KR102651041B1 - Phase change material microcapsule, method for manufacturing the same, and thermal energy storage concrete composite using the same - Google Patents

Abstract

The present invention uses a phase change material (PCM) as a core material, and a capsule wall made of a biodegradable polymer formed by the reaction of a fibrous natural polymer, an aliphatic crosslinker, and an aqueous surfactant solution surrounds the phase change material. The present invention relates to change material microcapsules, a method of manufacturing the same, and an energy storage concrete composite containing the same. In the present invention, phase change material microcapsules that are harmless to the human body are manufactured, even if the capsules are broken due to friction during the concrete mixing process and some leakage occurs. It is environmentally friendly as it decomposes in nature after use, does not pollute the environment, and does not leave any harmful substances on the human body, so it does not affect the skin, etc., and the concrete composite containing it emits or absorbs heat energy according to temperature changes, thereby using the energy of the building. It can contribute to carbon neutrality by reducing carbon dioxide emissions due to reduced fuel use, and by increasing thermal conductivity by using a mixture of carbon nanotubes, the highly efficient heat storage performance of phase change materials removes black ice from concrete pavements and protects buildings. It can be used as a material for buildings that require increased heating efficiency.

Description

Phase change material microcapsule, method for manufacturing the same, and thermal energy storage concrete composite using the same {Phase change material microcapsule, method for manufacturing the same, and thermal energy storage concrete composite using the same}

The present invention relates to phase change material microcapsules, a method of manufacturing the same, and a thermal energy storage concrete composite using the same. Specifically, the present invention relates to an environmentally friendly and harmless phase to the human body made by using a phase change material as a core material and encapsulating it with a biodegradable polymer material. This relates to a concrete composite that can store energy and has improved strength by manufacturing change material microcapsules and mixing them with concrete components and carbon nanotubes.

Today, thermal energy storage systems are recognized as very useful in reducing dependence on fossil fuels and environmental impacts such as energy consumption or carbon dioxide production, so thermal energy storage systems using phase change materials (PCMs) are used in buildings. Methods for achieving reductions in energy consumption and carbon dioxide production are being increasingly studied.

PCM is a material that stores a large amount of thermal energy in the phase change stage. It absorbs heat when the material changes phase from solid to liquid and absorbs heat at a constant temperature until it completely changes into liquid. Conversely, it absorbs heat when the material changes phase from solid to solid. released when

Through this, PCM began to be used in building materials such as gypsum board, plaster, and finishing materials for thermal energy storage applications. When applied to objects with greater density, the heat storage capacity is larger, and when applied to concrete, it has higher efficiency. Therefore, technology development to apply PCM to concrete is actively underway. However, when applying PCM to concrete, there is a high risk of PCM leaking. If leakage occurs, the physical properties of the concrete may change, corrosion may occur in the reinforcing bars in reinforced concrete buildings, or environmental problems such as soil or water pollution may occur. Measures to prevent leakage are necessary.

Accordingly, PCM microcapsule technology was developed to improve thermal performance by encapsulating PCM to prevent leakage and increase heat transfer area.

Therefore, as regulations and interest in the environment and environmentally friendly phase change material microcapsules with improved physical and chemical properties, economic efficiency, and usability increase, there is an increasing demand for the production of environmentally friendly phase change material microcapsules.

Accordingly, the purpose of the present invention is to provide a phase change material microcapsule that is environmentally friendly and harmless to the human body by using a phase change material as a core material and a polymer material as a capsule wall of the phase change material, and a method for manufacturing the same. there is.

In addition, the present invention provides a high-efficiency energy storage concrete composite by using carbon nanotubes that contain the above-mentioned environmentally friendly and harmless phase change material microcapsules and undergo ultrasonic dispersion to solve the problem of strength reduction due to mixing of the phase change material. It has a purpose.

The phase change material microcapsule according to the present invention is characterized by using a phase change material as a core material and encapsulating the phase change material inside the microcapsule wall made of a biodegradable polymer.

