• Polymer(Korea)
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• v.26 no.2
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• pp.245-252
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• 2002

Thermodynamics and gas transport properties of polymethylmethacrylate (PMMA) blends with polyvinylmethylether (PVME) containing various amount of poly (styrene-b-methylmethacrylate) copolymer (P(S-b-MMA)) as a compatibilizer were studied. To extract interaction energies of binary pairs involved in the blends from the phase separation temperatures using an equation-of-state theory, PVME blends with methylmethacrylate copolymers containing various amount of styrene (SMMA) were prepared. PVME formed miscible blends with methylmethacrylate copolymers containing more than 70 wt% styrene and these miscible blonds showed a LCST-type phase separation behavior. Based on the interaction information obtained here, P(S-b-MMA) copolymer was added to the PMMA/PVME blends to enhance their compatibility. The average diameter of the dispersed rubber particles was gradually decreased for the blends of containing P(S-b-MMA) from 0 to 5 phr and then leveled off at a fixed size. At a fixed bland composition, the gas permeation was also increased as the P(S-b-MMA) content increased from 0 to 5 phr and then leveled off when the P(S-b-MMA) content was higher than 5 phr.

• Korean Journal of Materials Research
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• v.16 no.2
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• pp.99-105
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• 2006

This paper reports an improved bonding method using the IPA (isopropyl alcohol) assisted low-temperature bonding process for the PMMA (polymethylmethacrylate) micro CE (capillary electrophoresis) chip. There is a problem about channel deformations during the conventional processes such as thermal bonding and solvent bonding methods. The bonding test using an IPA showed good results without channel deformations over 4 inch PMMA wafer at $60^{\circ}C$ and 1.3 bar for 10 minutes. The mechanism of IPA bonding was attributed to the formation of a small amount of vaporized acetone made from the oxidized IPA which allows to solvent bonding. To verify the usefulness of the IPA assisted low-temperature bonding process, the PMMA micro CE chip which had a $45{\mu}m$ channel height was fabricated by hot embossing process. A functional test of the fabricated CE chip was demonstrated by the separation of fluorescein and dichlorofluorescein. Any leakage of liquids was not observed during the test and the electropherogram result was successfully achieved. An IPA assisted low-temperature bonding process could be an easy and effective way to fabricate the PMMA micro CE chip and would help to increase the yield.

• Applied Chemistry for Engineering
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• v.21 no.3
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• pp.353-355
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• 2010

Poly(methyl methacrylate) (PMMA) particles were prepared by soap-free emulsion polymerization of MMA in the presence of a cationic initiator, 2,2'-azobis(2-methylpropionamidine) (AIBA). The Stober method has been adopted to coat silica on the surface of these cationic particles. Negatively charged silica precursors were coated onto cationic particle surfaces by electronic interaction. During the coating process, hollow particles were directly obtained by dissolution of PMMA.

• Korean Journal of Materials Research
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• v.9 no.5
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• pp.446-451
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• 1999

Surface of Polymethylmethacrylate (PMMA) was modified by ion assisted reaction in which ion beam of Ar or$ O_2$is irradiated on polymer in reaction gas environment. Ion beam energy was changed from 600 to 1000eV, and ion doses were varied from $5\times10^{14} ions/cm^2 to 1\times10^{17} ions/cm^2$. Contact angle and surface energy of modified PMMA were measured by contact angle micrometer using distilled water and formamide. In the case of $Ar^+$ ion irradiation only, the contact angle reduced from $68^{\circ} to $35^{\circ}$ and the surface energy was changed from 46 dyne/cm to 60 dyne/cm. The contact angle significantly decreased to $14^{\circ}$and the surface energy increased to 72 dyne/cm when the surface of PMMA was modified by oxygen ion irradiation in oxygen gas environment. Improvement of wettability results from the formation of new hydrophilic group which is identified as C-O chain by XPS analysis. Recovery of wettability in dry air and maintenance of it in water condition were explained in view of the formation of hydrophilic group.

