The silylation of borosilicate with APTS ((γ-aminopropyl)triethoxysilane) is studied as a tool to improve zeolite incorporation in PI (polyimide) films. Among other experimental parameters, a quantification of the zeolite outer surface silanols is performed in order to determine the most appropriate silylation conditions. Xylene sorptions, NMR (nuclear magnetic resonance) spectroscopy, and measurements of the specific surface of the zeolites were performed to characterize the silylation. Finally, the silylated zeolite was incorporated in PI films on which tensile strength, density, and xylene sorption were measured.

No abstract

Both P and A1 MAS NMR spectra of samples of excessively fertilized sandy soil provided information about the P and A1 speciation. Peak deconvolution was used to interpret reliably and quantitatively the 31P NMR spectra recorded. Most of the P was found to be associated with Al. Part of the P exhibited a chemical shift that could be attributed to octocalcium phosphate, amorphous calcium phosphate or apatite. Apatite has, however, never been reported to occur in sandy soils of temperate climates. A dithionite extraction used to remove interfering Fe from the samples also removed most of the octahedral ALP phase. After oxalate extraction more than 99% of the original P signal disappeared. About 7.5 to 1 1 % of the total oxalate extractable P of the excessively fertilized soil was present as a Ca-P phase, even though these soils are slightly acid to acid. The estimated size of the Ca-P phase roughly corresponds to the size of the labile P pool of these soils, as assessed in long-term batch desorption experiments. It still remains unclear whether the labile P pool should be attributed solely to such a Ca-P phase.

No abstract

No abstract