The microcapsule wall made of the biodegradable polymer is preferably formed by reacting a fibrous natural polymer and an aliphatic cross-linking agent in an aqueous surfactant solution.

The phase change material according to the present invention is n-octacosane, n-heptacosane, n-hexacosane, n-tetracosane, n-tricosan, n-docosane, n-heneicosane, and n-icosane. , n-nonadecane, n-octadecane, n-heptadecane, n-hexadecane, n-pentadecane, n-tetradecane, n-tridecane, and polyethylene glycol.

The phase change material microcapsule according to an embodiment of the present invention may have a diameter of 1 to 100 μm.

In one embodiment of the present invention, the fibrous natural polymer used to manufacture a microcapsule wall made of a biodegradable polymer is methyl cellulose, ethyl ether cellulose, ethyl-2-hydroxyethyl cellulose, hydroxymethyl cellulose, and hydroxyethyl. Cellulose, hydroxyethyl methylcellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose, hydroxybutyl methylcellulose, 2-aminoethyl 2-hydroxypropyl cellulose, hemicellulose, 6-carboxy cellulose, carboxymethyl cellulose, carboxymethyl ether It is preferred that it contains at least one material selected from the group consisting of cellulose, cellulose acetate, alginate, and sorbitol.

In addition, the aliphatic crosslinking agent that reacts with the fibrous natural polymer is 4,4'-dicyclohexylmethane diisocyanate, trans-1,4-cyclohexane diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, and trimethylhexamethylene diisocyanate. Isocyanate compounds containing at least one substance selected from the group consisting of methylene diisocyanate are preferred.

In addition, the surfactant includes polyvinyl alcohol, polyethylene glycol, polyoxyethylene methyl ether, polyoxyethylene lauryl ether, polyoxyethylene octylphenyl ether, polyoxyethylene laurylamine, polyoxyethylene monolaurate, and propylene glycol. Sostearate. At least one nonionic surfactant selected from the group consisting of polyoxyethylene glycerol ether, polyoxyethylene sorbitol monostearate, and polyoxypropylene 2-ethylhexyl ether is preferred.

The method for producing phase change material microcapsules according to the present invention includes the steps of mixing a phase change material and an aliphatic crosslinking agent to prepare a mixture; Mixing and emulsifying an aqueous surfactant solution in the mixture to form an oil/water phase emulsion; And it may include the step of adding a fibrous natural polymer to the oil/aqueous phase emulsion and reacting it to form a biodegradable microcapsule wall surrounding the phase change material as a core material and encapsulating it.

The biodegradable microcapsule wall is preferably a biodegradable polymer formed by reacting a fibrous natural polymer with an aliphatic cross-linking agent.

The aliphatic crosslinking agent may be included in an amount of 10 to 80 parts by weight based on 100 parts by weight of the fibrous natural polymer.

According to one embodiment of the present invention, the fibrous natural polymer is preferably contained in an amount of 5 to 60 parts by weight based on 100 parts by weight of the phase change material.

The surfactant is preferably included in an amount of 2 to 30 parts by weight based on 100 parts by weight of the phase change material.

Additionally, the present invention can provide an energy storage concrete composite using the prepared phase change material microcapsules.

According to one embodiment of the present invention, the composite may reinforce strength by further including multi-walled carbon nanotubes that have undergone ultrasonic dispersion using distilled water and a water reducing agent in an amount of less than 0.1% by weight relative to the weight of cement.

In addition, the phase change material microcapsules are preferably included in 3 to 10% by weight of the total concrete composite.

The concrete composite according to an embodiment of the present invention may include aggregate with a fine aggregate ratio (S/a) in the range of 0.42 to 0.51, and binder with a binder to water ratio (W/B) in the range of 0.3 to 0.4. there is.

