Aramid nanofiber‐reinforced poly(lactic acid) nanocomposites with enhanced thermal stability, melt‐crystallization rates, and mechanical toughness

Abstract The main goal of this study is to investigate the impact of aramid nanofiber (ANF) on enhancing various properties of poly(lactic acid) (PLA), including thermal stability, crystallization rates, melt‐rheological behavior, and mechanical properties. To achieve this, ANF fillers were produced using a modified deprotonation process from commercial aramid fibers, and a masterbatch (PLA/ANF = 90/10 by wt%) was prepared through solution blending and drying. The masterbatch was then combined with neat PLA through melt‐blending to create a range of PLA nanocomposites containing 1–10 wt% ANF loadings. Microscopic and spectroscopic analyses confirmed the uniform dispersion and intermolecular interaction of ANFs within the PLA matrix, respectively. As a result, the nanocomposites exhibited a slight increase in glass transition temperature with higher ANF loading, while the cold‐crystallization temperature decreased due to ANFs acting as nucleating agents during PLA crystallization. Isothermal crystallization analysis confirmed accelerated melt‐crystallization rates in nanocomposites with greater ANF content. The introduction of ANFs enhanced the thermal degradation temperature of the PLA matrix and the 700°C residue of the nanocomposites, attributed to ANFs' barrier and flame retardant effects on PLA. Moreover, the nanocomposites with higher ANF loading demonstrated superior tensile strength, strain at break, toughness, and impact strength owing to the effective bonding interactions at the interfaces between the PLA matrix and the ANF fillers. Highlights ANF‐reinforced PLA nanocomposites are prepared by masterbatch melt‐compounding. Uniform dispersion of ANFs in PLA is attained via effective interfacial bonding. ANFs boost the melt‐crystallization of the PLA matrix. ANFs enhance the thermal stability of the PLA matrix. Tensile strength and toughness of PLA are improved with higher ANF content.