• The KIPS Transactions:PartB
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• v.10B no.5
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• pp.503-508
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• 2003

Since surgical treatment of the spine should overcome neurological compromises, the operative procedures need to be carefully planned and carried out with high degree of precision. Percutaneous vertebroplasty is a surgical procedure that was introduced for the treatment of compression fracture of the vertebrae. This procedure includes puncturing vertebrae and filling with polymethylmethacrylate (PMMA). Recent studies have shown that the procedure could provide structural reinforcement for the osteoporotic vertebrae while being minimally invasive and safe with immediate relief of pain. However, failures of treatment due to excessive PMMA volume injection have been reported as one of complications in vertebroplasty. It is believed that the control of PMMA volume is one of the most critical factors that can reduce the incidence of complications. Therefore, clinical success of vertebroplasty can be dependent on the volume of PMMA injection for a given patient. In this study, the optimal volume of PMMA injection for vertebroplasty was predicted based on the image analysis of a given patient.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.32 no.3 s.58
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• pp.141-148
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• 2006

This study is intended to analyze the impact of PMMA on color changes comparatively by making 2 types of cheek color items with red-color pigments: one containing PMMA, which is one of the recently developed circular polymers and used when producing color make-up items that have aero powder as the chief ingredient, and the other without it. To accomplish the purpose, we have reviewed literature on raw materials that have aero powder as the chief ingredient. Also, after making compounds of PMMA and pigments lot aero powder, such as Talc, Mica, OMC Talc As, Mica As, we examined them compared to those without PMMA using spectrophotometer, a questionnaire survey, and Digital camera. Besides, the particles were analyzed using SEM. As a result of the analysis, cosmetics containing PMMA represent more vivid and rich colors, putting on one's face softly. Since the entire specific surface area of PMMA is large enough to absorb oil evenly, it yields vivid and rich colors. But, Mica, one of natural pigments, shows a result as opposed to that of Mica As, one of silicon-compounded pigments, suggesting that pearl effect may possibly causes defused reflection. Based on these findings, it is expected that cosmetics will have more vivid colors, or improved color presentation, as well as the softer sense of touch when a circular polymer of PMMa is added to the manufacturing process of color make-up items.

• Journal of Korean Neurosurgical Society
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• v.30 no.2
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• pp.173-179
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• 2001

Purpose : To assess therapeutic effects of percutaneous polymethylmethacrylate(PMMA) vertebroplasty on the pain caused by osteoporotic thoracic and lumbar vertebral body compression fractures in a large scale of a prospective clinical design, and to determine clinical factors influencing its therapeutic effects. Methods : A prospective clinical study was carried out in 349 vertebral levels of 159 patients between April 1998 and July 1999. The compression fractures were confirmed with bone scan and spine CT, and bone marrow density was measured. Visual analogue scale(VAS) score was used for pre- and post-operative assessments of the pain. All 159 patients were assessed immediately after surgery, and 140 patients of them were followed-up for about 6 months in average. Results : Partial and complete pain relief was sustained immediately after operation in 73%, through follow-up period in 88% of the patients. Pain relief was not proportional to the amount of PMMA or the rate of increase in the height of the compressed vertebral body. It appears that 3 to 6cc of PMMA was proper enough to sustain pain relief. Better clinical improvement was achieved in the patients treated within 6 months after occurrence of vertebral body fracture. The most frequent surgical complication was epidural leakage of PMMA, and the most serious complication was extravertebral leakage into the paravertebral muscles, which appeared to exert the worst influence on the outcome. However, surgery was not required in these patients. Conclusion : Therapeutic effects of PMMA percutaneous vertebroplasty on osteoporotic vertebral body compression fractures were confirmed in a relatively large scale of prospective clinical study. It appears that good outcome can be achieved in patients treated within 6 months after fracture, treated each level with 3 to 6cc of PMMA in amount. without serious complications.