The phase change material microcapsule according to the present invention prevents leakage of PCM through microencapsulation, which is a problem that occurs when using PCM in concrete, and can increase thermal performance by increasing the heat transfer area due to circular encapsulation. . In addition, it is manufactured to be harmless to the human body, so even if the capsule is broken due to friction during the concrete mixing process and some leakage occurs, it decomposes in nature after use and does not pollute the environment. No harmful ingredients remain in the human body, so it does not affect the skin, etc. It is possible to provide phase change material microcapsules that are friendly and have improved physical and chemical properties, economic efficiency, and usability compared to existing phase change material capsules.

Concrete according to the present invention using these phase change material microcapsules can reduce energy use in buildings by emitting or absorbing heat energy according to temperature changes and contribute to carbon neutrality by reducing carbon dioxide emissions due to reduced fuel use. In addition, the decrease in strength due to the use of phase change material microcapsules increases thermal conductivity by using a mixture of carbon nanotubes, and the highly efficient heat storage performance of phase change materials is used to remove black ice from concrete pavements and increase the heating efficiency of buildings. It can be used as a material for

Figure 1 is a diagram showing a phase change material microcapsule according to a preferred embodiment of the present invention.
Figure 2 shows a carbon nanotube dispersion solution left at room temperature for 60 days using a general dispersion method when ultrasonic dispersion of carbon nanotubes and a dispersion method used in the present invention.
Figures 3 and 4 show the results of confirming the strength of concrete according to the amount of carbon nanotubes contained in the concrete.
Figure 5 shows the results of the difference in strength between a general phase change material microcapsule concrete and the phase change material microcapsule concrete of the present invention.
Figure 6 shows the results of confirming the heat generation performance of concrete by measuring the difference between the phase change material concrete and the external temperature.

The present invention will be described in more detail below.

The terms used herein are used to describe specific embodiments and are not intended to limit the invention.

As used herein, the singular forms include the plural forms unless the context clearly indicates otherwise. Additionally, when used herein, “comprise” and/or “comprising” means specifying the presence of stated features, numbers, steps, operations, members, elements and/or groups thereof. and does not exclude the presence or addition of one or more other shapes, numbers, operations, members, elements and/or groups.

The present invention relates to a phase change material microcapsule encapsulating a phase change material with a polymer material and a method for manufacturing the same; and an energy storage concrete composite containing carbon nanotubes, aggregate, cement, silica fume, sand, and water ultrasonically dispersed in the prepared phase change material microcapsules.

As shown in FIG. 1, the phase change material microcapsule according to a preferred embodiment of the present invention has a phase change material as the core material 20 and the capsule wall 10 surrounds the phase change material. That is, the phase change material microcapsule is a polymer formed by reacting a fibrous natural polymer, an aliphatic crosslinker, and an aqueous surfactant solution to form the capsule wall 10 of the capsule, and the core material 20 and the capsule wall 10. The entire microcapsule it contains is characterized by having a diameter of 1 to 100㎛.

By using natural polymers, the phase change material microcapsules of the present invention do not decompose in nature after use, polluting the environment, and do not contain harmful components remaining in the human body, so they are environmentally friendly and harmless to the human body, including the skin.

Its manufacturing method includes mixing a phase change material and an aliphatic crosslinking agent; Mixing a mixture of a phase change material and an aliphatic crosslinking agent with an aqueous surfactant solution capable of emulsifying the phase change material and emulsifying the mixture to form an oil/water phase emulsion; It may include the step of mixing a fibrous natural polymer with the oil/water phase emulsion and reacting it with heat and stirring to form a capsule by using the phase change material as a core material to form a capsule wall.

The first process is mixing the phase change material and the aliphatic crosslinking agent.

The phase change material according to the present invention is n-octacosane, n-heptacosane, n-hexacosane, n-tetracosane, n-tricosan, n-docosane, n-heneicosane, n-icosane, It may be any one selected from the group consisting of n-nonadecane, n-octadecane, n-heptadecane, n-hexadecane, n-pentadecane, n-tetradecane, n-tridecane, and polyethylene glycol.

