Polymethylmethacrylate Powder Research Articles

Irradiation effect of nano-bubble dispersion strengthened (N-BDS) alloy

Nano-bubble dispersion strengthened (N-BDS) Fe was made from Fe and polymethylmethacrylate (PMMA) powder and irradiated by 6.4MeV Fe3+ ions to investigate the cavity strengthening and the bubble to void evolution. The bubbles accelerated the irradiation-induced cavity growth. The hardness of the N-BDS Fe was 500MPa higher than that of unalloyed Fe and the hardness increased by irradiation, while that of unalloyed Fe did not increase. Cavity is probably the origin of the irradiation hardening of N-BDS Fe.

Hydrophobization of polymer particles by tetrafluoromethane (CF4) plasma irradiation using a barrel-plasma-treatment system

In this study, tetrafluoromethane (CF4) plasma-treatments of polymethylmethacrylate (PMMA) powder were performed using a polygonal barrel-plasma-treatment system to improve the PMMA's hydrophobicity. Characterization of the treated samples showed that the PMMA particle surfaces were fluorinated by the CF4 treatment. The smooth surfaces of the particles changed into nano-sized worm-like structures after the plasma-treatment. The hydrophobicity of the treated PMMA samples was superior to that of the untreated samples. It was noted that the hydrophobicity of the treated samples and the surface fluorination level depended on the plasma-treatment time and radiofrequency (RF) power; high RF power increased the sample temperature, which in turn decreased the hydrophobicity of the treated samples and the surface fluorination because of the thermal decomposition of PMMA. The water-repellent effects were evaluated by using paper towels to show the application of the plasma-treated PMMA particles, with the result that the paper towel coated with the treated sample was highly water-repellent.

Effect of pore structure on the compressive property of porous Ti produced by powder metallurgy technique

Porous Ti with an average macro-pore size of 200–400μm and porosity in the range of 10–65% has been manufactured using polymethyl methacrylate (PMMA) powders as spacer particles. The compressive strength and elastic modulus of resultant porous Ti are observed in the range of 32–530MPa and 0.7–23.3GPa, respectively. With the increasing of the porosity and macro-pore size, the compressive strength and modulus decrease as described by Gibson–Ashby model. The failure due to cracking (complete fracture) of the struts on porous Ti is controlled primarily by macro-pores. Fractography shows evidence of the brittle cleavage fracture mainly, but containing a few fine shallow dimples and a small amount of transcrystalline fracture of similarly oriented laths. The failure mechanism has been discussed by taking the intrinsic microstructural features into consideration.

Effect of Mica Reinforcement on the Flexural Strength and Microhardness of Polymethyl Methacrylate Denture Resin

Conventional denture base polymethyl methacrylate (PMMA) is low in strength, soft, and brittle on impact. Improvements in the mechanical properties of denture base materials have been sought by adding different reinforcing phases to the PMMA matrix. The purpose of this work was to study the effects of mica reinforcement on the mechanical properties, flexural strength, and microhardness of PMMA denture base resin. Wet ground muscovite mica and Lucitone 199 original shade denture base resin were used. Two micas were tested: W200 and P66 with average particle sizes (d50) of 131 μm and 30 μm, respectively. The mica was silane treated in a solution of 3-methacryloxypropyl trimethoxysilane, ethanol, and water, and then dried. The specimens were fabricated using the denture base resin manufacturer's instructions with a powder : liquid ratio of 21 g/10 ml and a mixing time of 30 seconds. Five treatment groups were produced with differing amounts of mica added to the PMMA denture base resin: (A) control group with 0 vol% mica, (B) 10 vol% W200 mica, (C) 20 vol% W200 mica, (D) 10 vol% P66 mica, (E) 20 vol% P66 mica. The mica replaced equal volumes of the PMMA powder component to minimize changes in viscosity. The three-point bending flexural strength specimens were 70 × 11 × 3 mm(3) . Seven specimens were prepared for each treatment group. The hardness specimens were prepared from the ends of the three-point bend specimens after they were broken (N = 7). After deflasking, the specimens were polished with 600 grit silicon carbide paper to achieve smooth surfaces. A standard three-point bending jig with a span length of 50 mm was attached to an Instron universal testing machine. The specimens were placed on the jig, and loading was carried out using a 1 mm/min crosshead speed until failure. Microhardness was measured using a Clark microhardness tester with a Knoop indenter. The load was set to 200 g and the dwell time to 15 seconds. ANOVA and Tukey tests were used for statistical analyses (Alpha = 0.05). The flexural strength of the control group was between 77% and 94% higher than all the mica-containing groups (p≤ 0.05). No significant differences were found within the four mica groups. Microhardnesses of the 20% mica groups (both fine and coarse) were 33% and 26% higher than the control (p≤ 0.05). The 10% mica groups had higher hardness than the control group, but the increase was not statistically significant (p > 0.05). Mica additions to denture PMMA reduced flexural strength; however, with the specimens containing highest mica concentrations (20%), microhardness significantly increased.

