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Aiming at the application of energy-saving and energy storage materials for buildings, a series of octadecane/intumescent graphite forming phase change materials with different octadecane content were prepared by vacuum adsorption method, and the optimal content of octadecane adsorption and its properties were explored through microscopic morphological observation, leakage performance test, differential scanning calorimetry analysis and cold-thermal cycle stability analysis. Through the analysis, it is concluded that when the adsorption amount of octadecane is 90 wt%, the comprehensive performance of the octadecane/expanded graphite forming phase change material under the adsorption content is the best, and its enthalpy of molten enthalpy and solidification enthalpy are 188 J/g and 186.9 J/g, which has a higher enthalpy values compared with different composite phase change materials at home and abroad. After heating the oven at 50 ℃ for 2 h, there is no obvious phenomenon of octadecane exudation, and the quality loss rate is less than 1%, indicating that it has good anti-leakage performance and structural stability. [ABSTRACT FROM AUTHOR]

As a new material, phase change energy storage materials have irreplaceable advantages and application value in building energy conservation and ecological sustainability. The commonly used solid and liquid phase change materials, due to the problem of easy leakage of solid and liquid phase change materials to a certain extent, restrict the development and application of phase change composites. Aiming at the low temperature solid liquid phase change material encapsulation technology, this paper introduces the low temperature phase change latent heat storage material and its phase transformation in packaging technology research status quo. The porous mineral adsorption phase change material, such as diatomite, expanded vermiculite and expanded perlite, and porous carbon based phase change composites based on expanded graphite were given priority to, as well as the preparation of aerogel phase change composite material technology. The load capacity, thermal performance and thermal conductivity of phase change composites are introduced. On this basis, the future research direction of solid and liquid phase variable composites is proposed, in order to provide some reference for the application and promotion of solid and liquid phase variable composites. [ABSTRACT FROM AUTHOR]

Composite hydrogel particles are prepared by reverse suspension polymerization. Cellulose acrylic acid nanofiber (ACL-CNF) is used as the polymerization axis. Composite hydrogel microspheres P(AAACC) are prepared by reverse suspension polymerization of acrylamide (AM) and 2-acrylamide-2-methylpropanesulfonic acid (AMPS) with ammonium persulfate (NH4)2S2O8 as initiator. The polymerization process, microstructure, swelling, mechanical strength, temperature and salt resistance of P(AAACC) are studied. The results show that the equilibrium swelling ratio is 13.59 g/g at salt concentration of 10 wt% and 30.15 g/g at 120 ℃, which are 2.63 times and 3.15 times higher than that of ordinary hydrogels, respectively. When the compression ratio of composite hydrogel particles is 85%, the recovery of composite hydrogel particles is 84.8%, while the common hydrogel has been broken. TG-DTG analysis shows that the copolymerization reaction between ACL-CNF and monomer occurs, and the thermal stability is improved. After 7 days of aging under high temperature and high salt, the water retention rate of composite hydrogel particles is 92.1%, which is 11% higher than that of ordinary hydrogel, and the mechanical strength is 2.5 times higher in deionized water and 2.79 times higher in salt water. [ABSTRACT FROM AUTHOR]

The modified resins were aminated with styrene resin as matrix. The adsorption behavior of the modified resins for Cr(Ⅵ) was discussed and the modified resins was characterized. Characterization test results show that the surface of aminated resins had more porous channels, the specific surface area was 271.64 m~2/g, the element content of N in the modified resins reached 3.45% and the amination effect was ideal. The adsorption experiment results show that the adsorption equilibrium time of aminated resins was 2 h, the adsorption process of modified resins was more suitable for the Langmuir model of single molecular layer adsorption, and the kinetic adsorption behavior was in good agreement with the first-order kinetics. The adsorption process was endothermic. Amino modified styrene resins had ideal adsorption effect on heavy metal ion Cr(Ⅵ) and the adsorption were the results of the interaction of hydroxyl group, amino group and double bond on the surface of resin. The adsorption capacity of the modified resin was 298.75 mg/g, and the adsorption rate was 93.24%. The results of 20 repeated experiments were satisfactory with the relative standard deviation of 0.024. The experimental results show that the amine modified adsorption resin could be used for enrichment and purification of heavy metal ion Cr(Ⅵ) and had good reusability. [ABSTRACT FROM AUTHOR]

