阅读说明：本技术 一种有机相变储能材料及其制备方法 (Organic phase change energy storage material and preparation method thereof ) 是由 郭彦峰 李妍 付俊 付云岗 于 2020-04-28 设计创作，主要内容包括：本发明公开了一种有机相变储能材料,本发明还公开了该种有机相变储能材料的制备方法,步骤包括：1)将N-异丙基丙烯酰胺、N,N’-亚甲基双丙烯酰胺、聚乙二醇1000共同溶解于去离子水中；在过硫酸铵和四甲基乙二胺氧化还原体系中引发聚合反应,形成以聚乙二醇1000作致孔剂的聚N-异丙基丙烯酰胺凝胶；2)蒸馏水浸泡；3)将冷冻好的聚N-异丙基丙烯酰胺凝胶放进冷冻干燥机冷冻干燥；4)将冷冻干燥好的聚N-异丙基丙烯酰胺凝胶分别浸泡于二元有机复配物中溶胀,制得有机相变储能材料。本发明的材料及其制备方法,非常适用于果品及蔬菜的保鲜储运。(The invention discloses an organic phase change energy storage material and a preparation method thereof, wherein the preparation method comprises the following steps: 1) dissolving N-isopropyl acrylamide, N' -methylene bisacrylamide and polyethylene glycol 1000 in deionized water; initiating polymerization reaction in an ammonium persulfate and tetramethylethylenediamine redox system to form poly-N-isopropyl acrylamide gel with polyethylene glycol 1000 as a pore-foaming agent; 2) soaking in distilled water; 3) putting the frozen poly N-isopropylacrylamide gel into a freeze dryer for freeze drying; 4) and respectively soaking the freeze-dried poly N-isopropyl acrylamide gel in the binary organic compound for swelling to prepare the organic phase change energy storage material. The material and the preparation method thereof are very suitable for the fresh-keeping, storage and transportation of fruits and vegetables.)

1. An organic phase change energy storage material, characterized in that: polyethylene glycol is used as a pore-foaming agent to synthesize poly-N-isopropyl acrylamide gel as a supporting material, a binary organic compound is used as a phase-change material, and the supporting material is used for adsorbing the binary compound phase-change material to prepare the organic phase-change energy-storage material.

2. The organic phase change energy storage material of claim 1, wherein: when the binary organic compound adopts n-decanoic acid-methyl laurate, the molar ratio of the n-decanoic acid to the methyl laurate is 30: 70.

3. the organic phase change energy storage material of claim 1, wherein: when the binary organic compound adopts n-decanoic acid-n-decanol, the molar ratio of the n-decanoic acid to the n-decanol is 36: 64.

4. the organic phase change energy storage material of claim 1, wherein: when the binary organic compound adopts lauric acid-tetradecane, the molar ratio of the lauric acid to the tetradecane is 21: 79.

5. the preparation method of the organic phase change energy storage material is characterized by comprising the following steps of:

step 1, dissolving 1 mol/L of N-isopropylacrylamide as a monomer, 0.25% of N, N' -methylenebisacrylamide as a cross-linking agent and 40% of polyethylene glycol 1000 as a pore-forming agent in deionized water;

keeping the temperature of the reaction product in an ammonium persulfate and tetramethylethylenediamine redox system at 20 ℃ to initiate polymerization for 24 hours to form poly-N-isopropylacrylamide gel with polyethylene glycol 1000 as a pore-foaming agent;

step 2, taking out the poly N-isopropyl acrylamide gel obtained in the step 1, soaking the poly N-isopropyl acrylamide gel in distilled water for 3 days, and replacing the distilled water every 6 hours to remove unreacted monomers and pore-forming agents;

step 3, taking out the soaked poly N-isopropyl acrylamide gel, freezing the poly N-isopropyl acrylamide gel in a refrigerator at the temperature of-25 ℃ for 24 hours, and then putting the frozen poly N-isopropyl acrylamide gel into a freeze dryer for freeze drying for 72 hours, wherein the temperature of the cold hydrazine is-50 ℃ to-55 ℃, and the vacuum degree is 0.5 to 50 Pa;

and 4, respectively soaking the freeze-dried poly N-isopropylacrylamide gel in the binary organic compound, and swelling for 24 hours at the temperature of 60 ℃ to prepare the organic phase change energy storage material.

