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Electrical conductivity and fiber orientation of poly(methyl methacrylate)/carbon fiber composite sheets with various thickness
Author(s) -
Luo Xiaoling,
Qu Muchao,
Schubert Dirk W.
Publication year - 2021
Publication title -
polymer composites
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.577
H-Index - 82
eISSN - 1548-0569
pISSN - 0272-8397
DOI - 10.1002/pc.25846
Subject(s) - materials science , composite material , anisotropy , composite number , exponent , conductivity , fiber , percolation (cognitive psychology) , orientation (vector space) , poly(methyl methacrylate) , electrical resistivity and conductivity , methyl methacrylate , polymer , optics , geometry , physics , linguistics , philosophy , mathematics , monomer , quantum mechanics , neuroscience , biology
Poly(methyl methacrylate) (PMMA) composites containing carbon fibers (CFs) with the controlled aspect ratio (AR) at various concentrations were produced and hot pressed into rectangular sheets with a variety of thickness. The orientation of CFs on the surface and inside the specimen was obtained, and the conductivity σ in three different directions (X‐length, Y‐width, Z‐thickness) were investigated. A preferential orientation of CFs in XY plane was found inside the samples, resulting in higher σ X and σ Y . The orientation of CFs in Z direction increases with the sample thickness increasing, leading to an increasing σ Z . Thus the anisotropic conductivity between σ X (or σ Y ) and σ Z reduces from three orders of magnitude to one order of magnitude. The percolation thresholds (Φ c ) in three directions of the samples were revealed by fitting with McLachlan GEM equation, which lead to Φ c,X ≈ Φ c,Y ≈ Φ c,Z , independent of the thickness and the measuring direction. The values of exponent t in GEM equation were found to be t X > t Y > t Z , while t Z increases with the sample thickness. For the first time, the relationship between the exponent t and the sample thickness was revealed and discussed.