Pristine Poly Methyl Methacrylate Research Articles

Analysis of X-ray and gamma ray shielding performance of prepared polymer micro-composites

Polymethyl-methacrylate (PMMA) was used as the matrix to prepare micro composites for radiation shielding, with 10%, 20%, 30%, and 40% Bi2O3 filler loadings, by melt mixing method. The mass attenuation coefficients (MAC) of prepared micro composites along with pure PMMA were measured with a NaI (Tl) scintillator detector spanning a wide range of energies (59–1332 keV). Several radioactive point sources, which are commonly used in many industrial and medical applications, namely Co-60 (1173 and 1332 keV), Co-57 (122 keV), Cs-137 (662 keV), Am-241 (59.6 keV), Ba-133 (81 and 356 keV) and Ra-226 (242 keV), were used in the experimental work. The shielding performance increased substantially with increasing Bi2O3 filler loading especially in the low energy range and decreased with increasing energy except at 122 keV due to bismuth K-absorption edge. At higher energies 1173 and 1332 keV, Compton effect is the most dominant effect leading to minor variations as observed. XCOM software was used for comparison, by computing the mass attenuation coefficient for prepared micro composites at all used Bi2O3 loadings including pristine PMMA. In addition, the effective atomic number Zeff, electron density Neff as well as the photoelectric absorption and incoherent scattering contributions to MAC, were evaluated for further analysis. The prepared PMMA-Bi2O3 micro composites shielding materials performed very well in the whole energy range 59–1332 keV of interest to medical and industrial applications, and are excellent at lower energies and higher Bi2O3 loadings. In particular, at 40% loading, the experimental MAC for the Cs-137 gamma line (662 keV) reached 93.4% of that of lead element. Therefore, these composites are much recommended cost effective, light and safe shielding material for x and gamma rays.

Surface, mechanical and chemical properties of modified denture resin using natural biopolymer.

This laboratory study determined the surface, mechanical and chemical properties of polymethyl methacrylate (PMMA) denture resin reinforced with micron-sized Gum Arabic (GA) powder in different weight ratios. This laboratory study was conducted at the Dental Health Department of the College of Applied Medical Sciences, King Saud University, Riyadh, Saudi Arabia from November 2022 to February 2023. Three experimental denture resins were prepared by incorporating GA powder in heat-polymerized PMMA powder using different wt.% (5, 10, and 20 wt.%). While pristine PMMA served as the control group. A total of ten bar-shaped specimens with dimensions of 65 mm × 10 mm × 3.5 mm were prepared for each study group. The surface properties (micro CT and SEM evaluation), mechanical properties (Nanohardness, elastic modulus and flexural strength) and chemical properties (FTIR) were conducted. The data were statistically analyzed using the one-way analysis of variance and Tukey's post hoc tests (p<0.05). The surface and bulk properties of experimental GA-reinforced PMMA resin materials deteriorated while the mechanical properties were also negatively altered using GA-based PMMA denture resin. A linear correlation was observed between weak mechanical properties and increasing wt.% of GA in denture resin. The incorporation of GA powder in denture resin might not be a viable option. The surface and mechanical properties of experimental PMMA composites were adversely affected compared to the control group.

Study of Prepared Lead-Free Polymer Nanocomposites for X- and Gamma-ray Shielding in Healthcare Applications.

Polymer composites were synthesized via melt mixing for radiation shielding in the healthcare sector. A polymethyl-methacrylate (PMMA) matrix was filled with Bi2O3 nanoparticles at 10%, 20%, 30%, and 40% weight percentages. The characterization of nanocomposites included their morphological, structural, and thermal properties, achieved using SEM, XRD, and TGA, respectively. The shielding properties for all synthesized samples including pristine PMMA were measured with gamma spectrometry using a NaI (Tl) scintillator detector spanning a wide range of energies and using different radioisotopes, namely Am-241 (59.6 keV), Co-57 (122.2 keV), Ra-226 (242.0), Ba-133 (80.99 and 356.02 keV), Cs-137 (661.6 keV), and Co-60 (1173.2 and 1332.5 keV). A substantial increase in the mass attenuation coefficients was obtained at low and medium energies as the filler weight percentage increased, with minor variations at higher gamma energies (1173 and 1332 keV). The mass attenuation coefficient decreased with increasing energy except under 122 keV gamma rays due to the K-absorption edge of bismuth (90.5 keV). At 40% loading of Bi2O3, the mass attenuation coefficient for the cesium 137Cs gamma line at 662 keV reached the corresponding value for the toxic heavy element lead. The synthesized PMMA-Bi2O3 nanocomposites proved to be highly effective, lead-free, safe, and lightweight shielding materials for X- and gamma rays within a wide energy range (<59 keV to 1332 keV), making them of interest for healthcare applications.

