WO2023119263A1

WO2023119263A1 - Shape stable reprocessable hybrid organic-inorganic compositions for storing thermal energy

Info

Publication number: WO2023119263A1
Application number: PCT/IL2022/051213
Authority: WO
Inventors: Michael Gishboliner; Michael Shuster; Rotem SHEMESH; Yonatan Amit; Elizabeta SHANDALOV; Mohamad Masarwa
Original assignee: Carmel Olefins Ltd.; Bromine Compounds Ltd
Priority date: 2021-12-22
Filing date: 2022-11-14
Publication date: 2023-06-29
Also published as: WO2023119263A8

Abstract

A composition including: (a) one or more salt hydrate inorganic constituents capable of thermal energy storage (iTES); and (b) an organic matrix containing polymer. A related method is also disclosed.

Description

TITLE: SHAPE STABLE REPROCESSABLE HYBRI D ORGANIC-INORGANIC COMPOSITIONS FOR STORING THERMAL ENERGY

RELATED APPLICATIONS

This PCT application claims the benefit according to 35 U .S.C. §119(e) of US provisional patent application 63/292,532 filed on December 22, 2021 which is fully incorporated herein by reference.

FIELD OF THE INVENTION

The invention is in the field of Thermal Energy Storage (TES) materials.

BACKGROUND OF THE INVENTION

Thermal Energy Storage (TES) plays a role in sustainable energy use by allowing efficient energy saving and/or management and/or recovery and/or supply-demand matching and/or temperature control. Phase change materials (PCM) provide a convenientTES method via latent heat of phase transitions or thermochemical energy storage and release. PCMs can be organic (o-PCM) or inorganic (i-PCM). Currently the predominant TES mechanism for o-PCM is meltingcrystallization phase transitions. In contrast, i-PCM often employs salt hydrates that reversibly store and release thermal energy as a heat of dehydration-hydration reactions.

Historically, the most widely used PCM energy storage application is ice used for food preservation. More recently an increase in PCM use has occurred to provide significant energy efficiency improvements in various areas and applications.

O-PCM are attractive candidates for TES applications because they are non-corrosive and/or because they include substances with high latent heat and various temperatures of the phase transitions and/or because they are available in a shape-stable form. However, the inherent flammability of o-PCM limits their use in building and construction applications. In addition, incorporation of o-PCM in cementitious formulations may result in excessive gravitational phase separation due to the low density of o-PCM.

In contrast, i-PCM such as inorganic salt hydrates are nonflammable, have suitable hydration-dehydration temperatures, high energy of hydration-dehydration reactions along with high density which contribute to a high volumetric density of thermal energy and/or satisfactory thermal conductivity. Drawbacks of salt hydrates include corrosiveness, poor reversibility of the thermochemical reactions and low thermal cycling stability. SUMMARY OF THE INVENTION

One aspect of some embodiments of the invention relates to reducing corrosiveness of i-PCM.

Another aspect of some embodiments of the invention relates to improving hydrationdehydration reversibility of i-PCM.

Yet another aspect of some embodiments of the invention relates to enhancing thermal cycling stability and imparting shape stability and recyclability to i-PCM.

According to various exemplary embodiments of the invention, i-PCM is incorporated within a nonporous organic matrix, for example using melt processing techniques. In some embodiments, use of melt processing techniques contributes to a reduction in corrosiveness and/or to an increase in shape stability and/or to recyclability with high TES storage density and fire resistance. Since i-PCMs and organic compounds are strongly incompatible due to significantly different polarity, obtaining stable structures, comprising i-PCM phase finely and uniformly dispersed in organic matrix and restoring their morphology upon reprocessing, is challenging. However, once prepared, such structures are amenable to shaping, reshaping and rearrangement.

In some exemplary embodiments of the invention, shape stable (SS) recyclable TES materials - SS PCM having salt hydrate i-PCM incorporated within organic matrix - are capable of withstanding multiple hydration-dehydration cycles, while keeping their TES capacity, shape and dimensions unchanged. In some exemplary embodiments of the invention, these SS PCM with salt hydrate i-PCM incorporated within organic matrix are reprocessable and/or selfextinguishing and/or characterized by low corrosiveness and/or have adjustable density.

For purposes of this specification and the accompanying claims, the term "selfextinguishing" means able to cease burning once the source of the flame has been removed, as defined in McGraw-Hill Dictionary of Scientific and Technical Terms.

In some exemplary embodiments of the invention, higher concentrations of i-PCM in the composition contribute to the self-extinguishing property. For example when salt hydrate i- PCMs comprise at least 30% of the composition, the composition is self-extinguishing. It is emphasized that the self-extinguishing property remains when the composition undergoes shaping, reshaping and/or reprocessing. However, after even short exposure to open flame, the composition may irreversibly lose its shape, TES ability and other properties. In some exemplary embodiments of the invention, these SS PCM with salt hydrate i- PCM incorporated within organic matrix comprise 10%, 20%, 30%, 40%, 50%, 60%, 70% or intermediate or greater percentages of i-PCM by weight.