6. The method for preparing the organic phase-change energy storage material according to claim 5, wherein the molar ratio of the binary organic compound to the organic phase-change energy storage material is 30:70, or a molar ratio of 36:64, or a molar ratio of 21: 79 lauric acid-tetradecane.

Technical Field

The invention belongs to the technical field of low-temperature refrigeration composite phase change energy storage materials, relates to an organic phase change energy storage material, and further relates to a preparation method of the organic phase change energy storage material.

Background

Phase change materials are classified into organic phase change materials and inorganic phase change materials. The inorganic phase change material comprises crystalline hydrated salt, molten salt, alloy or metal, which has high heat storage density, high heat conductivity and low price but can generate supercooling and phase separation phenomena in the using process, thereby seriously affecting the practical application; organic phase change materials include paraffins, fatty acids, certain higher aliphatic hydrocarbons, alcohols, carboxylic acids and salts, which have little volume change, thermal conductivity and no supercooling or phase separation when undergoing phase change, and are promising phase change materials.

The organic phase-change material is a novel energy-saving environment-friendly material which can store or release energy in a matter phase-change mode, the occurrence of the organic phase-change material effectively improves the utilization rate of energy, and the problem that the traditional energy is not matched in time and space is solved. As the solid-liquid phase change material is easy to leak in the phase change process, the support material is required to adsorb the phase change material, and the support material plays a role of a porous carrier so that the loss degree of the phase change material in the phase change process is reduced.

Disclosure of Invention

The invention aims to provide an organic phase change energy storage material, which solves the problems that the organic phase change material in the prior art is poor in thermal conductivity and difficult to store.

The invention also aims to provide a preparation method of the organic phase change energy storage material.

The invention adopts the technical scheme that the organic phase-change energy storage material is prepared by taking polyethylene glycol as a pore-foaming agent to synthesize poly-N-isopropyl acrylamide gel as a supporting material, taking a binary organic compound as a phase-change material and adsorbing the binary compound phase-change material by the supporting material.

The invention adopts another technical scheme that a preparation method of the organic phase change energy storage material is implemented according to the following steps:

step 1, dissolving 1 mol/L of N-isopropylacrylamide as a monomer, 0.25% of N, N' -methylenebisacrylamide as a cross-linking agent and 40% of polyethylene glycol 1000 as a pore-forming agent in deionized water;

keeping the temperature of the reaction product in an ammonium persulfate and tetramethylethylenediamine redox system at 20 ℃ to initiate polymerization for 24 hours to form poly-N-isopropylacrylamide gel with polyethylene glycol 1000 as a pore-foaming agent;

step 2, taking out the poly N-isopropyl acrylamide gel obtained in the step 1, soaking the poly N-isopropyl acrylamide gel in distilled water for 3 days, and replacing the distilled water every 6 hours to remove unreacted monomers and pore-forming agents;

step 3, taking out the soaked poly N-isopropyl acrylamide gel, freezing the poly N-isopropyl acrylamide gel in a refrigerator at the temperature of-25 ℃ for 24 hours, and then putting the frozen poly N-isopropyl acrylamide gel into a freeze dryer for freeze drying for 72 hours, wherein the temperature of the cold hydrazine is-50 ℃ to-55 ℃, and the vacuum degree is 0.5 to 50 Pa;

and 4, respectively soaking the freeze-dried poly N-isopropylacrylamide gel in the binary organic compound, and swelling for 24 hours at the temperature of 60 ℃ to prepare the organic phase change energy storage material.

The invention has the beneficial effects that a new binary organic compound is obtained after single organic phase-change materials are mixed according to a certain molar ratio, and poly N-isopropyl acrylamide gel taking polyethylene glycol as a pore-forming agent is soaked in the binary organic compound for adsorption after being subjected to freeze-drying treatment, so that the new organic phase-change energy storage material is formed. The prepared organic phase change energy storage material has good heat conductivity and easy storage, the molecular weight of the used polyethylene glycol is 1000, and the monomer N-isopropylacrylamide is a material with good biocompatibility, so that the organic phase change energy storage material is very suitable for fresh-keeping storage and transportation of fruits and vegetables.

