22333-94-4Relevant articles and documents
Preparation of CaCO3 and CaO nanoparticles via solid-state conversion of calcium oleate precursor
Atchudan, Raji,Lone, Nasreena,Joo, Jin
, p. 1958 - 1964 (2018)
Calcium carbonate (CaCO3) and monodisperse calcium oxide nanoparticles (CaO NPs) are prepared by the calcination of solid-state calcium oleate precursor in air condition. The effect of calcination temperature on the synthesis of CaCO3 and CaO NPs is examined. The polymorphism is confirmed by X-ray diffraction spectroscopy (XRD), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA). The sample morphologies including their size and size distribution are investigated by field emission scanning electron microscopy (FESEM). Calcination of calcium oleate between 400 and 550 °C results in CaCO3 NPs with mean sizes from 82 to 98 nm, whereas monodisperse spherical CaO NPs are obtained at 650 °C and an average size is estimated to be 40 nm. Beyond 650 °C, the size of CaO NPs increases with broad size distribution. The results of this study provide a novel approach to monodisperse CaCO3 and CaO NPs that can be applied in a variety of fundamental and industrial fields.
Characterisation of metal carboxylates by Raman and infrared spectroscopy in works of art
Otero, Vanessa,Sanches, Diogo,Montagner, Cristina,Vilarigues, Mrcia,Carlyle, Leslie,Lopes, Joo A.,Melo, Maria J.
, p. 1197 - 1206 (2015/02/19)
This work introduces the complementary use of μ-Raman and μ-Fourier transform infrared (IR) spectroscopy for the detection of specific carbon chains and cations for the identification of metal carboxylates within oil paint microsamples. Metal carboxylates (metal soaps) form naturally when free fatty acids react with metal cations and may also be found as additives or degradation products. Twenty-two metal carboxylates were synthesised, and their spectra assembled in a reference database. Metal salts of cations commonly present in oil paintings were used, including lead, zinc, calcium, cadmium, copper and manganese. The fatty acids selected were the saturated acids palmitic (C1 6:0) and stearic (C18:0) and the polyunsaturated oleic acid (C1 8:1). Azelaic acid (C9 diacid), a product resulting from autoxidation of polyunsaturated acids, was also included. Metal carboxylates were characterised by Raman and IR spectroscopy, and their structures were confirmed by X-ray diffraction. Raman and IR spectroscopy proved to be complementary techniques for a full identification of the metal carboxylates in complex aged paint. Raman enables the differentiation of the carbon chain length in the C-C stretching region (1120-1040 cm-1), and IR distinguishes the metal cation in the COO- stretching absorption region (1650-1380cm-1). Principal component analysis was applied to the spectra in order to facilitate a fast and accurate method to discriminate between the different metal carboxylates and to aide in their identification. Finally, spectra from case studies were successfully projected in the principal component analysis models built, enabling a higher confidence level for the identification of copper palmitate and copper azelate in two 19th-century Portuguese oil paintings.
Liquid overbased mixed metal stabilizer composition of calcium, barium and zinc for stabilizing halogen-containing polymers
-
, (2008/06/13)
Liquid overbased calcium/barium/zinc ternary systems are provided for stabilizing halogen-containing polymers. These overbased ternary stabilizer systems are shelf stable liquids and provide polyvinyl chloride compositions with improvements in thermal stability, early color, clarity and plate-out resistance.