Still another aspect of some embodiments of the invention relates to a composition comprising salt hydrate i-PCMs and an organic matrix. In some embodiments, the organic matrix comprises at least one semicrystalline polymer. In some embodiments, the at least one semicrystalline polymer has a melting temperature below a temperature of massive loss of crystallization water of the salt hydrate i-PCM, but above intended service temperature range and above melting-crystallization temperature range of any other organic component of the composition. In some embodiments, melt viscosity of the polymer component is sufficiently low to ensure effective mixing with low viscosity salt hydrates. Alternatively or additionally, in some embodiments the organic matrix further includes at least one polymer or non-polymer surfactant (surface active agent). In some embodiments, the surfactant acts as an emulsifier. In some exemplary embodiments of the invention, the emulsifier facilitates formation of an emulsion with organic liquid being a continuous phase. In some embodiments, the surfactant/emulsifier is capable of reducing the matrix polymer melting temperature and/or of modifying the melt viscosity. Alternatively or additionally, in some embodiments emulsion is stable, capable of restoring its morphology during reprocessing via melt mixing and/or has controllable particle size of dispersed inorganic salt hydrate phase.

For purposes of this specification and the accompanying claims, the terms "surfactant", "polymer surfactant", "emulsion", "emulsifier", "partition", "partition ratio" have meanings in accord with IU PAC recommendations (Compendium of Chemical Terminology, Gold Book, Version 2.3.2, 2004).

In some exemplary embodiments of the invention, the salt hydrate i-PCM is dispersed within the organic matrix. Without being bound by theory, it is expected that particle size of the i-PCM phase within the organic matrix decreases with increasing efficiency of the surfactant (emulsifier). According to various exemplary embodiments of the invention factors relevant to performance of an emulsifier include, but are not limited to, balance between hydrophilic and hydrophobic properties of its molecules and their mobility within the composition. In some embodiments, mixtures of two and more emulsifiers can be used to achieve desired particle size of the i-PCM dispersed phase. In some exemplary embodiments of the invention, at least one of such emulsifiers is an organic PCM (o-PCM). In some embodiments, use of o-PCM as an emulsifier contributes to flexibility in tailoring structure and thermal performance of the compositions. In some embodiments, combination of multicomponent organic matrix with the i-PCM (also multicomponent in some embodiments), leads to formation of a stable multiphase system with i-PCM being finely dispersed and effectively immobilized within the composition. In some embodiments, this arrangement contributes to impedance of its ability to flow and/or leakage and/or migration and/or coalescence.

In some exemplary embodiments of the invention compositions comprise at least one amphiphilic o-PCM with melting-crystallization phase transitions at temperatures above dehydration-hydration temperatures of the i-PCM, above the highest anticipated service temperature, but below melting temperature of the matrix polymer. In some embodiments, amphiphilic o-PCM, having high crystallinity and certain affinity to inorganic phase, are capable of stabilizing and preserving internal structure of salt hydrate dispersed phase during multiple consequent dehydration-hydration cycles.

In some embodiments, the structure stabilization/preservation ability schematically can be described as follows. Solidification on cooling of melt processed compositions according to an embodiment of the invention starts from crystallization of the matrix polymer. In some embodiments, crystallization is accompanied with sharp increase of viscosity and complex modulus of the entire composition, leading to its three-dimensional structuring. In some embodiments, the structuring results in fixing position, spatial distribution and size of the dispersed i-PCM phase, contributing to a reduction in phase separation. U pon completion of the polymer crystallization, the dispersed salt hydrate phase, still in liquid state, largely loses its ability to flow, coalesce and change size. At this stage localization and size of the dispersed phase droplets is already well-defined and stable. Crystallization of the polymer is accompanied with shrinkage of the organic matrix exerting compression stresses on the dispersed phase droplets. Next starts crystallization of the structure stabilizing o-PCM. Having some hydrophilicity, amphiphilic o-PCM molecules tend to unevenly distribute throughout the polymer matrix, preferentially locating close to polar inorganic dispersed phase. Crystallizing nearby the dispersed salt hydrate droplets, o-PCM further restricts their movement, limit their size and geometry thus additionally stabilizing the forming structure and morphology. Alternatively or additionally, crystallization of the o-PCM partially relieves the compression stresses around the inorganic dispersed phase. Thermochemical hydration-dehydration reactions of i-PCM are accompanied with significant change of volume resulting from crystalline lattice transformations. Solidification of anhydrous salt hydrates via exothermic incorporation of crystallization water molecules in the forming crystalline lattice is accompanied with volume expansion. Vice versa, losing crystallization water during endothermic dehydration causes contraction of the volume. In some embodiments, multiple volume expansion-contraction cycles cause structural and thermal performance instability of salt hydrate i-PCM. In some embodiments, compression stresses acting on the dispersed salt hydrate i-PCM phase impede exothermic hydration processes accompanied with the volume expansion. Oppositely, o-PCM contracts during exothermic crystallization and expands during endothermic melting. Possibly, properly selected combination of salt hydrate i-PCM with o-PCM may improve reversibility of the i-PCM multiple structural transformations, thermal cycling stability and overall structural stability of the dispersed inorganic phase via reciprocal compensation of the corresponding volume fluctuations.