• Applied Chemistry for Engineering
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• v.9 no.2
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• pp.177-184
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• 1998

The contact angle on powder hydrophobic polymer PMMA(polymethylmethacrylate), PVC(poly vinyl chloride) and hydrophilic metal aluminium was measured by wicking method on the base of Washburn equation for water, glycerol, formamide, diiodomethane, 1,1,2,2-tetrabromoethane, 1-bromonaphthalene, acetone, chloroform, benzene, ethanol, methanol, and for anionic surfactant SDS(sodium dodecyl sulfate) and cationic surfactant CATB(cetyl trimethylamonium bromide) aqueous solution with concentrations. The values of ${\gamma}_c$ estimated by Zisman plot and adhesion tension plot for contact angle with organic liquids, SDS, and CTAB aqueous solutions were 43.5, 28.3, and $36.2mNm^{-1}$ for PMMA and 44.2, 25.0, and $34.8mNm^{-1}$ for PVC, respectively. From the results, it was considered that wettability and characteristics of solid surface were transformed by adding surfactant. The surface free energy, ${\gamma}_s$ and its components of PMMA, PVC, and aluminium were determined using harmonic equation.

• The korean journal of orthodontics
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• v.49 no.6
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• pp.404-412
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• 2019

Objective: To assess shear bond strength and failure mode (Adhesive Remnant Index, ARI) of orthodontic brackets bonded to polymethylmethacrylate (PMMA) blocks for computer-aided design/manufacture (CAD/CAM) fabrication of temporary restorations, following substrate chemical or mechanical treatment. Methods: Two types of PMMA blocks were tested: $CAD-Temp^{(R)}$ (VITA) and $Telio^{(R)}$ CAD (Ivoclar-Vivadent). The substrate was roughened with 320-grit sandpaper, simulating a fine-grit diamond bur. Two universal adhesives, Scotchbond Universal Adhesive (SU) and Assure Plus (AP), and a conventional adhesive, Transbond XT Primer (XTP; control), were used in combination with Transbond XT Paste to bond the brackets. Six experimental groups were formed: (1) $CAD-Temp^{(R)}/SU$; (2) $CAD-Temp^{(R)}/AP$; (3) $CAD-Temp^{(R)}/XTP$; (4) $Telio^{(R)}$ CAD/SU; (5) $Telio^{(R)}$ CAD/AP; (6) $Telio^{(R)}$ CAD/XTP. Shear bond strength and ARI were assessed. On 1 extra block for each PMMA-based material surfaces were roughened with 180-grit sandpaper, simulating a normal/medium-grit ($100{\mu}m$) diamond bur, and brackets were bonded. Shear bond strengths and ARI scores were compared with those of groups 3, 6. Results: On $CAD-Temp^{(R)}$ significantly higher bracket bond strengths than on $Telio^{(R)}$ CAD were recorded. With XTP significantly lower levels of adhesion were reached than using SU or AP. Roughening with a coarser bur resulted in a significant increase in adhesion. Conclusions: Bracket bonding to CAD/CAM PMMA can be promoted by grinding the substrate with a normal/medium-grit bur or by coating the intact surface with universal adhesives. With appropriate pretreatments, bracket adhesion to CAD/CAM PMMA temporary restorations can be enhanced to clinically satisfactory levels.

• Korean Journal of Materials Research
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• v.30 no.12
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• pp.650-654
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• 2020

A combination of Polycarbonate (PC) material and Polymethylmethacrylate (PMMA), fabricated using an injection molding machine, has been investigated to determine its advantages, as studied in Ref. 1). This paper aims to investigate the optimization of PMMA/PC blend for both tensile yield strength and impact strength. Furthermore, interaction effects of process conditions on mechanical properties including tensile yield strength and impact strength of PMMA/PC blend by injection molding process are interpreted in this study. Tensile and impact specimens are designed following ASTM, type V, and are fabricated by injection molding process. The processing conditions such as melt temperature, mold temperature, packing pressure, and cooling time are applied; each factor has three levels. As a result, in comparison with optimization of separated responses, mechanical properties of PMMA/PC are found to decrease when optimizing both tensile and impact strengths simultaneously. The melt temperature is found to be the most significant interaction parameter with the mold temperature and packing pressure. In addition, there is more interaction between the mold temperature and cooling time. This investigation provides a useful understanding of the control of injection molding processing of polymer blends in optical application.