<p>Interfacial interactions between constituent phases are critical determinants of mechanical and physical performance in polyurethane–wood composites (PU-WCs), especially when modified with bio-based components. Despite the growing interest in bio-based PU systems, a detailed understanding of interfacial interactions in PU-WCs remains limited. In this research, PU-WCs with various additions of bio-based polyol (BP) were characterized by atomic force microscopy (AFM) and scanning electron microscopy (SEM). Additionally, PeakForce Quantitative Nanomechanical Property Mapping (PeakForce QNM) was conducted to investigate the nanomechanical properties of PU-WCs. Our findings revealed a strong adhesion between the phases of the unmodified composite. A significant reduction of interphase thickness from 441.5 to 94.3&#xa0;nm was noticed after the addition of BP, suggesting a weakening of interfacial interactions and reduced compatibility between phases in the PU-WCs. The adhesion image revealed the existence of two separated phases with different adhesion forces, where the brighter domains may be assigned to relatively high-rigidity isocyanate-rich domains and darker ones to polyol-rich domains. The maximal adhesion force decreases from 2.8 nN for PU-WC0%/BP to less than 1 nN for PU-WC80%BP. These findings highlight the importance of molecular architecture and interfacial structure on PU-WC performance and provide interesting insights for the design of novel wood-based materials.</p>

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Are interfaces the key? Validation of interfacial interactions in bio-based polyurethane-wood composites by quantitative nanomechanical property mapping

  • Adam Olszewski,
  • Agnieszka Tercjak,
  • Łukasz Piszczyk

摘要

Interfacial interactions between constituent phases are critical determinants of mechanical and physical performance in polyurethane–wood composites (PU-WCs), especially when modified with bio-based components. Despite the growing interest in bio-based PU systems, a detailed understanding of interfacial interactions in PU-WCs remains limited. In this research, PU-WCs with various additions of bio-based polyol (BP) were characterized by atomic force microscopy (AFM) and scanning electron microscopy (SEM). Additionally, PeakForce Quantitative Nanomechanical Property Mapping (PeakForce QNM) was conducted to investigate the nanomechanical properties of PU-WCs. Our findings revealed a strong adhesion between the phases of the unmodified composite. A significant reduction of interphase thickness from 441.5 to 94.3 nm was noticed after the addition of BP, suggesting a weakening of interfacial interactions and reduced compatibility between phases in the PU-WCs. The adhesion image revealed the existence of two separated phases with different adhesion forces, where the brighter domains may be assigned to relatively high-rigidity isocyanate-rich domains and darker ones to polyol-rich domains. The maximal adhesion force decreases from 2.8 nN for PU-WC0%/BP to less than 1 nN for PU-WC80%BP. These findings highlight the importance of molecular architecture and interfacial structure on PU-WC performance and provide interesting insights for the design of novel wood-based materials.