Mixtures of methacrylic polymers are the most common materials for making composites to be used as resins for dental and cosmetic applications. Some of these mixtures are composed by poly(ethyl methacrylate) (PEMA) and poly(methyl methacrylate) (PMMA), which constitute a solid component to be mixed with a liquid component made out of methacrylate monomers. The reaction between the thermal initiator benzoyl peroxyde (BPO) present in the solid component and the activator of the polymerization process, N,N-dimethyl-p-toluidine (DMT) present in the liquid component, gives rise to thermoset materials. In the present study, different liquid formulations composed by a mixture of two methacrylic monomers, ethyl methacrylate (EMA) and triethylene glycol dimethacrylate (TEGDMA) for cosmetic applications, were prepared and characterized, using a commercial powder (POW) composed by PEMA and PMMA. With the aim of improving workability during final application of the material, it was necessary to slow down the polymerization rate of liquid formulations. Their thermal behavior was investigated by differential scanning calorimetric (DSC) in order to check the polymerization rate. Thermal stability of final materials was determined by thermogravimetric analysis (TGA). Dynamic mechanical thermal analysis (DMTA), microindentation hardness and impact tests were performed on final materials, to assess their performance with respect to standard formulation. The combination of thermal and mechanical properties allows choosing which formulations could be suitable for use in cosmetics.
Keywords: cosmetics; mechanical properties characterization; methacrylate monomers; polymerization rate; thermal properties characterization.