The Experts below are selected from a list of 312 Experts worldwide ranked by ideXlab platform

Jingwei He - One of the best experts on this subject based on the ideXlab platform.

  • preparation and characterization of high radio opaque e glass fiber reinforced composite with iodine containing Methacrylate Monomer
    Dental Materials, 2017
    Co-Authors: Jingwei He, Pekka K Vallittu, Lippo V J Lassila
    Abstract:

    Abstract Objective The purpose of this study was to prepare radio-opaque E-glass fiber-reinforced composite (EFRC) with synthesized iodine containing Methacrylate Monomer. Methods The synthesized iodine containing Methacrylate Monomer 2-hydroxy-3- methacryloyloxypropyl(2,3,5- triiodobenzoate) (HMTIB) was mixed with Bis-GMA and MMA in different mass ratio to prepare resin impregnating solution (RIS), and RIS without HMTIB was used as control. CQ and DMAEMA were added as photoinitiation system. E-glass fiber was thoroughly wetted by resin impregnating solution to prepare radio-opaque EFRC. Degree of double bond conversion (DC) was investigated by FT-IR analysis. Fiber volume fraction was analyzed by combustion and gravimetric analyzes. The Flexural strength (FS) and modulus (FM) of EFRC were measured using a three-point bending set up. Water sorption (WS) and solubility (SL) were measured until the mass variation of EFRC in distilled water kept stable. Radiographs were taken to determine the radiopacity of EFRC. Results The FT-IR and 1 H NMR spectra of HMTIB revealed that it was the same as designed. ANOVA analysis revealed that increasing HMTIB concentration in RIS would decrease DC and increase fiber volume fraction. When compared with control EFRC, all of HMTIB containing EFRCs had higher or comparable FS and FM, no matter before or after water immersion. WS of EFRC decreased with increasing HMTIB concentration, while SL was nearly kept the same. Radiopacity of EFRC increased with increasing HMTIB concentration. Significance The synthesized Monomer HMTIB could be used to prepare EFRC with high radiopacity. Moreover, HMTIB containing EFRC would also have high mechanical properties and low WS.

  • synthesis of antibacterial Methacrylate Monomer derived from thiazole and its application in dental resin
    Journal of The Mechanical Behavior of Biomedical Materials, 2015
    Co-Authors: Qiting Huang, Jingwei He
    Abstract:

    A non-quaternary ammonium antibacterial Methacrylate Monomer MEMT derived from thiazole was synthesized and applied into UDMA/TEGDMA dental resin with a series of mass fraction (10 wt%, 20 wt%, and 30 wt%). Double bond conversion, polymerization shrinkage, water sorption, solubility, flexural strength and modulus, and antibacterial activity of MEMT containing resin formulations were investigated with UDMA/TEGDMA as control resin. The results showed that MEMT containing dental resin had higher double bond conversion than control resin. Compared with control polymer, all MEMT containing polymer had comparable or lower polymerization shrinkage, water sorption and solubility, except for the polymer with 30 wt% of MEMT which had higher water sorption and solubility than control polymer. The MEMT had no influence on flexural strength and modulus before water immersion, but all MEMT containing polymers had lower flexural strength and modulus than control polymer after water immersion. The MEMT could endow dental polymer with obvious antibacterial activity by immobilizing MEMT into the polymeric network.

Michael Braden - One of the best experts on this subject based on the ideXlab platform.

  • X-ray microtomographic studies of novel radio-opaque polymeric materials for dental applications
    Materials Science and Technology, 2020
    Co-Authors: Paul H. Anderson, Y. Ahmed, Mangala P. Patel, Graham R. Davis, Michael Braden
    Abstract:

    Radio-opacity may be desirable for polymeric materials used in medical and dental applications. However, problems arise when radio opaque metallic salts are blended with polymer powders before polymerisation. A novel alternative approach is to use polymers in which the X-ray opaque element is chemically incorporated within the Monomer unit. The present study investigates two potential materials, a barium Methacrylate Monomer which is a powder at room temperature and a tin Methacrylate Monomer which is liquid at room temperature, both then mixed with a Methacrylate diluent. X-ray microtomography revealed that the powdered barium Methacrylate material did not blend well and particles of high X-ray attenuation were formed. Whereas, X-ray microtomography images of the tin Methacrylate material revealed that the mixture was completely homogenous. The possible application of these two materials as a pit and fissure sealant is described.

