Adhesion shear-enhanced

If the interfacial shear strength is weak, this results in early failure of the composite. Conversely, if the treatment is too strong, then the composite becomes brittle. Increasing the fiber matrix adhesion does enhance the composite compressive strength. 

One of the other benefits of incorporating polar monomers in the PSA is the enhancement in cohesive strength. This can be observed in the form of higher shear holding in a static shear test and/or better creep resistance of the adhesive when subject to a constant load. 

St. Clair et. al. investigated a series of maleimide and nadimide terminated polyimides and developed LARC-13 [8,9]. Changing the terminal group from maleimide to nadimide, the value of the lap shear strength of a titanium lap shear joint increased from 7 to 19 MPa [9]. They also added an elastomeric component to the adhesive formulation. The introduction of 15 wt% of a rubbery component, ATBN (amine terminated butadiene nitrile polymer) and ADMS (aniline terminated polydimethyl siloxane) enhanced the adhesive properties as follows 19 MPa to 25 MPa (ATBN) titanium T-peel strength 0.2 kN/m to 1.4... 

Nomura S, Tandon NN, Nakamura T, Cone J, Fukuhara S, Kambayashi J. High-shear-stress-induced activation of platelets and microparticles enhances expression of cell adhesion molecules in THP-1 and endothelial cells. Atherosclerosis 2001 158 277-287. 

Adherend stresses in weldbonded joints are lower and more uniform than those for comparable spot welded joints. This provides increased in-plane tensile shear and/or compressive buckling load-carrying ability for a given joint design. The presence of the spot weld provides enhanced out-of-plane load-carrying capability compared to adhesive bonding only. 

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