ChemistrySelect
·
2025
·Vol. 10
·期 9
·e202405355
·
IF 2
Shaogang Zhang,Xiaolong Ma,Xin Min,Xiaoguang Zhang,Jinhong Li
Graphical A series of EV-CaCl2·6H2O composite PCMs were prepared. SrCl2·6H2O and copper nanoparticles affect the supercooling and thermal conductivity of EV-CaCl2·6H2O composite PCMs, respectively. The non-isothermal melt crystallization process and crystallization activation energy were studied. Solid-liquid phase change materials (PCMs) made from calcium chloride hexahydrate (CaCl 2 ·6H 2 O) offer benefits such as significant latent heat during phase change, high heat storage efficiency, low preparation costs, a nearly constant temperature exothermic process, and environmentally friendly attributes. However, they also face challenges like poor thermal conductivity, susceptibility to leakage, supercooling, and phase separation. The melt impregnation method prepared shape-stable composite PCMs using expanded vermiculite (EV) and CaCl 2 ·6H 2 O as raw materials. The layered pore structure of EV can be used as an encapsulation matrix to prevent the leakage of the CaCl 2 ·6H 2 O liquid phase. Adding 1 wt% strontium chloride hexahydrate (SrCl 2 ·6H 2 O) nucleating agent and 3 wt% copper nanoparticle thermal conductivity enhancer can reduce the supercooling by 8 °C and increase the thermal conductivity by 0.2092 W/(m·K). The kinetic equation effectively describes the non-isothermal melt crystallization process. An increase in the cooling rate creates a thermal hysteresis effect on melt crystallization; the faster the cooling rate, the lower the temperature at which crystallization begins and the shorter the duration required for crystallization to complete. Both SrCl 2 ·6H 2 O and copper nanoparticles can reduce the crystallization activation energy, which is the essential reason for lowering the supercooling of CaCl 2 ·6H 2 O.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
SOLAR ENERGY MATERIALS AND SOLAR CELLS
·
2018
·
IF 5.018
Ning Xie,Jianmin Luo,Zhongping Li,Zhaowen Huang,Xuenong Gao,Yutang Fang,Zhengguo Zhang
An investigation on a new type of shape-stabilized phase change material (PCM) prepared by impregnating eutectic salt hydrate (Na 2 SO 4 ·10H 2 O-Na 2 CO 3 ·10H 2 O with 1:1 in mass ratio) into expanded vermiculite (EV) is carried out in this study. The maximum mass percentage of Na 2 SO 4 ·10H 2 O-Na 2 CO 3 ·10H 2 O eutectic within the composite is determined as 60%. The chemical composition of EV is measured by X-Ray Fluorescence Spectrometer (XRF). The specific surface area of EV and raw vermiculite (RV) is characterized by Brunauer-Aemmett-Teller (BET) method. The results from Scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) tests reveal that eutectic salt hydrate fully filled in the multilayer structure of EV and had good compatibility among the components of the composites. The phase change temperature and the melting enthalpy of the composites are 23.98 °C and 110.3 J/g respectively, which are measured by differential scanning calorimetry (DSC). Good thermal and structural reliability are also demonstrated by thermal gravimetric analysis (TG) techniques and thermal cycling tests. Moreover, the low thermal conductivity with 0.192 W/ (m K) tested by the Hot Disk via transient plane source method certifies that the composite is very applicable for insulation. The composite PCM is then tested in a reduced-scale test chamber outfitted with four thin PCM panels as insulated wallboards. The indoor temperature variations of the PCM room is compared with another identical chamber without PCM layer for evaluating the thermal regulating performance. The results show that the composite has the function of maintaining the indoor temperature at a comfortable range for a longer period and distinctly influenced the time delay. All analysis results indicate that the low-cost salt hydrate/EV composite can exert a great deal of influence on insulation in building energy conservation .
研究领域:
材料科学
·
能源工程
·
建筑技术
✓ 已验证
产品关联
DOI
高影响因子
Polymer-Plastics Technology and Materials
·
2024
·
IF 2.6
Lu Guo,Shiwei Wang,Weizhen Xie,Xuan Wu,Bo Zhao,Man Liu,Chaolu Yin,Qian Li
In order to improve the thermal insulation and smoking properties of expanded vermiculite matrix composites, a kind of expanded vermiculite (EV)/chitosan (CS) composites was prepared by hot pressing. The effects of CS on smoke density, fire-resistance, insulation, and mechanical properties of the EV/CS composites were studied. The results show that with the increase of CS content, the smoke absorption performance and energy storage modulus of the composites is improved. Thermogravimetric (TG) analysis shows that the thermal stability of the EV/CS composite is improved by the presence of chitosan. The pores appear on the surface of the composites after the single-side fire-resistance test. After that, the thermal conductivity of the composites gradually decreases and the insulation performance is improved as the CS content increases. The CS carbonized during the preparation of the composites and thermal decomposition during the test. The morphology results show phase separation of the composites, and the porosity of the composites increases after the test. The reticular structure formed between the EV particles, sodium silicate, and CS molecules reduces the strength loss of the composites.