  • Development of butyl elastomer/Methacrylate Monomer systems as denture soft lining materials.
    Biomaterials, 2002
    Co-Authors: P.d. Riggs, S. Parker, Michael Braden, S. Kalachandra
    Abstract:

    Abstract Previous studies have shown elastomer/Methacrylate Monomer formulations to have good strength; however, water uptake was high and they also suffered from oxidation. This study has looked at the use of three different butyl elastomers, well known for their oxidation resistance, butyl (PB), chlorobutyl (PCB) and bromobutyl (PBB). The tensile and water uptake properties of the three elastomers gelled with ethyl hexyl Methacrylate containing 1% ethylene glycol diMethacrylate and 1% lauryl peroxide (5+ formulation from previous studies) were studied. Water uptake of the pure elastomers was also measured. Tensile strengths were low (PCB5+=3.09±0.12 MPa and PBB5+=3.90±0.36 MPa); however, elongation to break values were high (PCB5+=797±17% and PBB5+=599±13%). Water uptake was high and protracted with none of the formulations reaching equilibrium. The PCB5+ had the highest uptake (∼6% at 203 days) with that for PBB5+ and PB5+ at a similar level (∼4% at 203 days). None of the materials showed any sign of oxidation. The PBB proved to be the most suitable of the three elastomers for further development in soft lining formulations.

  • blends of isoprene styrene Methacrylate Monomer systems as denture soft lining material
    Biomaterials, 2001
    Co-Authors: Showan N Nazhat, P.d. Riggs, S. Parker, Michael Braden
    Abstract:

    Abstract This work further develops the concept of using an elastomer gelled with Methacrylate Monomers to produce a Methacrylate-based soft lining material without the use of a plasticizer. An isoprene–styrene (SIS) block copolymer was mixed with methyl Methacrylate (MMA) and 1,6-hexandiol diMethacrylate (HDMA). The HDMA was used as a cross-linking agent. The elastomer/Monomer ratios were maintained at 50/50 whereas the Monomers ranged from 0 to 100% HDMA. Mechanical properties and water absorption/desorption characteristics were used to assess the effect of varying the Monomer compositions. The results indicated that phase separation took place, in particular at high HDMA content. This significantly increased the Young's modulus and decreased the elongation to break. Generally, the water uptake tended to decrease with increasing HDMA content, reflecting the effect of modulus. Second absorption cycles gave higher uptake values compared to the first. Formulations with a high amount of HDMA gave materials with modulus values too high for soft lining applications. This suggests that the optimum formulation requires a compromise between modulus and water uptake.

  • Blends of isoprene-styrene/Methacrylate Monomer systems as denture soft lining material.
    Biomaterials, 2001
    Co-Authors: Showan N Nazhat, P.d. Riggs, S. Parker, Michael Braden
    Abstract:

    Abstract This work further develops the concept of using an elastomer gelled with Methacrylate Monomers to produce a Methacrylate-based soft lining material without the use of a plasticizer. An isoprene–styrene (SIS) block copolymer was mixed with methyl Methacrylate (MMA) and 1,6-hexandiol diMethacrylate (HDMA). The HDMA was used as a cross-linking agent. The elastomer/Monomer ratios were maintained at 50/50 whereas the Monomers ranged from 0 to 100% HDMA. Mechanical properties and water absorption/desorption characteristics were used to assess the effect of varying the Monomer compositions. The results indicated that phase separation took place, in particular at high HDMA content. This significantly increased the Young's modulus and decreased the elongation to break. Generally, the water uptake tended to decrease with increasing HDMA content, reflecting the effect of modulus. Second absorption cycles gave higher uptake values compared to the first. Formulations with a high amount of HDMA gave materials with modulus values too high for soft lining applications. This suggests that the optimum formulation requires a compromise between modulus and water uptake.

Yuji Wada - One of the best experts on this subject based on the ideXlab platform.

Ulrich S Schubert - One of the best experts on this subject based on the ideXlab platform.

  • Increased stability in self-healing polymer networks based on reversible Michael addition reactions
    Journal of Applied Polymer Science, 2017
    Co-Authors: Natascha Kuhl, Robert Geitner, Stefan Bode, Jürgen Vitz, M. Schmitt, Jurgen Popp, Ulrich S Schubert, Martin D. Hager
    Abstract:

    A reversible thiol-ene click reaction is utilized to design novel self-healing polymers. These materials are based on a new Methacrylate Monomer featuring a benzylcyanoacetamide derivative, which is copolymerized with butyl Methacrylate. Afterwards, the crosslinking is performed by the addition of a dithiol and a tetrathiol, respectively. Self-healing behavior is obtained by heating the crosslinked polymers to 100 °C (150 °C) for several hours and is monitored by scratch healing experiments utilizing an optical microscope. The thermal properties are studied in detail by differential scanning calorimetry as well as thermogravimetric analysis. Moreover, depth-sensing indentation measurements are performed to determine the mechanical properties. The healing process is based on the reversible cleavage/closing of the bonds (i.e., thiol-ene reaction), which could be demonstrated by Raman spectroscopy. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44805.

