• Journal of Adhesion and Interface
• /
• v.11 no.3
• /
• pp.106-111
• /
• 2010

Na-MMT intercalated with PEGMA macromer was prepared using an EtAc/acetone mixture (1/1 by volume) as a solvent. PEGMA/(Na-MMT)-co-MMA/MA nanocomposites was synthesized by copolymerizing intercalated compound with MMA and MA, and then characterization was performed. The results of X-ray diffraction (XRD) showed that in the case of Na-MMT intercalated with PEGMA macromer the d-spacings of silicate of Na-MMT increased with increasing of Na-MMT loading. As the Na-MMT loading increases Tg showed increasing trend through the DSC measurement. TGA result showed that thermal stability of PEGMA/(Na-MMT)-co-MMA/MA nanocomposites improved a little more than the pure PEGMA-co-MMA/MA.

• 제어로봇시스템학회:학술대회논문집
• /
• 1997.10a
• /
• pp.309-312
• /
• 1997

The dynamic characteristics of a continuous MMA/MA free-radical solution copolymerization reactor were studied. A mathematical model was developed and kinetic parameters which had been estimated in the previous work were used. With this model, bifurcation diagrams were constructed with various parameters as the bifurcation parameter to predict the region of stable operating conditions and to enhance the controller performance. It was shown that the steady-state multiplicity existed over wide ranges of residence time and jacket inlet temperature. Periodic solution branches were found to emanated from Hopf bifurcation points. Under certain conditions isola was also observed, which would result in poor performance of feedback controllers.

• Proceedings of the Polymer Society of Korea Conference
• /
• 2006.10a
• /
• pp.324-324
• /
• 2006

In copolymerization of methyl acrylate (MA) and methyl methacrylate (MMA) with various ratios of MA to MMA and $[CuCl]/[PMDETA]/[PVAc-CCl_{3}]$ catalyst system in bulk at $80^{\circ}C$ via ATRP, several terpolymer with different copolymer composition, were synthesized. The atom transfer radical copolymerization of MA and MMA with macroinitiator, is very sensitive to molecular weight and its distribution. In this work it was possible to calculate the molecular weight of the terpolymers and show that it is close to the experimentally determined number average molecular weight from GPC.

• Journal of the Korean Electrochemical Society
• /
• v.16 no.4
• /
• pp.198-203
• /
• 2013

Copolymer consisted of MMA and tBMA was synthesized by radical polymerization and poly(MMA-co-MA) was prepared by selective hydrolysis of tert-butyl group. The obtained polymer was coupled with epoxy functionalized PEO of various molecular weight to synthesize poly(MMA-co-PEGMA) with different side chain length. The AC-impedance measurement shows $1.88{\times}10^{-6}Scm^{-1}$ of room temperature ionic conductivity from 48mol% of MMA while $5.11{\times}10^{-8}Scm^{-1}$ was observed in 82mol% sample. In addition, there was an effect of PEGMA molecular weight on ionic conductivity possibly due to the steric hindrance in grafting-onto coupling reaction. Finally, the polymer electrolytes shows electrochemical stability up to 6V at room temperature.

• Journal of the Microelectronics and Packaging Society
• /
• v.10 no.4
• /
• pp.21-27
• /
• 2003

The copolymers with various composition of methyl methacrylate (MMA), ethyl methacrylate (EMA), methacrylic acid (MA) and hydroxyethyl methacrylate (HEMA) were synthesized for capacitive humidity sensitive materials. The capacitive humidity sensor consisted of a polymethacrylate film coated on both sides with gold electrode. Capacitance versus relative humidity increased with HEMA content in the copolymer. In the case of self-crosslinkable MMA/MA/HEHA= 40/10/10, the average capacitance at 30%RH, 60%RH and 90%RH are 102, 134 and 166 pF, respectively. And also, the hysteresis, temperature cycle and long-term stability were evaluated as a capacitance humidity sensor.

• Proceedings of the Korean Fiber Society Conference
• /
• 2003.10a
• /
• pp.94-94
• /
• 2003

Cross-linked polystyrene (PS) particles with carboxyl and/or poly(ethylene glycol) units on surface were formed by an emulsifier-free emulsion polymerization using styrene, methacrylic acid (MA), and poly(ethylene glycol) dimethacrylate (PEG-diMMA) at pH 7, and followed by freeze-drying to give the corresponding powders. Monodisperse polymer particles could be obtained at a concentration of PEG-diMMA 1 mol% relative to styrene. Zeta potential of polymer surface was measured to be 91 mV at a polymer of PEG-diMMA 1 mol% and was dropped as the content of MA increased.

