Effect of frozen conditions on dispersion morphologies of carbon nanotubes and electrical conductivity of carbon fiber/epoxy composites

• A freeze-drying method was used to optimize CNT distribution in composite.
• Different frozen conditions were used to affect CNT dispersion morphologies.
• Electrical conductivity of composite could be controlled by frozen conditions.

Carbon nanotubes (CNTs) were introduced into three-dimensional carbon fiber fabric/epoxy composites with assistance of freeze-drying technique. Different frozen conditions, including slow-freezing, quick-freezing and unidirectional freezing, were utilized to affect CNT dispersion morphologies in fiber/CNTs preforms and composites. Electrical conductivity of composites was measured. The results demonstrated that: (1) frozen conditions had an obvious effect on dispersion morphologies of CNTs in preforms; (2) quick-freezing and unidirectional freezing were beneficial for CNTs to disperse in preforms and improve electrical conductivity of composites, compared to slow-freezing; (3) application of unidirectional freezing made the arrangement of CNTs possess certain orientation and, as consequence, electrical conductivity along freezing direction of composites was enhanced significantly.