Phase Change Materials (PCM) microcapsules with different shell compositions: Preparation, characterization and thermal stability

In this study, phase change materials (Rubitherm® RT 27) microcapsules were successfully obtained by two different methods. The main difference between them remains on the shell composition, as they are composed of different coacervates (Sterilized Gelatine/Arabic Gum for the SG/AG method and Agar-Agar/Arabic Gum for the AA/AG method). Microcapsules were thermally characterized by thermo-optical microscopy and differential scanning calorimetry. Using scanning electron microscopy, their spherical morphology (sphericity factor of 0.94-0.95) and their particle size distribution were determined, obtaining an average diameter of 12 μm for the SG/AG method and lower values for the AA/AG method, where nanocapsules were also observed (average diameter of 4.3 μm for the microcapsules and 104 nm for the nanocapsules). The thermal stability determination was carried out by Thermogravimetric analyses (TG) and the results show a high decomposition temperature, although the process takes places in four steps for the two mentioned methods. Moreover, the microcapsules obtained by the AA/AG method decompose in a more gradual way, as in the TG results a double step, instead of one, is appreciable. On the whole, the prepared microencapsulated PCM are totally capable of developing their role in thermal energy storage

Melting behaviour in the n-alkanol family. Enthalpy-entropy compensation

no abstrac

Crystal structure determination of 1-pentanol from low-temperature powder diffraction data by Patterson search methods

5 pages.-- PACS: 61.66.Hq; 61.50.LtIn the course of our research on normal alkanols, the crystal structure of 1-pentanol has been solved by applying Patterson-search methods to laboratory powder X-ray diffraction data recorded on a curved position-sensitive detector (CPS120) at 183 K. The crystal structure was refined with the rigid-body Rietveld least-squares method. The cell is monoclinic, space group P21/c, Z=4, and the cell parameters are a=15.592(9) Å, b=4.349(1) Å, c=9.157(1) Å, =104.7(7)°, V=600.6(3) Å3. There is one molecule in the asymmetric unit with the O–H bond in gauche conformation with respect to the alkyl skeleton. Packing is defined by the hydrogen bonds linking the 1-pentanol molecules along zigzag chains parallel to b.Peer reviewe

The γ-form of n-eicosanol

In the crystal of the title compound, C20H42O, the mol­ecules are packed in layers parallel to the (100) plane. The alkyl chains are parallel to the [30inline image] direction and these molecular chains are hydrogen‐bonded into chains parallel to the c axis. All C¿C bonds of the alkyl chain show an antiperiplanar (trans) conformation, with a slight deviation from the ideal value (180°) in the C¿C bonds close to the hydrogen bonds. The length of the alkyl chain is 27.92 (2) Å and the tilt angle is 59.7 (2)°