The aliphatic crosslinking agent is one selected from the group consisting of 4,4'-dicyclohexylmethane diisocyanate, trans-1,4-cyclohexane diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, and trimethylhexamethylene diisocyanate. The above isocyanate-based monomers can be preferably used.

The second process is a step of mixing and emulsifying the mixture of the phase change material and the aliphatic crosslinking agent with an aqueous surfactant solution capable of emulsifying the phase change material to form an oil/water phase emulsion.

The surfactant is polyvinyl alcohol, polyethylene glycol, polyoxyethylene methyl ether, polyoxyethylene lauryl ether, polyoxyethylene octylphenyl ether, polyoxyethylene laurylamine, polyoxyethylene monolaurate, propylene glycol isostea. Rate. It may be an aqueous solution containing one or more nonionic surfactants selected from the group consisting of polyoxyethylene glycerol ether, polyoxyethylene sorbitol monostearate, and polyoxypropylene 2-ethylhexyl ether. It is preferable to add 2 to 30 parts by weight of the surfactant based on 100 parts by weight of the phase change material to emulsify the phase change material to form an appropriate oil/water phase emulsion.

The final step is to mix fibrous natural polymers with the oil/aqueous phase emulsion and react them with heat and stirring. Using the phase change material as a core material, the fibrous natural polymers and the aliphatic cross-linking agent react to form a capsule wall, forming a capsule. goes through the process of forming. It is preferable to add 10 to 80 parts by weight of the aliphatic crosslinking agent per 100 parts by weight of the fibrous natural polymer to react appropriately to form a capsule wall capable of enclosing the phase change material.

Therefore, the capsule wall is a biodegradable polymer formed by the reaction of a fibrous natural polymer and an aliphatic cross-linking agent, and has the characteristic of being naturally decomposed after use.

The fibrous natural polymers include methyl cellulose, ethyl ether cellulose, ethyl-2-hydroxyethyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, hydroxyethyl methylcellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose, and hydroxyethyl cellulose. It may contain one or more materials selected from the group consisting of oxybutyl methylcellulose, 2-aminoethyl 2-hydroxypropyl cellulose, hemicellulose, 6-carboxy cellulose, carboxymethyl cellulose, carboxymethyl ether cellulose, cellulose acetate, alginate, and sorbitol. You can.

It is preferable to add 5 to 60 parts by weight of the fibrous natural polymer per 100 parts by weight of the phase change material to form an appropriate microcapsule wall.

The phase change material microcapsules according to the present invention prepared in this way have a diameter of 1 to 100 μm.

In addition, the present invention can provide a highly efficient thermal energy storage strength improved concrete composite using the prepared phase change material microcapsules and carbon nanotubes.

That is, the concrete composite according to the present invention uses cement and silica fume as binders, and in addition to typical components such as aggregate (including coarse aggregate and fine aggregate), the strength decreases due to the use of the phase change material microcapsules. Carbon nanotubes may be further included to improve and enhance thermal performance.

The phase change material microcapsules included in the concrete composite according to the present invention may be included in an amount of 3 to 10% by weight relative to the weight of the binder included in the concrete composite. If it is less than 3% by weight, thermal performance is insufficient, and 10% by weight is used. If it is exceeded, the strength of the concrete decreases significantly, so caution is required.

In addition, the ratio (W/B) of the binder mixed with cement and silica fume to water in the concrete composite can be used flexibly within the range of 0.3 to 0.4. Although there is a proportional relationship between the water binder ratio and the strength of concrete, if the water binder ratio is used below 0.3, workability is lowered and pouring is not easy, and if used in excess of 0.4, there is a risk of strength reduction, which is not desirable. .

The unit cement amount of the present invention is 380 to 480 Kg/m³, focusing on increasing strength by using a larger amount of cement than when pouring concrete in general.