In some exemplary embodiments of the invention, fully solidified hybrid organic- inorganic composition with the i-PCM immobilized within organic matrix, remain solid upon the salt hydrate undergoing multiple solid-liquid phase transition. In some embodiments, the composition includes other additives.

Yet another further additional aspect of the invention relates to a melt processing procedure allowing facile production of the compositions described above with good thermal performance and shape stability using conventional melt processing equipment. In some embodiments, the process includes intimate melt mixing of the organic matrix components with liquefied i-PCM, using continuous or batch melt mixing devices, where the i-PCM is fed into the device in solid or liquid state. In some embodiments, i- PCM is fed in liquid state via a liquid feeding system. In some embodiments, the liquid feeding system is heated to prevent i-PCM solidifying during feeding.

It will be appreciated that the various aspects described above relate to solution of technical problems associated with shape stability of hybrid organic-inorganic compositions TES materials based on salt hydrate i-PCM.

Alternatively or additionally, it will be appreciated that the various aspects described above relate to solution of technical problems associated with flammability of hybrid organic- inorganic compositions TES materials based on salt hydrate i-PCM. Alternatively or additionally, it will be appreciated that the various aspects described above relate to solution of technical problems associated with corrosiveness of hybrid organic- inorganic compositions TES materials based on salt hydrate i-PCM.

Alternatively or additionally, it will be appreciated that the various aspects described above relate to solution of technical problems associated with density adjustment of hybrid organic-inorganic compositions TES materials based on salt hydrate i-PCM.

Alternatively or additionally, it will be appreciated that the various aspects described above relate to solution of technical problems associated with repeated processability and recyclability of hybrid organic-in organic compositions TES materia Is based on salt hydrate i-PCM.

Alternatively or additionally, it will be appreciated that the various aspects described above relate to solution of technical problems associated with using 10-70% by weight of inorganic PCM in a shape stable reprocessable hybrid organic-inorganic composition.

In some exemplary embodiments of the invention there is provided a composition including: (a) one or more salt hydrate inorganic constituents capable of thermal energy storage (iTES); and (b) an organic matrix containing polymer. In some embodiments, the salt hydrate iTES includes one or more salt hydrate inorganic Phase Change Materials (i-PCM). Alternatively or additionally, in some embodiments the Inorganic salt hydrate i-PCMs have a hydration number at least 4. Alternatively or additionally, in some embodiments the Inorganic salt hydrate i-PCMs comprise at least 10% of the composition by weight. Alternatively or additionally, in some embodiments the Inorganic salt hydrate i-PCMs comprise less than 75% of the composition by weight. Alternatively or additionally, in some embodiments the matrix includes: at least one thermoplastic semi-crystalline polymer (A) with melting temperature below a temperature of massive loss of crystallization water of the i-PCM, but above an intended service temperature range and above a melting-crystallization temperature range of any other organic component of the composition; and at least one surfactant (B). Alternatively or additionally, in some embodiments the surfactant includes one or more members of the group consisting of mono- or polyfunctional carboxylic or mono- or polyfunctional sulfonic acids, salts of the acids, alcohols of the acids, esters of the acids, amides of the acids, and nitriles of the acids and blends thereof. Alternatively or additionally, in some embodiments the surfactant includes at least one member of the group consisting of mono-functional carboxylic acids, poly-functional carboxylic acids, their salts, esters and amides. Alternatively or additionally, in some embodiments the surfactant includes at least one member of the group consisting of oligomeric alcohols, polymeric alcohols, acids, amides, esters, and ethers. Alternatively or additionally, in some embodiments the surfactant includes at least one amphiphilic organic PCM (o-PCM). Alternatively or additionally, in some embodiments content of the surfactant in the organic matrix is at least 5%. Alternatively or additionally, in some embodiments content of the surfactant in the organic matrix is less than 70% W/W relative to the matrix. Alternatively or additionally, in some embodiments the composition includes one or more additives selected from the group consisting of diluents, viscosity modifiers, polarity modifiers, fillers, antioxidants, functionalized polymers, light stabilizers, acid scavengers and colorants. Alternatively or additionally, in some embodiments the composition is self-extinguishing.