Development of a polygonal barrel-plasma enhanced chemical vapor deposition method for preparing powdered materials with a diamond-like carbon film

A novel polygonal barrel-plasma enhanced chemical vapor deposition (PB-PECVD) method was developed to prepare powdered materials with diamond-like carbon (DLC) films. To investigate the effects of frequency on the DLC film preparation, frequency power supplies of 250kHz and 13.56MHz were used and a DLC film was successfully formed on an SiO2 glass plate at 250kHz. The PB-PECVD process was further examined by using polymethyl methacrylate (PMMA) powder sample. It was determined that a DLC film could be uniformly deposited onto the PMMA particles by rotating a hexagonal barrel including the PMMA sample during the PB-PECVD procedure while operating at 250kHz.

Safety and utility of a PMMA-based tissue adhesive for closure of surgical incision wounds

This study aimed to investigate the safety and utility of the polymethylmethacrylate (PMMA)-based tissue adhesive (PMMA-ta) for wound closure. This product is composed of 4-methacryloyloxyethyl trimellitate anhydride and methylmethacrylate as monomers, tri-n-butylborane as initiator, and PMMA powder as filler. These components are mixed at the time of use. This resulting paste hardens within several minutes. The safety of PMMA-ta was evaluated in an internal wound model using a cultured dermal substitute (CDS), i.e. a fibroblast-embedded collagen gel sheet. PMMA-ta was applied to one CDS, covered with a second CDS, and then cultured for 1 week (group II). A commercially available 2-octyl cyanoacrylate-based tissue adhesive (OCA) was used for comparative purposes (group I). No tissue adhesive was applied to the CDSs in the control group. Fibroblast viability was measured using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Cell viability in the group I was 36%, and cell viability in the group II was 84%, of that in the control group. These results indicate that PMMA-ta has lower cytotoxicity than OCA. Next, the usefulness of PMMA-ta as a tissue adhesive was evaluated in three different wound models using Sprague–Dawley rats: (1) a thin skin incision wound, (2) a thick skin incision wound, and (3) a full-thickness incision wound through the abdominal wall. The third experiment is the surgical incision model with the most severe condition. The comparative study using OCA was conducted only in the third experiment. Each wound healing process was evaluated macroscopically and histologically after 1 week, 2 weeks, and 3 months. An excellent macroscopic wound appearance was observed with both PMMA-ta and OCA, with only a slightly visible fine-line scar. Histologically, a typical primary healing was observed for both adhesives. Considering its safety and utility, PMMA-ta is therefore promising for use as a tissue adhesive in wound closure.

A Study of the Optical Properties of Cosmetics Measured by Polarized Light Goniophotometry

Polymethylmethacrylate powders are commonly used to improve the spreadability and blurring effects of powder foundation cosmetics. In this study, the opacity and haze effect of four types of polymethylmethacrylate powders and their 10wt% powder foundation formulation was evaluated. The distorted random hemispherical particulates with both concave and convex portions showed the highest haze and opacity value as a single powder substance. And as a formulated phase, the powder foundation formulation containing particulates with fine pores provided the highest haze and opacity value. We also examined the quantity of reflected light over the angular range 20-75° by polarized light goniophotometry. The total reflected light intensity, surface-reflected light, and internally reflected light were characterized. These studies demonstrated that hemispherical PMMA powders produce natural brilliance by creating high internally reflected light which is similar to the total reflection profile of artificial skin.

