TIT# Properties and semicrystalline structure evolution of
     polypropylene/montmorillonite nanocomposites under mechanical load
AUT# Stribeck, Norbert; Zeinolebadi, Ahmad; Ganjaee Sari, Morteza; Botta, Stephan; Jankova, Katja; Hvilsted, Síren;
     Drozdov, Aleksey; Klitkou, Rasmus; Potarniche, Catalina-Gabriela; Christiansen, Jesper deClaville; Ermini, Valentina;
SOU# Macromolecules (2011), submitted Sept 1
LOC# xv133
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ABS# Small-angle X-ray scattering (SAXS) monitors tensile and load-cycling
     tests of metallocene isotactic polypropylene (PP), a blend of PP and
     montmorillonite (MMT), and 2 block-copolymer compatibilized PP/MMT
     nanocomposites. Mechanical properties of the materials are similar, but
     the semicrystalline nanostructure of the PP differs. This is explained by
     a nucleation effect of the MMT. Competitive crystal growth diminishes
     crystallite sizes. The reinforcing effect of the MMT filler appears
     consumed by weakening the PP matrix. Decays of mechanical and
     nanostructure response in dynamic load-cycling indicate materials fatigue.
     Lifetimes describe the reinforcing and weakening effects. Addition of
     3 % MMT halves the fortifying effect of the PP nanostructure. A net gain
     of reinforcement (11 %) is observed with the highly compatibilized
     composite in which the strength of the semicrystalline PP is reduced to
     25 %. Other results concern the evolution of Strobl's block structure and
     void formation during tensile loading.