JOURNAL OF CHEMICAL THERMODYNAMICS
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2023
·
IF 2.6
Xiong Zheng,Yanqiong Bao,An Huang,Linfeng Yu,Guangzhao Qin
The knowledge of the thermophysical properties of phase change materials (PCMs) is of great importance in the design of thermal energy storage systems. In this work, several thermophysical properties of four PEGs with different molecular weights from 800 to 2000 were studied experimentally. Differential scanning calorimetry (DSC) was used to study the phase change temperatures and latent heat in the melting and crystallization processes of PEGs. The thermal conductivities of PEGs covering both solid and liquid phases were measured by a transient hot-wire thermometer at a temperature range from 283.15 to 353.15 K. Density and viscosity of liquid PEGs were determined by densimeter and viscometer, respectively. Phase change latent heat, thermal conductivity, and density increase with PEG molecular weight, which indicates that PEGs with higher molecular weight show better energy storage ability per volume. Phase change temperatures vary with molecular weight, so a wide range of operating temperatures can be satisfied using different molecular weight PEGs. Viscosity increases dramatically with PEGs molecular weight, so higher pump energy consumption is needed for larger PEG when it flows in the liquid phase. Furthermore, available literature data were used to compare with our results, our data agree well with most literature data.
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RSC Advances
·
2023
·Vol. 13
·期 49
·34576-34586
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IF 3.9
Mingyu Shang,Yanfei Wei,Herong Zhou,Tao Wu,Ke Wang,Hongxiang Chen,Beisong Fang,Yang Zhao
PEG2000 (polyethylene glycol, molecular weight: 2000) is commonly used for the dehydration and reinforcement of waterlogged wooden cultural relics, but its photo-aging degradation will seriously affect the long-term conservation of the wooden cultural relics. In this study, the photo-aging characteristics and mechanisms of PEG2000 under UV (ultraviolet) irradiations of three wavelengths were comprehensively investigated, and the surface morphology, crystal structure, and relative molecular weight of PEG2000 were systematically characterized. The results showed that PEG2000 showed a higher gloss loss rate, carbonyl index and crystallinity, and a wider molecular weight distribution with increasing aging time, especially under the irradiation of 313 nm ultraviolet light. The evolution of the PEG2000 from surface to interior during photoaging was elucidated by SEM (scanning electron microscopy) and FTIR (Fourier transform infrared spectroscopy), and it was determined that photodegradation not only occurs on the surface of PEG2000 but also gradually extends to the interior of the sample with the prolongation of irradiation time, resulting in the transformation of the basic component unit of spherical crystals in PEG2000 from fibrous crystals to spherical particles. Based on 1H-NMR (nuclear magnetic resonance spectroscopy), the photochemical reactions for the generation of degradation products were proposed, and it was found that the degradation occurred at the C–H and C–O–C bonds on the main chain, forming a large number of ester and ethoxy structures. The aging degree of PEG2000 was evaluated from the perspective of surface morphology and chemical structure by gloss and FTIR spectroscopy, and it was found that the combination of gloss loss rate and carbonyl index was more suitable to evaluate the aging degree of the sample. The relevant theoretical research will provide reliable guidance for the preservation of polyethylene glycol in waterlogged wooden cultural relics.
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PubMed
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2021
·
IF 7.312
Wenyan Shi,Xiaolong Han,Fang Bai,Chao Hua,Xingzhong Cao
The metal–organic framework MOF-505 particles were synthesized and incorporated into the polyethylene glycol (PEG) matrix to prepare mixed matrix membranes. A series of methods were used to characterize the structure and morphology of MOF-505 particles and membranes. The prepared MOF-505 had a well-developed pore structure, a large number of metal sites for selective adsorption of thiophene and good compatibility with polymer matrix. Accordingly, the desulfurization performance of the membrane was improved effectively. The effects of the content of MOF-505, operating temperature and feed sulfur content on membrane performance were investigated by pervaporation experiments. The membrane with 3 wt% MOF-505 showed the optimal desulfurization performance with a permeation flux of 2.66 kg/(m 2 ·h) and an enrichment sulfur factor of 8.15, which were increased by 158% and 25% versus pristine membrane, respectively.
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POLYMERS FOR ADVANCED TECHNOLOGIES
·
2021
·Vol. 32
·期 10
·4061-4069
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IF 3.665
Fucheng Wu,Shanjun Gao,Yingying Zeng,Yunzhe Li,Zhixin Zhao,Chunhui Shen
Release agent is an indispensable kind of processing aids for composite molding. A kind of release agents was synthesized by using polyethylene glycol (M n = 200, 300, 400) with different molecular weight as raw material, reacting with fatty acids with different carbon chains length (lauric acid, myristic acid, hexadecanoic acid, and stearic acid), and further crosslinking with phosphoric acid. The chemical structure of the synthesized release agent was confirmed by FT-IR and 1 H-NMR. Through the performance test of the synthesized demolding agent, five release agents with excellent performance were screened out. The results showed: The release agents can be well dissolved in ethanol, a green and environment-friendly solvent. The molecular weight was 480–630. The release agent's acid value was between 0.05 and 0.06KOH/(mg/g). The peeling strength was 0.066–0.087 MPa and the interlaminar shear strength was 1.101–1.323 MPa. The film-forming time of the release agents on the mold was 1.5 min–3.5 min. The number of demolding was 16–20 times. The micro-morphology of the resin surface demolded by NnP release agent synthesized in the present study and Meishu brand release agent widely-used in the market was observed and compared by scanning electron microscope, indicating that the surface morphology of the resin demolded by NnP release agent was smoother after release. So the NnP release agents can be used in actual production.