Drawings

FIG. 1 is a schematic diagram of a portion of the process of the present invention;

FIG. 2a is a Fourier infrared scanning spectrum of hydrogel PN without polyethylene glycol, and FIG. 2b is poly N-isopropylacrylamide hydrogel PN with polyethylene glycol 1000 as a pore-foaming agent₁₀₀₀40, fourier infrared scan pattern;

FIG. 3a is a Fourier infrared spectrum of n-decanoic acid, FIG. 3b is a Fourier infrared spectrum of methyl laurate, FIG. 3c is a Fourier infrared spectrum of n-decanol, FIG. 3d is a Fourier infrared spectrum of lauric acid, and FIG. 3e is a Fourier infrared spectrum of tetradecane;

FIG. 4a is a Fourier infrared spectrum of a dibasic organic compound n-decanoic acid-methyl laurate, FIG. 4b is a Fourier infrared spectrum of a dibasic organic compound n-decanoic acid-n-decanol, and FIG. 4c is a Fourier infrared spectrum of a dibasic organic compound lauric acid-tetradecane;

FIG. 5a is a differential scanning calorimetry curve for n-decanoic acid, FIG. 5b is a differential scanning calorimetry curve for methyl laurate, FIG. 5c is a differential scanning calorimetry curve for n-decanol, FIG. 5d is a differential scanning calorimetry curve for lauric acid, and FIG. 5e is a differential scanning calorimetry curve for tetradecane;

FIG. 6a1 shows the differential scanning calorimetry curve of a binary organic compound of n-capric acid-methyl laurate with the molar ratio of 3: 97-24: 76, FIG. 6a2 is a differential scanning calorimetry curve of a binary organic compound of n-decanoic acid-methyl laurate with a molar ratio of 27:73 to 48:52, FIG. 6a3 is a differential scanning calorimetry curve of a binary organic compound n-capric acid-methyl laurate with a molar ratio of 51:49 to 72:28, FIG. 6b1 is a differential scanning calorimetry curve of a binary organic compound of n-decanoic acid-n-decanol with a molar ratio of 3:97 to 33:67, FIG. 6b2 is a differential scanning calorimetry curve of a binary organic compound of n-decanoic acid-n-decanol with a molar ratio of 36:64 to 66:34, FIG. 6c is a differential scanning calorimetry curve of a binary organic compound lauric acid-tetradecane with a molar ratio of 3: 97-30: 70;

fig. 7 shows thermophysical data (phase transition initial temperature, phase transition termination temperature and phase transition enthalpy) of the binary organic compound n-decanoic acid-n-decanoic acid methyl ester, fig. 7a shows thermophysical data (phase transition initial temperature, phase transition termination temperature and phase transition enthalpy) of the binary organic compound n-decanoic acid-n-decanol, and fig. 7c shows thermophysical data (phase transition initial temperature, phase transition termination temperature and phase transition enthalpy) of the binary organic compound lauric acid-tetradecane;

FIG. 8 is differential scanning calorimetry curve and thermophysical data of poly-N-isopropylacrylamide gel with polyethylene glycol 1000 as a pore-forming agent in three binary organic compounds, wherein FIG. 8a is N-decanoic acid-methyl laurate (molar ratio 30: 70), FIG. 8b is N-decanoic acid-N-decanol (molar ratio 36: 64), and FIG. 8c is lauric acid-tetradecane (molar ratio 21: 79);

FIG. 9 is the swelling result of poly N-isopropylacrylamide gel with polyethylene glycol as a pore-forming agent in N-capric acid-methyl laurate, N-capric acid-N-decanol and lauric acid-tetradecane in a binary compound, wherein FIG. 9a shows the influence of polyethylene glycols with different molecular weights as the pore-forming agent on the adsorption performance of the gel, and FIG. 9b shows the influence of polyethylene glycol 1000 with different molecular weights as the pore-forming agent on the adsorption performance of the gel;