In some exemplary embodiments of the invention there is provided a method including: (a) melt mixing one or more salt hydrate inorganic thermal energy storing (iTES) constituents with a matrix containing organic polymer to produce a mixture; and (b) solidifying the mixture. In some exemplary embodiments of the invention, the salt hydrate iTES includes one or more salt hydrate inorganic Phase Change Materials (i-PCM). Alternatively or additionally, in some embodiments the matrix includes: at least one semi-crystalline polymer (A); and at least one surfactant (B). Alternatively or additionally, in some embodiments the method includes adding at least one amphiphilic organic PCM (o-PCM) during the melt mixing. Alternatively or additionally, in some embodiments the method includes shaping the mixture into the desired shape. Alternatively or additionally, in some embodiments the shaping includes at least one member of the group consisting of casting into a mold, injection molding and extrusion. Alternatively or additionally, in some embodiments the melt mixing is performed continuously using a co-rotating twin-screw extruder. Alternatively or additionally, in some embodiments the melt mixing is performed at temperature below a temperature of massive loss of crystallization water of the i-PCM. Alternatively or additionally, in some embodiments the method includes feeding the i-PCM into a pre-mixed molten organic matrix. Alternatively or additionally, in some embodiments the method includes sonicating the mixture during the melt mixing. Alternatively or additionally, in some embodiments the method includes fragmenting the solidified mixture into particles using at least one process selected from the group consisting cutting, pelletizing, crumbling and grinding.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although suitable methods and materials are described below, methods and materials similar or equivalent to those described herein can be used in the practice of the present invention. In case of conflict, the patent specification, including definitions, will control. All materials, methods, and examples are illustrative only and are not intended to be limiting.

As used herein, the terms "comprising" and "including" or grammatical variants thereof are to be taken as specifying inclusion of the stated features, integers, actions or components without precluding the addition of one or more additional features, integers, actions, components or groups thereof. This term is broader than, and includes the terms "consisting of" and "consisting essentially of" as defined by the Manual of Patent Examination Procedure of the United States Patent and Trademark Office. Thus, any recitation that an embodiment "includes" or "comprises" a feature is a specific statement that sub embodiments "consist essentially of" and/or "consist of" the recited feature.

The phrase "consisting essentially of" or grammatical variants thereof when used herein are to be taken as specifying the stated features, integers, steps or components but do not preclude the addition of one or more additional features, integers, steps, components or groups thereof but only if the additional features, integers, steps, components or groups thereof do not materially alter the basic and novel characteristics of the claimed composition, device or method.

The phrase "adapted to" as used in this specification and the accompanying claims imposes additional structural limitations on a previously recited component.

The term "method" refers to manners, means, techniques and procedures for accomplishing a given task including, but not limited to, those manners, means, techniques and procedures either known to, or readily developed from known manners, means, techniques and procedures by practitioners of architecture and/or computer science.

Percentages (%) of are W/W (weight per weight) unless otherwise indicated.

BRIEF DESCRIPTION OF DRAWINGS

In order to understand the invention and to see how it may be carried out in practice, embodiments will now be described, by way of non-limiting example only, with reference to the accompanying figures. The attached figures are:

FIG. 1 is a plot of normalized heat flow Endo UP (W/g) as a function of temperature in degrees Celsius (DSC thermogram) recorded on heating and cooling of shape stable hybrid PCM containing 50% of i-PCM ( exemplary embodiment of Example 5, see Table 1) demonstrating thermal energy storage ability of the composition with the heating thermogram (upper curve) showing endothermal (heat absorption) effect with peak temperature (the temperature of maximum heat absorption rate) at 34.5°C, the peak onset at 30.5°C and the peak end at 36.1°C; heat absorption is associated with dehydration of the i-PCM component of the composition; Enthalpy of the dehydration reaction (stored heat amount) was 60 J per gram of the composition. The cooling thermogram (lower curve) of the sample shows exothermal (heat release) effect with peak temperature at 22.3°C, the peak onset at 24.0°C and the peak end at 20.3°C. The heat release is associated with thermochemical reaction of the i-PCM hydration. Enthalpy (amount of released heat) of the hydration reaction was 57.8 J per gram of the composition (in a reasonable agreement with heat of the corresponding dehydration reaction). Both the DSC endothermal and exothermal peaks are well-shaped and reasonably narrow implying both heat absorption and release processes occur in a controlled manner. Moreover, close values of the reactions heat indicate good reversibility of the processes. Moderate (12°C) overcooling (the difference between peak temperatures at heating and cooling), indicates ability of the inventive compositions to stabilize temperature of the surrounding media close to ambient or, at least, to reduce the temperature fluctuations. Worth mentioning that the recorded thermal effects of the reactions are close to the values calculated according to the additivity rule taking into consideration actual percentage of i-PCM in the composition.

