Using biodiesel as a green solvent in the polymerization reactions: the attempt to separate the biodiesel from the polymer by thermal treatment

In this work, the products of the polymerization reaction of epoxidized methyl esters with phthalic anhydride catalyzed by 2-methyl-imidazole, in the presence of biodiesel as a green solvent, were evaluated. The presence of biodiesel enabled reaction at 180 °C during 40 min in a system with good thermal conductivity, homogeneous conditions, and products with physical aspect varying from rubber to high viscous liquid. The products include polyesters, with and without biodiesel, were characterized by: DSC—Differential Scanning Calorimetry, TGA—thermogravimetric analysis, and TGA/MS -TGA coupled to Mass Spectrometer, swelling tests, plane strain compression, and morphological analysis using scanning electronic microscopy (SEM). Considering that biodiesel presents a temperature degradation around 215 °C and the polyesters around 320 °C, a simple thermal treatment was introduced to separate the solvent biodiesel from the reaction products. This treatment includes heating until 250 °C and consequent cooling to the room temperature. The second heating, up to 500 °C, was used to prove, through TGA/MS, that the thermal treatment (heating until 250 °C) not affected the polyester matrix and is sufficient to remove biodiesel.