Influence of Nanoclay on the Morphology, Adhesive and Mechanical Properties of Polysulfide Modified Epoxy Resin

Addition of nanoclay particles to a typical tertiary amine cured polysulfide modified epoxy adhesive leads to large increase in the single-lap shear strength of aluminum-aluminum joint. The nanoclay particles are very well dispersed (near fully exfoliated) in the polymer matrix even at 8 wt.% of nanoclay concentration. X-ray diffraction (XRD) and transmission electron microscopy (TEM) studies provide evidences for the excellent dispersion of the nanoclay platelets in the polymer matrix. The addition of nanoclay particle results in a significant increase in the elongation at break values along with the marginal increase in the tensile strength. The nanoclay provides good ductility to the epoxy-polysulfide adhesive by forming very flexible interface, which leads to less brittle composite having good strength. The increase in work to break (W _b ) values by the addition of nanoclay represents the potential for dissipating a greater amount of energy during the bond rupture process of the lap shear test, and hence the adhesive strength increases. In addition, the increase in joint strength by the addition of nanoclay can also be attributed to the good interaction between the epoxy-polysulfide adhesive and the aluminum substrate in the presence of nanoclay.