In vitro osteoconductivity of PMMA-Y2O3 composite resins

Polymethyl methacrylate (PMMA) bone cements are used as “glue” between orthopedic/orthodontic implants and bone, since they can be modeled and easily applied by the surgeon, while being chemically and biologically stable for many years after surgery. In this research, Y2O3 powder was added to commercial PMMA bone cement to produce a composite resin, which was then characterized and tested in vitro to evaluate the cell proliferation and the quality of osteoblastic bone formed in vitro on the composite. Biological assays showed an increase in cell proliferation on the Y2O3-PMMA composite as compared to the pristine sample. Alizarin Red staining (ARS) showed the amount of bone formed on a composite PMMA resin was about 30% higher than that on the pristine PMMA bone cement reference. The quality of bone tissue was evaluated using Raman spectroscopy, showing the bone tissue formed on the composite had a better degree of mineralization and a higher maturity as compared to the tissue grown on the control sample. These preliminary results suggest that Y2O3 plays a biologically active role in bone growth and Y2O3-composites are affordable, superior candidates as bone cement materials.

Influence of the Physical Inclusion of ZrO2/TiO2 Nanoparticles on Physical, Mechanical, and Morphological Characteristics of PMMA-Based Interim Restorative Material.

Polymethyl methacrylate (PMMA) is often used in restorative dentistry for its easy fabrication, aesthetics, and low cost for interim restorations. However, poor mechanical properties to withstand complex masticatory forces are a concern for clinicians. Therefore, this study aimed to modify a commercially available PMMA-based temporary restorative material by adding TiO2 and ZrO2 nanoparticles in different percentages as fillers and to investigate its physio-mechanical properties. Different percentages (0, 0.5, 1.5, and 3.0 wt%) of TiO2 and ZrO2 nanoparticles were mixed with the pristine PMMA resin (powder to liquid ratio: 1 : 1) and homogenized using high-speed mixer. The composites obtained were analyzed for their flexural strength (F.S.), elastic modulus (E.M.), Vickers hardness (H.V.), surface roughness Ra, morphology and water contact angle (WCA). The mean average was determined with standard deviation (SD) to analyze the results, and a basic comparison test was conducted. The results inferred that adding a small amount (0.5 wt%) of TiO2 and ZrO2 nanoparticles (NPs) could significantly enhance the physio-mechanical and morphological characteristics of PMMA interim restorations. EM and surface hardness increased with increasing filler content, with 3.0 wt.% ZrO2 exhibiting the highest EM (3851.28 MPa), followed by 3.0 wt.% TiO2 (3632.34 MPa). The WCA was significantly reduced from 91.32 ± 4.21° (control) to 66.30 ± 4.23° for 3.0 wt.% ZrO2 and 69.88 ± 3.55° for 3.0 wt.% TiO2. Therefore, TiO2 and ZrO2 NPs could potentially be used as fillers to improve the performance of PMMA and similar interim restorations.

Effect of Cu Ions Implantation on Structural, Electronic, Optical and Dielectric Properties of Polymethyl Methacrylate (PMMA).

In this work, the effect of ion bombardment on the optical properties of Polymethylmethacrylate (PMMA) was studied. Polymer samples were implanted with 500 keV Cu+ ions with a fluence ranging from 1 × 1012 to 1 × 1014 ions/cm2. X-ray Diffractometer (XRD) study indicated a relatively lower variation with a higher dose of ions. Fourier Transform Infrared (FTIR) spectra exhibited that with the implantation of Cu ions the intensity of existing bands decreases, while the result confirms the existence of a C=C group. The pristine and ion-implanted samples were also investigated using photoluminescence (PL) and Ultra Violet-Visible (UV-VIS) spectra. The optical band gap (Eg) was observed up to 3.05 eV for the implanted samples, while the pristine sample exhibited a wide energy-gap up to ~3.9 eV. The change in the optical gap indicated the presence of a gradual phase transition for the polymer blends. The dielectric measurements of the pristine and Cu-implanted PMMA were investigated in the 10 Hz to 2 GHz frequency range. It was found that the implanted samples showed a significant decrease in the value of the dielectric constant. The value of the dielectric constant and dielectric loss of the PMMA and Cu-implanted samples at a 1-kHz frequency were found to be ~300 and 29, respectively. The modification of the PMMA energy bandgap in the current research suggested the potential use of Cu implanted PMMA in the field of optical communications and flexible electronic devices.

