base material. [ABSTRACT FROM AUTHOR]

Functionalizing organic–inorganic materials for use in packaging technologies, such as polymers wrapped in thin metal, has proven to be one of the more successful strategies. In this study, the direct current (DC) sputtering technique under a vacuum of 3 × 10−5 Torr was used to deposit silver (Ag) films of thicknesses of 100 and 300 nm on poly (methyl methacrylate) (PMMA) polymer. The structural, optical, antibacterial activity, and wettability properties of Ag/PMMA were carried out using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), field emission scanning electron microscope (FE-SEM), atomic force microscopy (AFM), UV spectrophotometer, and contact angle. The cubic crystal structure phase of Ag was confirmed by the XRD. The Ag coating layer has consistent nanomorphology, according to AFM, and the PMMA substrate surface was well coated with Ag nanoparticles. As the Ag film thickness rose, the optical band gap values of Ag/PMMA slightly increased. In addition, it has been found that these optical characteristics such as extension coefficient, optical density, and optical surface resistance essentially depend on the thickness of the Ag layers. Both samples of pure PMMA and Ag/PMMA polymers show no activity against E. coli. In the meantime, S. aureus activity is detected in the Ag/PMMA samples, and the antibacterial activity is slightly influenced by the Ag thickness. The contact angle rose as the Ag film thickness grew over the PMMA, resulting in a decrease in the wettability of the liquid which is required for food packaging technology. [ABSTRACT FROM AUTHOR]

As a proxy for pollutants that may be simultaneously present in urban wastewater streams, the effects of two microplastics—polystyrene (PS; 10, 80 and 230 μm diameter) and polymethylmethacrylate (PMMA; 10 and 50 μm diameter)—on fertilisation and embryogenesis in the sea urchin Arbacia lixula with co-exposure to the pyrethroid insecticide cypermethrin were investigated. Synergistic or additive effects were not seen for plastic microparticles (50 mg L−1) in combination with cypermethrin (10 and 1000 μg L−1) based on evaluation of skeletal abnormalities or arrested development and death of significant numbers of larvae during the embryotoxicity assay. This behaviour was also apparent for male gametes pretreated with PS and PMMA microplastics and cypermethrin, where a reduction in sperm fertilisation ability was not evidenced. However, a modest reduction in the quality of the offspring was noted, suggesting that there may be some transmissible damage to the zygotes. PMMA microparticles were more readily taken up than PS microparticles, which could suggest surface chemical identity as potentially modulating the affinity of larvae for specific plastics. In contrast, significantly reduced toxicity was noted for the combination of PMMA microparticles and cypermethrin (100 μg L−1), and may be related to less ready desorption of the pyrethroid than PS, as well as cypermethrin activating mechanisms that result in reduced feeding and hence decreased ingestion of microparticles. [ABSTRACT FROM AUTHOR]

The well-known principle of time–temperature superposition (TTS) is of prime interest for polymers close to their glass transition. First demonstrated in the range of linear viscoelasticity, it has been more recently extended to large deformations in tension. However, shear tests were not yet addressed. The present study depicted TTS in shearing conditions and compared it to results in tensile conditions both for low and high strains for a polymethylmethacrylate (PMMA) of different molar masses. The main objectives were to enlighten the relevance of the principle of time–temperature superposition for shearing at high strain and to discuss the way shift factors should be determined. It was suggested that shift factors could be dependent on compressibility, which should be taken into account when addressing various types of complex mechanical loadings. [ABSTRACT FROM AUTHOR]

Background. Polymethylmethacrylate (PMMA) is the most used material for the manufacturing of eye prostheses. Objectives. To investigate the cytotoxicity of different cleaning agents for ocular prostheses on human conjunctival cells. Materials and methods. Six groups ofspecimens were created (saline, soap, 4% chlorhexidine, hydrogen peroxide, 1% triclosan, and citronella oil). Three specimens were made for each disinfectant ateach disinfection period (1, 7, 15, 30, 60, and 90 days), totaling 108 specimens. Thus, the specimens were disinfected, with different disinfectants, for different periods of time. After each disinfection process, thespecimens were washed with sterile distilled water. A human conjunctival cell line was grown ontheacrylic resin specimens and then cytotoxicity tests (MTT and Neutral Red (NR)) were performed. A negative control (untreated cell cultures) and positive control (Tween 20) were created. Two-way analysis ofvariance (ANOVA) and Bonferroni test were performed (p < 0.05). Results. For the MTT and NR tests, when there was a significant difference between thedisinfectant and negative control, thedisinfectant generated asignificant reduction incell proliferation most of thetime. Conclusions. All reductions in cell proliferation caused by the disinfectants were clinically acceptable. Alldisinfectants tested inthis study were found tobe non-cytotoxic tohuman conjunctival cells. [ABSTRACT FROM AUTHOR]

