Investigação da cinética de cura e degradação do sistema óleo de soja epoxidado/anidrido.

Abstract

Compounds based on epoxidized soybean oil (ESO) were thermally cured with methyl tetrahydrophthalic anhydride (MTHPA) as hardener and 2,4,6tris (dimethylaminomethyl) phenol (DEH 35) as catalyst. In order to understand the influence of MTHPA and DEH 35 contents on the curing and degradation, ESO/MTHPA/DEH 35 system was investigated using Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). From the FTIR spectra collected before curing, secondary interactions between ESO carbonyl groups and DEH 35 hydroxyl/amine. The curing was followed based on the reactive chemical groups evolution and data were corroborated with DSC results. The curing activation energy (Ea), was evaluated using Friedman model and presented values between 44,3 e 37,1 kJ/mol ( α = 0,8) for the compounds ESO:MTHPA 87:5 and 87:10, respectively; upon the hardner and catalyst content increased greater thermal stability was verified. Friedman, Ozawa, Flynn and Wall models were used to investigate the degradation, as well as to measure the associated activation energy, which presented values between 105,4 e 14,5 kJ/mol. The achieved results in this study provide understanding and control tools to the curing and degradation mechanisms of ESO/MTHPA/DEH 35 system.