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SAFETY SCIENCE
·
2020
·
IF 4.105
Ru Zhou,Jingjing Mu,Xiaoyan Sun,Yanming Ding,Juncheng Jiang
A novel intumescent flame retardant (IFR) composed of aluminum diethyphosphinate, neopentyl glycol, and melamine was incorporated into linear low-density polyethylene (LLDPE). The flame retardancy, thermal properties, and flame retardant mechanism of the materials were investigated. The chemical structures of composites were characterized by Fourier-transform infrared spectroscopy. Samples with thicknesses of 3 mm achieved the UL-94 V-0 rating during vertical burning tests, and the limiting oxygen index was 26.9% when 28 wt% IFR was introduced. The results of the thermogravimetric analysis showed that the addition of the IFR promoted the degradation and carbonization of the materials initially, increased the amount char residue, and improved the thermal stabilities of the composites at high temperatures. Cone calorimeter tests indicated that the peak value of the heat release rate was considerably reduced with the incorporation of the IFR. The digital photographs and scanning electron microscopy images of the char residue after cone calorimeter tests showed the formation of compact and thermally stable char layers on the polymer composites surfaces.
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JOURNAL OF MEMBRANE SCIENCE
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2020
·
IF 7.183
Dinglei Zhong,Zhaogen Wang,Jiemei Zhou,Yong Wang
Hemodialysis membranes have been widely used for the treatment of chronic kidney disease. However, as common hemodialysis membranes, polysulfone based membranes are suffering from complicated modification to improve hemocompatibility and safety issues of additive leaching-out. Facing these challenges, here hemodialysis membranes with excellent hemocompatibility and biocompatibility were fabricated by nonsolvent induced phase separation (NIPS) of a block copolymer , polysulfone- block -poly(ethylene glycol) (PSF- b -PEG), without using any additives. During NIPS, mesopores were formed throughout the membrane and the PEG chains were preferentially enriched on surfaces, thus improving the hydrophilicity. In-vitro compatibility and performance of the PSF- b -PEG membranes as well as protein adsorption, hemolysis, platelet adhesion, ultrafiltration coefficient, solute rejection and toxin clearance were studied. Due to the intrinsic existence of hydrophilic and biocompatible PEG on surface, the PSF- b -PEG membranes exhibited superior hemodialysis performances than traditional membranes, demonstrating their promise for hemodialysis.
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INTERNATIONAL JOURNAL OF ENERGY RESEARCH
·
2020
·Vol. 45
·期 5
·7675-7688
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IF 3.741
Qinrong Sun,Nan Zhang,Xiaoping Yu,Fali Ju,Imre Miklós Szilágyi,Yanping Yuan
Summary Phase change materials (PCMs) have limited use in thermal storage because of their poor conductivity and lack of multi driving energy. Therefore, to overcome these problems, polyethylene glycol-calcium chloride/expanded graphite (PEG-CaCl 2 /EG) functional composite PCMs with high electrical and thermal conductivities were synthesized by ligand substitution using PEG-CaCl 2 as the PCM and EG as the highly electrically and thermally conductive framework material. The PEG-CaCl 2 /EG PCMs were thoroughly investigated, and the experimental results revealed the significance of EG in the composite structure, which leads to high electrical conductivity and high thermal conductivity. The resistivity of the functional PCM decreased to 1.67 Ω m, and the thermal conductivity ( k ) increased to 8.4 W/(m K) when the EG content was 10 wt%. In addition, the electro-thermal conversion efficiency of the functional PCM reached 86.9%, and its energy storage could be inspired at low voltages (2.0-5.0 V). The heating and energy storage rates increased with the working voltage and EG content, respectively. Melting-crystallization experiments and electro-thermal cycle tests showed that the functional PCMs had good thermal stability. Therefore, this study provides a new perspective for various fields of energy conversion and storage.
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DIAMOND AND RELATED MATERIALS
·
2020
·
IF 2.65
Xiaoyu Shi,Shengnan Bai,Yuanyuan Li,Xiaoyan Yu,Kimiyoshi Naito,Qingxin Zhang
Nanodiamond (ND) was surface modified by polyethylene glycol (PEG) to improve the interfacial adhesion between ND and the polylactic acid (PLA) matrix and achieve uniform nanoparticle dispersion in the matrix. PEG functionalized ND (ND-PEG) was successfully prepared by a novel and scalable modification method. Firstly, the ND particles oxidized by air was treated with dopamine, and then the hydroxyl groups on PEG and polydopamine (PDA) were covalently linked by isocyanate groups . The Fourier Transform Infrared spectroscopy, Thermogravimetric analysis and X-ray photoelectron spectroscopy reveal that PEG has been covalently boned on the surface of ND. Compared with those of pure PLA film, the tensile strength , tensile modulus and elongation at break of the nanocomposite films with PEG modified ND increase by 66.64%, 37.6% and 187.43%, respectively. In the meantime, the degradation temperature at the initial stage and the temperature at the maximum weight loss rate of the nanocomposite films are significantly increased. It is suggested that the incorporation of ND-PEG into PLA matrix is an effective method to improve the mechanical properties and thermal stability of PLA.