Quasi-static and dynamic nanomechanical characterization of PMMA/ZnO nanocomposite thick films synthesized by ultrasonication and spin-coating

Polymer nanocomposite films, comprising of polymethylmethacrylate (PMMA) as the matrix and zinc oxide (ZnO) nanoparticles as reinforcement, have been prepared using ultrasonication and spin-coating techniques, with ZnO content up to 20 wt.%. The effect of the processing on the microstructure and nanomechanical properties have been investigated. The nanocomposite film thickness is found to vary from 2.4 ± 0.2 µm for pristine PMMA to 33.1 ± 0.5 µm for PMMA/20 wt.% ZnO nanocomposite. Quasi-static nanoindentation showed that the indentation modulus varied from 4.68 ± 0.07 GPa for pristine PMMA to 5.04 ± 0.14 GPa for PMMA/20 wt.% ZnO nanocomposite, while the indentation hardness varied from 275.94 ± 5.67 MPa to 292.39 ± 10.88 MPa in the same range. However, the highest indentation modulus and the highest hardness are exhibited by PMMA/10 wt.% ZnO nanocomposite. Scanning electron microscopy of the synthesized films provided the evidence behind such variation in material properties. In addition, the experimentally obtained elastic moduli were compared with values predicted by using Eshelby-Mori-Tanaka micromechanics. Nanoindenter-based dynamic mechanical analysis of the PMMA nanocomposite thin films revealed the variation of storage modulus, loss modulus and loss factor of the films in the frequency range of 10 Hz to 201.5 Hz. For all PMMA/ZnO nanocomposites, the storage modulus is found to increase monotonically from 10 Hz to ∼100 Hz, beyond which the values reached a plateau. The loss modulus and loss factor for all PMMA/ZnO nanocomposites are found to decrease with increasing frequency. These results form an essential step toward establishing process-structure-nanomechanical property relationships for PMMA/ZnO nanocomposite films.

Investigating mechanical properties of polymethylmethacrylate/silver nanoparticle composites by molecular dynamics simulation

The molecular dynamics simulation (MD) was carried out to investigate the mechanical properties of pristine polymethylmethacrylate (PMMA) and the composites of PMMA mixed with the silver nanoparticles (PMMA/AgNPs) at two AgNP weight fractions at 0.60 and 1.77 wt%. From the stress–strain profiles by the tensile process, it can be seen that the improvement on Young’s modulus is insignificant at these lower AgNP fractions. The tensile strength of pristine PMMA can be slightly improved by the embedded AgNPs at 1.77 wt%, because the local density and strength of PMMA in the vicinity of AgNP surface within about 8.2 A are improved. For the temperature effect on the mechanical properties of pristine PMMA and PMMA/AgNP composite, the Young’s moduli and strength of pristine PMMA and PMMA/AgNP composite significantly decrease at temperatures of 450 and 550 K, which are close to the predicted melting temperature of pristine PMMA about 460 K. At these temperatures, the PMMA materials become more ductile and the AgNPs within the PMMA matrix display higher mobility than those at 300 K. When the tensile strain increases, the AgNPs tend to get closer and the fracture appears at the PMMA part, leading to the close values of Young’s modulus and ultimate strength for pristine PMMA and PMMA/AgNP composite at 450 and 550 K.

Design and characterization of neurodurable gellan-xanthan pH-responsive hydrogels for controlled drug delivery

ABSTRACTObjectives: The purpose of this study was to develop novel, porous neurodurable interpenetrating networks of gellan-xanthan hydrogel conduits intercalated with pristine polymethyl methacrylate (PMMA) particles for the sustained and concurrent release of two model compounds: bovine serum albumin (BSA) and diclofenac sodium.Methods: Hydrogel conduits were synthesized using a thermal-ionic crosslinking mechanism with direct incorporation of PMMA. The 15 formulations, generated using a Box-Behnken experimental design, were analyzed for drug release, swelling, erosion and textural properties.Results: The 15 formulations provided a near zero-order release of BSA (37–75% fractional release) and diclofenac sodium (14–22% fractional release) over 20 and 30 days, respectively, modulated via a combination of pH-responsive (pH 7.4) dissolution of the intercalated pristine polymer particles and the unique gelling and erosion properties imparted by the graded addition of xanthan gum to the hydrogel blend. The concentration-dependent intercalation of PMMA extended drug release rates and enhanced matrix resilience from 31% to 56%.Conclusions: The gellan-xanthan ratio variability and the pore-inducing effects of intercalated PMMA yielded a means for fine tuning the mechanical attributes of the hydrogel matrices, particularly matrix rigidity and flexibility, offering an appealing strategy for the design and development of synthetic bioactive-releasing peripheral nerve repair conduits.

