Thermal Evaluation by DSC and Tensile Strength of Extrudated Blends from Polyethylene Terephthalate and Kraft Lignin

Polyethylene terephthalate is a polymer commonly used in food packaging which recycling potential should be explored with new studies. Lignin is the second most abundant biomass resource in the nature. Kraft lignin is a byproduct of the kraft pulping process, it is produced in large quantities. In this work PET/KL blends were produced in 1, 2, 5, 10 wt% of KL. These polymers were processed by extrusion, aiming to produce an alternative engineering material. Samples were investigated by Fourier Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC), X-Ray Diffraction (XRD), Scanning Electronic Microscopy (SEM) and Tensile Test. Samples of extruded PET and PET/KL show differences in the pre-crystallization temperature. PET has higher pre-crystallization and melting temperature, as well as higher melting enthalpies. At 140 °C the presence of lignin reorders PET morphology, inducing the increase of the crystalline phase in the systems. The amount of KL in the sample influences also the sample morphology, which can results in a phase separation.