Silica fume according to the present invention is a by-product generated when producing metallic silicon and silicon alloy. It is a very fine spherical powder with a fineness of about 200 m2/g and has high pozzolanic reactivity, so when added to concrete, it creates voids in the transition area of concrete. It fills the role of increasing strength and durability.

The silica fume according to the present invention can be used to improve the strength by filling the micropores of the cement paste within 10% by weight of the cement weight in the total binder, preferably 2 to 3% by weight, and within the above range, the phase change material By using microcapsules, the microstructure of the cement paste can be densified by filling additional voids in the concrete. However, if it exceeds 15% by weight, it is not recommended due to concerns about a decrease in strength and durability.

The aggregate included in the concrete composite according to the present invention can be used flexibly within the range of fine aggregate ratio (S/a) of 0.42 to 0.51. Fine aggregate content (S/a) If it exceeds 0.51, gaps in the material will occur, reducing strength and durability, and if it is used below 0.42, the fluidity of the material will increase and there will be an increase in empty space, which may reduce strength. The type of aggregate is not particularly limited, and ordinary materials can be used.

In particular, the present invention attempted to solve the problem of strength reduction that may occur when using the phase change material microcapsules in a concrete composite by using silica fume and carbon nanotubes.

Carbon Nano Tube (CNT) has mechanical strength about 100 times better than iron, and has electrical conductivity and high thermal conductivity similar to copper.

The physical properties of the carbon nanotube used in the present invention are as follows, and the carbon nanotube is divided into single wall carbon nanotube (SWCNT) and multi-wall carbon nanotube (Multi Wall Carbon Nano Tube) depending on the number of graphene layers. , MWCNT), and in the present invention, multi-walled carbon nanotubes, which are frequently used in bulky construction and civil engineering fields such as buildings and structures due to their low cost of synthesis, are preferred.

The multi-walled carbon nanotubes of the present invention preferably have a diameter of 5 to 7 nm, a length of 50 to 150 μm, a BET specific surface area of 500 to 700 m ² /g, and a specific gravity (Bulk Density) of 0.07 to 0.09 g/ml.

Since these multi-walled carbon nanotubes have cohesive properties during the synthesis process, which may reduce the advantages of the carbon nanotubes, it is preferable to use multi-walled carbon nanotubes dispersed using ultrasound in the present invention. When ultrasonic dispersion is performed, the outer wall of the multi-walled carbon nanotube (MWCNT) begins to be destroyed, and the dispersion power can be increased by cutting the length and reducing the thickness.

Normally, when CNTs are dispersed by ultrasonic waves, there are many cases where CNTs precipitate and clump together over time, which often reduces performance. Accordingly, in the present invention, distilled water and a superplasticizer are added together during ultrasonic dispersion so that CNTs do not precipitate even after a long period of time, so that when applied to concrete, they are mixed well without clumping and are effective in increasing strength and improving thermal performance. The water reducing agent is a type of admixture that plays a role in increasing workability even when a small amount of water is used in the production of concrete, and is also used as a surfactant to easily mix the CNT with distilled water. Preferably, it is a polycarboxylic acid-based agent. High-performance AE water reducing agents are mainly used, and water reducing agents used for slump concrete, early strength/high flow concrete, ultra-high strength concrete, and gypsum boards are also used, but are not limited to these.

In addition, in the present invention, when dispersing CNTs ultrasonically, using distilled water purified from impurities rather than ordinary tap water increases the holding power of the dispersed CNT solution, allowing the CNTs to be evenly mixed when pouring concrete, thereby improving thermal conductivity, durability, and strength. It is desirable from a practical point of view.

The content of these CNTs is preferably contained within 0.1% by weight of the cement weight. If the CNT content exceeds 0.1% by weight of the cement weight, the strength of concrete is reduced, which is not desirable.

