APPLIED CLAY SCIENCE
·
2021
·
IF 5.467
Xing Li,Ya Wen,Yulian Zhang,Zhiqiang Ge
Insect pheromone is a class of natural non-toxic and harmless biological pesticide. To improve the utilization efficiency of the pheromone pesticides, controlled release in response to circadian rhythm of insects is a feasible approach because some insects act and release pheromones with a circadian rhythm. Thus, myrcene, as the insect pheromone model, was first loaded into the hollow nano-cavity of halloysite nanotubes (Hal), which were further enclosed with melted n-octadecane as a coating to form a composite (PMHal). The latter was simply blended into chitosan solution to cast a chitosan composite film (PMHal@CS) for preventing n-octadecane leakage during the phase change process . The effects of temperature change on the release rate of myrcene from the composite film were evaluated. Results showed the combination of Hal with n-octadecane could significantly slow the release rate of myrcene from the composite film when the ambient temperature was below 15 °C. If the ambient temperature was near to the melting point of n-octadecane, the release rate of myrcene would be enhanced. In alternating temperature cycles test of PMHal@CS film, the average release rate of myrcene was 0.65 μg/h at 30 °C and 0.022 μg/h at 15 °C, the persistent temperature sensitivity and good temperature rhythm were still remained after 7 cycles. These results suggested that the composite film had a good controlled release effect on myrcene and could adapt well to the circadian rhythm activity of some insects.
研究领域:
农业科学
·
材料科学
·
昆虫学
✓ 已验证
产品关联
DOI
高影响因子
THERMOCHIMICA ACTA
·
2021
·
IF 3.115
Lei Liu,Xiang Cheng,Xiwang Miao,Ying Zhang,Min Guo,Fangqin Cheng,Mei Zhang
In this work, a series of SiO 2 @n-octadecane capsules were prepared by one step emulsion polymerization, the influence of emulsifying speed, ammonia and TEOS contents, reaction temperature, concentration of emulsifier and the amount of PVP on the size, structure and performance was detailed investigated. It can be seen from SEM characterization that among these factors emulsification speed had the greatest influence on capsule size, while followed by the ammonia and TEOS content. According to TEM results, the ammonia and TEOS contents were the most important factors on the structure (shell thickness and surface smoothness) of the capsules, attributing to ammonia and TEOS were the catalyst and reactant of hydrolysis polymerization, respectively. Generally, the crystallinity of the samples became worse as the size decreased. DSC results showed that excessive ammonia or TEOS caused a significant drop in the enthalpy of the samples, furthermore, the enthalpy basically decreased with the attenuation of the inner radius of the sample. The target SiO 2 @n-octadecane capsule was sample C2 with high enthalpy (127.7 J/g), size of 1.62 μm, shell thickness of 68 nm, and smooth surface. More importantly, within the parameters studied, a series of SiO 2 @n-octadecane capsules were successfully synthesized with different enthalpy values (min 85.9 J/g, max 144.3 J/g), sizes ranging from 0.63–2.75 μm, shell thickness 32–79 nm and different smooth surfaces. Therefore, the controllable synthesis of SiO 2 @n-octadecane capsules within the above range can be achieved by simulating different parameters and their development.
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
ENERGY
·
2018
·
IF 4.968
Zhishan Zhang,Guruprasad Alva,Min Gu,Guiyin Fang
In this work, polystyrene–based form–stable composite phase change materials (CPCMs) were fabricated by a solution and reflux method. In the composites, the n–octadecane (ODE) was used as thermal energy storage material, the polystyrene (PS) acted as the supporting material, and expanded graphite (EG) was employed as thermal conductive filler to improve the thermal conductivity of the composites. The toluene was adopted as solvent. Both polystyrene and n–octadecane smoothly dissolve in toluene. EG was also easily dispersed into the matrix. CPCMs were obtained after distillation of the toluene. The differential scanning calorimeter (DSC) and a thermogravimetry analyzer (TGA) were adopted to assess the thermal properties and thermal stability of the CPCMs, respectively. Fourier transformation infrared (FT–IR) spectroscope and scanning electronic microscope (SEM) were utilized to determine the chemical structure and microstructure of the ODE/PS/EG composites. The thermal conductivity of the CPCM with 5 wt% content of EG can reach up to 1.01 W/m·K, which is nearly 7 times higher than that of the CPCM without the EG. The latent heat value of CPCM with the highest ODE content (48.5 wt%) is 98.05 J/g, the melting temperature is 27.5 °C, which is close to room temperature. Therefore, the form–stable CPCMs are promising thermal energy storage materials in solar thermal energy storage systems , such as solar heating system in buildings.
