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The intumescent flame retardant (IFR) filled polypropylene (PP) composites were prepared using a twin-screw extruder. The tensile and impact fracture behavior of the composites were measured at room temperature. It was found that the Young's modulus increased roughly, while the tensile strength decreased slightly with increasing the IFR weight fraction; the toughening effect of the filler on the PP resin was significant. Both the V-notched Izod impact strength and the V-notched Charpy impact strength of the PP/IFR composites showed a nonlinear increase with increasing the filler weight fraction (ϕ f ) as ϕ f was less than 20%, then it decreased. The limited oxygen index of the composites increases nonlinearly with increasing ϕ f . The relationship between them obeyed a quadratic equation. The impact fracture surface was observed by means of a scanning electronic microscope to understand the toughening mechanisms for the composite systems.

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The flame-retardant properties and impact fracture toughness for the polypropylene (PP) composites filled, respectively, with intumescent flame retardant (IFR) and nanometer calcium carbonate/polyolyaltha olefin were measured in the present paper. It was found that the limited oxygen index increased nonlinearly, whereas the horizontal combustibility rate decreased with increasing the IFR weight fraction (φ IFR ). The smoke density rank increased with increasing φ IFR . The values of both the V-notched Izod impact strength and Charpy impact strength of the composites were higher than those of the unfilled PP; they decreased slightly with an increase of φ IFR when φ IFR was more than 10%. Moreover, the fracture surface of the specimens was observed using a scanning electronic microscope to discuss the mechanisms of the flame retardant and toughening. C 2015 Wiley Periodicals, Inc. Adv Polym Technol 2016, 35, 21551; View this article online at wileyonlinelibrary.com.