Wood Residue-Derived Biochar as a Low-Cost, Lubricating Filler in Poly(butylene succinate-co-adipate) Biocomposites

Abstract

This study focused on the development of a novel biocomposite material formed by a thermoplastic biodegradable polyester, poly(butylene succinate-co-adipate) (PBSA), and a carbonaceous filler as biochar (BC) derived by the pyrolysis of woody biomass waste. Composites with various BC contents (5, 10, 15, and 20 wt.%) were obtained by melt extrusion and investigated in terms of their processability, thermal, rheological, and mechanical properties. In all the composites, BC lowered melt viscosity, behaving as a lubricant, and enhancing composite extrudability and injection moulding at high temperatures up to 20 wt.% of biochar. While the use of biochar did not significantly change composite thermal stability, it increased its stiffness (Young modulus). Differential scanning calorimeter (DSC) revealed the presence of a second crystal phase induced by the filler addition. Furthermore, results suggest that biochar may form a particle network that hinders polymer chain disentanglement, reducing polymer flexibility. A biochar content of 10 wt.% was selected as the best trade-off concentration to improve the composite processability and cost competitiveness without compromising excessively the tensile properties. The findings support the use of biochar as a sustainable renewable filler and pigment for PBSA. Biochar is a suitable candidate to replace more traditional carbon black pigments for the production of biodegradable and inexpensive innovative PBSA composites with potential fertilizing properties to be used in agricultural applications.

The Effect of Biochar Addition on Thermal Stability and Decomposition Mechanism of Poly(butylene succinate) Bionanocomposites

“…The results showed that biochar exhibits a stable behavior, with a minimal mass loss of <15% up to 600 °C. This outcome was expected, given that biochar is already subjected to thermal degradation during the pyro-gasification process [ 18 ] The thermal profiles observed for biochar are typical of a pyrolyzed carbonaceous material derived from agricultural and forestry waste. The slow rate of mass loss observed in the thermograms was mainly attributed to the presence of refractory organic matter, degraded lignin, and strong C–C covalent bonds that are resistant to degradation [ 18 ].…”

“…Due to the increasing interest in ecofriendly and sustainable materials, biochar has been intensively studied as a promising filler and reinforcement in polymers [ 18 ]. Biochar is a byproduct of biomass pyrolysis and, thus, can be characterized as a biobased filler.…”

Highly dispersed biochar as a sustainable filler for enhancing mechanical performance and biodegradation of polybutylene succinate

“…The PBS/BC composites exhibited a decreasing tendency in the storage modulus and complex viscosity with increasing filler content, which was more pronounced at lower frequencies. This was due to a lack of interfacial bonding between the PBS matrix and the BC, and the bonding was further reduced with increasing filler content, resulting in a decrease in the complex viscosity 28,29 . Therefore, the decrease in the complex viscosity with the addition of BC reduces the viscosity of the composite and improves its processability.…”

Seawater Biodegradable Poly(butylene succinate-co-adipate)—Wheat Bran Biocomposites

“…Moreover, no significant shift or new bands attributable to chemical interactions between the filler and polymer matrix were observed. In conclusion, the addition of bran only reduced the intensity of significant PBSA peaks, indicating that bran acts as an inert filler [ 59 ].…”