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
Journal of Energy Storage
·
2022
·
IF 8.907
Lei Liu,Xiwang Miao,Xiang Cheng,Huigang Wang,Min Guo,Fangqin Cheng,Mei Zhang
In this work, PCM nanocapsules composed of ZnO/SiO 2 shell and n-octadecane core were successfully synthesized by emulsion polymerization and hydrothermal method . The crystallinity of ZnO was enhanced on the SiO 2 shell by MPTS modification. The granule-like ZnO were distributed on the SiO 2 shell. The encapsulation rate of n-octadecane in nanocapsules was about 45.2 % with enthalpy of 95.0 J/g melting at room temperature 28.3 °C. Furthermore, due to the presence of ZnO, the synthesized PCM nanocapsules had excellent UV absorption properties for whole wavelengths, and the absorbed UV light can be converted into heat energy for storage, and the photothermal conversion efficiency had reached 25.0 %. Hence, the prepared ZnO/SiO 2 @n-octadecane nanocapsules had broad application prospects due to its thermal energy storage , UV protection and photothermal conversion performance.
研究领域:
材料科学
·
能源工程
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF WOOD CHEMISTRY AND TECHNOLOGY
·
2022
·
IF 2.865
Yulan Jian,Shaowei Lu,Wei Tang,Mingjun Shao,Fuhua San,Hui Wan,Linkun Xie
To explore the typical alkyltrichlorosilane and optimal volume ratio of the alkyltrichlorosilane-toluene solutions for preparing superhydrophobic Pinus kesiya wood, four alkyltrichlorosilanes: methyltrichlorosilane (MTCS), butyltrichlorosilane (BTCS), dodecyltrichlorosilane (DTCS), and octadecyltrichlorosilane (OTCS) were each used to modify the wood samples at different volume ratios of alkyltrichlorosilane-toluene solutions. The Pinus kesiya wood specimens were immersed in the solutions to fabricate superhydrophobic coatings on the wood surface. The wettability of the modified wood surfaces was characterized by water contact angle and water uptake values. The chemical composition of the wood samples was analyzed using X-ray photoelectron spectroscopy (XPS) and attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), and the surface morphology of the modified wood samples was observed using scanning electron microscopy (SEM). The result showed that all types of alkyltrichlorosilane-modified wood changed from hydrophilic to hydrophobic. The wood specimens had the highest water contact angle of 151.8 ± 0.4° and lowest water uptake of 18 ± 0.6 wt.% when 0.25 vol.% MTCS and 0.25 vol.% OTCS solutions were applied, respectively.
研究领域:
材料科学
·
林学
✓ 已验证
产品关联
DOI
高影响因子
Science of Advanced Materials
·
2019
·Vol. 11
·期 5
·647-654
·
IF 1.158
Yin Qing,Guo Maolian,Li Wei,Ren Huizhang,Wang Jianping,Zhang Xingxiang
The polyurethane/polyurea microcapsules containing n-octadecane were prepared and modified by interfacial polymerization, where styrene maleic anhydride copolymer (SMA) was selected as emulsifier, polyurea based shell material was synthesized with isophorone diisocyanate (IPDI)
and diethylenetriamine (DETA). Besides, polyethylene glycol 400 (PEG-400) was also added to form polyurethane shell and modify the microcapsules morphology. SEM images proved that with the modification of polyethylene glycol 400, the microcapsules morphology improved significantly. The microstructure
of microcapsules under varying factors such as emulsification rates, DETA dropping rates and core/shell ratios were analyzed systematically. In particular, the equipments such as field emission scanning electron microscope (FE-SEM), different scanning calorimetry (DSC) and thermogravimetric
(TG) were used to investigate the morphology, phase change properties and thermal stability of microcapsules. The DSC results verified the phase transition behavior of octadecane microcapsules, and microcapsules also displayed pretty thermal stability.
研究领域:
材料科学
·
热能工程
✓ 已验证
DOI
高影响因子
SOLAR ENERGY MATERIALS AND SOLAR CELLS
·
2022
·
IF 7.305
Tao Shi,Meng Zhang,Huan Liu,Xiaodong Wang
To offer a solution for low heat transfer and solar energy-storage performance of conventional phase-change fluids, we designed a direct absorption solar energy collecting system based on n -octadecane/phosphorene (PR) nanosheet phase-change nanofluids for capturing solar energy with high energy conversion efficiency and rapid heat response and transfer. The phase-change nanofluids were fabricated through homogenously dispersing PR nanosheets in the n -octadecane aqueous emulsion. The resultant nanofluids exhibit good dispersion stability and suitable viscosity under an optimal emulsifier content of 9.0 wt % and a homogenization rate of 16,000 rpm. Although the nanofluids show a relatively lower latent-heat capacity compared to pristine n -octadecane emulsion, their thermal response and heat transfer were enhanced significantly due to the introduction of PR nanosheets, leading to an increase in thermal conductivity by 98.59% for the nanofluids containing 1.0 wt % PR nanosheets. More importantly, the n -octadecane/PR nanosheet nanofluids exhibit an excellent optical absorption capacity for solar photothermal conversion and thermal energy storage . The nanofluid containing 1.0 wt % phosphorene nanosheets presents a relative thermal storage capacity of 152% by taking pristine n -octadecane emulsion as a control. The nanofluids also show good working stability for the long-term use in solar photothermal conversion and thermal energy storage. The phase-change nanofluids developed in this study exhibit great application potential in solar energy capture and photothermal energy utilization thanks to their enhanced thermal conductivity, high energy-storage density, suitable viscosity, thermal reliability, and excellent photothermal conversion and energy-storage capability.