  • Increased stability in self‐healing polymer networks based on reversible Michael addition reactions
    Journal of Applied Polymer Science, 2017
    Co-Authors: Natascha Kuhl, Robert Geitner, Stefan Bode, Jürgen Vitz, M. Schmitt, Jurgen Popp, Ulrich S Schubert, Martin D. Hager
    Abstract:

    A reversible thiol-ene click reaction is utilized to design novel self-healing polymers. These materials are based on a new Methacrylate Monomer featuring a benzylcyanoacetamide derivative, which is copolymerized with butyl Methacrylate. Afterwards, the crosslinking is performed by the addition of a dithiol and a tetrathiol, respectively. Self-healing behavior is obtained by heating the crosslinked polymers to 100 °C (150 °C) for several hours and is monitored by scratch healing experiments utilizing an optical microscope. The thermal properties are studied in detail by differential scanning calorimetry as well as thermogravimetric analysis. Moreover, depth-sensing indentation measurements are performed to determine the mechanical properties. The healing process is based on the reversible cleavage/closing of the bonds (i.e., thiol-ene reaction), which could be demonstrated by Raman spectroscopy. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44805.

  • Polymerization of free secondary amine bearing Monomers by RAFT polymerization and other controlled radical techniques
    Journal of Polymer Science Part A: Polymer Chemistry, 2012
    Co-Authors: Tobias Janoschka, Armin Krieg, Anke Teichler, Martin D. Hager, Ulrich S Schubert
    Abstract:

    This work describes the polymerization of the free secondary amine bearing Monomer 2,2,6,6-tetramethylpiperidin-4-yl Methacrylate (TMPMA) by means of different controlled radical polymerization techniques (ATRP, RAFT, NMP). In particular, reversible addition-fragmentation chain transfer (RAFT) polymerization enabled a good control at high conversions and a polydispersity index below 1.3, thereby enabling the preparation of well-defined polymers. Remarkably, the polymerization of the secondary amine bearing Methacrylate Monomer was not hindered by the presence of the free amine that commonly induces degradation of the RAFT reagent. Subsequent oxidation of the polymer yielded the polyradical poly(2,2,6,6-tetramethylpiperidinyloxy-4-yl Methacrylate), which represents a valuable material used in catalysis as well as for modern batteries. The obtained polymers having a molar mass (Mn) of 10,000–20,000 g/mol were used to fabricate well-defined, radical-bearing polymer films by inkjet- printing. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

B W Darvell - One of the best experts on this subject based on the ideXlab platform.

  • methyl Methacrylate Monomer polymer equilibrium in solid polymer
    Dental Materials, 2007
    Co-Authors: Christie Ying Kei Lung, B W Darvell
    Abstract:

    Abstract Objective Poly(methyl Methacrylate) (PMMA) is commonly processed in dentistry by thermally initiating the free-radical polymerization of methyl Methacrylate (MMA). Residual MMA, a tissue irritant, is a concern. The concentration of MMA ([MMA]) versus time and temperature was studied to identify optimum processing conditions. Materials and methods One hundred milligram portions of plain and dental PMMA powders were incubated (10–170 °C, 1–384 h), with and without 6.0 μL MMA added. After incubation, [MMA] was determined by GC. Results For plain PMMA alone, equilibrium was attained in about 100 h. The equilibrium data for log[MMA] versus 1/ T was better fitted by a quadratic than a straight line, and formed an upper bound to the values of [MMA] when PMMA was incubated with MMA at temperatures >∼120 °C. The response surface for [MMA] versus log(time) and reciprocal temperature was fitted. An ‘overshoot’ in the equilibration process was identified, and postulated to be due to a rapidly formed intermediate of unknown chemistry. Significance Minimization of the residual MMA in acrylic denture bases prepared by processing a mixture of PMMA and MMA is important for reasons of mechanical properties and irritancy. The response surface mapped here allows direct identification of the optimum processing conditions.