Flexural, Thermomechanical and Low-Velocity Impact Studies of CFRP Composites with Nanoclay and Multiwalled Carbon Nanotubes

Abstract

Fiber reinforced polymer (FRP) composites show significantly superior performance over many traditional metallic materials because of their superior strength to weight ratio and higher stiffness. Significant development in the use of nanoparticles for modification of epoxy matrix has led to improved mechanical properties of the FRP composites. Carbon fiber reinforced epoxy composites were modified with 2 wt. % Montmorillonite nanoclay and 0.3 wt. % multi-walled carbon nanotubes (MWCNTs). A hybrid system wherein 2 wt. % of nanoclay and 0.1 wt. % of MWCNTs was also developed. Dynamic Mechanical Analysis (DMA), Thermo- Mechanical Analysis (TMA), and 3-point bending tests were conducted for characterizing samples. Low Velocity Impact (LVI) tests were conducted at different energy levels. Impact damage was characterized through thermography. Results obtained from these experiments were compared with unmodified carbon/epoxy composites. Reinforcement with nanoparticles was found to significantly improve the mechanical and thermo-mechanical properties of composites. Addition of nanoparticles in composites caused significant improvement in mechanical and viscoelastic properties compared to those of control ones. Best results were obtained for addition of 0.1% MWCNT/2% MMT hybrid nanoparticles in epoxy. Composites modified with hybrid nanoparticles exhibited about 15% increase in storage modulus as well as 10° C increase in glass transition temperature. Flexural modulus for hybrid nanoparticle modified composites depicted about 30% improvement compared to control ones. Viscoelastic properties like storage and loss modulus increased by over 40% and coefficient of thermal expansion decreased both in the inplane and through the thickness directions. Carbon fiber reinforced epoxy composites modified with MMT/MWCNTs hybrid nanoparticles displayed better impact resistance than control samples. Improved impact resistance of modified composites will help to address some of the major issues with using composite materials in naval vessels and offshore structures without sacrificing the advantages of composite structures.