FIG. 10 is the latent heat of phase change of poly N-isopropylacrylamide gel with polyethylene glycol as a pore-forming agent in N-decanoic acid-methyl laurate, N-decanoic acid-N-decanol and lauric acid-tetradecane in a binary compound, wherein FIG. 10a shows the effect of polyethylene glycols with different molecular weights as pore-forming agents on the enthalpy of phase change of a phase change cold storage material; FIG. 10b shows the effect of different mass of polyethylene glycol 1000 as a pore-forming agent on the enthalpy of phase change of the phase change cold storage material;

FIG. 11 is a scanning electron micrograph of a gel of different compositions, wherein FIG. 11a is a poly-N-isopropylacrylamide gel without a porogen; FIG. 11b is poly-N-isopropylacrylamide gel with polyethylene glycol 200 as a pore-forming agent (40% by mass of the monomer); FIG. 11c is a poly-N-isopropylacrylamide gel with polyethylene glycol 1000 as a porogen (40% by mass of monomer); FIG. 11d is poly-N-isopropylacrylamide gel with polyethylene glycol 4000 as a pore-forming agent (40% by mass of the monomer); FIG. 11e is poly N-isopropylacrylamide gel with polyethylene glycol 8000 as a pore-forming agent (40% by mass of the monomer); FIG. 11f is a poly-N-isopropylacrylamide gel with polyethylene glycol 1000 as a porogen (40% by mass of monomer).

Detailed Description

The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

The organic phase-change energy storage material is prepared by taking polyethylene glycol as a pore-foaming agent to synthesize poly (N-isopropyl acrylamide) gel as a supporting material, taking a binary organic compound as a phase-change material, and adsorbing the binary compound phase-change material by using the supporting material.

The binary organic compound adopts the following three combination modes:

1) when the binary organic compound adopts n-decanoic acid-methyl laurate, the n-decanoic acid and the methyl laurate have good thermophysical properties (see fig. 5a and 5b), and can coexist, i.e. no chemical reaction occurs in the mixing process, and the fourier infrared spectrum of the binary organic compound shows that no new functional group is formed (see fig. 3a, fig. 3b and fig. 4 a). When the molar ratio of n-decanoic acid increased to 33%, methyl laurate was saturated and no excess n-decanoic acid could be dissolved, the diorgano complex had insoluble material at room temperature, the differential scanning calorimetry curve of the diorgano complex n-decanoic acid-methyl laurate showed a second endothermic peak (fig. 6a2), (similarly, one endothermic peak was also shown in fig. 6a1, fig. 6a3, respectively) so that the molar ratio of n-decanoic acid to methyl laurate was selected to be 30:70, the initial phase-change temperature of the obtained binary organic compound is 1.62 ℃, the end phase-change temperature is 8.15 ℃, and the enthalpy of phase change is 193.40J/g (see figure 7 a);

2) when the binary organic compound adopts n-decanoic acid-n-decanol, n-decanoic acid and n-decanol have good thermal property (see fig. 5a and 5c), and can coexist, i.e. no chemical reaction occurs in the mixing process, and the Fourier infrared spectrum of the binary organic compound shows that no new functional group is formed (see fig. 3a, 3c and 4 b). When the molar ratio of n-decanoic acid was increased to 39%, n-decanol was saturated and unable to dissolve the excess n-decanoic acid, the binary organic formulation had insoluble material at room temperature, the differential scanning calorimetry curve of the binary organic formulation n-decanoic acid-n-decanol showed a second endothermic peak (fig. 6b2) (the same is true for fig. 6b 1), so the molar ratio of n-decanoic acid to n-decanol was chosen to be 36:64, the phase transition initial temperature of the obtained binary organic compound is 3.80 ℃, the phase transition termination temperature is 11.72 ℃, and the phase transition enthalpy is 180.94J/g (see figure 7 b);

3) when lauric acid-tetradecane is used as the binary organic compound, lauric acid and tetradecane have good thermophysical properties (see fig. 5d and 5e), and can coexist, i.e., no chemical reaction occurs during the mixing process, and the fourier infrared spectrum of the binary organic compound shows no new functional group formation (see fig. 3d, 3e and 4 c). When the molar ratio of lauric acid increased to 24%, tetradecane was saturated and no excess lauric acid could be dissolved, the meta organic formulation had insoluble material at room temperature, the differential scanning calorimetry curve of the binary organic formulation lauric acid-tetradecane showed a second endothermic peak (fig. 6c), so the molar ratio of lauric acid to tetradecane was chosen to be 21: 79, the initial temperature of the phase transition of the obtained binary organic compound is 5.51 ℃, the termination temperature of the phase transition is 26.74 ℃, and the enthalpy of the phase transition is 209.42J/g (see figure 7 c).

