Tuning Functional Properties of Poly(butylene Furandicarboxylate-co-butylene Succinate) via Nanosilica and Layered Double Hydroxide Nanofillers.

Nanocomposites of poly-(2,5-butylene furandicarboxylate-co-butylene succinate) (PBFS) containing nanosilica (SiO2) or layered double hydroxides (LDHs) were successfully prepared by extrusion. Nanosilica and LDH inclusions were found to consist of aggregates with variable size. The estimated density of the nanofiller aggregates attested to the presence of empty spaces within them. The thermal, permeability, mechanical, and viscoelastic properties of PBFS/SiO2 and PBFS/LDH nanocomposites were investigated as a function of the nanofiller aggregation status. The study of the thermal properties of PBFS/SiO2 and PBFS/LDH nanocomposites revealed that the interactions between PBFS and the nanofillers were nonstrong. Gas permeability to oxygen and water vapor was found to increase with the nanofiller amount because of the empty spaces included in the nanofiller aggregates and the rubbery state of the PBFS amorphous phase. The fractional free volume within the SiO2 aggregates was estimated to be approximately around 1%. Mechanical tests revealed a sufficiently good load transfer between the PBFS matrix and the nanofillers, particularly in semicrystalline samples. The elastic modulus of the semicrystalline PBFS/LDH nanocomposites turned out to be approximately doubled in comparison with neat PBFS. In the melt state, the viscosity of PBFS-based nanocomposites was found to be higher than that of neat PBFS, due to restriction in polymer mobility induced by the nanofillers. Under composting conditions, PBFS and PBFS/SiO2 nanocomposites revealed fragmentation below the 90% required in 90 days for full compostability. The disintegration rate was, however, higher than that of the homopolymer PBF, confirming that the incorporation of butylene succinate units improves the biodegradation of furandicarboxylate-based materials.