FIG. 2a is a photograph (top view) illustrating the shape stability and melt processability of the same exemplary inventive composition (from Example 5), cast into a flat circular mold.

FIG. 2b is a photograph (edge view) illustrating the shape stability and melt processability of the same exemplary inventive composition (from Example 5), cast into a flat circular mold.

FIG. 3a is a photograph depicting ignition (white arrow) of the same exemplary inventive composition (from Example 5), by an external flame.

FIG. 3b is a photograph depicting the self-extinguishing behavior (white arrow) of the sample of Fig 3a as the external flame is removed.

FIG. 3c is a photograph depicting the complete absence of flame (white arrow) in the sample of Fig 3a 1 second after the external flame is removed; note the absence of dripping.

FIG. 4 is a photograph depicting the same flammability test as in Fig. 3a to Fig. 3c for shape stable composition, containing polypropylene matrix and typical organic PCM (paraffin wax); in this case the sample continues burning (white arrow) after the external flame is removed until it is totally burned down, with heavy dripping (dashed white circle). DETAILED DESCRIPTION OF EMBODIMENTS

Embodiments of the invention relate to compositions and methods of manufacture.

Specifically, some embodiments of the invention can be used to provide shape stable reprocessable hybrid organic-inorganic compositions capable of storing and releasing thermal energy as a latent heat and/or heat of thermochemical reaction and staying in solid state, while some of their major constituents undergo multiple solid to liquid and liquid to solid phase transitions.

The principles and operation of a composition and/or method according to exemplary embodiments of the invention may be better understood with reference to the accompanying descriptions.

Before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details set forth in the following description or exemplified by the Examples. The invention is capable of other embodiments or of being practiced or carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein is for the purpose of description and should not be regarded as limiting.

Exemplary composition

In some exemplary embodiments of the invention, there is provided a composition including one or more salt hydrate inorganic constituents capable of thermal energy storage (iTES) and an organic matrix containing polymer. In some embodiments, the salt hydrate iTES includes one or more salt hydrate inorganic Phase Change Materials (i-PCM). Inorganic salt hydrate i-PCMs include, but are not limited to various hydrates of salts of alkali and/or alkali earth metals, such as lithium, sodium, potassium, magnesium, calcium, and strontium. In some embodiments, the Inorganic salt hydrate i-PCMs have a hydration number at least 4. Alternatively or additionally, in some embodiments the Inorganic salt hydrate i-PCMs comprise at least 10% of the composition by weight. Alternatively or additionally, in some embodiments the Inorganic salt hydrate i-PCMs comprise less than 75% of the composition by weight. For example, in some embodiments the Inorganic salt hydrate i-PCMs comprise 20 to 65% by weight, or 30 to 60% by weight.

Alternatively or additionally, in some embodiments the matrix includes at least one thermoplastic semi-crystalline polymer (A) with melting temperature below a temperature of massive loss of crystallization water of the i-PCM, but above an intended service temperature range and above a melting-crystallization temperature range of any other organic component of the composition and at least one surfactant (B).

In some exemplary embodiments of the invention, surfactant (B) includes one or more members of the group consisting of mono- or polyfunctional carboxylic or mono- or polyfunctional sulfonic acids, salts of said acids, alcohols of said acids, esters of said acids, amides of said acids, and nitriles of said acids and blends thereof. Alternatively or additionally, in some embodiments the surfactant comprises at least one member of the group consisting of monofunctional carboxylic acids, poly-functional carboxylic acids, their salts, esters and amides. Alternatively or additionally, in some embodiments the surfactant comprises at least one member of the group consisting of oligomeric alcohols, polymeric alcohols, acids, amides, esters, and ethers. Examples of these compounds include but are not limited to polyethylene glycol, polypropylene glycol, polyvinyl alcohol, polycaprolactone, copolymers of ethylene with acrylic acid, acrylic esters, vinyl acetate, maleic anhydride. Alternatively or additionally, in some embodiments the surfactant includes at least one amphiphilic organic PCM (o-PCM). In some embodiments, the amphiphilic organic o-PCM is characterized by melting-crystallization phase transitions at temperatures above dehydration-hydration temperatures of the i-PCM, above the highest anticipated service temperature but below melting temperature of the matrix polymer. In some exemplary embodiments of the invention, content of the surfactant in the organic matrix is at least 5% W/W relative to the matrix. According to various exemplary embodiments of the invention content of the surfactant in the organic matrix is between 5 and 70%, between 30 and 65%, or between 40 and 60% by weight. Alternatively or additionally, in some embodiments content of the surfactant in the organic matrix is less than 70% W/W relative to the matrix. Alternatively or additionally, in some embodiments the composition includes one or more additives selected from the group consisting of diluents, viscosity modifiers, polarity modifiers, fillers, antioxidants, functionalized polymers, light stabilizers, acid scavengers and colorants.

