Poly(lactic acid)/halloysite nanotubes nanocomposites: Structure, thermal, and mechanical properties as a function of halloysite treatment

Poly(lactic acid) (PLA)/halloysite nanotubes (HNT) nanocomposites were prepared by melt extrusion using a masterbatch dilution process. Effect of addition of both unmodified halloysites (HNT) and quaternary ammonium salt treated halloysites (m-HNT) was investigated at different nanofiller contents. A homogeneous distribution/dispersion of halloysites in the PLA matrix is obtained for both unmodified and modified nanotubes within the studied composition range. The nucleating effect of halloysites, resulting in a limited increase of degree of crystallinity, is more pronounced in the case of m-HNT. Besides, the rigidity, tensile, flexural, and impact resistances of PLA significantly increase on addition of halloysites, the property improvement being higher for m-HNT than for HNT. Interestingly, there is no significant embrittlement (almost constant elongation at break). Based on micromechanical models, this superior reinforcement efficiency of m-HNT was ascribed to the better interfacial compatibility induced by the modification of the nanotube surface. (c) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013