Surface topographical and structural analysis of Ag+-implanted polymethylmethacrylate

Specimens of polymethylmethacrylate (PMMA) were implanted with 400-keV Ag+ ions at different ion fluences ranging from 1×1014 to 5×1015ions/cm2 using a 400-kV NEC ion implanter. The surface topographical features of the implanted PMMA were investigated by a confocal microscope. Modifications in the structural properties of the implanted specimens were analyzed in comparison with pristine PMMA by X-ray diffraction (XRD) and Raman spectroscopy. UV–Visible spectroscopy was applied to determine the effects of ion implantation on optical transmittance of the implanted PMMA. The confocal microscopic images revealed the formation of hillock-like microstructures along the ion track on the implanted PMMA surface. The increase in ion fluence led to more nucleation of hillocks. The XRD pattern confirmed the amorphous nature of pristine and implanted PMMA, while the Raman studies justified the transformation of Ag+-implanted PMMA into amorphous carbon at the ion fluence of ⩾5×1014ions/cm2. Moreover, the decrease in optical transmittance of PMMA is associated with the formation of hillocks and ion-induced structural modifications after implantation.

Design of chitospheres loaded with pristine polymer particles for extended drug delivery via polyelectrolyte complexation and particulate leaching

The aim of this study was to investigate the drug release from swellable chitospheres laden with pristine polymethylmethacrylate (PMMA) nanoparticles. Chitosan matrices were prepared by sodium tripolyphosphate crosslinking from a chitosan suspension containing the model BCS class II drug, indomethacin. PMMA particles were added to the chitospheres as the modulator for drug release. Swelling and erosion studies in conjunction with textural profiling provided an understanding of the dominant and underlying drug release mechanisms of the ionically crosslinked chitospheres loaded with the pristine PMMA particles. A series of drug release studies performed in PBS pH 7.4 showed that the pristine particle-loaded chitospheres released indomethacin over 144h in a first-order manner with 50% drug release occurring over 48h. The study also revealed that in situ porogen leaching for pore creation and polyelectrolyte complex formation were the main mechanisms of release from the chitospheres. The results of this study may be utilized for the development of neuro-implants for controlled delivery of bioactives to the brain where scaffolds of superior mechanical strength and reduced swelling properties are required.

UV 개질된 PMMA 미세유체 장치의 열가소성 폴리머 용융 접합

Thermoplastic fusion bonding is widely used to seal polymer microfluidic devices and optimal bonding protocol is required to obtain a successful bonding, strong bonding force without channel deformation. Besides, UV modification of the PMMA (poly-methyl methacrylate) is commonly used for chemical or biological application before the bonding process. However, study of thermal bonding for the UV modified PMMA was not reported yet. Unlike pristine PMMA, the optimal bonding parameters of the UV modified PMMA were 103˚C, 71 kPa, and 35 minutes. A very low aspect ratio micro channel (AR=1:100, 20 μm depth and 2000 μm width) was successfully bonded (over 95%, n>100). Moreover, thermal bonding of multi stack PMMA chips was successfully demonstrated in this study. The results may applicable to fabricate a complex 3 dimensional microchannel networks.

Investigation of antibacterial and wettability behaviours of plasma-modified PMMA films for application in ophthalmology

The main objective of this research is the experimental investigation of the surface properties of polymethyl methacrylate (PMMA) such as wettability and the roughness effect on Escherichia coli (gram negative) cell adhesion. Radio frequency (RF; 13.56 MHz) oxygen plasma was used to enhance the antibacterial and wettability properties of this polymer for biomedical applications, especially ophthalmology. The surface was activated by O2 plasma to produce hydrophilic functional groups. Samples were treated with various RF powers from 10 to 80 W and different gas flow rates from 20 to 120 sccm. Optical emission spectroscopy was used to monitor the plasma process. The modified surface hydrophilicity, morphology and transparency characteristics were studied by water contact angle measurements, atomic force microscopy and UV–vis spectroscopy, respectively. Based on the contact angle measurements of three liquids, surface free energy variations were investigated. Moreover, the antibacterial properties were evaluated utilizing the method of plate counting of Escherichia coli. Also, in order to investigate stability of the plasma treatment, an ageing study was carried out by water contact angle measurements repeated in the days after the treatment. For biomedical applications, especially eye lenses, highly efficient antibacterial surfaces with appropriate hydrophilicity and transparency are of great importance. In this study, it is shown that the plasma process is a reliable and convenient method to achieve these purposes. A significant alteration in the hydrophilicity of a pristine PMMA surface was observed after treatment. Also, our results indicated that the plasma-modified PMMAs exhibit appropriate antibacterial performance. Moreover, surface hydrophilicity and surface charge have more influence on bacterial adhesion rate than surface roughness. UV–vis analysis results do not show a considerable difference for transparency of samples after plasma treatment.

