Decreased out of plane shape of unsymmetrical laminates using carbon nanotubes

In this paper, a method was proposed to decrease the out of plane deformation of unsymmetrical laminated composites by addition of carbon nanotubes (CNTs). Due to the negative thermal expansion and high modulus of CNTs, addition of CNTs result in a great reduction in the transverse coefficient of thermal expansion (CTE) of a lamina as well as, ultimately, on the out of plane deformation of unsymmetrical laminates. The results from the thermo-mechanical analysis (TMA) confirm that considerable reductions in the CTE of a lamina can be achieved by a suitable addition of CNTs through the polymeric matrix. By addition of 1 wt.% CNTs, the difference between the longitudinal and transverse CTE of a carbon/epoxy lamina decreased up to %21. In the next step, three phase CNT/Carbon fiber/Epoxy [902/02]T unsymmetrical laminate were fabricated using the hand-lay-up method in different CNTs weight loadings. The specimens then was allowed to cool to room temperature naturally and after that the curvature of laminated was measured accurately. A considerable decrease was observed in out of plane deformation of laminates by increasing in CNT contents. These findings confirm that CNTs possess excellent potential to be used as a thermal expansion compensator for the modification of the out of plane deformation of the unsymmetrical fiber/epoxy laminated composites.