Purpose: To study the surface and mechanical properties of 3D printed denture‐base resin materials and compare them with conventional heat‐cured polymethylmethacrylate (PMMA). Materials and methods: Three brands of 3D printed denture‐base resin materials and one conventional heat‐cured PMMA were tested in this study: NextDent 3D printed resin, Dentona 3D printed resin, ASIGA 3D printed resin, and Meliodent conventional PMMA. Sixty specimens (25 × 25 × 3 mm) were fabricated (n=15 per group) to perform the following tests: wettability, surface roughness, and microhardness. One hundred twenty specimens (65 × 10 × 3 mm) were fabricated (n=30 per group) and stored in distilled water at (37 ±1°C) for 7 days. Specimens (N = 15) in each group were subjected to the three‐point bending test and impact strength test, employing the Charpy configuration on un‐notched specimens. The morphology of the fractured specimens was studied under scanning electron microscope (SEM). Statistical analysis was performed using one‐way ANOVA and Tukey‐pairwise multiple comparisons with 95% confidence interval. P‐values of ≤0.05 were considered significant. Results: The conventional heat‐cured specimens demonstrated the highest means of surface roughness (0.23 ± 0.07 μm), Vickers hardness number (18.11 ±0.65) and flexural strength (92.44 ±7.91 MPa), and the lowest mean of contact angle (66.71° ±3.38°). ASIGA group showed the highest mean of contact angle (73.44° ±2.74°) and the lowest mean of surface roughness (0.19 ±0.03 μm). The highest mean of impact strength was recorded in the Dentona group (17.98 ±1.76 kg/m2). NextDent specimens showed the lowest means of Vickers hardness number (16.20 ±0.93), flexural strength (74.89 ±8.44 MPa), impact strength (15.20 ±0.69 kg/m2), and recorded the highest mean of bending modulus (2,115.80 ±178.95 MPa). Conclusions: 3D printed resin exhibited noticeable differences in surface and mechanical properties between different brands and with conventional heat‐polymerized PMMA. [ABSTRACT FROM AUTHOR]

Pigment red 53 is a synthetic dye that has been banned in cosmetic products due to the possibility of causing blood disorders and spleen sarcoma. The indicator strip employs qualitative analysis methods that are simpler, easier, and quicker than an instrumental analysis. The indicator strip is made of a polymethylmethacrylate (PMMA) and polystyrene (PS) mixture using a reagent blending method with specific reagents of concentrated sulfuric acid (H2SO4), concentrated hydrochloric acid (HCl), or 10% sodium hydroxide (NaOH). Pigment red 53 detections with an indicator strip are based on the occurrence of a specific color change reaction between the reagent and pigment red 53 through sulfonation with concentrated H2SO4, neutralization with 10% NaOH, and reaction of pigment red 53's azo group with concentrated HCl. PMMA was made with a concentration of 5% (w/t), and mixtures of PS:PMMA 1:2, 1:3, and 1:4 had solvent-to-specific reagent ratios of 60:40, 80:20, and 90:10. The best results were obtained for PMMA-H2SO4 (90:10), PMMA-HCl (80:20), and PMMA-NaOH (60:40), with the lowest detection limits equaling 20 ppm, 50 ppm, and 20 ppm, respectively. Meanwhile, the best PS:PMMA (1:4)-based indicator strips obtained were PS:PMMA-H2SO4 (90:10), PS:PMMA-HCl (80:20), and PS:PMMA-NaOH (60:40), with the lowest detection limits being 20 ppm, 10 ppm, and 20 ppm, respectively. All indicator strips are stable for at least 80 days. Indicator strips can be used as a simple and applicable method for detecting pigment red 53 in cosmetic products with a good performance. [ABSTRACT FROM AUTHOR]

The widespread occurrence of plastic has become a significant problem in the natural environment and may give rise to a range of deleterious impacts in biota, particularly where plastic particles overlap in size with that of the particles that are naturally ingested by filter-feeders. In this context, the effects of two particle sizes (10 μm and 50 μm) of polymethylmethacrylate (PMMA) on ecologically and commercially significant mussel Mytilus galloprovincialis have been investigated. Mussel health status was evaluated by measuring the condition index and stress-on-stress test during and after 72 h exposure to PMMA microparticles in the 0.1–10 mg L−1 concentration range. The decreased condition and fitness indices in the exposed mussels pointed to significant physiological effects at the entire organism level. The 10 μm and 50 μm PMMA particles were noted to rapidly increase the total haemocytes count in haemolymph, and significantly reduce cell viability at higher concentrations of both particle sizes. The results also indicated a significant increase in levels of vacuolised haemocytes as a result of PMMA exposure. While both microparticles were detected in the haemolymph, only the 10 μm PMMA was observed in the gill tissue and digestive gland by histological cryosections, indicating their rapid uptake, transport, and accumulation in tissue. Lack of accumulation of 50 μm microparticles in tissue may be related to a combination of chemical identity and size considerations, enabling more efficient depuration of microparticles in pseudofaeces. The PMMA particles did not induce significant changes in activity of a range of enzymes involved in neurotransmission and responses to oxidative stress. [ABSTRACT FROM AUTHOR]