ポリメタクリル酸メチル樹脂の水素プラズマ曝露と低エネルギーアルゴンイオンビームによるエッチング

Effects of hydrogen plasma exposure in polymer dry etching processes have been investigated with a low-energy mass-selected ion beam system. In the present study, we use a spin-coated polymethylmethacrylate (PMMA) film on a quartz crystal microbalance as a model polymer. The surface modification of the PMMA film by the hydrogen plasma exposure in an inverter plasma system was investigated by X-ray photoelectron spectroscopy (XPS) and spectroscopic ellipsometry. XPS results show that oxygen atoms were preferentially sputtered from the PMMA film by the hydrogen plasma exposure. Spectroscopic ellipsometry results show that depth of the modified layer of the hydrogen plasma exposed PMMA film was about 40 nm. Etching yields of the pristine PMMA film and the hydrogen plasma exposed PMMA film by 470 eV Ar+ ion beam injections were measured. It is found that the etching yield of the hydrogen plasma exposed PMMA film was about half of that of the pristine PMMA film.

Effect of Tetrafluoromethane Plasma Treatment of PMMA on MCF-7 Cell Proliferation

Polymethyl methacrylate (PMMA) was surface modified by tetrafluoromethane (CF4) plasma and its effect on the human breast cancer cells (MCF-7) adhesion and proliferation were investigated. The promotion of MCF-7 cell growth was positively and quantitatively related to the CF4 plasma modification as revealed by different characterizations. From ESCA analysis, it is revealed that CF4 plasma treatment chemically alters the capability of PMMA to adsorb proteins from cell culture medium, which is about four times comparing to that of pristine PMMA. In addition to chemical alteration, CF4 plasma also concurrently delivered physical modification by doubling the surface roughness, as observed by AFM analysis.

The effect of polyoxypropylene‐montmorillonite intercalates on polymethylmethacrylate

AbstractPolymethylmethacrylate (PMMA)‐layered silicate nanocomposites have been prepared by in situ polymerization of commercial type of methylmethacrylate monomer (MMA), for denture base material, into organoclay. Organoclay was prepared through an ion exchange process between sodium cations in montmorillonite and NH3+ groups in polyethertriamine hydrochloride and polyoxypropylene triamine hydrochloride with different molecular weight (5000, 440). X‐ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) have been used to investigate the structure of the resulting composites. Both intercalated and exfoliated nanocomposites were obtained depending on the type and amount of organoclay. The thermal decomposition temperatures of the nanocomposites were found to be higher than that of pristine polymer. PMMA was strongly fixed to inorganic surfaces, due to cooperative formation of electrostatic bonding between NH3+ group and negatively charged surface of layered silicate and amide linkage between PMMA and polyethertriamine or polyoxypropylene triamine. The effect of the organoclay on the hardness, toughness, tensile stress, and elongation at break of the polymer was studied and was compared with pristine polymer. The hardness and Izod impact strength of PMMA‐organoclay nanocomposites were enhanced with the inclusion of clay. Tensile properties appear to be enhanced at certain organoclay content. However, the water absorption is slightly higher than the pristine PMMA. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers

Characterization of polystyrene and doped polymethylmethacrylate thin layers

About 1 μm thick films of polystyrene (PS) and polymethylmethacrylate (PMMA) were prepared from solutions using spin-coating method. The PMMA films were doped with diphenylsulfoxide (DS) up to 45 wt%. Glass transition temperature (T g ) of doped PMMA films was determined by DSC technique and relative permittivity (e) as a function of the sample temperature was determined from capacitance measurement. The dependence of polarization (P) on electric field (E) and the temperature was measured using a standard Sawyer-Tower circuit. Spectral dependence of film refractive index was measured using a refractometer. The glass transition temperature T g of PMMA/DS composite was found to be decreasing function of the DS concentration. Relative permittivity e of unpolar PS is lower than that of polar PMMA. The PS permittivity does not depend on the sample temperature. For PMMA the permittivity is increasing function of both, DS dopant concentration and sample temperature. The dependence of the polarization on the electric field on PS film does not exhibit a hysteresis and indicate no polarization contrary to PMMA. PMMA/DS composites exhibit easier and larger polaribility and a permanent dipole moment. Resulting polarization is an increasing function of DS concentration. Refractive index of both pristine PS and PMMA decreases with increasing wave length. The refractive index of PMMA/DS composites depends on the DS concentration.