Using the above three combinations twoOrganic phase change energy storage material prepared from organic complex and poly N-isopropyl acrylamide gel, referred to as PN for short₁₀₀₀40/n-decanoic acid-methyl laurate, PN₁₀₀₀40/n-decanoic acid-n-decanol, PN₁₀₀₀40/lauric acid-tetradecane, which belong to low-temperature composite phase-change materials, have the respective physicochemical characteristics that:

1)PN₁₀₀₀the appearance of the 40/n-capric acid-methyl laurate presents transparent gel, the phase transition temperature is 3.2 ℃, and the phase transition enthalpy is 188.1J/g (see figure 10 b);

2)PN₁₀₀₀the appearance of the 40/n-decanoic acid-n-decanol is transparent gel, the phase transition temperature is 1.2 ℃, and the phase transition enthalpy is 177.74J/g (see figure 10 b);

3)PN₁₀₀₀the 40/lauric acid-tetradecane appeared as a transparent gel with a phase transition temperature of 4.2 ℃ and enthalpy of phase transition of 206.17J/g (see FIG. 10 b).

The microstructure analysis of the poly-N-isopropyl acrylamide gel prepared by using polyvinyl alcohol as a pore-foaming agent is as follows: FIG. 11a shows a poly-N-isopropylacrylamide gel without a porogen; the gels in FIGS. 11b, 11c, 11d, 11e and 11f contain abundant micelle structures inside. When the molecular weight of polyethylene glycol is larger, the cell size is larger, and the microcell spacing is larger. When the molecular weight of the polyethylene glycol is 4000, 8000 and 10000, the intercellular heat conduction performance is low and the gel adsorption capacity is poor due to large space and weak capillary force; when polyethylene glycol is not contained or the molecular weight of polyethylene glycol is 200, the gel is a microcell unit which is small (see fig. 11b), the capacity of adsorbing the binary organic compound is poor (see fig. 9a), and the phase change latent heat of the correspondingly obtained organic phase change cold storage material is also small (see fig. 10 a); the gel is completely immersed into the binary organic compound to form a whole, and the whole micelle presents a transparent gel state, which shows that the mass of the binary organic compound exceeds the saturated adsorption quantity of the gel.

The following is an example of polyethylene glycol 1000, molecular formula is H (OCH)₂CH₂)_nOH has an average molecular weight of 900-1100 and is in the form of white waxy solid flakes or granular powder.

Referring to fig. 1, the preparation method of the organic phase change energy storage material of the invention is implemented according to the following steps:

step 1, taking 1 mol/L N-isopropylacrylamide as a monomer, taking N, N '-methylene bisacrylamide as a cross-linking agent and accounting for 0.25 percent of the total mass of the monomer, taking polyethylene glycol 1000 as a pore-forming agent and accounting for 40 percent of the total mass of the monomer, dissolving the N-isopropylacrylamide, the N, N' -methylene bisacrylamide and the polyethylene glycol 1000 into deionized water, keeping the temperature of 20 ℃ in an ammonium persulfate and tetramethylethylenediamine redox system to initiate polymerization for 24 hours to form poly N-isopropylacrylamide gel taking the polyethylene glycol 1000 as the pore-forming agent, wherein the ammonium persulfate is widely applied to water-phase free radical polymerization, and the tetramethylethylenediamine is used as an accelerator to accelerate the polymerization;

step 2, taking out the poly N-isopropyl acrylamide gel obtained in the step 1, soaking the poly N-isopropyl acrylamide gel in distilled water for 3 days, and replacing the distilled water every 6 hours to remove unreacted monomers and pore-forming agents; the pore-forming agent polyethylene glycol 1000 does not participate in the chemical reaction of gel formation, and the gel PN without the pore-forming agent and the gel PN with the pore-forming agent₁₀₀₀40 (see fig. 2a and 2b) are identical;

