This work reports the fabricating of open-cell Al foams which were manufactured through infiltration processes employing a device with controlled atmosphere for the fusion and infiltration processes of the metal, which is separate from the heating furnace. The device allows controlling its internal atmosphere with an inert gas to protect the metal of the fast oxidation, avoiding the employment of a controlled atmosphere furnace (a furnace of this kind incorporate the heating and the control atmosphere systems itself). The metal used for the present study was Al in ingot form with 99.8 % purity. Equiaxial NaCl granules in three ranges of particle sizes were chosen as space holder particles (SHP). The range I from 4.7 to 4.0 mm, the range II from 4.0 to 3.3 mm, and the range III from 3.3 to 2.0 mm. The obtained foams showed a highly porous structure with interconnected cells in all cases. The maximum porosity and minimum density values resulted to be 73.7 % and 0.71 g/cm 3 , respectively. This work demonstrates that it is possible to use NaCl with different particle sizes in the manufacturing of Al foams with high porosity, low density and roughly 100 % interconnected cells employing a device with controlled atmosphere and an electrical furnace, both separated from one another. The results are interpreted in terms of NaCl particle sizes and its content in the samples.
In order to demonstrate that the cross-linking of diacetylene-containing polymers depends on the morphology of the polymers, the cross-linking of amorphous aliphatic diacetylene-containing polymers is investigated. It was found that amorphous aliphatic diacetylene-containing polymers underwent cross-linking at room temperature in the solid state without irradiation, incorporating oxygen into the polymers. FT-IR spectra and elemental analysis gave evidence of formation of carbonyl and hydrogen peroxide groups during cross-linking. The cross-linking depended on the types of polymer main chains and also how the polymer molecules are accommodated in the solid. For example, slowly cast thick films underwent cross-linking rapidly, while the cross-linking of fibrous polymers precipitated from the solution was slow or negligible, indicating that the dense packing is an important factor for cross-linking. The mechanism of such crosslinking is discussed.
Excellent quadratic non-linear optical (ONL-2) properties of the poly(2,5-bis(but-2-ynyloxy) benzoate, containing a polar diacetylene as a chromophore, were found. According with the Maker fringes method, oriented polymer films showing an order parameter of ∼0.23 can display outstanding and stable Second Harmonic Generation (SHG) effects under off-resonant conditions (SHG-532 nm). Also, the macroscopic non-linear optical (NLO)-coefficients were evaluated under the rod-like molecular approximation, obtaining: χzzz(2) and χzxx(2) in the order of 280 ± 10 and 100 ± 10 pm V−1, respectively. The mechanical and chemical properties, in addition to the large ONL-2 coefficients exhibited by this polymer, make it a promising organic material in the development of optoelectronic/photonic devices.
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