Phase changing nanocomposites for low temperature thermal energy storage and release

Abstract

It is well known that through thermal energy storage (TES) systems it is possible to store (release) thermal energy by heating (cooling) a medium in order to utilize the stored energy when required. Possible applications involve power generation systems [1][2][3][4] and building constructions [5], where about one half of the energy demand is in the form of thermal energy, and the requirement may markedly vary in time [6][7][8]. TES technology have been also investigated in the textiles industry for the production of 'smart' fabrics able to maintain the right temperature of the body [9][10][11][12][13][14]. Other applications could be represented by the food storage [15,16] and the development of innovative solar plants [17][18][19]. Latent heat TES systems has recently attracted the attention of researchers, because these systems are characterized by a high energy storage density at constant temperature corresponding to the transition temperature of the phase change material (PCM) [18,20]. Generally speaking, a solid/liquid or a solid/solid phase transition could occur, and depending on their chemical nature these materials can be classified as organic, inorganic or eutectic. Organic PCM have several advantages [21,22] Abstract. The aim of this paper is to develop new elastomeric phase change materials (PCM) for the thermal energy storage/release below room temperature. In particular, poly(cyclooctene) (PCO)/paraffin blends filled with various concentrations of carbon nanotubes (CNTs), were prepared by a melt compounding process. The microstructural, thermo-mechanical and electrical properties of the resulting materials were investigated. The microstructure of these materials was characterized by the presence of paraffin domains inside the PCO, and CNTs were located only inside the paraffin domains in forms of aggregated clusters. DSC tests evidenced the existence of two distinct crystallization peaks at -10 and at 6°C, respectively associated to the paraffin and the PCO phases, indicating that both the polymeric constituents are thermally active below room temperature. Moreover, CNT addition did not substantially alter the melting/crystallization properties of the material. Noticeable improvements of the mechanical properties and of the electrical conductivity with respect to the neat PCO/paraffin blend could be obtained upon CNT addition, and also thermal conductivity/diffusivity values were considerably enhanced above the percolation threshold. Finite element modeling demonstrated the efficacy of the prepared nanocomposites for applications in the thermal range from -30 to 6°C.

Thermo‐mechanical and adhesive properties of polymeric films based on ZnAl‐hydrotalcite composites for active wound dressings

“…For instance, an increase of 40 and 24 times of E 5% can be detected for the CMC2-HTlc3 composite at RH 5 30% and 50%, respectively. The strong dependency of the material stiffness on filler aggregation was highlighted in recent articles of this group, in which a new theoretical model was proposed to model the elastic properties of particulate nanocomposites [28,29]. According to our previous findings, filler aggregation may constrain a portion of matrix, thus limiting the mobility of macromolecules and providing a stiffening effect.…”

Application of the thermal energy storage concept to novel epoxy–short carbon fiber composites

“…The first method is the so‐called “shape stabilization,” which consists of the confinement of the PCM with a polymer matrix, a nanostructured layered material, or a percolative network constituted of an inorganic nanofiller . If a metallic or a carbon‐based material is used as stabilizing agent, it is also possible to increase the thermal conductivity of the system . The second possibility is the encapsulation of the PCMs in organic or inorganic shells, which also protect the PCM from the external environment and enhance its thermal stability …”

Thermal mending in novel epoxy/cyclic olefin copolymer blends

“…Interestingly, cyclic olefin copolymers (COCs) have not been yet considered as thermoplastic healing additive in an epoxy matrix. COC is an amorphous polymer that can be synthesized through the copolymerization of norbornene and ethylene, and possesses outstanding mechanical and optical properties, elevated stiffness, high chemical resistance, good low moisture absorption, moisture barrier properties and low density [40][41][42]. Because of their peculiar properties, COCs are generally used for the production of transparent parts (i.e.…”