step 3, taking out the soaked poly N-isopropyl acrylamide gel, freezing the poly N-isopropyl acrylamide gel in a refrigerator at the temperature of-25 ℃ for 24 hours, and then putting the frozen poly N-isopropyl acrylamide gel into a freeze dryer for freeze drying for 72 hours, wherein the temperature of the cold hydrazine is-50 ℃ to-55 ℃, and the vacuum degree is 0.5 to 50 Pa;

and 4, respectively soaking the freeze-dried poly N-isopropylacrylamide gel in a binary organic compound (N-capric acid-methyl laurate with a molar ratio of 30:70, N-capric acid-N-decanol with a molar ratio of 36:64, and lauric acid-tetradecane with a molar ratio of 21: 79), and swelling at 60 ℃ for 24 hours to obtain the corresponding organic phase change energy storage material.

According to the preparation method, N-isopropyl acrylamide is used as a monomer, polyethylene glycol 1000 (with the molecular weight of 1000) is used as a pore-foaming agent, and poly N-isopropyl acrylamide gel with a uniform pore structure is prepared. The PN finally obtained₁₀₀₀40/n-capric acid-methyl laurate phase-change cold-storage material,at this time, the swelling degree reaches 53.31% (see fig. 9b), the phase change initial temperature of the phase change cold storage material is 3.2 ℃ (see fig. 8a), and the phase change enthalpy is 188.10J/g (see fig. 10 b); PN (pseudo-noise)₁₀₀₀The phase change cold storage material of 40/n-decanoic acid-n-decanol has the swelling degree of 53.70% (see fig. 9b), the initial phase change temperature of the phase change cold storage material is 1.2 ℃ (see fig. 8b), and the phase change enthalpy is 177.74J/g (see fig. 10 b); PN (pseudo-noise)₁₀₀₀The 40/lauric acid-tetradecane phase-change cold storage material has the swelling degree of 52.47% (see fig. 9b), the phase-change initial temperature of the phase-change cold storage material is 4.2 ℃ (see fig. 8c), and the phase-change enthalpy is 206.17J/g (see fig. 10 b).

And (3) experimental verification:

the PN with the same series of mass percentages is prepared by adopting the preparation method of the invention₂₀₀40、PN₄₀₀₀40、PN₈₀₀₀40 and PN₁₀₀₀₀40 gel (i.e., poly-N-isopropylacrylamide gel) as a comparative material for experimental analysis. Adopting engineering measurement method to PN₂₀₀40、PN₄₀₀₀40、PN₈₀₀₀40 and PN₁₀₀₀₀40, carrying out test analysis on the adsorption performance of the gel and the phase change enthalpy of the finally obtained phase change cold storage material, wherein the test steps are as follows:

step 1, dissolving a monomer N-isopropylacrylamide, a cross-linking agent N, N' -methylene bisacrylamide and a pore-foaming agent polyethylene glycol (the molecular weights are respectively 200, 4000, 8000 and 10000) in deionized water according to the proportion, and initiating a polymerization reaction in an ammonium persulfate and tetramethylethylenediamine redox system at 20 ℃ for 24 hours to form poly N-isopropylacrylamide gel using the polyethylene glycol as the pore-foaming agent;

and 2, taking out the poly N-isopropyl acrylamide gel obtained in the step 1, soaking the poly N-isopropyl acrylamide gel in distilled water for 3 days, and replacing the distilled water every 6 hours to remove unreacted monomers and pore-forming agents.

And 3, taking out the soaked poly N-isopropylacrylamide gel, freezing the poly N-isopropylacrylamide gel in a refrigerator at the temperature of-25 ℃ for 24 hours, and then putting the frozen poly N-isopropylacrylamide gel into a freeze dryer (the temperature of cold hydrazine is-50 ℃ to-55 ℃, and the vacuum degree is 0-50 Pa) for freeze drying for 72 hours.

And 4, soaking the freeze-dried poly N-isopropyl acrylamide gel in the N-capric acid-methyl laurate, the N-capric acid-decanol and the lauric acid-tetradecane in the molar ratio, and swelling the gel in an environment at 60 ℃ for 24 hours to obtain three phase change cold storage materials.

