AbstractIn this study, thermoplastic polyurethanes (TPUs) containing trisilanol isooctyl polyhedral oligomeric silsesquioxane (POSS), a reactive nanofiller, were synthesized and characterized rheologically and morphologically, and the effects of POSS content on the melt thermal stability of the TPUs are investigated. Samples containing 0, 0.23, 0.57, 1.14, and 2.23% (w/w) POSS were synthesized by reactive extrusion and characterized by Fourier transform infrared spectroscopy (FTIR), oscillatory and extensional rheometry, atomic force microscopy (AFM), and small- and wide-angle X-ray scattering (SAXS and WAXS, respectively). The rheological properties of molten TPU are time-dependent and the melt thermal stability of the TPU is maximal at 1.14% of POSS. The addition of 0.23 and 0.57% POSS promotes strain-hardening at low extensional strain rates (0.01 and 0.10 s−1), not affecting the extensional characteristics at higher strain rates. The addition of increasing amounts of POSS leads to the formation of POSS-rich clusters well dispersed in the TPU matrix. SAXS and WAXS results show that the POSS domains are amorphous and that POSS does not modify the crystalline structure of TPU. Therefore, this work indicates that synthesizing TPU in the presence of trisilanol isooctyl POSS can increase the melt thermal stability of the polymer, facilitating its processing.
ANNEALING OF UNFERMENTED (POLVILHO DOCE) AND FERMENTED (POLVILHO AZEDO) CASSAVA STARCHES
