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The Effect of Spray‐Freeze Drying of Montmorillonite on the Morphology, Dispersion, and Crystallization in Polypropylene Nanocomposites
Author(s) -
Abdallah Wissam,
Tan Victor,
Kamal Musa R.
Publication year - 2020
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.25270
Subject(s) - polypropylene , materials science , montmorillonite , nanocomposite , ultimate tensile strength , crystallization , nucleation , thermal stability , maleic anhydride , composite material , chemical engineering , polymer , copolymer , chemistry , organic chemistry , engineering
The spray‐freeze drying (SFD) technique was applied to sonicated aqueous suspensions of spray‐dried montmorillonite clay (MMT) to produce highly porous agglomerates (SFD‐MMT). Both MMT (used as a reference) and SFD‐MMT were subsequently incorporated in polypropylene (PP) via melt compounding to produce 2 wt % nanocomposites with and without maleic anhydride grafted polypropylene (PP‐ g ‐MA). Polypropylene nanocomposites containing SFD‐MMT exhibited thinner silicate flake layers compared to large agglomerates in PP/MMT nanocomposites. SFD‐MMT particles became even more finer in the presence of PP‐ g ‐MA (i.e., in PP/PP‐g‐MA /SFD‐MMT) where it hindered PP crystallization instead of serving as nucleation sites for the PP crystallization during rapid cooling. SFD‐MMT improved the thermal stability of PP/PP‐ g ‐MA by 30°C compared to only 5–8°C for MMT/nanocomposites. MMT acts as a heterogeneous nucleating agent in the nucleation‐controlled PP nanocomposites, but the hindrance effect was observed for the PP/PP‐ g ‐MA with SFD‐MMT. PP/PP‐ g ‐MA/SFD‐MMT exhibited twice the edge surface energy as compared to PP/PP‐ g ‐MA/MMT. The incorporation of both types of MMT raised the tensile moduli of PP and PP/PP‐ g ‐MA, with no improvement in their tensile strength and a decrease in the elongation at break. The PP/PP‐ g ‐MA/SFD‐MMT showed brittle failure. POLYM. ENG. SCI., 60:168–179, 2020. © 2019 Society of Plastics Engineers