Self-sensing and interfacial evaluation of single-carbon fiber/carbon nanotube (CNT)-phenol gradient nanocomposites using electro-micromechanical test and wettability analysis

Abstract

Self-sensing and interfacial evaluation were investigated for single-carbon fiber/phenol and carbon nanotube (CNT)-phenol nanocomposites by electro-micromechanical technique combined with wettability test. Compressive strengths of neat phenol and CNT-phenol nanocomposites were compared using the Broutman compressive test as well as the tensile test. Comparative dispersion degree of nanocomposites was obtained indirectly by measuring electrical resistance. Buckling and kicking fiber breaks were observed based on transverse tensile stress, which were related to compressive interfacial shear strength (IFSS). The contact electrical resistance of CNT-phenol gradient nanocomposites was obtained by using two and four-point methods. Static and dynamic contact angles by Wilhelmy plate technique of CNT-phenol nanocomposites in various solvents were measured to obtain work of adhesion, Wa between carbon fiber and phenol matrix. The IFSS by microdroplet test was correlated with thermodynamic work of adhesion. Since heterogeneous domains are formed at CNT-phenol surface, the advancing contact angle exhibited the hydrophobicity as more than 90°. CNT-phenol nanocomposite also exhibited a higher apparent modulus than neat phenol resin due to better stress transferring effect. The IFSS between single-carbon fiber and CNT-phenol nanocomposite increased due to the added CNT.