activation energy.

Frictional and Elastic Components of the Viscosity of Polysterene-Toluene Diluted Solutions

We studied the gradient dependence of the effective viscosity η for the diluted solution of the polystyrene in toluene under three concentrations ρ = 0.5∙105, 1∙105 and 2∙105 g/m3 and for four polystyrene fractions with average molar weights М = 5.2∙104, 4.4∙104, 3.3∙104 and 1.8∙104 g/mol, in the temperature range of 293–308 K. The experiments have been carried out with the use of rotary viscometer “Rheotest 2.1” at various cylinder rotation angular rate ω (r/s).

Light Curable Dental Composites – Kinetics by Plasma and Halogen Lamps

A series of commercial dental composites curable by visible light have been investigated and compared in terms of their photoreactivity thanks to the photocalorimetry technique by using two different types of lamps, a conventional lamp (halogen lamp) from ESPE and a plasma lamp, Apollo 98E manufactured by DMDS. In terms of kinetics, dental composites cure in just a few seconds with plasma lamp compared to 20-40 s with halogen lamp allowing dentists to save time.