Synthesis and Study of Fully Biodegradable Composites Based on Poly(butylene succinate) and Biochar

Abstract

Biodegradable polymers offer a promising alternative to the global plastic problems and especially in the last decade, to the microplastics problems. For the first time, samples of poly(butylene succinate) (PBSu) biocomposites containing 1, 2.5, and 5 wt% biochar (BC) were prepared by in situ polymerization via the two-stage melt polycondensation procedure. BC was used as a filler for the PBSu to improve its mechanical properties, thermal transitions, and biodegradability. The structure of the synthesized polymers was examined by 1H and 13C nuclear magnetic resonance (NMR) and X-Ray diffraction (XRD) along with an estimation of the molecular weights, while differential scanning calorimetry (DSC) and light flash analysis (LFA) were also employed to record the thermal transitions and evaluate the thermal conductivity, respectively. It was found that the amount of BC does not affect the molecular weight of PBSu biocomposites. The fine dispersion of BC, as well as the increase in BC content in the polymeric matrix, significantly improves the tensile and impact strengths. The DSC analysis results showed that BC facilitates the crystallization of PBSu biocomposites. Due to the latter, a mild and systematic increase in thermal diffusivity and conductivity was recorded indicating that BC is a conductive material. The molecular mobility of PBSu, local and segmental, does not change significantly in the biocomposites, whereas the BC seems to cause an increase in the overall dielectric permittivity. Finally, it was found that the enzymatic hydrolysis degradation rate of biocomposites increased with the increasing BC content.

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

“…Transmission electron microscopy (TEM) revealed that biochar is dispersed on a nanoscale in the PBSu matrix. Thus, our work confirmed that biochar can act as an effective reinforcing [ 29 , 30 ] and crystallization agent [ 29 , 30 ]. In addition to the mechanical properties, the thermal stability of a polymer is very important for processing and applications.…”

“…As determined in our previous work by TEM, biochar is dispersed in the PBSu matrix at a nanoscale, acting as an effective reinforcing agent [ 29 , 30 ], whereby it improves the mechanical properties. This dispersion could be a result of the evolved interactions taking place between biochar and the PBSu matrix, which could also affect the thermal decomposition of nanocomposites.…”

“…In our previous work, PBSu/biochar bionanocomposites were prepared using in situ polymerization and characterized as a function of thermal conductivity, diffusivity and crystallization kinetics, mechanical properties, and molecular mobility [ 29 , 30 ]. Transmission electron microscopy (TEM) revealed that biochar is dispersed on a nanoscale in the PBSu matrix.…”

Non-Isothermal Crystallization Kinetics of PBSu/Biochar Composites Studied by Isoconversional and Model Fitting Methods

“…Furthermore, it is clear that some aggregates are formed in the nanocomposites containing 2.5 and 5 wt.% biochar, but even in these samples the sizes of aggregates are not larger than 1 μm. From these micrographs, we can conclude that the in situ technique that was used for the preparation of nanocomposites is appropriate to break down the initial large particles of biochar (10–15 μm) at nanosized level [ 15 ].…”

“…One of the main challenges in the use of PBSu biochar composites is the optimization of their properties and performance This can be achieved through the careful selection of the biochar and PBSu materials and the processing conditions used to produce the composite. From our previous work it was found that the fine dispersion of biochar in PBSu matrix improves the tensile and impact strengths [ 15 ]. Further research and development in this area could lead to the creation of new and improved PBSu biochar composites with enhanced capabilities and wider applications.…”