研究领域:
材料科学
·
火灾安全工程
✓ 已验证
产品关联
DOI
高影响因子
Journal of Energy Storage
·
2025
·
IF 9.8
Shibing Ren,Xingzhao Liu,Min Li,Jiamin Yan,Mu Yang,Ge Wang
Traditional shape-stabilized Phase Change Materials (PCMs) are generally obtained by vacuum impregnation PCM into prefabricated porous supports, and therefore, they have fixed shapes. The preparation process is complicated, and the energy storage density is low. Herein, we report a new synthetic method to obtain vermiculite nanosheets (VNSs) by exfoliation of Expanded Vermiculite (EVM), take metal ions to disrupt the electrostatic repulsion between VNSs, shape in-situ a three-dimensional porous network, and restrict the flow of PEG to obtain VNSs-based composite PCMs. By regulating the size of VNSs to obtain stable thermal properties and adding nano-Al 2 O 3 to increase the nucleation sites to improve the energy storage efficiency and thermal conductivity. The composite PCMs own high energy storage density, up to 90.76 %, high thermal conductivity of 0.47 W/m·K, an increase of 80.77 % compared to pure PEG. At the same time, the composite PCMs are flexible and can be reshaped above the phase transition temperature. It brings a new synthetic method for the preparation of composite PCMs and broadens the application scope of PCMs.
研究领域:
材料科学
·
能源工程
✓ 已验证
产品关联
DOI
高影响因子
Materials Today Communications
·
2024
·
IF 3.7
Lu Guo,Shiwei Wang,Yuting Leng,Chaolu Yin
In this study, in order to enhance the water resistance of expanded vermiculite (EV) composites. Three hydrophobic modifiers, hydrogenated silicone oil (HO), sodium methylsiliconate (SM), and waterborne polyurethane (WP), were used to prepare the EV/HO, EV/SM, and EV/WP composites. The microstructure, water resistance, thermal insulation and fire resistance of the composites were studied. The results indicate that the EV/HO composite exhibit the best water resistance. Rough structure appears on the surface of the EV/HO composite. The water contact angle (WCA) of the EV/HO composite reaches 128.8° when the HO content is 2.4 wt%. The water absorption ability of the composites decreased, softening coefficient and WCA increased with the increase of HO content. The backside temperature of the EV/HO composite was recorded to be 381.2 ℃ after 90 min single-side fire-resistance test, 13.3 % lower than that of the EV composite. The EV/HO composites maintain better integrity after fire-resistance test. Besides, the fiber-like network structures appear in the EV/SM and EV/WP composites. This structure enhances the thermal insulation properties of the EV/SM and EV/WP composite. The thermal conductivity of the composites modified with 8.97 wt% of SM and WP decreased by 9.29 % and 8.70 % respectively.
研究领域:
材料科学
·
建筑技术科学
✓ 已验证
DOI
高影响因子
JOURNAL OF MATERIALS SCIENCE
·
2018
·Vol. 53
·期 18
·13067-13080
·
IF 2.993
Zhang Xiaoguang,Qiao Jiaxin,Zhang Weiyi,Cheng Fei,Yin Zhaoyu,Huang Zhaohui,Min Xin
An innovative way to enhance the thermal conductivity of composite phase change materials (PCMs) is by carbonizing the carbohydrate-coated mineral substrate to modify its porous structure. Here, we study the effect of introducing different amounts of carbonized starch acting as a filler for enhancing the thermal conductivity of the shape-stabilized composite PCMs (ss-CPCMs) based on polyethylene glycol (PEG) and modified expanded vermiculite (MEV). The experimental exploration of the thermal behavior of composite PCMs has been explored sufficiently in depth. The MEV is shown by SEM images to tightly adhere to the carbon layer and to be composed of a dense micropore structure. Results from DSC indicate that the latent heat of the PEG/MEV ss-CPCMs gradually decreases with the increase of carbon layer mass fraction. Results obtained from FT-IR and TGA show that PEG/MEV ss-CPCMs exhibit good chemical and thermal stabilities. The thermal conductivity of the PEG/MEV ss-CPCMs increases with the carbon layer mass fractions and reaches up to 1.94 times that of PEG/EV ss-CPCMs. The PEG/MEV ss-CPCMs result in a promising material for applications in energy-efficient buildings due to its excellent thermal properties, ideal thermal conductivity and good chemical and thermal stability.
研究领域:
材料科学
·
热能存储
·
建筑节能
·
纳米复合材料
·
功能材料
✓ 已验证
DOI
高影响因子
IRANIAN POLYMER JOURNAL
·
2021
·Vol. 30
·期 11
·1149-1158
·
IF 1.899
Wang Limei,Guan Guoying,Wang Jingwei
Abstract The eco-friendly and low-cost poly(itaconic acid)/poly(sodium allyl sulfonate) (PIA/PSAS) new superabsorbent polymers (SAP) were prepared based on the monomers of itaconic acid (IA), sodium allyl sulfonate (SAS) and the cross-linking agent of N , N′ -methylene bisacrylamide (MBA) by aqueous solution process. Moreover, the expanded vermiculite (EV) particles were used as reinforcement for SAP. The absorption behaviour of SAP in different liquids were studied by the teabag method, including deionized water, 0.9% NaCl solution and cement filtration. The results showed that SAP could reach the optimal liquid adsorption state under certain experimental conditions such as the molar ratio of IA/SAS as 2:1, the IA neutralization degree of 70%, the cross-linker dosage of 0.6%, and the EV content of 2.0%. The morphology and structure of the synthetic SAP were characterized. Furthermore, the effects of SAP type and content on concrete properties were evaluated. Results showed a reduction in shrinkage and revealed SAP particles acted as miniature reservoirs lead to cure concrete internally by supplying water during hydration. The EV particles reinforced SAP composite slightly and alleviated the negative influence on the compressive strength of concrete relative to PIA/PSAS. This designed SAP showed its potential to be used as an internal curing agent for concrete due to its ability to provide comprehensive protection against shrinkage and fracture. Graphic abstract
研究领域:
材料科学
·
土木工程
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）