Anisotropy in CNT composite fabricated by combining directional freezing and gamma irradiation of acrylic acid

• Process with directional freezing and gamma irradiation polymerization was designed.
• Acrylic acid was applied as a polymerizable structure guiding medium.
• Organized CNT filler in inter-crystalline domains of PAA matrix was identified.
• Differences in electrical conductivity was 2 order magnitude to crystal growth directions.
• Composites possess anisotropic storage modulus regarding crystal growth direction.

A novel fabrication process for composite consisting of organized modified carbon nanotubes (CNT) in the polyacrylic acid (PAA) matrix has been developed. The CNT were organized along crystallite domains during a directional freezing process and subsequently fixed by the gamma irradiation induced polymerization and crosslinking in solid state. Different morphology and distribution of CNT in fabricated and conventionally prepared composites were investigated by scanning and transmission electron microscopies. The interactions in the polymer matrix were elucidated by a broad dielectric spectroscopy. Importantly, the composite exhibited anisotropic electrical and mechanical properties studied by electrical conductivity measurement and dynamic mechanical analysis, respectively. Differences of two orders of magnitude in the electrical conductivity and 5 times higher storage modulus at 10− 2 Hz in the direction along and perpendicular to freezing in composite with 0.1% CNT in feed were observed.

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