Bone bonding ability and handling properties of a titania–polymethylmethacrylate (PMMA) composite bioactive bone cement modified with a unique PMMA powder

One of the challenges of using bioactive bone cements is adjusting their handling properties for clinical application. To resolve the poorer handling properties of bioactive bone cements we developed a novel bioactive bone cement containing a unique polymethylmethacrylate (PMMA) powder, termed SPD-PMMA (40 μm in diameter), composed of cohered minute particles of PMMA (0.5 μm). The present study aimed to examine the mechanical and handling properties and the in vivo bone bonding strength of this cement. The titania content of the cement varied from 10 to 30 wt.% (Ts10, Ts20, and Ts30). The mechanical and thermal properties of Ts10 and Ts20 exceeded those of commercially available PMMA cements (PMMAc). The setting properties of Ts20, including a shorter dough time and a working time that was comparable with that of PMMAc, were adequate for clinical application. Hardened cylindrical cement specimens were inserted into rabbit femurs and the interfacial shear strengths were measured by a push-out test at 6, 12, and 26 weeks after the operation. The interfacial shear strength values (in Newtons per square millimeter) of Ts10, Ts20, and Ts30 at 12 weeks and those of Ts20 and Ts30 at 26 weeks were significantly higher than that of PMMAc ( P < 0.05). These results show that a bioactive titania–PMMA composite bone cement modified by SPD-PMMA particles possesses adequate mechanical and handling properties, as well as osteoconductivity and in vivo bone bonding ability, and can be used for prosthesis fixation.

Influence of Microstructure on the Thermal Diffusivity of Sintered Porous YSZ

The microstructure of sintered porous yttria‐stabilized zirconia (YSZ) pellets was controlled by adjusting the sintering temperature and adding appropriate amounts of polymethyl methacrylate powder to produce pores. The thermal diffusivity of the pellets was measured using the laser flush technique. The influence of pellet microstructure on its thermal diffusivity was investigated. At both high and low temperatures, the influence of the density, pore size, YSZ grain size, grain‐boundary concentration, and the ratio of closed pores on the phonon diffusion and photon heat radiation was clarified.

Evaluation of a newly developed polymethyl methacrylate powder for brush-dip technique

The aim of this study is to evaluate a newly developed polymethyl methacrylate (PMMA) powder. The particle size distribution, surface area, and particle shape of both new and traditional powders were compared. The shear bond strength of the resin cement with the new powder to a silver-palladium-copper-gold alloy was determined and compared to that for a cement with the traditional powder. Also, the weight of mixture held by the brush at one time of both powders was also calculated and compared as an index of mixability. The surface area of the new powder was smaller than that of the traditional powder, while the particles size distributions were similar. The new powder included various-sized spherical particles as well as irregular particles, while the traditional powder consisted of only irregular particles. The new powder showed significantly higher mixability, although its bond strength was not significantly different from that of traditional powder. The results of this study show that the interminglement of spherical and irregular particles cannot influence the bond strength to the alloy but is helpful to improve the working properties.

Flexural properties of ethyl or methyl methacrylate-UDMA blend polymers

Light-curing polyethyl methacrylate (PEMA)-urethane dimethacrylate (UDMA) resins and polymethyl methacrylate (PMMA)-UDMA resins were prepared by two processes. For first step, PEMA or PMMA powders were fully dissolved in ethyl methacrylate (EMA) or methyl methacrylate (MMA) and then the PEMA-EMA/PMMA-MMA mixtures were mixed with UDMA. The flexural properties of cured PEMA-UDMA and PMMA-UDMA polymers were measured using two PEMA (Mw: 300,000-400,000 and 650,000-1,000,000) and three PMMA (Mw: 30,000-60,000, 350,000 and 650,000-1,000,000) powders with different molecular weight, four mixing ratios of PMMA-MMA, and three mixing ratios of PMMA-MMA mixture and UDMA oligomer. Polymers with PMMA(Mw: 350,000) MMA=25/50, and with PMMA(Mw: 350,000)-MMA/UDMA=1/2 and =1/1, showed no-fracture in a flexural test at 1 mm/min and flexural strength and flexural modulus showed no significant difference compared with those of commercially available heat- and self-curing acrylic resins (p>0.01). Within limitation of this investigation, methyl methacrylate-UDMA blend polymer of this composition is available for denture base resin.

