INTERNATIONAL JOURNAL OF FOOD SCIENCE AND TECHNOLOGY
·
2019
·Vol. 55
·期 5
·1900-1908
·
IF 2.281
Min Pang,Xiuxiu Wang,Lili Cao,Zhaojuan Shi,Zheng Lei,Shaotong Jiang
Summary Oleogels of β-sitosterol (Sit) and beeswax (BW) were combined at varying ratios (w/w) and added to sunflower oil (SFO) at concentrations of 10 g per 100 g and 20 g per 100 g oil to prepare oleogels (Sit/BW/SFO). Structural and thermal properties were characterised and results showed that the hardness and enthalpy of oleogels were affected by the amount of β-sitosterol and beeswax in the oleogelator combination (Sit/BW, w/w). Oleogels with beeswax as the only oleogelator (Sit0/BW10) had the highest hardness and maximum enthalpy change. Gel network form was influenced by the crystalline behaviour of the oleogelator, and Sit0/BW10-oleogel was densely packed, spherical and white while Sit10/BW0-oleogel displayed a needle shape. X-ray diffraction patterns showed that the oleogel width of the crystals and D- spacing increased with increasing amounts of β-sitosterol and the FTIR spectra revealed that oleogels formed via non-covalent bonding and may be stabilised with physical entanglements.
研究领域:
食品科学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
POSTHARVEST BIOLOGY AND TECHNOLOGY
·
2020
·
IF 4.303
Mingyi Yang,Zisheng Luo,Sunan Gao,Tarun Belwal,Lei Wang,Ming Qi,Zhaojun Ban,Bin Wu,Fengzhong Wang,Li Li
Plant cuticular wax is the first barrier to resist biotic and abiotic stress. However, little is known about the compositional differences between the epicuticular and intracuticular wax in grape berry. The compositional, morphological and functional features of cuticular wax in grape berries of Vitis vinifera cv. ‘Kyoho’, ‘Muscat Hamburg’, ‘Redglobe’, and ‘Zuijinxiang’ were investigated. The total and epicuticular wax of four berries were mainly composed of terpenoids, hydrocarbons, alcohols, fatty acids and esters. Oleanolic acid was the most abundant terpenoid among the four cultivars. Scanning electron microscopy revealed the crystalline flakes structure of the cuticular wax. Additionally, the removal of epicuticular wax accelerated the weight loss, browning, and softening of grape berries, indicating the plastic-wrap-like effect of the cuticular wax on postharvest quality. This study provided the theoretical basis for further application of the fruit wax or waxy analogue.
研究领域:
植物学
·
园艺学
·
食品科学
✓ 已验证
产品关联
DOI
高影响因子
ENERGY CONVERSION AND MANAGEMENT
·
2013
·
IF 2.775
Keping Chen,Xuejiang Yu,Chunrong Tian,Jianhua Wang
Polyurethane phase change material (PUPCM) has been demonstrated to be effective solid–solid phase change material for thermal energy storage. However, the high cost and complex process on preparation of PUPCMs with high enthalpy and broad phase transition temperature range can prohibit industrial-scale applications. In this work, a series of novel form-stable paraffin/PUPCMs composites ( n -octadecane/PUPCM, n -eicosane/PUPCM and paraffin wax/PUPCM) with high enthalpy and broad phase transition temperature range (20–65 °C) were directly synthesized via bulk polymerization. The composites were prepared at different mass fractions of n -octadecane (10, 20, 25, 30% w/w). The results indicated that the maximum encapsulation ratio for n -octadecane/PUPCM10000 composites was around 25% w/w. The chemical structure and crystalline properties of these composites were characterized by Fourier transform infrared spectroscopy (FT-IR), polarizing optical microscopy (POM), wide-angle X-ray diffraction (WAXD). Thermal properties and thermal reliability of the composites were determined using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). From DSC analysis, the composites showed a typical dual phase change temperature. The enthalpy for the composite with 25% w/w n -eicosane was as high as 141.2 J/g. TGA analysis indicated that the composites degraded at considerably high temperatures. The process of preparation of PUPCMs and their composites was very simple, inexpensive, environmental friendly and easy to process into desired shapes, which could find the promising applications in solar energy storage and building.