Exemplary method

In some exemplary embodiments of the invention there is provided a method including: (a) melt mixing one or more salt hydrate inorganic thermal energy storing (iTES) constituents with a matrix containing organic polymer to produce a mixture; and (b) solidifying the mixture. In some embodiments, the salt hydrate iTES includes one or more salt hydrate inorganic Phase Change Materials (i-PCM). Alternatively or additionally, in some embodiments matrix includes: at least one semi-crystalline polymer (A); and at least one surfactant (B). Alternatively or additionally, in some embodiments the method includes adding at least one amphiphilic organic PCM (o-PCM) during the melt mixing. Alternatively or additionally, in some embodiments the method includes shaping the mixture into the desired shape. In some embodiments, shaping includes at least one member of the group consisting of casting into a mold, injection molding and extrusion. Alternatively or additionally, in some embodiments the melt mixing is performed continuously using a co-rotating twin-screw extruder. Alternatively or additionally, in some embodiments the melt mixing is performed at temperature below a temperature of massive loss of crystallization water of the i-PCM.

Alternatively or additionally, in some embodiments the method includes feeding the i-PCM into a pre-mixed molten organic matrix. Alternatively or additionally, in some embodiments the method includes sonicating the mixture during the melt mixing. Alternatively or additionally, in some embodiments the method includes fragmenting said solidified mixture into particles using at least one process selected from the group consisting cutting, pelletizing, crumbling and grinding.

It is expected that during the life of this patent many o-PCMs and/or i-PCMs will be developed and the scope of the invention is intended to include all such new technologies a priori.

As used herein the term "about" refers to 10 %.

Although the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, it is intended to embrace all such alternatives, modifications and variations that fall within the spirit and broad scope of the appended claims.

Specifically, a variety of numerical indicators have been utilized. It should be understood that these numerical indicators could vary even further based upon a variety of engineering principles, materials, intended use and designs incorporated into the various embodiments of the invention. Additionally, components and/or actions ascribed to exemplary embodiments of the invention and depicted as a single unit may be divided into subunits. Conversely, components and/or actions ascribed to exemplary embodiments of the invention and depicted as sub-units/individual actions may be combined into a single unit/action with the described/depicted function.

Alternatively, or additionally, features used to describe a method can be used to characterize an apparatus and features used to describe an apparatus can be used to characterize a method.

It should be further understood that the individual features described hereinabove can be combined in all possible combinations and sub-combinations to produce additional embodiments of the invention. The examples given above are exemplary in nature and are not intended to limit the scope of the invention which is defined solely by the following claims.

Each recitation of an embodiment of the invention that includes a specific feature, part, component, module or process is an explicit statement that additional embodiments of the invention not including the recited feature, part, component, module or process exist.

Alternatively or additionally, various exemplary embodiments of the invention exclude any specific feature, part, component, module, process or element which is not specifically disclosed herein.

All publications, references, patents and patent applications mentioned in this specification are herein incorporated in their entirety by reference into the specification, to the same extent as if each individual publication, patent or patent application was specifically and individually indicated to be incorporated herein by reference. In addition, citation or identification of any reference in this application shall not be construed as an admission that such reference is available as prior art to the present invention.

The terms "include", and "have" and their conjugates as used herein mean "including but not necessarily limited to".

Additional objects, advantages, and novel features of various embodiments of the invention will become apparent to one ordinarily skilled in the art upon examination of the following examples, which are not intended to be limiting. Additionally, each of the various embodiments and aspects of the present invention as delineated hereinabove and as claimed in the claims section below finds experimental support in the following examples.

EXAMPLES

Reference is now made to the following examples, which together with the above descriptions, illustrate the invention in a non limiting fashion.

MATERIALS AND METHODS Calcium bromide hexahydrate (CaBr2*6H2O) is an i-PCM commercially available from Quality Chemicals (CAS number 71626-99-8, catalogue number 041610).

Calcium chloride dihydrate (CaCl2*2H2O) is an i-PCM commercially available from Sigma- Aldrich (CAS number 10035-04-8, catalogue number 223506, 99% purity).

High density polyethylene (HDPE) Marlex HHM TR-144 is a polymer, purchased from from Chevron-Philips.

Low density polyethylene (Ipethene 900) is a polymer, commercially available from Carmel Olefins.

Stearic acid is a surfactant, commercially available from Sigma Aldrich (CAS number 57- 11-4, catalogue number 175366, 95% purity

Polyethylene glycol PEG-3000 is a viscosity modifier (thickener), purchased from Sigma Aldrich (CAS number 25322-68-3, catalogue number 1546525).

