Posts Tagged ‘X-850-0000’

X-726-0000 Serves as HEMA Alternative and Improves Degree of Conversion

Wednesday, March 31st, 2010
Share This Post!

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


Share This Post!

Camphorquinone Decomposition Rates Vary Among UDMA and BisGMA/TEGDMA Formulations

Thursday, March 18th, 2010
Share This Post!

Photobleaching of camphorquinone during polymerization of dimethacrylate-based resins

Silvana Asmusen, Gustavo Arenas, Wayne D. Cook, Claudia Vallo

Dental Materials, December 2009 (Vol. 25, Issue 12, Pages 1603-1611)

Abstract: Objective: The aim of this study was to compare the photobleaching rate of CQ in different dental resins. Methods: The photodecomposition rate of CQ/amine system in bis-GMA/TEGDMA, bis-EMA and UDMA polymerizing monomers was evaluated at different light intensities. The photobleaching of the CQ was studied by monitoring the decrease in light absorption as a function of continuous irradiation time. The absorption changes were assessed by recording the transmitted light that passed through samples of monomers containing CQ/amine. Results: Complete photobleaching of CQ was observed in all the monomer tested and the rate constant for the photobleaching was proportional to the radiation intensity. Hydrogen abstraction from amines by the excited CQ state via electron transfer and direct hydrogen abstraction from monomer structures were involved in the CQ photoreduction. CQ was photobleached in the absence of coinitiator in a dimethacrylate monomer containing a carbamate functional group (UDMA). This behavior was attributed to the presence of labile hydrogen atoms in the UDMA monomer. The CQ photobleaching rate constant in UDMA containing CQ/amine was similar to that in UDMA in the absence of amine. Moreover, the efficiency of CQ to photoinitiate the polymerization of UDMA in the absence of amine demonstrated that the radicals derived from the UDMA monomer via hydrogen abstraction are highly reactive toward double bonds.

Significance: CQ photoinitiates the polymerization of the UDMA monomer in the absence of amine and the efficiency of this process is comparable to that of traditional bis-GMA and bis-EMA monomers activated with CQ/amine.

Link:  http://www.demajournal.com/article/S0109-5641(09)00285-1/abstract


Share This Post!

Esstech Inc. – Creating custom products & formulations to meet your unique needs!