A rhodium(III)-catalyzed redox-neutral ring-opening of
7-azabenzonorbornadienes
with aromatic ketoximes giving 2-arylated hydronaphthylamines in a
highly diastereoselective manner is described. Later, the 2-arylated
hydronaphthylamines were converted into highly sensitive 13,14-dehydro
benzophenanthridine derivatives by HCl hydrolysis. Further, 13,14-dehydro
benzophenanthridines were aromatized into biologically important benzophenanthridine
derivatives in the presence of DDQ. A possible reaction mechanism
was proposed and supported by deuterium labeling studies and isolation
of a rhodacycle intermediate.
The present work aims to demonstrate the effect of multiwalled carbon nanotube (MWCNT) on mechanical behavior and damage of woven carbon fiber/epoxy composites through experimental characterizations and multi-scale modeling. Tensile tests were conducted for MWCNT/epoxy nanocomposites, and carbon nanotube (CNT) reinforced laminated open hole composites with different MWCNT weight ratios. The tensile modulus in CNT/epoxy nanocomposite was enhanced by 15.0%, 37.86%, and 22.86% for MWCNT reinforcement of 0.5%, 1.0%, and 1.5% wt, respectively. The corresponding improvement of tensile modulus for woven composites was 3.45%, 10.25%, and 1.53%; whereas tensile strength was increased by 19.76%, 25.78%, and 6.70%. The enhancement of tensile modulus and strength was less for 1.5% wt MWCNT laminates due to the formation of MWCNT agglomeration. The effective elastic isotropic/orthotropic properties for nanocomposite/woven composite were estimated through Mori-Tanaka approach and numerical homogenization. The finite element simulations were performed with Hashin's damage model and extended finite element method-based crack growth study. The delaminations between layers have been demonstrated through cohesive zone modeling. Damage propagation, interface delamination, and fiber/ matrix failure were demonstrated by numerical simulations in line with scanning electron microscope observations.
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