The method of manufacturing a concrete composite for thermal energy storage by mixing the phase change material microcapsules includes the steps of manufacturing microencapsulated PCM, pouring aggregate and mixed materials, and curing.

When PCM microcapsules are mixed together with aggregate when pouring concrete of the present invention, the microcapsules are broken due to friction of the aggregate. To prevent this as much as possible, mix cement, silica fume, fine aggregate, and coarse aggregate, dry mix, and then mix with water and CNT. It is advisable to add it when the concrete dough becomes thin after adding the solution and mixing. Through the above process, PCM leakage problems occurring in concrete can be prevented and thermal performance can be improved.

Hereinafter, preferred embodiments of the present invention will be described in detail. The following examples are only for illustrating the present invention, and should not be construed as limiting the scope of the present invention by these examples. In addition, although the examples below are exemplified using specific compounds, it is obvious to those skilled in the art that equivalent effects can be achieved even when equivalents thereof are used.

Example 1: Preparation of phase change material microcapsules 1

A ratio prepared by mixing 105 g of n-tetradecane, a phase change material (PCM), and 5 g of the aliphatic cross-linking agent isophorone diisocyanate in a 500 ml beaker, and then mixing 5 g of the nonionic surfactant polyoxyethylene methyl ether and 155 g of water into this mixture. An oil/water phase emulsion was prepared by adding an aqueous ionic surfactant solution and stirring it for about 20 minutes at a speed of 3,000 rpm using a homomixer.

Put the above oil/aqueous emulsion in a 500 mL four-necked flask, add 10 g of carboxymethyl cellulose, a fibrous natural polymer, raise the temperature to 80°C, mix and react for about 2 hours, and the aliphatic crosslinking agent isophorone diisocyanate and The reaction of carboxymethyl cellulose formed a biodegradable capsule wall surrounding the phase change material (PCM) n-tetradecane as a core material. Afterwards, while stirring, 10 g and 10 g of preservatives Hexylene glycol and Hydroxyacetophenone, respectively, were added and cooled to room temperature to produce eco-friendly phase change material microcapsules.

The average particle diameter of the eco-friendly phase change material microcapsule particles obtained at this time was 8㎛.

Example 2: Preparation of phase change material microcapsules 2

Phase change in the same manner as Example 1 except that 105 g of n-pentadecane was used instead of 105 g of n-tetradecane (PCM), and 5 g of polyvinyl alcohol was used instead of 5 g of polyoxyethylene methyl ether, a nonionic surfactant. Material microcapsules were prepared.

The average particle diameter of the biodegradable capsule particles obtained at this time was 11㎛.

Examples 3-4: Preparation of concrete composite containing phase change material microcapsules

First, in order to manufacture ultrasonic dispersed carbon nanotubes, distilled water from which impurities were removed was placed in a beaker, carbon nanotubes and a water reducing agent (DONGNAM's high-performance water reducing agent for concrete) were mixed there, an ultrasonic disperser was installed 1 cm apart from the beaker, and the ultrasonic disperser was set at 500 Hz. Disperse for 45 minutes.

If the temperature of the solution rises due to continuous vibration during ultrasonic dispersion, it may adversely affect the dispersion effect and the characteristics of the microcapsule phase change material when mixed. Therefore, a heat dissipation time of 10 seconds was added for every 20 seconds of dispersion to dissipate heat. Therefore, the dispersion time of pure carbon nanotubes, excluding the heat dissipation time, was set to 30 minutes.

Next, the phase change material microcapsules prepared in Example 1 were changed to 5% by weight (Example 3) and the phase change material microcapsules prepared in Example 2 were changed to 10% by weight (Example 4), with the remaining contents respectively. Based on 450kg/㎥ of cement, a binder containing 10% by weight of silica fume based on the weight of the cement, aggregate mixed with a fine aggregate ratio (S/a) of 0.48, and 0.05% by weight of ultrasonically dispersed multi-walled carbon nanotubes are added. The concrete composite was mixed, poured, and cured so that the water binder ratio was 0.35.

