Abstract In this work, bottle-grade poly(ethylene terephthalate) (PETR), kraft lignin (KL), and chemically modified lignin (ML) were used to form blends to improve the mechanical and thermal properties of pure PET. The PET/KL and PETR/ML blends were produced with 0.5, 1, 3, and 5 wt.% of lignin via melt extrusion and injection molding. The produced blends and PETR were characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetry (TGA), differential scanning calorimetry (DSC) and mechanical properties testing. The FTIR measurements confirmed the chemical modifications of the ML samples, while the TGA results showed KL to be thermally more stable than ML. The glass transition temperature of PETR changed as a function of the amount of lignin, as revealed by the DSC measurements. The PET/KL blends demonstrated their potential for use as an engineering material due to their improved thermal and mechanical properties compared to those of PETR.

The objective of this investigation was to evaluate the influence of surface modification by femtosecond laser (with average fluence of 0.6 J/cm2 and scanning speed of 0.1 mm/s) on the fatigue resistance of Ti-6Al-4V ELI alloy. A significant reduction in the fatigue strength of the material modified by laser was observed. Residual tensile stresses generated during surface modification were negligible, presenting lower values than those found on the unmodified surface. Based on a recently developed and published prediction model, the reduction of the fatigue strength was ascribed to the surface roughness created during the laser treatment of the alloy. An evidence was that the fatigue crack nucleation occurred in the modified region, rather than at the edge of the rectangular specimens as in the untreated condition.