| 摘要 |
Cement compositions including initiation systems containing at least one peroxide or amine which has a higher molecular weight than the heretofore-employed peroxide BPO and amine DMpT, respectively. In particular, derivatives of peroxides and amines bearing large substituents relative to BPO and DMpT and polymeric peroxides and amines are suitably employed in the reaction mixture. Through the use of these initiator systems in which one or more of the components has reduced mobility relative to the materials employed in the conventional mixtures, it is possible to control the exothermicity and the peak temperature of the polymerization, while nonetheless achieving timely and adequate polymerization of the material. Concurrently, the choice of components for use in the initiation system advantageously results in a reduction in the generation of waste products and in the potential toxicity of the composition. In general, initiators having structures with substituents attached to the benzoyl peroxide or the amine skeleton and equivalent to at least about 4 additional carbon atoms are preferred. Porosity and shrinkage of cement products are addressed through selection of appropriate comonomers for use with or in place of methyl methacrylate. Hydrophilic comonomers and/or monomers with lower vapor tension than methyl methacrylate are preferred for this purpose. These modifications are broadly useful in a wide variety of vinyl-based polymerization systems, including but not limited to those used in biomedical applications. |
