Expandable Graphite, Thermo-sensitive Gel And Its Complex Compound Carrier Phase Change Heat Storage Materials Preparation And Performance

Solid- liquid phase change materials for thermal storage become the research hotspot because of its big phase change enthalpy at the present time. However, Solid- liquid phase change materials has a so big volume that it is difficult to load when materials change solid to liquid. Aim at this phenomenon, solid- liquid phase change materials for thermal storagewas compounded to expanded graphite(EG) and EG/polymer gel carriers in this paper. A kind of new-style composite materials which needn't container to fill was prepared.In order to gain a phase change energy storage material(PCM) which has high thermal conductivity, controllable phase change temperature and reasonable thermal properties. Expanded graphite(EG) was used as a carrier which containing Palmitic Acid and Lauric Acid in the condition of ultrasonic. A new Fatty acid/EG composite material is prepared. And this composite material have been used as filling to make a energy saving dope.DSC,SEM and Energy Store-Release Test were performed to investigate on composite material's structure and properties. Results show that: under different expend temperature, EG which was expanded under 800℃has a maximal adsorption capacity for fatty acid, it was 15g/g which allowing no liquid leakage after 100 times'circular test; the phase change enthalpy and the phase change temperature were 139.4J/g and 38-42.1℃respectively. The physical sorption of EG's inner-finestra was the dominating action; thermal conductivity test and the energy saving dope's simulate heat Store-Release test shows that the thermal conductivity of composite material are double of pure mix-fatty acid's;the energy saving dope can slow down the temperature's change rate in the simulator.In the second, organical composite thermal storage materials which take the PNIPAAm gels as the carriers and the palmitic acid and the lauric acid mixture for phase change materials were Synthesized by radical polymerization . Structure and thermal performance of the composite material are characterized and analyzed by infrared spectroscopy(IR) and differential scanning calorimetry(DSC),thermogravimetric(TG) and Scanning Electron Microscope(SEM). It finds out that phase change temperature and enthalpy for composite material increase , Phase change material and gels are more compatible as increasing the content of organic acid.Thirdly, this dissertation synthesize expanded graphite/ polyacrylamide (EG/PAAm) composite gel by solution intercalation and melt intercalation methods. At the same time, this dissertation analyze the influence of supersonic disperse technique by Comparative Analysis and explored the optimum synthetic conditions by orthogonal experiments. And then the swelling properties of the composite material has been tested in the distilled water and saline solution.The structure and performance of EG/PAAm composite are characterized by infrared spectrometer(IR),scanning electron microscope(SEM) and thermogravim-etric analysis (TG) .The results showed that the method of solution intercalation was more suitable for synthesizing the composites. The EG would be exfoliated at the influence of supersonic disperse technique, which would be good for EG's decentralization in the solution.By testing swelling properties of the different EG/PAAm composite samples. at the same condition, the EG/PAAm composites which synthesized by in-situ intercalation polymerization had the higher equilibrium swelling ratio than which was made by supersonic disperse method.When the temperature changed from 23℃to 80℃, the changes of the EG/PAAM composites' volume were little. The results of the EG/gel swelling in saline solution shows that the adsorption capability of the EG/gels composites would better than the adsorption capability of gels. IR analysis showed that the EG doping was a common physical blending process and there were no chemical changes. The results of the TG analysis shows that EG had little influence on the thermal decomposition temperature and rate of PAAM,the composites maintained the heat resistant property of the gels. The results of the SEM analysis showed that the layered structure of the EG/PAAm were very obvious. It proved that the structure of EG was lamella structure. The surface of the lamella structure was covered by the net work molecular of the gel and it formed the sponge structure.In a word, the EG/PAAm composites would increase gel's thermal conductivity and swelling properties, that are indispensable for gel used as container for the solid-liquid phase change energy storage materials.