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 MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
·
2018
·Vol. 29
·期 17
·15241-15248
·
IF 2.324
Ma Xiaochun,Liu Yanjun,Liu Han,Xu Bin,Zhou Jing,Xiao Fan
In this study, the microencapsulated phase change material with paraffin as core and inorganic TiO 2 shell was successfully synthesized by in situ hydrolysis and polycondensation of tetrabutyl titanate in a nonaqueous oil-in-water emulsion using formamide as aqueous phase. The chemical compositions, crystalline structure, morphology and microstructure of paraffin@TiO 2 microcapsules were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffractometer (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The thermal properties and thermal stability of the microcapsules were measured by differential scanning calorimeter (DSC) and thermo-gravimetric analyzer (TGA). FT-IR and XRD results proved that there was no chemical reaction between paraffin core and TiO 2 shell material. SEM images indicated that the paraffin@TiO 2 microcapsules showed a regular spherical shape with the average diameters of 2–5 µm with a smooth shell. SEM and TEM studies also confirmed the paraffin was fully encapsulated with TiO 2 . DSC analysis indicated that the microcapsules had similar phase change behaviors as those of pure paraffin. Typical sample froze at 52.24 °C with a latent heat of 110.42 J g −1 and melt at 60.41 °C with a latent heat of 107.54 J g −1 , of which the encapsulation ratio achieved to 54.58%. TGA results indicated the thermal stability of paraffin was improved by the protection of TiO 2 shell through the encapsulation.
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
·
2020
·Vol. 13
·期 4
·894
·
IF 3.057
Yafang Zhang,Wang Li,Juhua Huang,Ming Cao,Guoping Du
In this work, expanded graphite/paraffin/silicone rubber composite phase-change materials (PCMs) were prepared by blending the expanded graphite (EG), paraffin wax (PW) and silicone rubber (SR) matrix. It has been shown that PW fully penetrates into the three dimensional (3D) pores of EG to form the EG/PW particles, which are sealed by SR and evenly embedded in the SR matrix. As a result of the excellent thermal stability of SR and the capillary force from the 3D pores of EG, the EG/PW/SR PCMs are found to have good shape stability and high reliability. After being baked in an oven at 150 °C for 24 h, the shape of the EG/PW/SR PCMs is virtually unchanged, and their weight loss and latent heat drop are only 7.91 wt % and 11.3 J/g, respectively. The latent heat of the EG/PW/SR composites can reach up to 43.6 and 41.8 J/g for the melting and crystallizing processes, respectively. The super cooling of PW decreased from 4.2 to 2.4 due to the heterogeneous nucleation on the large surface of EG and the sealing effect of the SR. Meanwhile, the thermal conductivity of the EG/PW/SR PCMs reaches 0.56 W·m−1·K−1, which is about 2.8 times and 3.73 times of pure PW and pristine SR, respectively. The novel EG/PW/SR PCMs with superior shape and thermal stabilities will have a potential application in heat energy storage and thermal interface materials (TIM) for electronic devices.Keywords:phase change material;expanded graphite;paraffin;silicon rubber;composite
研究领域:
材料科学
·
热能存储
·
电子器件
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF APPLIED POLYMER SCIENCE
·
2019
·Vol. 136
·期 21
·47552
·
IF 2.188
Dong Xu,Rui Yang
Microencapsulated phase-change materials (MEPCMs) with paraffin as the core and poly(methyl methacrylate) (PMMA) and PMMA copolymers as the shell were prepared by emulsion polymerization using redox initiators at low temperatures. Fourier transform infrared spectroscopy was used to characterize the chemical composition of MEPCMs. The thermal properties and thermal stabilities of MEPCMs were tested by differential scanning calorimetry and thermogravimetric analysis. The morphologies and sizes of the microcapsules were investigated by scanning electron microscopy and particle size distribution analysis. The results indicated that the yield of microcapsules is as high as 96.2%, and the encapsulation efficiency of paraffin is nearly 100% when the paraffin content in MEPCM is 70%. The MEPCMs have good stability: the leakage ratios of MEPCMs can be less than 1% after 50 heating–cooling cycles. Therefore, the microencapsulation of paraffin using redox initiators has good production and application prospects. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136 , 47552.
