STRUCTURE AND THERMAL PROPERTIES OF MALEATED LIGNIN-RECYCLED POLYSTYRENE COMPOSITES

In this work, the changes caused by a chemical modification of the properties and chemical structures of lignin are studied. Lignin from a mixture of Eucalyptus globulus and Eucalyptus nitens obtained through the kraft pulping process was used. The lignin was isolated by acid precipitation and modified by a reaction with maleic anhydride. Maleated lignin (ML) was incorporated to recycled polystyrene (rPS) at 2, 5, and 10 wt-% by a melt-blending process. Fourier transformed infrared spectroscopy (FT-IR) was used to determine the ML structure, and the morphology of rPS/ML composites was studied by scanning electron microscopy (SEM). Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used to study the glass-transition temperature (T-g) and the thermal stability of rPS and rPS/ML composites and were compared with virgin PS. The T-g values of rPS and their composites were higher than those of the virgin PS. TGA revealed that the thermal stability of rPS with 2 and 5% of ML was slightly greater than that of the virgin PS. These results suggest that postconsumer PS can be used to obtain composite materials with good thermal properties.