Hygrothermal effects on interfacial stress transfer characteristics of carbon nanotubes-reinforced composites system

On the basis of the existence of strong bonding between carbon nanotubes (CNTs) and polymer matrix, and considering the axial and radial thermal expansion coefficients of CNTs as nonlinear functions of temperature changes, this article presents an analytical method to investigate hygrothermal effects on the interfacial stress transfer characteristics of single-multiwalled CNTs-reinforced composites system under hygrothermal loading by means of thermoelastic theory and conventional fiber pullout models. According to the known literature, the thermal expansion coefficient of CNTs is considered as transverse isotropy, and is a nonlinear function of temperature changes. The thermal expansion coefficient of polymer matrix is isotropy, and is a linear function of temperature changes. Numerical examples show that the interfacial shear stress transfer behavior can be described and affected by several parameters such as the temperature changes in CNTs-polymer composite, the moisture concentration changes in polymer matrix, the layer numbers, volume fractions, and chiral vectors of CNTs. From the results obtained it is found that mismatch of the thermal and moisture expansion coefficients between the CNTs and polymer matrix may be more important in governing interfacial stress transfer characteristics of CNTs-reinforced composites system.