Comparative Example 1: Preparation of concrete composite containing CNT dispersed using tap water

A concrete composite was manufactured in the same manner as in Example 3, except that CNTs were added to ordinary tap water instead of distilled water without using a water reducing agent and ultrasonically dispersed CNTs were used.

Comparative Example 2: Preparation of concrete composite containing general phase change material microcapsules

In Example 3, the melamine-formaldehyde polymer (Melamine-Formaldehyde Prepolymer) obtained by emulsifying the phase change material with an anionic surfactant, not prepared in the present invention, and reacting this emulsion with melamine and formalin at a molar ratio of 1:3. ), except for using melamine-based phase change material microcapsules in which the capsule wall was formed, a concrete composite was manufactured using the same process.

Comparative Example 3

In Example 3, carbon nanotubes were used at 0.15% by weight when manufacturing the composite, and compared with the present invention.

Experimental Example 1: Confirmation of change in state of CNT dispersion solution according to ultrasonic dispersion method of carbon nanotubes

The ultrasonically dispersed carbon nanotube dispersion solutions according to Comparative Example 1 and Example 3 were left at room temperature for 60 days, and then the state of the solution was observed with the naked eye, and the results are shown in FIG. 2.

Referring to FIG. 2, it can be seen that the carbon nanotube dispersion solution (left) dispersed ultrasonically in the process of Comparative Example 1 precipitated over time, causing CNTs to aggregate and phase separation to occur. However, it can be seen that the carbon nanotube dispersion solution (right), which is dispersed ultrasonically by mixing distilled water and water reducing agent as in the present invention, has CNTs evenly dispersed without phase separation, giving an overall black color.

Experimental Example 2: Strength test of concrete

The compressive strength of each concrete manufactured according to Examples 3 to 4 and Comparative Examples 1 to 3 was measured at a speed of 0.1 mm/min, and the results are shown in Figures 3 to 5, respectively.

Next, Figure 3 is a comparison of concrete according to Example 3 containing 5% by weight of phase change material microcapsules and 0.05% by weight and 0.1% by weight of carbon nanotubes of the present invention and 0.15% by weight of carbon nanotubes. As a result of confirming the strength of concrete according to Example 3, when ultrasonically dispersed carbon nanotubes are included up to 0.1% by weight, excellent strength results are shown, but in the case of Comparative Example 3 where the content is 0.15% by weight, the content is 0.05% by weight. It was confirmed that the strength was reduced by more than 20% compared to concrete. Therefore, it can be seen that even if carbon nanotubes manufactured through the same process are used, if the content exceeds the appropriate amount, the strength of concrete is lowered, which is not desirable.

These results were similarly measured in Figure 4, which shows the results of concrete containing 10% by weight of phase change material microcapsules. However, it can be seen that in Example 4, which contains twice as much phase change material microcapsules at 10% by weight, the concrete strength is lower regardless of the CNT content compared to Example 3 which contains 5% by weight, which is This can be seen as a result of the phase change material microcapsules acting as foreign substances.

In addition, referring to FIG. 5 showing the strength measurement results of the concrete manufactured according to Comparative Example 2, which is a concrete containing general phase change material microcapsules, and Example 3 of the present invention, it can be seen that the strength differs by more than 30%. You can check it. In other words, it was confirmed that the concrete composite using eco-friendly phase change material microcapsules as in the present invention can have more environmentally friendly effects without reducing its strength compared to conventional phase change material microcapsules.

Experimental Example 3: Phase change microcapsule concrete heating temperature measurement results

Concrete was manufactured by mixing phase change temperature microcapsules, and the outdoor temperature (room) difference (heating temperature) of the concrete was measured 3 and 30 times in a constant temperature and humidity chamber at -5℃ to 15℃, and the results are shown in Figure 6. .

The specimens used in the graph are as follows.

