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Posts Tagged ‘polymerization’
Friday, November 11th, 2011

Do not sacrifice conversion and the risk of residual monomer contamination to achieve low-shrink properties. New testing has demonstrated that EXOTHANE(TM) Elastomers have low shrinkage stress, low volumetric shrinkage, AND high conversion.
- Exothane 8, 94% Conversion, 3% Shrinkage, high % elongation
- Exothane 26, 96% Conversion, 4% Shrinkage, increased flexibility/toughness
- Exothane 32, 97% Conversion, 3% Shrinkage, low color and low viscosity
This new data, in addition to superior toughness, tensilse strength and percent elongation make the EXOTHANE product line ideal form many applications including, low-shrink dental restoratives, non-curling industrial coatings, unique UV nail enhancements, tougher anaerobic adhesives and more.
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Tags: dental research, esstech, EXOTHANE, EXOTHANE Elastomers, High conversion, low shrinkage stress, low volumetric shrinkage, Monomer, polymerization, Resin, Shrinkage, stress, tough Posted in Announcements | No Comments »
Monday, May 23rd, 2011
Efficiency of 4,4′-bis(N,N-diethylamino) benzophenone for the polymerization of dimethacrylate resins in thick sections
Walter F Schroeder, Silvana L Asmussen, Wayne D Cook, Claudia I Vallo
Article first published online: 2 MAY 2011, DOI: 10.1002/pi.3089, Copyright © 2011 Society of Chemical Industry
Abstract
The efficiency of 4,4′-bis( N, N-diethylamino)benzophenone (DEABP) for the polymerization of dimethacrylate monomers in thick sections ( 1– 2 mm) was studied. DEABP (λ max = 365 nm) represents a complete initiating system as it contains both ketone and amine functional groups. During irradiation, DEABP photobleaches at a fast rate causing deeper penetration of light through the underlying layers, but the photoinitiation efficiency (rate of polymerization per photon absorption rate) is relatively poor. As a result, irradiation of methacrylate monomers at 365 nm results in a slow average polymerization rate and a reduced monomer conversion for thick sections due to the light attenuation caused by the high absorptivity of DEABP and photolysis products. These results highlight the inherent interlinking of light attenuation and photobleaching rate in polymerization of thick sections.
Materials
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Tags: bis-GMA, polymerization, TEGDMA, X-943-7446, X-950-0000 Posted in Research Paper | No Comments »
Monday, January 24th, 2011
Modification of polymer networks with bone sialoprotein promotes cell attachment and spreading
Wailen D. Chan, Harvey A. Goldberg, Graeme K. Hunter, S. J. Dixon, Amin S. Rizkalla, Journal of Biomedical Materials Research Part A
Tags: HEMA, Hydroxyethyl Methacrylate, Medical, medical device, Polymer, polymerization, X-968-7044 Posted in Research Paper | 1 Comment »
Friday, September 10th, 2010
Contraction stress related to composite inorganic content
F. Gonçalvesa, Y. Kawanob, R.R. Bragaa
Dental Materials Volume 26, Issue 7, Pages 704-709 (July 2010).
Objectives: The role of inorganic content on physical properties of resin composites is well known. However, its influence on polymerization stress development has not been established. The aim of this investigation was to evaluate the influence of inorganic fraction on polymerization stress and its determinants, namely, volumetric shrinkage, elastic modulus and degree of conversion.
Methods: Eight experimental composites containing 1:1 BisGMA (bisphenylglycidyl dimethacrylate):TEGDMA (triethylene glycol dimethacrylate) (in mol) and barium glass at increasing concentrations from 25 to 60vol.% (5% increments) were tested. Stress was determined in a universal test machine using acrylic as bonding substrate. Nominal polymerization stress was obtained diving the maximum load by the cross-surface area. Shrinkage was measured using a water picnometer. Elastic modulus was obtained by three-point flexural test. Degree of conversion was determined by FT-Raman spectroscopy.
Results: Polymerization stress and shrinkage showed inverse relationships with filler content (R2=0.965 and R2=0.966, respectively). Elastic modulus presented a direct correlation with inorganic content (R2=0.984). Degree of conversion did not vary significantly. Polymerization stress showed a strong direct correlation with shrinkage (R2=0.982) and inverse with elastic modulus (R2=0.966).
Significance: High inorganic contents were associated with low polymerization stress values, which can be explained by the reduced volumetric shrinkage presented by heavily filled composites.
Link: http://www.demajournal.com/article/PIIS0109564110000801/fulltext
Tags: bis-GMA, bisGMA, dental research, esstech, polymerization, Shrinkage, stress, TEGDMA, X-950-0000 Posted in Research Paper | 1 Comment »
Wednesday, June 30th, 2010
Tags: dental research, esstech, FIT 852 Resin, IADR, low-shrink, polymerization, Resin, Shrinkage, X-852-0000 Posted in Announcements | 2 Comments »
Wednesday, March 31st, 2010
Polymerization Shrinkage and Stress Development in Amorphous Calcium Phosphate/Urethane Dimethacrylate Polymeric Composites
J.M. Antonucci, W.F. Regnault, and D. Skrtic
Journal of Composite Materials, Feb 2010; vol. 44: pp. 355 – 367. DOI: 10.1177/0021998309345180
Abstract: This study explores how substituting a new high molecular mass oligomeric poly(ethylene glycol) extended urethane dimethacrylate (UDMA) (PEG-U) for 2-hydroxyethyl methacrylate (HEMA) in photo-activated UDMA resins affects degree of vinyl conversion (DC), polymerization shrinkage (PS), stress development (PSSD) and biaxial flexure strength (BFS) of their amorphous calcium phosphate (ACP) composites. The composites were prepared from four types of resins (UDMA, PEG-U, UDMA/HEMA, and UDMA/PEG-U) and zirconia-hybridized ACP. Introducing PEG-U improved DC, while not adversely affecting PS, PSSD, and the BFS of composites. This improvement in DC is attributed to the long, more flexible structure between the vinyl groups of PEG-U and its higher molecular mass compared to poly(HEMA). The results imply that PEG-U has the potential to serve as an alternative to HEMA in dental and other biomedical applications.
…material research program supported by FDA, NIST, and ADAF. Generous contribution of UDMA, PEG- U, and HEMA monomers from Esstech, Essington, PA, USA, is gratefully acknowledged. Polymerization Shrinkage and Stress in ACP Composites 365 The authors also…
This version was published on February 1, 2010
Link: http://jcm.sagepub.com/cgi/content/abstract/44/3/355
Tags: composite, dimethacrylate, Extended, HEMA, polymerization, Shrinkage, stress, UDMA, urethane, X-726-0000, X-850-0000, X-968-7044 Posted in Research Paper | No Comments »
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