Graphene modified polyurethane (PU)/bronze composite coating was prepared though scraping method by using bronze powders，polyurethane and graphene as functional pigments，adhesives and modifier，respectively. The effects of heat treatment temperature and time on the appearance，microstructure，infrared emissivity and adhesion strength of the prepared coating were systematically investigated. The results show that graphene modification can improve the heat conduction and heat dissipation effects of the coating，thereby improving the heat resistance of the coating. Compared w i t h the unmodified coating，the appearance，microstructure ？ infrared emissivity and adhesion strength of the coating after graphene modification have higher thermal stability. The prepared graphene modified coating can be used long-term at 170 °C，after heat treatment at 170 °C for 100 h. The appearance and microstructure of the coating remain unchanged，the emissivity can be as low as 0.216，and adhesion strength can be maintained at 1 grade. [ABSTRACT FROM AUTHOR]

Improving the heat resistance of polyurethane is a hot topic in the application of polyurethane. Polyurethane (PU) is prepared by prepolymer method with polyether polyol (PPG), 4,4′-diphenylmethane diisocyanate (MDI) and 3,3-dichloro-4,4-diaminodiphenylmethane (MOCA) as main raw materials. The effect of chain extension coefficient on the properties of PU is discussed. The results show that with the increase of chain extension coefficient, the comprehensive mechanical properties and heat resistance of PU first increase and then decrease. Dynamic mechanical analysis (DMA) shows that the internal friction peak of glass transition temperature (TG) of PU shifted to high temperature with the increase of chain extension coefficient. When the chain extension coefficient is 0.04, the mechanical properties of polyurethane are the best, the tensile strength is 64.16 MPa, the bending strength is 84.69 MPa, the impact toughness is 8.88 kJ/m2, the maximum damping factor (Tan δmax) is 1.108, and the initial thermal decomposition temperature reaches 315 ℃. [ABSTRACT FROM AUTHOR]

4D printing technology is a variable characteristics rapid prototyping technology, which is mainly based on 3D printing. It additively manufactures the desired object with intelligent materials. The molding firmware can be stimulated by the external environment, in terms of its shape, structure or function of the time dimension changes. Since the technology was proposed, it has attracted the attention of a large number of scholars. With the continuous deepening of research on 4D printing technology, this technology plays a significant advantage in the interdisciplinary integration. This paper first reviews the research status of shape memory intelligent materials in 4D printing, and then elaborates the application research of 4D printing technology based on shape memory intelligent materials in the fields of medical, bionic, military and life product manufacturing. Finally it looks forward to the potential applications and challenges of 4D printing shape memory intelligent materials in the future development. [ABSTRACT FROM AUTHOR]

In recent years, the development of sound-absorbing materials has advanced rapidly, and been widely used in traffic buildings and other areas. Tn this paper, the characteristics and research progress of sound absorption materials are reviewed, and the basic principle of sound absorption is discussed. Tn addition, starting from the preparation of sound absorbing materials, this paper mainly introduces the research progress of the sound absorbing characteristics and material structure of porous, resonant and composite sound absorbing materials. Tt is a key research direction that how to use the improvement of the internal structure of the material to achieve efficient noise reduction in the field of sound absorbing materials. Finally, the problem about how to correlate the damping loss factor of acoustic materials with the acoustic coefficient is put forward. And the sound absorption effect is studied based on the correlation. So the acoustic performance can be controlled by the design of material damping factor. [ABSTRACT FROM AUTHOR]

The black silicon material with high-efficiency anti-reflection microstructure has important applicat ion value in the field of optoelectronics. In this paper, two-step metal-assisted chemical etching was used to prepare the "pyramid" silicon and "pyramid-nanowire" micro-nano composite black silicon materials. The field emission scanning electron microscope, near-infrared spectrometer ind Raman spectroscopy were used in turn to charracterize the microscopic morphology, reflectivity and structural properties of the samples. The quantum confine ment model ( QCM) was used to explain the mechanism of the obvious enhancement of the Raman spectrum scattered light intensity of black silicon, and the light trapping model and multilayer film interference theory were used to ;malyze the anti-reflection mechanism of the black silicon microstructure. The results show that the average reflectivity of the black silicon material, with the micro-nano composite structure, in the band of 900 nm~l 700 nm was 11.94%, which was reduced by 77.:32% and 54.95% compared with the pyramidal silicon and the polished silicon wafer, respectively. The analysis of Raman spectroscopy shows that there was no change in the black silicon material compositions before and ;1fter etching. It was still single crystal silicon wa fer. The nano-swle microstructure on the surface of the black silicon incre;1sed the intensity of the Raman spec trum scattered light. The decrease in reflectivity of black silicon was due to the fact that the incident light was repeatedly reflected inside the micro-nano structure. /\lso, the refractive index gradient layer was established between the micro-nano st ructure to reduce the reflection caused by the sudden change in refractive index. The research conclusion had reference value for improving the laser absorpt ion efficiency of functional nrnteri;ds in the near-infrared band. [ABSTRACT FROM AUTHOR]