• 제어로봇시스템학회:학술대회논문집
• /
• 2001.10a
• /
• pp.97.3-97
• /
• 2001

An experimental study was performed to establish the validity of an on-line state estimator for a semibatch MMA-MA copolymerization reactor by using on-line densitometer and viscometer under two different operating conditions; one without additional solvent feed and the other with solvent fed additionally. A conventional extended Kalman filter (EKF) was used as the state estimator and the experiment was conducted for the purpose of application to the control of copolymer properties. Further analysis was made by using off-line measurement data for the mole fraction of MMA in the remaining monomers and the solid content. It was found that the EKF could provide a good estimate for the states of the copolymerzation system ...

• Applied Chemistry for Engineering
• /
• v.10 no.3
• /
• pp.450-455
• /
• 1999

Unsaturated diol (UD) was prepared from the esterification of maleic anhydride with diethylene glycol (DEG). Unsaturated polyesters modified with rosin (UPMR) or with rosin maleic anhydride adduct (RMA) from 2-hydroxyethylmethacrylate (HEMA) and rosin (UPMRH) were prepared by the reaction of UD with RMA or RMA-HEMA. After crosslinking of UPMR and UPMRH with styrene and methylmethacrylate (MMA), respectively, solvent resistance, tensile strength, and adhesion property of the resins were measured. UPMR crosslinked with styrene or MMA shows an excellent resistance to water and acid. Solvents resistance and tensile strength of UPMR using styrene as crosslinking agent were increased compared with those of UPMR using MMA as crosslinking agent. UPMRH showed better solvents resistance and tensile strength than UPMR. Adhesion strengths of UPMR crosslinked with styrene and MMA were 1.61 and 3.02 MPa, and those of UPMRH were 2.32 and 3.89 MPa, respectively.

• Journal of Life Science
• /
• v.20 no.12
• /
• pp.1792-1800
• /
• 2010

In this study, we isolated five macrolactin compounds from a fermentation broth of Bacillus polyfermenticus KJS-2. The macrolactin compounds were structurally identified as macrolactin A (MA), 7-O-malonyl macrolactin A (MMA), 7-O-succinyl macrolactin A (SMA), macrolactin E (ME) and macrolactin F (MF) via a variety of NMR techniques, COZY, DEPT, HMQC and HMBC, and mass and specific rotation assays. The three macrolactin compounds, MA, MMA and SMA, profoundly inhibited the growth of both vancomycin-resistant Enterococci (VREs) and methicillin-resistant Staphylococcus aureus (MRSA), the inhibition of which were estimated via a disc agar diffusion bioassay. MA, MMA, and SMA exhibited antibacterial activities superior to those of vancomycin and teicoplanin.

• The Journal of Advanced Prosthodontics
• /
• v.8 no.4
• /
• pp.285-289
• /
• 2016

PURPOSE. This study evaluated the effect of chemical surface treatment using methyl formate-methyl acetate (MF-MA) solution on the tensile bond strength between acrylic denture teeth and auto-polymerized acrylic resin. MATERIALS AND METHODS. Seventy maxillary central incisor acrylic denture teeth for each of three different brands (Yamahachi New Ace; Major Dent; Cosmo HXL) were embedded with incisal edge downwards in auto-polymerized resin in polyethylene pipes and ground with silicone carbide paper on their ridge lap surfaces. The teeth of each brand were divided into seven groups (n=10): no surface treatment (control group), MF-MA solution at a ratio of 25:75 (v/v) for 15 seconds, 30 seconds, 60 seconds, 120 seconds, 180 seconds, and MMA for 180 seconds. Auto-polymerized acrylic resin (Unifast Trad) was applied to the ground surface and polymerized in a pressure cooker. A tensile strength test was performed with a universal testing machine. Statistical analysis of the results was performed using two-way analysis of variance (ANOVA) and post-hoc Dunnett T3 test (${\alpha}$=.05). RESULTS. The surface treatment groups had significantly higher mean tensile bond strengths compared with the control group (P<.05) when compared within the same brand. Among the surface treatment groups of each brand, there were no significantly different tensile bond strengths between the MF-MA groups and the MMA 180 second group (P>.05), except for the Yamahachi New Ace MF-MA 180-second group (P<.05). CONCLUSION. 15-second MF-MA solution can be an alternative chemical surface treatment for repairing a denture base and rebonding acrylic denture teeth with auto-polymerized acrylic resin, for both conventional and cross-linked teeth.