EFFECT OF CHEMICAL MODIFICATION ON STRENGTH OF ADHESIVELY BONDED SINGLE LAP JOINTS

Abstract

In engineering materials; composites and polymer are becoming more and more prominent due to their high strength and stiffness to weight ratios. Composites and polymer are being used in the structural and aerospace applications. In fabrication of complex parts joining of composites is very important. Joint is the point of discontinuity which bears the entire load applied to the structure; it means reliability of the mechanical structure entirely depends upon the strength of the joint. Researchers have been working in the field of process development to increase the joint strength. In the Present study, Epoxy/Glass Fiber composite and PMMA were used. The GFRP and PMMA Joints were prepared by using HUNTSMAN adhesive and tested for the tensile shear load on the UTM and these experimental results were validated by Finite Element Analysis (FEA). Further, Chemical techniques have been investigated to increase the joint strength. Gas phase nitration (N0x) and Amination have been employed to the joint. Functional groups attached to the surface of glass fiber reinforced polymer (GFRP) during modification techniques have been verified by the Fourier Transform Infrared Spectroscopy (FTIR). It has been found that the strength of the single lap GFRP joints was increased by 35% (approx.) under the tensile shear loading (when treated with NOR) as compared to the parent joint strength (without any chemical modification) and further increase in strength by 12% (approx.) in case of Amination treatment as compared to the joint strength of unmodified samples. In case of PMMA, no effect of chemical modification was observed on the joint strength. It may be because of absence of active sites or porosity.