Fuente: Journal of applied polymer Lugar: RESEARCH ARTICLE This study evaluates interfacial engineering in high-loading bamboo fiber/epoxy composites using stearate shielding and nano-CaCO3 pinning. Results establish a 50 wt% critical loading threshold, beyond which performance collapses due to porosity. Optimal modifications yield exceptional flexural rigidity, long-term hygrothermal stability, and intrinsic V-0 flame retardancy without traditional additives.

ABSTRACT
This study evaluates three interfacial strategies—alkalization (T1), sodium stearate modification (T2), and nano-CaCO3 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

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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.