Myristic acid is a surfactant, purchased from from Sigma Aldrich (CAS number 544-63-8, catalogue number 70082' 98% purity).

Polypropylene random copolymer (PP-R) Capilene QM50F is a polymer, commercially available from Carmel Olefins.

Lauric acid is a surfactant, commercially available from Sigma Aldrich (CAS number 143- 07-7, catalogue number W261416, 98% purity).

KLK Oleo PA/SA is a blend of palmitic and stearic acids, a surfactant, purchased from KLK OLEO.

12-Hydroxy stearic acid (HSA) is a viscosity modifier (thickener), commercially available from Sigma Aldrich (CAS number 106-14-9, catalogue number 1331008).

Procedure:

The exemplary compositions were prepared according to the following procedure:

Step 1 - Preparation of the organic matrix:

The polymer, the modifier and the surfactant were weighed and mixed together in a beaker at room temperature. The mixture was heated in a silicon oil bath to temperature just above the polymer melting using MRC OBR-1 integrated thermostatic magnetic blender. The mixture was stirred during heating using an I KA EUROSTAR 200 overhead control stirrer to form a homogenous melt.

Step 2 - preparation of the inorganic phase:

Salt hydrate was weighed, placed in a beaker, heated, and stirred using Heidolph MR Hei-standard hot plate with magnetic stirrer, until reaching fully liquified (dehydrated) state. The temperature was monitored by IKA ETS-D5 temperature controller. Upon completion of dehydration stage and reaching the target temperature, thickening agent was blended in.

Step 3 - preparation and characterization of hybrid organic-inorganic PCM composition:

Salt hydrate containing inorganic phase, prepared during step 2, was added dropwise to various polymer/modifier/surfactant molten organic matrices, prepared in step 1, under intensive mixing at constant temperature to obtain homogeneous melt. After full homogenization, the composition was poured into the proper vessel or casted into the desired mold and cooled down to room temperature to solidify.

Characterization:

Thermal characterization:

Characterization of thermal energy storage and release capability of the inventive compositions was performed by DSC heating - cooling cycles. Endothermal and exothermal effects associated with dehydration and hydration thermochemical reactions were described in terms of their corresponding enthalpies, onset, peak and end temperatures. The DSC tests were conducted using a Perkin-Elmer DSC 8000 instrument equipped with liquid nitrogen cooling device at heating/cooling rate 10°C/min.

Flammability characterization:

Flammability tests were conducted using a burner and SS-PCM specimens, clamped horizontally above a metal tray. The tests were performed inside a hood. Tip of the burner flame was brought in contact with free edge of the tested specimen for 10 sec, then the burner was removed and time to self-extinguishing of the specimen was measured. The composition was considered self-extinguishing if the burning time of the specimen after flame removal was less than 30 sec.

Shape stability:

Shape stability at room temperature of the compositions was evaluated visually after casting the molten composition into the mold and solidification the casted composition and its removal from the mold. The composition was considered shape stable if it retained its shape (that of the mold) at room temperature for at least three days in the absence of an externally applied deforming force.

Reshaping and reprocessing:

5 Reshaping of the composition was performed by melting the previously shaped composition in the mold and casting it into another mold and then letting it to solidify by cooling to room temperature. The so reshaped composition should retain the form of the second mold, while thermal energy storage/release and other properties remain substantially unchanged.

Examples 1-6.

10 In order to illustrate advantages of the inventive compositions, examples 1-6 are summarized in Table 1. These advantages include high thermal energy storage and release capacity, congruency of heat storage and release (close values of the enthalpy change on heating and cooling), good reproducibility of the thermal storage and release cycle (the enthalpy change remained substantially unchanged during multiple heating-cooling cycles), self-extinguishing

15 behavior, shape stability and reshaping/reprocessing ability. Some of the compositions (e.g., examples 4 and 5) show especially low super-cooling (the difference between peak temperatures on heating and on cooling).

20 Table 1. Examples 1-6

Control Examples 7-9.

In order to further emphasize the advantages of the inventive compositions, control examples 7-9 are summarized in Table 2.

Control example 7 represents composition, comprising 50% of i-PCM balanced by the organic matrix, which, however, unlike those of examples 1-6, does not contain any polymer. Such composition, prepared using the process similar to that of examples 1-6, exhibits phase separation that could not be prevented by reasonable change in process parameters, like temperature and mixing speed. The composition was unstable, demonstrating visible change of its structure within two minutes after stopping the mixing. When casted into the mold, this composition lost its shape immediately after removal from the mold.

Control example 8 represents a composition, comprising an i-PCM and an organic matrix, containing a polymer, wherein the content of i-PCM is as low as 5% by weight. Such composition exhibits shape stability and reprocessing ability, is stable over time and does not exhibit phase separation. However, it demonstrates extremely low thermal energy storage and release ability, and is lacking self-extinguishing ability.