Investigations on drop penetration and wetting characteristics of powder-liquid systems in relation to the mixing of acrylic bone cement

This study investigated methyl methacrylate – polymethyl methacrylate powder bed interactions through droplet analyses, using model fluids and commercially available bone cement. The effects of storage temperature of liquid monomer and powder packing configuration on drop penetration time were investigated. Methyl methacrylate showed much more rapid imbibition than caprolactone due to decrease in both contact angle and fluid viscosity. Drop penetration of caprolactone through polymethyl methacrylate increased with decrease in bed macro-voids and increase in bulk density as predicted by the modified constant drawing area penetration model and confirmed by drop penetration images. Linear relationships were found between droplet mass and drawing area with imbibition time. Further experiments showed gravimetric analysis of the polymerised methyl methacrylate – polymethyl methacrylate matrix under various storage temperatures correlated with Reynolds number and Washburn analyses. These observations have direct implications for the design of mixing and delivery systems for acrylic bone cements used in orthopaedic surgery.

Antibacterial Effect of Experimental Chlorhexidine-releasing Polymethyl Methacrylate–based Root Canal Sealers

Introduction This study evaluated the extent of chlorhexidine release from experimental chlorhexidine-containing polymethyl methacrylate (PMMA)-based root canal sealers prepared from a methacrylate-based sealer (SuperBond Sealer, Sun Medical Co Ltd, Shiga, Japan) and to examine its antimicrobial effect against Enterococcus faecalis using the direct contact test. Methods Chlorhexidine diacetate powder was mixed with PMMA powder of SuperBond Sealer to obtain chlorhexidine concentrations of 1 wt%, 2 wt%, and 3 wt%, respectively. PMMA disks were fabricated by self-curing the experimental PMMA powder and pure SuperBond sealer (control) and immersing them in distilled water at 37 °C for 12 weeks. Chlorhexidine release was analyzed by high-performance liquid chromatography. The direct contact test was performed on wells of 96-well plates coated with the respective experimental root canal sealers ( n = 6). Bacterial suspensions were placed directly on the sealers that were aged for 12 weeks. Results The cumulative chlorhexidine release after 12 weeks of water immersion was largely dependent on the amount of chlorhexidine powder that was initially incorporated into the PMMA-based sealer. Kruskal-Wallis test revealed that chlorhexidine concentration had a significant effect on the cumulative release (p = 0.0005). Experimental sealers with the incorporation of 2 wt% and 3 wt% chlorhexidine exhibited sustained antimicrobial effect for at least 4 weeks and 8 weeks. Conclusion The incorporation of 2wt% and 3wt% chlorhexidine in the PMMA-based sealer had a long lasing antimicrobial effect against Enterococcus faecalis as a result of the turbidimetric determination of bacterial growth.

Microstructure Control of Ni-ScSZ Anode Support for LT-SOFC

A microstructure control method of the Ni-scandia-stabilized zirconia (ScSZ) cermet anode support, which is used for a low temperature solid oxide fuel cells prepared by low temperature processes for fabrications of electrolyte film and cathode electrode, was studied. In this study, addition of Polymethyl methacrylate (PMMA) powder as a pore-former and changing the sintering temperature were conducted to change the microstructure of the Ni-ScSZ cermet anode support. Effects of the size and the amount of the PMMA powder particle and the sintering temperature on the sizes of Ni particle, ScSZ particle and pore were investigated. The pores were classified into three kinds depending on the origin. Effects of the amount and size of the PMMA powder particle and the sintering temperature on the size and volume of the three kinds of pores were also examined.

Effect of Polymethyl Methacrylate (PMMA) Powder to Liquid Monomer (P/L) Ratio and Powder Molecular Weight on the Properties of PMMA Cement

The present study investigated the effect of PMMA powder to liquid monomer (P/L) ratio and molecular weight of PMMA powder on the properties of PMMA cement. Two types of PMMA powder (Mw: 120,000 and 350,000) were prepared with different P/L ratios (based on wt/wt ratios); 0.75:1, 1:1, 1.25:1, and 1.5:1. Characterization of PMMA powders, handling characteristics and flexural properties of cured PMMA samples were investigated. In conclusion, low P/L ratio and high molecular weight of PMMA powders are desirable to produce PMMA cement with good handling properties and high flexural properties.

