ABSTRACT This study evaluates three interfacial strategies—alkalization (T1), sodium stearate modification (T2), and nano‐CaCO 3 anchoring (T3)—on the performance of bamboo fiber/epoxy composites at high filling fractions (40–60 wt%). The results empirically identify a critical fiber loading threshold at 50 wt%, beyond which macroscopic performance collapses abruptly due to an exponential surge in internal porosity (reaching up to 18.7%). Below this threshold, targeted interfacial engineering yields significant quantitative enhancements. Specifically, the T2 modification demonstrated a remarkable 86.5% increase in flexural modulus (reaching 5588 MPa) compared to the neat epoxy, alongside high flexural strength retention (64.9 MPa). Furthermore, T2 exhibited exceptional long‐term hygrothermal stability, restricting the 15‐day water absorption to a mere 0.55%. Conversely, the T3 system created a robust interfacial “pinning effect” (evidenced by a T g elevation to 92.0°C), yielding a peak compressive strength of 108.6 MPa and delaying the maximum degradation temperature (Tmax) by 22.6°C. Notably, both T2 and T3 modifications endowed the bio‐composites with excellent intrinsic fire safety, successfully achieving a UL‐94 V‐0 rating without the incorporation of traditional bulk flame retardants. These quantitative findings provide a mechanistic framework for designing high‐performance, dimensionally stable, and fire‐safe structural biocomposites.
Hu et al. (Thu,) studied this question.