"Ms Gunduz, in collaboration with other members in our research group, has studied the photopolymerization kinetics of the four new dimethacrylate monomers and of the viscous monomer used in present dental resins," Shultz says. "A close approximation to present dental practice was followed by using a camphor quinone/amine photoinitiator system and blue light activation. The instrumentation employed was a commercial double beam light accessory (Perkin-Elmer DPA 7) attached to a DSC apparatus (Perkin-Elmer DSC 7)." He described the process: "The blue light illuminated both a reaction cell and a reference cell; the differential power input required to maintain the same temperature in the two cells is equal to the heat generation rate of the reacting material. The heat generation rate is proportional to the reaction rate," Shultz says. "Nazan could therefore calculate the reaction rate at any chosen time and the total amount of reaction that occurred in a given time period. Variation of photoiniator amount, light intensity and temperature produced a great amount of data of both scientific and practical value. Analyses of the rates of monomer conversion and the ultimate conversion of the monomers to hardened network products allowed comparison of the kinetics, efficiencies, and activation energies of the different monomers."

The new monomers were found to be superior in all aspects, Shultz reports. The Virginia Tech research group includes post doctoral fellows M. Sankarapandian and H.K. Shobha -- who are husband and wife, Gunduz, Shultz, and James McGrath, director of the NSF Science and Technology Center for High Performance Polymeric Adhesives and Composites. The work is supported by the NSF center and Virginia Tech's chemistry department.

Shultz, who has worked pro b
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Contact: Allan Shultz
ashultz@vt.edu
540-231-7222 or 5646
Virginia Tech
22-Nov-1998