The present paper considers the state of investigations and developments in form-stable phase change materials for thermal energy storage. Paraffins, fatty acids and their blends, polyethylene glycol are widely used as latent heat storage component in developing form-stable materials while high-density polyethylene (HDPE), styrene–butadiene–styrene (SBS) triblock copolymer, Eudragit S, Eudragit E, poly (vynil chloride) (PVC), poly (vynil alcohol) (PVA) and polyurethane block copolymer serve as structure supporting component. A set of organic and metallo-organic materials with high transition heat in solid–solid state is considered as perspective for-stable materials to store thermal energy. Another perspective class of form-stable materials are the materials on the basis of such porous materials as expanded perlite and vermiculite impregnated with phase change heat storage materials. The technology of producing new form-stable ultrafine heat storage fibers is developed. It opens availability to produce the clothers with improved heat storage ability for extremely cold regions. The perspective fields of application of form-stable materials are discussed. The further directions of investigations and developments are considered.

Form-stable phase change materials for thermal energy storage

Experimental and literature data concerning the solubility of individual light fullerenes (C60 and C70) in binary (individual fullerene + solvent), ternary (C60 + C70 fullerenes + solvent; C60 or C70 fullerenes + solvent 1 + solvent 2), and multicomponent (fullerenes + natural fats and oils) systems as well as the data on solubility of industrial fullerene mixtures and fullerene derivatives in various organic solvents are presented and discussed.

Solubility of Light Fullerenes in Organic Solvents

Principles for the interpretation of modulated temperature DSC measurements. Part 1. Glass transition

Polymorphism and solvatomorphism 2010.

The structure, IR harmonic frequencies and intensities of normal vibrations of 20 molecular crystals with the X–Cl···Cl–X contacts of different types, where X = C, Cl, and F and the Cl···Cl distance varying from ∼3.0 to ∼4.0 A, are computed using the solid-state DFT method. The obtained crystalline wave functions have been further used to define and describe quantitatively the Cl···Cl interactions via the electron-density features at the Cl···Cl bond critical points. We found that the electron-density at the bond critical point is almost independent of the particular type of the contact or hybridization of the ipso carbon atom. The energy of Cl···Cl interactions, Eint, is evaluated from the linking Eint and local electronic kinetic energy density at the Cl···Cl bond critical points. Eint varies from 2 to 12 kJ/mol. The applicability of the geometrical criterion for the detection of the Cl···Cl interactions in crystals with two or more intermolecular Cl···Cl contacts for the unique chlorine atom is not str...

Cl···Cl Interactions in Molecular Crystals: Insights from the Theoretical Charge Density Analysis

The anisotropy of the intermolecular interactions in the low-temperature ordered phases of three chemically and structurally related compounds [neopentylglycol, (CH3)2C(CH2OH)2, pivalic acid, (CH3)3C(COOH), and neopentylalcohol, (CH3)3C(CH2OH)], all of which display an orientationally disordered high-temperature phase, has been shown by means of the isobaric thermal-expansion tensor. The variation of the directions of the principal components of the thermal-expansion tensor as a function of temperature, as well as the variation of its principal coefficients, is evidence of the large differences in the intermolecular interactions for each compound; or, more precisely, between the strong intermolecular hydrogen bonds and the weak van der Waals interactions. In addition, the differences in the hydrogen-bonding schemes expected a priori from the molecular structures of the studied compounds have been enhanced. Finally, the volume expansivity as well as the packing coefficient have been analysed in the orientationally disordered high-temperature phase of each of the three compounds.Part of this work was presented at the EPDIC 1997 meeting (5th European Powder Diffraction Conference).

Anisotropy of Intermolecular Interactions from the Study of the Thermal-Expansion Tensor

The polymorphism of dibromodichloromehtane (CBr2Cl2) has been studied by means of a wide set of experimental techniques as a function of temperature and pressure. From the p–V–T diagram and the derived p–T diagram the volume variations at the transition points have been calculated and compared with those obtained by means of X-ray and neutron powder diffraction. By combining the experimental techniques, it has been demonstrated the existence of a high-pressure orientationally disordered rhombohedral phase (aR ≈ 14.6 ± 0.3 A and α ≈ 89.2 ± 0.2°). The existence of a glass transition within the monoclinic (C2/c, Z = 32) low-temperature ordered phase associated with the freezing of exchange positions between Cl and Br atoms is analyzed considering the asymmetry of the intermolecular interactions by means of the study of the thermal expansion tensor. The change of the derivative of the aspherism index, previously reported as a possible “fingerprint” for this kind of glass transitions, is found.

Polymorphism of CBr2Cl2

The polymorphism of 2-bromo-2-methyl-propane ((CH3)3CBr) has been investigated by both thermal and X-ray powder diffraction experiments. The long time unknown structure of the low-temperature phase...

/pdf/structure-of-phase-iii-and-polymorphism-of-ch3-3cbr-iwrjea3p19.pdf

Structure of Phase III and Polymorphism of (CH3)3CBr

The phase diagram of the plastic crystals Neopentylglycol (HPG) and Pentaglycerin (PG) has been established from 288 Κ until the liquid state. The NPG/PG system exhibits a demixing region in the solid state as a consequence of the difference between the ordered low-temperature forms of the pure compounds; the solid solution boundaries have been determined (0.07 and 0.53 molar fraction of PG) at 288 K. The equilibrium domains between the two solid phases and the plastic phase show an eutectoid invariant, with eutectoid composition of 0.29 ± 0.02 molar fraction of PG and eutectoid temperature of 298.1 ± 1.1 K. In the plastic phase, total miscibility is observed and, from a crystallographic point of view, an ideal behaviour can be assumed for the alloys. The plastic-liquid equilibrium shows a Gibbs minimum corresponding to a concentration of 0.21 ±0.02 molar fraction of PG and a temperature of 379.6 ± 2.0 K.

Binary system neopentylglycol/pentaglycerin

The polymorphism of hexachloroethane, Cl3C–CCl3, has been reinvestigated by means of X-ray and neutron scattering. The long time unknown structure of the intermediate phase II of Cl3C–CCl3 has been determined as monoclinic C2/m, with lattice parameters a = 17.9835(21) A, b = 10.3642(11) A, c = 6.3014(8) A, and β = 94.410(5)° at 323 K, Z = 6. The polymorphism of 1,2-dichloro-1,1,2,2-tetrafluoro-ethane, ClF2C–CF2Cl, has also been investigated, and the structure of the intermediate phase II has been found to be orthorhombic (Cmca, Z = 4) with lattice parameters a = 6.305(4) A, b = 10.177(12) A, c = 8.714 (7) A. The high-temperature phase I of ClF2C–CF2Cl has been found to be isomorphous with the orientationally disordered phase I of Cl3C–CCl3 (body centered cubic, Im3m), a consequence of the pseudospherical molecular shape of halogeno-ethane C2X6–nYn (X = Cl, Y = F) molecular crystals. The similarities of the intricate disorder of the intermediate phases II of both Cl3C–CCl3 and ClF2C–CF2Cl compounds are an...

https://hal.archives-ouvertes.fr/hal-00790597/document

J. L. Tamarit

Papers

Anisotropy of Intermolecular Interactions from the Study of the Thermal-Expansion Tensor

Polymorphism of CBr2Cl2

Structure of Phase III and Polymorphism of (CH3)3CBr

Binary system neopentylglycol/pentaglycerin

Polymorphism in Halogen–Ethane Derivatives: CCl3–CF2Cl and CF3–CF2Cl