Interfacial influence on mechanical properties of polypropylene/polypropylene‐grafted silica nanocomposites

Abstract

Three types of polypropylene‐grafted silica (PGS‐2 K, PGS‐8 K and PGS‐30 K) with different grafting chain lengths were prepared. After melt‐blending PGS with polypropylene (PP), we studied the PP/PGS interface properties and the influence of PP/PGS interfaces on mechanical properties of nanocomposites. The strong matrix/particle interface was observed in PP/PGS‐30 K nanocomposites with 5 wt % particle loading as evidenced by 2.5 °C increased glass transition temperature (Tg) compared with neat PP, whereas the weak matrix/particle interface was observed in PP/PGS‐2 K nanocomposites with decreased Tg. The variations in the matrix/particle interfacial strength lead to a transition in the yield stress of nanocomposites. Compared with the unfilled PP, the yield stress of the PP/PGS‐2 K nanocomposites is decreased by 0.7 MPa, and the yield stress of the PP/PGS‐30 K nanocomposites is enhanced by 1.4 MPa. In addition, benefiting from good dispersion, the PP/PGS‐masterbatch nanocomposites with a strong matrix/particle interface not only exhibit increased Young's modulus and yield stress, but also the strain at break remains in line with the unfilled PP, which is in contrast to the conventional wisdom that the gain in modulus and strength must be at the expense of the decreased break strain. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45887.

Effect of Surface Properties of Nanoparticles on the Crystallization Behavior of Polypropylene/Polypropylene‐g‐Silica Nanocomposites

“…However, the poor compatibility between SiO 2 NPs and PP matrix gradually induces the aggregation of nanoparticles with the increase of particle loading. [49] In this case, the confinement effect of aggregates results in the appearance of LCP with lower T c and nucleation ability. Besides, more and more aggregates begin to form and lead to the increase of LCP area in multiple cycling experiment with the increase of Φ.…”