Preparation Of Modified Montmorillonite And Its Application In Phase Change Materials

Paraffin is selected as the phase change material（PCM）due to its advantages such as smaller volume variation,good chemical stability,noncorrosiveness,and cheapness.But as a type of phase transformation material,the volume of paraffin may change when the phase transition occurred,and it also exhibits a flow state and a worse stability.Especially for the inorganic hydrated salt phase change materials,there also exhibits corrosive problems.MMT contains a large amount of layered silicates,and can be modified by surfactant and hyperbranched polymer to produce the composite materials.And the composite materials now get widely used in many areas.In this article,liquid paraffin and modified MMT were used to prepare the phase change composite materials for energy storage.In this paper,inorganic acids,quaternary ammonium salts,amino acids and hyperbranched polymers were used to modify Na-MMT.Then,they were combined with paraffin to get the non-corrosive,optional organic composite phase change energy storage materials.Due to the wide range of phase transition temperature and the practicability,the-se materials overcome the shortcomings of traditional phase change materials.The main research contents of this paper were presented as follows:（1）Preparation of inorganic modified montmorillonite composites（I-PCM）.Orthogo-nal experiments of four factors and three levels were designed about I-PCM to examine each factor and level on the energy storage results and the experiment numbers were I1^I9.And results of the experiments according to phase change latent heat of DSC in the tem-perature ranges from 0 to 200 to 0°C and diffusion-oozing circle method.The most rea-sonable and effective experimental conditions were:the mass ratio of solid and liquid par-affin was 2:1,the mass ratio of MMT and paraffin was 1.5:1,the water was 45 m L,and the mass of Na-MMT was 10 g.According to the test results of the best simple by XRD,FTIR,SEM and TG,the d₀₀₁ spacing of MMT was not expanded,the amorphously overlapping structure of MMT showed a poor stability of energy storage when heating.（2）Preparation of organic modified montmorillonite composites（O-PCM）.Orthogo-nal experiments of four factors and three levels were designed about O-PCM by using CTAB and other surfactant to modified MMT,and the numbers were O1^O9.And also the most reasonable and effective experimental conditions were:the mass ratio of solid and liquid paraffin was 2:1,the mass ratio of MMT and paraffin was 1:1,the surfactant was CTAB,and the molar ratio of cationic surfactants and the exchangeable cations that MMT contained was 1.5.According to the test results by XRD,FTIR,SEM and TG,the d₀₀₁spacing of MMT was expanded from 1.502 nm to 3.508 nm.（3）Preparation of hyperbranched polymer modified montmorillonite composites（H-PCM）.Firstly,L-glutamic acid was used to modify Na-MMT under acidic conditions.Then,AB₂ intermediate by 1,3-diamino-2-propanol and methyl acrylate was prepared.Fi-nally,this AB₂ intermediate was mixed with the amino acid modified Na-MMT,and hyperbranched polymer modified Na-MMT,H-MMT,was prepared.Last,liquid paraffin was added into H-MMT,and non-corrosive organic phase change material,H-PCM,was prepared.According to the test results by XRD,FTIR,SEM,H-NMR,MALDI-TOF-MS,and TG,the interlayer spacing of MMT was obviously enlarged.In addition,the thermal stability of H-PCM was increased,and H-PCM samples owned a better heat storage and release capacity.