Control example 9 represents a composition, comprising an i-PCM and an organic matrix, containing a polymer, wherein the content of i-PCM is as high as 85% by weight. Such composition exhibits high thermal energy storage and release ability, however, it undergoes unpreventable phase separation, and lacks uniformity, shape stability and reprocessing ability. Particularly, such composition lacks also repeatability of thermal effects in consequent heatingcooling cycles.

Summarizing, the compositions wherein the organic matrix does not contain polymer, or wherein the concentration of i-PCM is extremely low or extremely high, do not exhibit all the advantages of the inventive compositions, as shape stability, reprocessing and reshaping ability, high thermal energy storage and release capacity and self-extinguishing ability. Alternatively or additionally, their tendency towards phase separation does not allow their facile preparation using melt mixing procedures. Table 2. Control examples 7-9.

Claims

CLAIMS:

1. A composition comprising:

(a) one or more salt hydrate inorganic constituents capable of thermal energy storage (iTES); and

(b) an organic matrix containing polymer.

2. A composition according to claim 1, wherein said salt hydrate iTES comprises one or more salt hydrate inorganic Phase Change Materials (i-PCM).

3. A composition according to claim 2, wherein said Inorganic salt hydrate i-PCMs have a hydration number at least 4.

4. A composition according to claim 2 or claim 3, wherein said Inorganic salt hydrate i- PCMs comprise at least 10% of the composition by weight.

5. A composition according to one of claims 2 to 4, wherein said Inorganic salt hydrate i- PCMs comprise less than 75% of the composition by weight.

6. A composition according to one of claims 1 to 5, wherein said matrix comprises: at least one thermoplastic semi-crystalline polymer (A) with melting temperature below a temperature of massive loss of crystallization water of said i-PCM, but above an intended service temperature range and above a melting-crystallization temperature range of any other organic component of the composition; and at least one surfactant (B).

7. A composition according to one of claims 1 to 6, wherein said surfactant comprises one or more members of the group consisting of mono- or polyfunctional carboxylic or mono- or polyfunctional sulfonic acids, salts of said acids, alcohols of said acids, esters of said acids, amides of said acids, and nitriles of said acids and blends thereof.

8. A composition according to one of claims 1 to 7 , wherein said surfactant comprises at least one member of the group consisting of mono-functional carboxylic acids, poly-functional carboxylic acids, their salts, esters and amides.

9. A composition according to one of claims 1 to 8, wherein said surfactant comprises at least one member of the group consisting of oligomeric alcohols, polymeric alcohols, acids, amides, esters, and ethers.

10. A composition according to one of claims 1 to 9, wherein said surfactant comprises at least one amphiphilic organic PCM (o-PCM).

11. A composition according to one of claims 1 to 10, wherein content of the surfactant in the organic matrix is at least 5%.

12. A composition according to one of claims 1 to 11, wherein content of the surfactant in the organic matrix is less than 70% W/W relative to the matrix.

13. A composition according to one of claims 1 to 12, comprising one or more additives selected from the group consisting of diluents, viscosity modifiers, polarity modifiers, fillers, antioxidants, functionalized polymers, light stabilizers, acid scavengers and colorants.

14. A composition according to any one of claims 1 to 13, which is self extinguishing.

15. A method comprising:

(a) melt mixing one or more salt hydrate inorganic thermal energy storing (iTES) constituents with a matrix containing organic polymer to produce a mixture; and

(b) solidifying the mixture.

16. A method according to claim 15, wherein said salt hydrate iTES comprises one or more salt hydrate inorganic Phase Change Materials (i-PCM).

17. A method according to claim 15 or claim 16, wherein said matrix comprises: at least one semi-crystalline polymer (A); and at least one surfactant (B).

18. A method according to any one of claims 15 to 17, comprising adding at least one amphiphilic organic PCM (o-PCM) during said melt mixing.

19. A method according to any one of claims 15 to 18, comprising shaping the mixture into the desired shape.

20. A method according to claim 19, wherein said shaping comprises at least one member of the group consisting of casting into a mold, injection molding and extrusion.

21. A method according to anyone of claims 15 to 20, wherein said melt mixing is performed continuously using a co-rotating twin-screw extruder.

22. A method according to anyone of claims 15 to 21, wherein said melt mixing is performed at temperature below a temperature of massive loss of crystallization water of said i-PCM.

23. A method according to any one of claims 15 to 22, comprising feeding said i-PCM into a pre-mixed molten organic matrix

24. A method according to any one of claims 15 to 23, comprising sonicating said mixture during said melt mixing.

25. A method according to any one of claims 15 to 24, comprising fragmenting said solidified mixture into particles using at least one process selected from the group consisting cutting, pelletizing, crumbling and grinding.