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MICROCHEMICAL JOURNAL
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2020
·
IF 3.594
Lanting Li,Yuhong Zhang,Zhenlei Peng,Chuan Wang
Monoethylene glycol (1, 2-ethanediol; MEG) is an important monomer for producing polyester. It must be very pure, which is usually indicated by a high ultraviolet (UV) transmittance. Low UV transmittance, especially at wavelength of 220, 250 and 275 nm, usually indicates the presence of undesirable impurities that lower polyester quality. Without a practical analytical method, tracing these impurities is difficult, rather than improving the refining process. Therefore, a facile, fast and sensitive method based on ultra-high performance liquid chromatography (UHPLC) equipped with photodiode array (PDA) detector and coupled with quadrupole time-of-flight mass spectrometry (Q-TOF MS) was developed for qualification and quantification of UV impurities in this paper. The UV impurities were identified as 3-methyl-1, 2-cyclopentanedione, 3, 5-dimethyl-1, 2-cyclopentanedione, and 3-ethyl-1, 2-cyclopentanedione. For tracing these impurities, the samples were directly injected without pretreatment and the compounds were analyzed within 8 min. The limit of detection (LOD) of the proposed method was around 0.07 mg/L. This method has been used to trace these impurities in MEG plants for optimizing process parameters and developing purification techniques. A probable pathway of impurity formation by base (or acid)-catalyzed model was proposed. Hydroxypropanone and 1-hydroxy-2-butanone were identified after 2, 4-dinitrophenylhydrazine (DNPH) treatment and they were supposed to be the precursors of UV impurities.
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INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
·
2020
·
IF 5.162
Lei Wang,Yujie Li,Dong Xiang,Weimin Zhang,Xinpeng Bai
Lutein is a hydrophobic carotenoid with diverse bioactivities. For encapsulating the molecule in a novel method, we prepared two emulsions from xanthan and propylene glycol alginate at the ratios of 3:7 and 4:6. The instability index and particle size of the emulsions were determined using a stability analyzer and laser particle size analyzer. The influence of crystallization on the emulsions was observed under a polarizing microscope. The effects of centrifugal force and storage on the lutein emulsions were analyzed by measuring the changes in absorbance. The results showed that the emulsion fabricated by xanthan and propylene glycol alginate at the ratio of 4:6 was highly stable, and crystals were dispersed when xanthan and propylene glycol alginate existed. These results revealed that the hydrophobicity and absorption kinetics of emulsifiers would determine the stability of emulsion when the viscosity of emulsifiers reached a certain value, and the stability of emulsions would affect the stability of lutein in the emulsions.
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PubMed
高影响因子
CHINESE JOURNAL OF CHEMISTRY
·
2020
·Vol. 38
·期 5
·453-457
·
IF 3.826
Chuang Li,Guangyue Xu,Xiang Zhang,Yao Fu
Summary of main observation and conclusion The conversion of fructose to 1,2-propylene glycol (PG) is an important process from cellulosic biomass to high-value added chemicals. Herein, Ru-WO x /hydroxyapatite (HAP) catalyst was employed for this reaction and reached up to 91.3% yield of PG at 180 °C, 1 MPa initial hydrogen for 8 h in water. On this catalyst, Ru and WO x were highly dispersed on HAP support and they interacted with each other to form a special catalytic center. The lack of isolated Ru or RuW alloy site led to a moderate activity for hydrogenolysis and hindered the further conversion of PG to propanol. The weak basic HAP support efficiently prevented the humin formation. This precisely controlled catalyst has potential in green PG production.
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SURFACE AND INTERFACE ANALYSIS
·
2021
·Vol. 53
·期 12
·1027-1034
·
IF 1.607
Qi Chen,Renhui Zhang,Zhongyi He,Liping Xiong
N-containing heterocyclic compound (NCHC) was a common used green lubricant addictive due to their extreme pressure, antiwear and friction–reduction performance, and high thermal stability, and ethylene glycol (EG) as lubricant exhibited superior tribological performance, combining of NCHCs, which was a suitable candidate for further improving the tribosystems' tribological properties. Thus, in this work, the synergistic effect between EG and 2,4,6-Tris(2-pyridinyl)-s-triazine (TPT) on the tribological performance was explored coupling of the applied loads and rotational speed. The tribological tests showed that TPT played an important role in improving the tribological properties as sliding in TPT@EG; the formation of the tribofilms induced by tribochemical reaction was in charge of enhancing the tribosystem's lubrication performance sliding in TPT@EG.
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危险品化学品经营许可证（带存储）