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Herein, we proposed a new strategy to enhance compatibility and flame retardancy of the immiscible and flammable polylactic acid (PLLA)/polypropylene (PP) blend materials simultaneously. It is found that the boehmite nanorods are located at the PLLA-PP interface by in-situ reactions and the compatibility between phases is greatly improved, resulting in significant enhancement of mechanical properties and flame retardancy: tensile strength and elongation at break of the blends with 7 wt% reactive nanorods are 163% and 601% higher than that without nanorods, respectively. Meanwhile, the peak heat release rate (PHRR) decreases 51.4% and limiting oxygen index (LOI) increases 22.6%. The synergetic improvements are directly attributed to the strengthened interface and the interface takes the role of the flame retarding belt. The research opens a new avenue to fabricate non-halogen flame retardant multicomponent polymer materials with simultaneously enhanced mechanical properties. [Display omitted] •Ternary Poly(L-lactic acid)/Polypropylene/boehmite nanorods nanocomposites were prepared. •Epoxide groups modified boehmite nanorods are thermodynamically located at the PLLA/PP blend interface by the in-situ reactions. •The interfacially located nanorods improve the mechanical properties and flame retardancy of the PLLA/PP blends simultaneously. [ABSTRACT FROM AUTHOR]

Polymer blend nanocomposites with the nanoparticles exclusively located at the interface have attracted significant attention while the compatibilization functions of such nanoparticles in the blends are still controversial. Herein, the pristine boehmite nanorods (p-BNRs) and epoxide group modified boehmite nanorods (m-BNRs) have been synthesized and incorporated in the immiscible Poly(l -lactide)/Poly(1,4-butylene succinate) (PLLA/PBSU) blends. It is found that both p-BNRs and m-BNRs are thermodynamically located at the interface and the phase morphologies of the two nanocomposites are very similar at the same nanofiller loadings. However, the two nanocomposites exhibit different mechanical properties. The PLLA/PBSU blend nanocomposites with m-BNRs show increased elongation at break, enhanced notched impact strength and improved yield strength, as compared with the binary PLLA/PBSU blends. In contrast, p-BNRs lead to drastically deteriorating mechanical properties of the PLLA/PBSU blends even with all p-BNRs located at the interface. The investigation indicates that p-BNRs at the interface have barren surface and are lack of specific interactions with the polymers in the neighboring phases. In contrast, the epoxide groups on m-BNRs reacted with the end carboxylic acid groups of both PLLA and PBSU and the polymer chains were chemically bonded onto the surface of nanorods. The chemically bonded polymer chains on the nanorods at the interface can entangle with the molecular chains of the two polymers to enhance the interfacial adhesion. This paper demonstrates the significance of molecular chain entanglements of the compatibilizing nanoparticles and paves a new possibility to fabricate new materials with simultaneously enhanced strength and toughness. Image 1 • Ternary Poly(l -lactide)/Poly(1,4-butylene succinate)/boehmite nanorods nanocomposites were prepared. • Both pristine boehmite nanorods and epoxide groups modified boehmite nanorods are thermodynamically located at the interface of PLLA/PBSU. • Barren nanorods deteriorate the mechanical properties of PLLA/PBSU blends, but surface grafted nanorods enhance the mechanical properties drastically. • Molecular entanglements of the grafted nanorods are the prerequisite for the compatibilization of immiscible polymer blends. [ABSTRACT FROM AUTHOR]