Accelerated Weathering Tests of Linseed and Passion Fruit Oil-Based Polyurethanes

The accelerated weathering of polyurethanes (PUs) is a process induced by exposure to ultraviolet (UV) radiation, resulting in the breakdown of chemical bonds and consequent changes in the material’s properties. The reason for this phenomenon is the oxidation, by free radicals, of the polymeric structure, caused by the absorption of energy by the chromophores present in it. This paper studies the accelerated weathering of PU foams synthesized by linseed and passion fruit oil (OL and PFO, respectively), prepared with 0.8 and 1.2 [NCO]/[OH] ratios. After weathering, the samples were analyzed by Fourier transform infrared spectroscopy (FTIR), stereomicroscopy, thermogravimetry (TG), and derivative thermogravimetry (DTG). After the accelerated weathering process, changes were observed in the FTIR spectra of the PU samples compared to the spectra of the original PUs, indicating that the process occurred, even if partially. TG/DTG analysis of the photoaged PUs showed that the degradation process had started, as these materials presented lower thermal stability than the original PUs.