Model compound vulcanization studied by XANES

Liquid chromatography/mass spectrometry identification of intermediates and vulcanization products by using squalene as vulcanization model compound.

RATIONALE Sulfur-vulcanized rubber is a three-dimensional polymer network, insoluble in all organic solvents. For this reason, vulcanization products are difficult to study and identify by conventional analytical techniques. To simplify this task, low molecular weight olefins have been used as model compounds (MCs) in place of rubber in vulcanization experiments. METHODS In this work, the vul...

New methodology to follow the evolution of squalene by-products during model compound vulcanization studies.

In this work, a new analytical methodology is proposed to separate squalene from its by-products after vulcanization, using reverse phase liquid chromatography. Regarding previous methods described in literature, the separation between reaction products and their detection have been clearly improved. A light scattering detector has been coupled to the HPLC equipment substituting the traditional...

Catalytic reduction of NO on copper/MCM-41 studied by in situ EXAFS and XANES.

Speciation of copper in the channels of MCM-41 during reduction of NO with CO at 473-773 K was studied by in situ extended X-ray absorption fine structural (EXAFS) and X-ray absorption near edge structural (XANES) spectroscopies in the present work. The component fitted (in situ) XANES spectra of the catalyst showed that about 72% of metallic copper (Cu(0)) in MCM-41 was oxidized to higher oxid...

Local Electronic Structure of PbVO3, a New Member of PbTiO3 Family, studied by XANES/ELNES

Recently an interesting multi-ferroic system PbVO3 [Chem. Mater. 2004] was successfully prepared using a high-pressure and high-temperature technique. The crystallographic features were reported. In this note we concentrate on the theoretical XANES spectra by considering the K-edge of Vanadium. The tetragonality [c/a=1.229 at 300 K] of PbVO3 is the largest in the PbTiO3 family of compounds. Thu...

Theory & Practice Of Vulcanization