And (3) analyzing an experimental result:

1) the influence of different molar ratios of the single organic material on the phase transition initial temperature of the binary organic compound.

The initial phase change temperature of the binary compound of the n-decanoic acid and the methyl laurate is changed at 1.5-3.5 ℃, the fluctuation is small, the latent heat of phase change is 165.35-193.40J/g, when the molar ratio of the n-decanoic acid is increased to 33%, the binary compound of the n-decanoic acid and the methyl laurate is not completely blended and has the phenomenon of phase separation, and the latent heat of phase change of the binary compound of the n-decanoic acid and the methyl laurate is high and can be used as a phase change material at about 0 ℃; the initial phase change temperature of the binary n-decanoic acid-n-decanol compound is changed at-2-8 ℃, the initial phase change temperature is firstly reduced from 4.6 ℃ to-2 ℃, when the molar proportion of n-decanoic acid reaches 28%, the initial phase change temperature starts to rise, the fluctuation is large, the latent heat of phase change is 154.97-198.27J/g, the initial phase change temperature range of the binary n-decanoic acid-n-decanol compound is wide, the latent heat of phase change is high, the regularity is obvious, and the binary n-decanoic acid-n-decanol compound is an ideal phase change material capable of being used at 0-6 ℃ and adjustable in temperature; when the molar proportion of lauric acid in the lauric acid-tetradecane compound is increased to 24%, a serious phase separation phenomenon occurs, the initial phase change temperature is changed at 5-6 ℃, the fluctuation is minimum, the latent heat of phase change is 205.80-217.94J/g, the tetradecane cost is high, the cost is greatly reduced by compounding with lauric acid, and the compound is a phase change material applicable to low-temperature refrigeration.

The result shows that the lauric acid-tetradecane (molar ratio is 21: 79) has the best thermal physical property and the lowest cost, the phase change initial temperature is 5.51 ℃, and the phase change latent heat is 209.42J/g; the binary compound with good phase change adjustable regularity is n-decanoic acid-n-decanol; the binary compound of n-decanoic acid-methyl laurate has high phase change latent heat, low phase change initial temperature and stability, and is a good phase change material at about 0 ℃.

2) Influence of monomer molar concentration on the adsorption properties of poly (N-isopropylacrylamide) gels.

In the experiment, the poly-N-isopropylacrylamide gel systems with the monomer molar concentrations of 0.5 mol/L, 1.0 mol/L, 1.5 mol/L and 2.0 mol/L and 0.5 mol/L respectively cannot be gelatinized, and the poly-N-isopropylacrylamide gels prepared from 1.0 mol/L, 1.5 mol/L and 2.0 mol/L (N-capric acid-methyl laurate, N-capric acid-N-decanol and lauric acid-tetradecane) and with the monomer of 1.0 mol/L have the highest swelling degree mainly because the swelling degree is smaller as the monomer molar concentration increases and the crosslinking degree of the monomer increases.

3) Influence of the content of the crosslinking agent on the adsorption properties of the poly (N-isopropylacrylamide) gel.

In the test, the concentrations of the cross-linking agent were selected to be 0.25 wt%, 0.50 wt%, 0.75 wt% and 1.00 wt%, and poly-N-isopropylacrylamide gel with a cross-linking agent content of 0.25 wt% had the best adsorption performance in the binary organic compound. The cross-linking agent dosage in the free radical copolymerization has great influence on the performance of the product. The larger the amount of the cross-linking agent is, the higher the cross-linking density of the reaction product is, the smaller the network space of the polymer is, and a large amount of organic molecules are difficult to absorb in the binary organic compound.

4) The influence of the molecular weight and the mass of the polyethylene glycol on the adsorption performance and the phase change latent heat of the poly-N-isopropylacrylamide gel.

With the increase of the molecular weight and the feeding amount of the polyethylene glycol, the pore diameter in the poly-N-isopropylacrylamide gel is increased, the larger the pore diameter is, the worse the capillary force is, the highest swelling rate and the fastest response rate are achieved for the poly-N-isopropylacrylamide gel with the molecular weight of the polyethylene glycol of 1000 at 60 ℃.