Room: Outside temperature

P5: Concrete composite containing only 5% by weight of phase change material microcapsules

P10: Concrete composite containing only 10% by weight of phase change material microcapsules

P5SC0.05: 5% by weight of phase change material microcapsules + 0.05% by weight of ultrasonically dispersed CNT (Example 3)

P5SC0.10: 5% by weight of phase change material microcapsules + 0.1% by weight of ultrasonically dispersed CNTs

P5SC0.15: 5% by weight of phase change material microcapsules + 0.15% by weight of ultrasonically dispersed CNTs (Comparative Example 3)

P10SC0.05: 10% by weight of phase change material microcapsules + 0.05% by weight of ultrasonically dispersed CNT (Example 4)

P10SC0.10: 10% by weight of phase change material microcapsules + 0.10% by weight of ultrasonically dispersed CNTs

P10SC0.15: 10% by weight of phase change material microcapsules + 0.15% by weight of ultrasonically dispersed CNTs

Referring to Figure 6, all concrete specimens had a slower temperature change than the outside temperature (Room), and a temperature difference of up to 6.9°C was confirmed. Additionally, as a result of measuring long-term temperature changes over 30 cycles for long-term measurement, it was confirmed that performance did not decrease.

From these results, it was confirmed that the concrete composite containing phase change material microcapsules manufactured in the present invention had a slightly higher or similar heating effect compared to existing products even when admixtures such as CNT were added.

10: capsule wall
20: Functional oil

Claims (16)

A phase change material selected from n-tetradecane or n-pentadecane is used as the core material, and the capsule wall surrounds the core material,
The capsule wall is composed of 4.7 parts by weight of isophorone diisocyanate as an aliphatic crosslinking agent, 9.5 parts by weight of carboxymethyl cellulose, a fibrous natural polymer, and polyoxyethylene methyl ether nonionic surfactant or polyester, based on 100 parts by weight of the phase change material. A phase change material microcapsule encapsulating the phase change material, characterized in that it is a biodegradable polymer formed by reacting 4.7 parts by weight of an aqueous solution of a 3% by weight surfactant selected from vinyl alcohol surfactants.
delete delete delete delete delete delete Preparing a mixture by mixing 4.7 parts by weight of an isophorone diisocyanate aliphatic crosslinking agent with 100 parts by weight of a phase change material selected from n-tetradecane or n-pentadecane;
An aqueous solution of a surfactant at a concentration of 3% by weight selected from polyoxyethylene methyl ether nonionic surfactant or polyvinyl alcohol surfactant is mixed with the mixture in an amount of 4.7 parts by weight based on 100 parts by weight of the phase change material and emulsified to form an oil/aqueous phase. allowing an emulsion to form; and
Carboxymethyl cellulose, a fibrous natural polymer, is added to the oil/water phase emulsion in an amount of 9.5 parts by weight based on 100 parts by weight of the phase change material and reacted at 80°C to form a core material surrounding the phase change material and the natural polymer and aliphatic polymer surrounding it. A method for producing phase change material microcapsules comprising the step of forming a biodegradable microcapsule wall formed by reacting a system crosslinking agent and encapsulating it.
delete delete delete delete 5 to 10% by weight of the total concrete composite of the phase change material microcapsules according to paragraph 1,
Mix distilled water with impurities removed and superplasticizer, install it 1cm apart from the ultrasonic disperser, and undergo ultrasonic dispersion for 45 minutes at 500 Hz. During ultrasonic dispersion, 10 seconds of heat dissipation time is added for every 20 seconds of dispersion, and pure carbon nano particles excluding the heat dissipation time are added. The dispersion of the tube was allowed to occur for 30 minutes, so that the manufactured multi-walled carbon nanotubes were within 1.0% by weight of the weight of cement,
Aggregate with a fine aggregate ratio (S/a) of 0.48, and
Energy storage concrete composite containing a binder with a ratio of silica fume binder to water (W/B) of 0.35.
delete delete delete