研究领域:
材料科学
·
纳米技术
·
太阳能
·
热工程
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2025
·
IF 13.2
Chen Wang,Shugang Wang,Junkai Zhang,Wenji Song,Jihong Wang
The growing demand for efficient thermal management has increased the importance of phase change materials (PCMs). Microencapsulation technology mitigates the leakage issue of liquid-state PCMs. However, enhancing the thermal conductivity and structural stability of microencapsulated PCMs (MEPCMs) remains a challenge. Graphene oxide (GO) and its chemically functionalized derivatives have shown great potential in enhancing the performance of MEPCMs. In this study, GO and octadecylamine-grafted GO (GO-ODA) were employed as thermally conductive fillers to modify n -octadecane@melamine-formaldehyde resin microcapsules. Four formulations were developed by varying the spatial distribution of GO and GO-ODA within the microcapsules. The dispersion of GO-ODA in the core was found to reduce defects in the shell structure, while distributing the additives across the core, interface, and shell promoted the formation of a continuous thermal conduction network. The experimental results indicate that, with a filler content of 0.2 wt%, the thermal conductivity increased by 5.8 times, reaching 0.587 W/(m·K), compared to the unmodified MEPCM with a value of 0.086 W/(m·K). Additionally, the leakage rate was reduced by 87.5%, significantly enhancing the structural stability of the microcapsules.
研究领域:
材料科学
·
纳米技术
·
化学工程
·
热管理
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
·
2023
·Vol. 149
·期 2
·595-607
·
IF 4.4
Song Lingjun,Yang Yukai,Hu Haopan,Wang Yitong,Jia Xinlei,Sun Lixian,Xu Fen,Li Bin,Yu Ting,Zhang Huanzhi,Zeng Julan,Cao Zhong
The low thermal conductivity and liquid-phase leakage of phase change materials seriously hinder their large-scale applications. Porous materials have been identified as an effective way to address the leakage and provide a thermally conductive network. Therefore, we designed an expanded graphite-based multifunctional composite phase change thermal storage materials for personal thermal management and antimicrobial in medical protection. Expanded graphite (EG) was used as the matrix, silver nanowires (Ag NWs) as the functional enhancement materials, and n -octadecane (OD) as the thermal storage materials. OD and Ag NWs were adsorbed in the porous structure of EG by vacuum-assisted impregnation. Finally, EG/Ag NWs/OD were combined with non-woven fabrics (N) by one-step hot pressing method to obtain EG/Ag NWs/OD-N composite with excellent comprehensive performance. With the mass ratio of EG to Ag NWs of 13:7, EG/Ag NWs/OD-N exhibited a thermal conductivity of 2.0130 W m −1 K −1 , which was improved by 1070.3% compared with pure OD. EG/Ag NWs/OD-N has a melting enthalpy of 137.85 J·g −1 and a crystallization enthalpy of 128.97 J·g −1 . In addition, EG/Ag NWs/OD-N display great antibacterial properties, thermal cycling stability, shape stability, and cycling persistence and showed excellent temperature control in protective clothing applications, offering great potential for large-scale applications.
研究领域:
材料科学
·
热力学
·
纳米技术
·
储能
·
生物医学工程
✓ 已验证
DOI
高影响因子
POLYMER INTERNATIONAL
·
2019
·Vol. 69
·期 2
·140-148
·
IF 2.433
Jianhua Zhou,Jiaojiao Zhao,Yanjiao Cui,Wenjing Cheng
A novel kind of bifunctional nanoencapsulated phase change material with thermal energy storage and ultraviolet absorption functions was successfully prepared through surfactant-free emulsion polymerization with reactive emulsifiers. These nanocapsules consisted of n-octadecane and n-butyl stearate as binary core materials and polyacrylate supplemented with titanium dioxide nanoparticles (nano-TiO2) as hybrid shell materials. The experimental results show that the monomer conversion and thermal conductivity increased and the particle size and distribution decreased with increase in nano-TiO2 content when the nano-TiO2 dosage was below 0.2 wt%. Fourier transform infrared spectroscopy and XRD confirmed that the binary phase change materials were well encapsulated inside the polyacrylate-TiO2 hybrid shell and nano-TiO2 was also successfully crosslinked in the nanocapsules. TEM demonstrated that the synthesized nanocapsules exhibited a regular spherical profile and a well-defined core–shell structure with diameter ranging from 70 to 100 nm. In addition, the results obtained from DSC, TGA and UV–visible spectrophotometry showed that the as-prepared nanocapsules had good thermal storage capacity, thermal stability and ultraviolet absorption properties. It can be considered that the resultant nanoencapsulated phase change materials with polyacrylate-TiO2 hybrid shell may have high feasibility and hold good promise in the applications of intelligent thermoregulation fabrics. © 2019 Society of Chemical Industry
研究领域:
材料科学
·
纳米技术
·
热能存储
·
纺织工程
✓ 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）