Insights into the nucleophilic substitution of pyridine at an unsaturated carbon center

The nucleophilic substitution of carbonyl, imidoyl, and vinyl carbon centers with pyridine or halides is investigated in this paper.

Investigation of time-dependent behavior of sandwich panel with poly vinyl carbon foam and fiber glass/epoxy faces

The main purpose of this study is to investigate the time-dependent behavior of a sandwich panel numerically and experimentally. The core of the panel is made of poly vinyl carbon Airex 70.75, and shells are made by vacuum injection method from 600 g glass fiber per square meter. To determine the time-dependent compressive and shear modulus of the core, dynamic tests are performed at different temperatures. Using appropriate equations, time-dependent Bulk modulus and Poison's ratio are calculated. Performing three-point-bend tests on sandwich panels, time-dependent behavior of this material is investigated. Finally, these three-point-bend tests are simulated using finite element method and calculated values of viscoelastic parameters. Accordingly, numerical simulation results are compared with experimental data. Regarding the well matching of the quasi-static model, modeling of the relaxation behavior of the beam sample is investigated.