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Foam processing and cellular structure of polypropylene/clay nanocomposites
Author(s) -
Nam Pham Hoai,
Maiti Pralay,
Okamoto Masami,
Kotaka Tadao,
Nakayama Takashi,
Takada Mitsuko,
Ohshima Masahiro,
Usuki Arimitsu,
Hasegawa Naoki,
Okamoto Hirotaka
Publication year - 2002
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.11083
Subject(s) - materials science , polypropylene , composite material , nanocomposite , maleic anhydride , scanning electron microscope , transmission electron microscopy , montmorillonite , copolymer , polymer , nanotechnology
Polypropylene (PP)/clay nanocomposites (PPCNs) were autoclave‐foamed in a batch process. Foaming was performed using supercritical CO 2 at 10 MPa, within the temperature range from 130.6°C to 143.4°C, i.e., below the melting temperature of either PPCNs or maleic anhydride‐modified PP (PP‐MA) matrix without clay. The foamed PP‐MA and PPCN2 (prepared at 130.6°C and containing 2 wt% clay) show closed cell structures with pentagonal and/or hexagonal faces, while foams of PPCN4 and PPCN7.5 (prepared at 143.4°C, 4 and 7.5 wt% clay) had spherical cells. Scanning electron microscopy confirmed that foamed PPCNs had high cell density of 10 7 –10 8 cells/mL, cell sizes in the range of 30–120 μm, cell wall thicknesses of 5–15 μm, and low densities of 0.05–0.3 g/mL. Interestingly, transmission electron microscopic observations of the PPCNs' cell structure showed biaxial flow ‐ induced alignment of clay particles along the cell boundary. In this paper, the correlation between foam structure and rheological properties of the PPCNs is also discussed.