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 CONVERSION AND MANAGEMENT
·
2020
·
IF 8.208
Yanwei Hu,Lei Shi,Zhenduo Zhang,Yurong He,Jiaqi Zhu
The addition of external force provides an alternative way to promote the application of phase change materials in thermal-energy storage, space heating, and cooling systems. However, the experimental investigation using external magnetic force to regulate the phase change process is still limited. Here, magnetic Fe 3 O 4 nanoparticles were added to paraffin wax to form phase change nanocomposites with enhanced thermal properties and controllable magnetism. The thermal properties of nanocomposites were measured and the phase change processes under magnetic controlling were experimentally and numerically investigated. A two-dimensional enthalpy-based lattice Boltzmann model with considering the external magnetic force was proposed and the measured thermal properties were used in the simulation. Good agreement between the experiment and simulation was achieved. The effects of different mass fractions of Fe 3 O 4 nanoparticles (0, 1, 2, 3 and 4 wt%), magnetic directions, magnetic field intensities (0, 20, 40, 60 mT) on the phase change characteristics are discussed. The heat transfer efficiency in a square cavity filled with the nanocomposites developed more quickly when the paraffin wax was doped with a higher Fe 3 O 4 mass fraction. Moreover, the phase change characteristics were controlled by the intensity and direction of the magnetic field. This study presents a method to achieve magnetically regulating phase change heat transfer characteristics that have potential applications in the energy-storage industry.
研究领域:
能源存储
·
热传递
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING COMMUNICATIONS
·
2023
·
IF 2.5
Yanxiao Chen,Huifen Zhang,Xian Luo,Shiyun Jiao,Baocai Li,Mi Zhang
Crude montan wax (CMW) is a natural wax extracted directly from lignite by organic solvents that can be prepared into deresined montan wax (DMW) by the deresination process and then bleached into refined montan wax (RMW) by an oxidation process. Based on the different requirements for the DMW properties in different applications, a study on effects of the different factors on the deresination rate in CMW and the residual montan resin (MR) content on basic properties of DMW was carried out in this work. It was found that ethyl acetate displays an improved deresination effect, and that time and temperature are the two key factors that affect the CMW deresination rate (ǀ r ǀ > 0.9). With the increase in the residual MR contents in DMWs, the melting point of DMW decreased while its melting range widened, and its friability, acidity and saponification values increased. Gas chromatography-mass spectrometry analysis revealed that DMWs are rich in fatty esters and acids. It is concluded that the differences in their properties are related to the changes in the amount and content of the acids and esters.
研究领域:
化学工程
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
FUEL PROCESSING TECHNOLOGY
·
2021
·
IF 7.033
Yang Liu,Zhengnan Sun,Guolin Jing,Shuo Liu,Yihai Yang,Jianqi Xu
The alkali-catalyzed alcoholysis of polyethylene vinyl acetate (EVA) was used to obtain the product ethylene-vinyl alcohol copolymer (EVAL), and the grafting product poly(ethylene-vinyl alcohol)-graphene oxide (EVAL-GO) was prepared in the form of chemical grafting by utilization of the groups on the surface of GO and EVAL through the esterification reaction. The products were analyzed by Fourier transform infrared (FTIR), 1 H nuclear magnetic resonance (NMR) and Thermogravimetric (TG). The rheological properties of the oil sample and changes in the morphology of wax crystals were characterized by Advanced Hybrid Rheometer and polarized optical microscopy (POM) respectively. The degree of alcoholysis of EVAL reached 74.51%, and the grafting rate of EVAL-GO (0.5%) was 36.18%. Reduction of pour point and gel point of nanocomposite treated crude oil was 12 °C and 4 °C from undoped crude oil at the optimum additive concentration of 1000 mg/kg. Moreover, it decreased the viscosity and yield value of virgin crude oil by 99.5% and 78.3%, respectively. From the morphological analysis, it was indicated that EVAL-GO could make the wax crystals form sphere-like crystals, and the increased void space promoting more liquid oil to be released thus significantly improving the low-temperature fluidity of Daqing waxy crude oil.
