| Research Abstract |
In this study, three kinds of expansible monomers,1-vinyl-4-ethy1-2,6,7-trioxabicyclo [2,2,2] octane, isophorone diisocyanate and trimethyl hexamethylene diisocyanate containing bicyclic ortho ester structure were synthesized, and various expansible composite resins, which had various expansible monomer/dilute monomer [triethylene glycol dimethacrylate or di (methacryloxy ethyl) trimethyl hexamethylene diurethane] ratio and trial microspherical filler with improved surface (75wt% const.) were prepared. The physical and mechanical properties of various expansible composite resins were examined, and the following results were obtained.
1. In the examination of mixing time, expansible composite resins tended to take a long time in proportion to increase additive volume of expansible monomer. 2. In the examination of curing time, expansible composite resins tended to behind time in proportion to increase additive volume of expansible monomer. 3. In the examinations of compressive and tensile strength, expansible composite resins tended to decrease in proportion to increase additive volume of expansible monomer. 4. Cationic catalyst, (C_2H_5)_2O・BF_3 which used this study, had a short life time and more late in rate of polymerization than radical catalyst benzoyl peroxide.
In the future, it is necessary that kinds and additive volume of expansible monomers, catalysts and accelerator are investigated,in order that expansible composite resins become practicable.
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