In situ polymerised polyamide 6/sepiolite nanocomposites: Effect of different interphases

•Two model nanocomposites have been prepared which differ only for the interphase.•Enhanced strain-at-break and work-of-fracture for “grafted-from” nanocomposite.•A “soft” polymer/clay interphase invoked to explain these phenomenon.

The success of a polymer/clay nanocomposite depends from a number of factors including the intrinsic properties of the clay, nanofiller dispersion and orientation, matrix/filler interactions, etc. This manuscript focuses on the effect of matrix/filler interphases on the final physical properties of nanocomposite.Two PA6/sepiolite nanocomposites masterbatches are prepared via in situ polymerisation and then diluted via melt-compounding to different filler contents: one based on unreactive pristine sepiolite and another based on reactive amino-silane functionalised sepiolite. This offers a unique comparison opportunity, in which only the latter nanocomposite has PA6 molecules grafted directly from the sepiolite clay. Both nanocomposites are characterised in terms of morphology, thermal behaviour, semi-static tensile tests and dynamic mechanical tests. Interestingly, the grafted-from nanocomposites presented an enhanced strain at break and work of fracture, up to 100% in correspondence of 5 wt.% of filler, which is explained by the presence of a “soft” interphase.

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