Poly(butylene adipate-co-terephthalate) composites containing spray-dried tobacco crude extract for potential agricultural applications

Abstract

This study developed biodegradable poly(butylene adipate-co-terephthalate) (PBAT) composites containing spray-dried tobacco crude extract (TCE)/maltodextrin carrier (TCE powder) as a nicotine-releasing additive. TCE powder was prepared by ultrasound-assisted extraction, purification, mixing with maltodextrin and spray drying. The dispersion behavior, chemical composition and morphology of TCE powder were characterized prior to incorporation into PBAT at 5–20 wt%. The effects of TCE powder loading on the chemical structure, thermal properties, morphology, mechanical properties and nicotine-release behavior of the PBAT composites were evaluated. Morphological analysis showed microspherical TCE powder. Dynamic light scattering revealed smaller hydrodynamic particle sizes of TCE powder dispersed in water, whereas its larger aggregates were observed in alcohol-based media. Preliminary agar-well diffusion method indicated changes in the growth pattern of Aspergillus sp. exposed to TCE solutions, although distinct inhibition zones were not observed. DSC analysis showed that TCE powder reduced PBAT crystallinity, while TGA indicated that the main thermal degradation behavior of the PBAT matrix remained largely preserved. Among the tested formulations, the composite containing 5 wt% TCE powder exhibited the the most favorable balance of tensile strength, stiffness and ductility, whereas higher TCE powder loadings reduced ductility and were associated with increased particle agglomeration and interfacial defects. Release studies demonstrated predominantly diffusion-governed nicotine release from the PBAT matrix, with quasi- or pseudo-Fickian behavior at lower TCE powder loadings and anomalous transport at the highest loading. The absolute amount of released nicotine increased with increasing TCE powder loading, although the fractional release relative to the theoretical nicotine content was formulation-dependent. A preliminary cradle-to-gate carbon footprint assessment indicated that incorporation of waste-derived TCE powder reduced the estimated carbon footprint by 13.30% compared with neat PBAT. These findings demonstrate the feasibility of incorporating tobacco-derived extract into biodegradable PBAT composites as a nicotine-releasing additive and support further investigation of their potential agricultural applications.