Applied and computational investigation of plasticizing effects of dibutyl maleate on polymethyl methacrylate acrylic resin material

Abstract

In this study, the amount of change in the glass transition temperature (Tg) of PMMA was analyzed by DSC by adding different ratios of dibutyl maleate (DBM) plasticizer to polymethyl methacrylate (PMMA), which is used as the main ingredient of prosthetics in dentistry. For this, liquid DBM was added to powdered PMMA at a rate of 2, 5, 8 and 15 % by mass, and polymerization was carried out at 100 °C. Mechanical tests such as impact resistance, transverse resistance and maximum flexion tests were applied to these prepared mixtures. It was observed that there was a significant parallelism between the Tg values calculated from the DSC curves and the mechanical tests. The Tg value of PMMA was reduced by approximately half with the addition of DBM plasticizer. Additionally, the chemical interaction between PMMA and DBM was analyzed in the light of the Density Functional Theory (DFT) calculations. The binding energy for the mentioned interaction was determined as 1.591 eV. After both species interacted with each other, the glass transition temperature of the formed complex system was theoretically also predicted through the quantitative structure-property relationship (QSPR) model. For theoretical prediction of Tg, the molecular traceless quadrupole moment Θ and the molecular average hexadecapole moment Φ, are used. The change determined as experimental in glass transition temperature as a result of the interaction between PMMA and DBM was supported with theoretical calculations. Experimental and theoretical data are in good agreement.