PMMA-based polymer electrolytes with LiCF3SO3 lithium salt, EC plasticizer, and SiO2 filler are prepared using the solution cast method. SiO2 filler sizes at 10 µm and 63 µm are used to estimate the particle size in the polymer electrolytes system. EIS analysis calculates ionic conductivity based on the Cole-Cole plot generated in frequency ranging from 0.1 Hz to 1 MHz. The calculation results in ionic conductivity at 1.44 × 10-4 S/cm and 8.1 × 10-5 S/cm for 10 µm and 63 µm SiO2 filler, respectively. FWHM measurement is performed for each diffraction peak based on the XRD spectra. Debye-Scherrer equation is used to estimate the resultant particle size. Peak broadening effect caused by the instrument is considered for a more accurate estimation of particle size in the polymer electrolyte system. Linear regression is employed to determine the average particle size arising from these diffraction peaks. The results showed that larger filler size results in the formation of a larger particle size. [ABSTRACT FROM AUTHOR]

PMMA (Poly methyl methacrylate) composites have promising potential for applications in optics and dielectric energy storage. To investigate the effects of TeO 2 contents in PMMA in this respect, we studied their composites on light absorption in the UV visible range, structural analysis via X-ray diffraction, dielectric characteristics, and free volume behavior. We added up to approximately 7 % of the weight concentration of the TeO 2 micropowder to the PMMA matrix for effective dispersion because of the limitations of ultrasonic agitation. The XRD data demonstrate a widening of the peaks with a filler content of up to 4.8 % and agglomeration at 7 %, indicating TeO 2 particle contact. An increase in absorbance was observed in the UV visible spectrum of the PMMA/TeO 2 composites with increasing TeO 2 content up to 4.8 %. The dielectric constants exhibit a positive correlation with higher quantities of TeO 2 , and the polarization mechanism is interpreted by interface polarization and free volume. The free volume measured by positron annihilation lifetime spectroscopy (PALS) increases to 4.8 % but decreases to 7 %. The effect of the free volume within the matrix on the polarization distribution of TeO 2 influenced the dielectric constant and the loss factor, which increased to 4.8 % and then decreased to 7 % due to agglomeration. • Free volume behavior of PMMA/TeO 2 was investigated using the Positron Spectroscopy in both the glassy and molten phases. • The XRD spectrum reveals a broadened peak with TeO 2 content consistent with the free volume. • UV–visible absorbtion spectra aligns well with composite free volume. • Free volume quantity interpretes dielectric permitivity and loss factor using filler-matrix interface polarization. • PMMA/TeO 2 composites exhibit highly favorable dielectric characteristics, increasing the dielectric constant about 20 %. [ABSTRACT FROM AUTHOR]

The conventional method of graphene transfer involving Polymethylmethacrylate (PMMA) often results in residual PMMA, negatively impacting the optical and electrical properties of the transferred graphene layer. This study employs the Taguchi optimization technique to minimize PMMA contamination during the graphene transfer process. The quality of the transferred graphene layer was evaluated utilizing atomic force microscopy (AFM), Raman spectroscopy, and Hall Effect measurement. The optimized conditions identified were a PMMA concentration (P) of 4.5 %, a spin rotation (S) speed of 3000 rpm, an acetone bath temperature (A) at 40 °C, and a dissolution duration (T) of 60 min. These parameters achieved a promising surface coverage of 3.42 %. Interestingly, further characterization highlighted that sample #8, prepared with different parameters (P = 12 %, S = 3000 rpm, A = 24 °C, T = 60 min), exhibited a surface coverage of 5.10 % and superior properties, including high transparency, exceptional film quality, low electrical resistance (8691 Ω), and an I D /I G ratio of 0.13. These findings suggest that the optimized conditions are suitable for applications prioritizing surface coverage, while the parameters for sample #8 are recommended for achieving minimal electrical resistance, high transparency, and superior film quality. This research contributes insights into PMMA-assisted graphene transfer, offering practical guidance for tailored processes. [Display omitted] • Optimized graphene transfer minimizes PMMA residue and boosts graphene layer performance. • Achieved enhanced optical and electrical properties in graphene layers, surpassing unoptimized samples. • Reduced PMMA residues with a surface coverage of 3.42 % using optimized transfer parameters. • Provided practical guidelines for achieving high-quality PMMA-assisted graphene transfer. [ABSTRACT FROM AUTHOR]