Microstructure Control of Sintered Porous Yttria‐Stabilized Zirconia as a Durable Thermal Shielding Material

The microstructure of a thermal shielding material affects its thermal conductivity and mechanical property. In this study, the effects of the sintering temperature and the polymethyl methacrylate powder as a pore‐former on the microstructure of a sintered porous yttria‐stabilized zirconia (YSZ), which is used as a durable thermal shielding material, were investigated. It became clear that the microstructure of the sintered YSZ could be controlled by the particle size and the amount of the pore‐former and the sintering temperature. The effect of the yttria amount in the YSZ on the microstructure was also clarified.

Modelling a new composite from a recycled GFRP

The mechanical reprocessing of different types of plastic scrap in high-energy disintegrator mills in direct and selective milling systems is considered. The grindabilty and separation of components of composites-an acrylic plastic and glass fibers-are analyzed. The relation between the density of the filler material and the fractions of a polymethylmethacrylate powder is modelled on the basis of experimental data. Artificial neural networks and a hybrid genetic algorithm are used to design a new composite from a recycled glass-fiber-reinforced plastic.

Does Antibiotic Elution From PMMA Beads Deteriorate after 1-year Shelf Storage?

Antibiotic-impregnated polymethylmethacrylate beads are widely used as an adjunct in the treatment of orthopaedic infections. Because there is no commercially available bead in the United States, surgeons must manufacture bead sets at the time of implantation. This can be time consuming and wasteful. We hypothesized antibiotic-impregnated beads would maintain consistent elution for up to 1 year after manufacturing and storage. Tobramycin-impregnated antibiotic beads were manufactured using a bead mold. The antibiotic was either hand-mixed into the polymethylmethacrylate powder (1.2 g/40 g) or came premixed from the factory (1 g/40 g). Packages of beads were gas-sterilized and stored at room temperature. Beads were tested at 0, 1, 2, 3, 6, and 12 months. Antibiotic levels in the eluent from each day of the month were measured. We were unable to detect any difference in the amount of antibiotic elution between beads tested immediately after manufacture and beads manufactured and stored for 6 or 12 months. Beads with hand-mixed antibiotics eluted higher levels of antibiotics than the beads prepared with factory-mixed antibiotics. We conclude antibiotic beads can be made, sterilized, and used after 1 year of storage with no deleterious effect on antibiotic elution characteristics.

Synthesis and characterization of nano-Ag spot-coated polymethylmethacrylate powders by hydrothermal-assisted attachment method

Nano-Ag spot-coated polymethylmethacrylate (PMMA) powders were synthesized by the hydrothermal-assisted attachment (HAA) method using oleic acid-capped Ag hydrosol in a high-pressure bomb at 250 °C and 450 psi, respectively. The oleic acid-capped Ag hydrosol with a high specific surface was successfully synthesized through the precipitation–redispersion method. The oleic acid-capped Ag nano-particles showed a narrow size distribution and were less than 20 nm in diameter. In the case of the nano-Ag spot-coated PMMA powders, nano-sized Ag particles adhered onto the surface of the PMMA through the HAA method. The components of C, O, and Ag were homogeneously distributed on the PMMA coating layer.

Reinforcement of Denture Base Resin with Short-rod Glass Fiber

The present study investigated the feasibility of a high short-rod fiber content in denture base resins using polymethylmethacrylate (PMMA) powder with a small particle diameter. The effects of fiber contents on mechanical properties of composite resins were studied. A commercial denture base PMMA powder (AC; average particle size, 150 microm) and an industrial PMMA powder (MB; average particle size, 4 microm) were selected. Short-rod glass fibers were mixed with the two powders at a mass ratio of 0-50%. Flexural strengths and moduli of the mixtures were evaluated by a three-point bending test. The flexural strength of AC composites did not change regardless of fiber content, while that of MB composites increased significantly at fiber contents exceeding 40%. The flexural moduli of AC and MB composites at fiber contents exceeding 20% were significantly greater than those of AC and MB resins without short-rod glass fibers, respectively.