研究领域:
石油工程
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
POLYMER COMPOSITES
·
2023
·Vol. 44
·期 5
·2757-2765
·
IF 5.2
Linyu Pu,Yu Li,Jingyuan Tang,Yiting Long,Wei Wang,Yatang Dai,Xu Huang
Firstly, the BaTiO 3 nanoparticles were coated with a layer of paraffin, forming a core shell structure. Then, as-prepared paraffin@BaTiO 3 nanofillers were directly blended with polyimide (PI) prepolymer to fabricate paraffin@BaTiO 3 /PI composite films. The microstructure, thermal, and dielectric properties were investigated in detail. The surface-modified paraffin@BaTiO 3 nanoparticles exhibited a typical core shell structure with uniform and complete coverage. The char yield of the composite film with 10 wt% paraffin@BaTiO 3 increased from 56.40% to 70.73%. It is obvious that the paraffin@BaTiO 3 nanofillers have a positive effect on ablative performance of the composite film. Compared with pure PI, the ε r of paraffin@BaTiO 3 /PI composites with 40% mass fraction increased from 3.41 to 9.35 (1 kHz). The tanδ of paraffin@BaTiO 3 /PI composites was just 0.0065 (1 kHz) when the filler loading was 40 wt%. Temperature dependency of the permittivity of the composites reveals a zero-temperature-coefficient from 80°C to 180°C.
研究领域:
材料科学
·
电子工程
✓ 已验证
产品关联
DOI
高影响因子
FUEL
·
2024
·
IF 6.7
Shikun Tong,Yuemeng Ren,Kele Yan,Yanxin Jin,Pengfei Li,Jianbo Zhang,Zhiyuan Wang
The coupling deposition and plugging caused by hydrate formation and wax precipitation during the development of deep water natural gas resources bring new industrial challenges and theoretical difficulty. We designed a single-pass pipeline with two types to investigate deposition behavior and systematically performed the coupling deposition and plugging of hydrate and wax experiments in gas–liquid annular flow . The experimental results illustrate that the single solid phase of hydrate is covered layer sheet deposition, while the coupling solid phase of hydrate and wax is bulk aggregations arch bridge deposition. Meanwhile, the natural eddy zone in reducing pipeline accelerates coupling solid particles deposition. Our finds provided the first knowledge on the double effect that wax crystals inhibit particles adhesion and gel network increases aggregations arch bridge blockage. For the low water content in emulsion system, the gel network provides gathering place for hydrate particles, and the arch bridge structure formed by aggregations accelerates the pipeline blockage. The plugging time is shortened by up to 72.6% with the wax concentration increase from 0 wt% to 3 wt%. For the high water content in emulsion system, the majority of wax crystals adsorbed on the hydrate particles and reduce particles cohesion force, which increase the plugging time. Combined with the microscopic morphology evolution perspective of hydrate particles coupled wax, the coupling deposition of hydrate and wax in gas–liquid annular flow has four stages: gas–liquid flow, coupling solid phase formation, coupling solid phase deposition and sloughing, and coupling solid phase plugging. This study can provide theoretical support and design basis for flow assurance program of deep water gas fields and low temperature natural gas transportation pipelines.
研究领域:
石油工程
·
化学工程
✓ 已验证
DOI
高影响因子
CHEMICAL ENGINEERING SCIENCE
·
2021
·
IF 4.311
Dongxu Zhang,Qiyu Huang,Rongbin Li,Wei Wang,Xiangrui Zhu,Huiyuan Li,Yijie Wang
In this study, the effects of waxes on carbon dioxide hydrate formation and dissociation in asphaltene-containing emulsions were systematically investigated using a high-pressure stirred autoclave equipped with an on-line viscometer. The results showed that the presence of waxes strengthened the inhibiting effect of asphaltenes on hydrate formation. Specifically, the induction time increased and the amount of formed hydrates decreased with increasing wax content in water-in-oil emulsion containing asphaltenes. The results indicated that waxes increased the viscosity of emulsions. It was observed that wax crystals dispersed in the bulk phase and got adsorbed at water–oil interface through the synergistic effect with asphaltenes. Furthermore, waxes inhibited the dissociation of hydrates in these emulsions. Both the gas emission rate and the average rate of hydrate dissociation decreased with an increase in wax content. The possible mechanisms were proposed to illustrate the effects of waxes on hydrate formation and dissociation in asphaltene-containing water-in-oil emulsions.
研究领域:
化学工程
·
石油工程
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）