Polypropylene nanocomposites produced by in‐situ grafting of maleic anhydride using different mixing procedures

Abstract

Nanocomposites (NC) of polypropylene (PP) and organophilic montmorillonite(oMt) are produced by reactive mixing with simultaneous grafting of maleicanhydride (MA) onto PP using organic peroxide as initiator. Five differentstrategies of incorporating reactants and clay into a laboratory mixer are used.The structure of composites is examined by FT-IR spectroscopy, x-ray diffractionand scanning electron microscopy. Rotational rheometry, thermogravimetry andoxygen permeability are used to evaluate properties. The preparation methodhas a remarkable influence on NC´s structure. Simultaneous addition of peroxideand MA to molten PP followed by incorporation of clay 20 minutes laterproduces the best degree of clay exfoliation/disaggregation. The NCs obtainedusing this procedure are highly transparent and have very thin tactoids withinterlayer spacing more than 50% larger than the original oMt. The incorporationof just 2 wt% of clay gives place to more than 30% reduction in PP oxygenpermeability. Additionally, the temperature at the maximum thermal degradationrate in nitrogen reduces in about 60C while the temperature at which thethermal degradation process begins is not affected.