Composition Analysis of an Unknown Redispersible Powder

摘要

As an important type of additive, the redispersible powder is widely applied in cement-based and gyp-based materials, so as to improve the cementing strength, impermeability, workability, hydrophobicity and so on. The chemical composition of the redispersible powders dominated its applicability, as well as the degree of improvement to the matrix materials. In this paper, the chemical composition of an unknown redispersible powder was analyzed. Firstly, Fourier transform infrared spectroscopyanalysis indicated that the polymer was polymerized with monomers of vinyl esters. Secondly, pyrolysis-gas chromatography- mass spectrometry (Py-GC/MS) analysis showed that the pyrolysis products were mainly acetic acid, methyl acetate and methyl versatates. Considering the pyrolysis mechanism of synthetic polymers and the results from FTIR spectra, the polymer in the redispersible powder was deduced to be the copolymer of vinyl acetate and vinyl ester of versatic acid (VeoVa), which was a monomer with a unique highly branched carbon-rich structure. Thermogravimetry analysis revealed that the powder contained 74.0% of polymer, 14.5% of calcium carbonate and 11.4% of other inorganic materials.