JOURNAL OF CHEMICAL THERMODYNAMICS
·
2018
·
IF 2.631
Qingnan Zhang,Aijie Yan,Zixiang Cui,Yongqiang Xue
As an electrode material, the many excellent properties of nano-Bi 2 O 3 have been researched. However, the influences of particle size on the electrode reaction thermodynamic properties of nano-Bi 2 O 3 electrode are not clear. In this paper, the effect of particle size on electrochemical thermodynamic functions of nano-Bi 2 O 3 electrode was analyzed theoretically. In experiment, the spherical nano-Bi 2 O 3 with different particle sizes and the corresponding nano-Bi 2 O 3 electrodes were prepared, then the temperature coefficients of nano-Bi 2 O 3 electrodes and the thermodynamic functions of the electrode reaction were obtained by measuring the electrode potentials of nano-Bi 2 O 3 electrodes with different particle sizes at different temperatures. The experimental results show that the particle size has significant influence on the thermodynamic properties of nano-Bi 2 O 3 electrode, the standard electrode potentials and the equilibrium constants increase with the particle size decreases, while the temperature coefficient, the mole Gibbs energy change, the mole enthalpy change and the mole entropy change reduce. In addition, these physical quantities are all linearly related with the reciprocal of average particle size when the radius exceeds 10 nm. The experimental regularities are consistent with the theoretical analysis.
研究领域:
材料科学
·
电化学
✓ 已验证
DOI
高影响因子
CATALYSIS COMMUNICATIONS
·
2023
·
IF 3.7
Mengnan Li,Huiyue Xin,Tongyang Song,Chen Zhao,Peng Wu,Xiaohong Li
Pt/Co 0.5 Fe 0.5 Al 2 O 4 catalysts with the average Pt particle size of 1.6–3.4 nm were prepared and applied to the selective hydrogenation of cinnamaldehyde (CAL). Not only the TOF was promoted from 0.19 to 2.70 s −1 , but also the selectivity to cinnamyl alcohol (COL) was improved from 68% to 94%, with the increase of Pt particle size. Stronger interaction occurred between Co 0.5 Fe 0.5 Al 2 O 4 and smaller-sized Pt particles, resulting in electron-deficient Pt particles, so that C O and C C bond could be activated simultaneously. However, electron-rich Pt species existed on Pt/Co 0.5 Fe 0.5 Al 2 O 4 with larger Pt size, which is beneficial for the preferential activation of C O bond.
研究领域:
催化化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF POLYMER RESEARCH
·
2024
·Vol. 31
·期 7
·1-15
·
IF 2.6
Xu Lu,Zhang Mingyao,Liu Baijun
Methyl methacrylate-acrylonitrile-butadiene-styrene (MABS) was obtained by blending the rubber phase with matrix resin. Matching the refractive index was crucial for transmittance in MABS resins. Additionally, the superimposed effect of particle size and the interfacial area further determined the MABS resin transparency. The MABS resin with a rubber particle size of 201nm had a transmission of 88.9% when the refractive indexes of the two phases were close. By utilizing a bimodal distribution of toughened particles in the phase domain structure, the rubber particle size could be altered while maintaining control over the interfacial area. It resulted in an increase in the transmittance of the MABS to 90.1%. The analysis of mechanical properties and morphology shows that the phase structure with a bimodal distribution of toughened particles is also beneficial to the impact and tensile strength of MABS resin. When toughening particles with a size of 73nm and 304nm were mixed in a mass ratio of 60:40, the impact strength was 145 J/m, the tensile strength was 47MPa, and the elongation at break was 20%. And the study investigated the impact of rubber content on the properties of transparent MABS resins.
研究领域:
材料科学
·
高分子化学
✓ 已验证
产品关联
DOI
高影响因子
POLYMER INTERNATIONAL
·
2017
·Vol. 67
·期 1
·78-84
·
IF 2.07
Zhe Sun,Haojun Fan,Yi Chen,Junjiang Huang
The effect of structural factors, including the type of diisocyanates and glycols, degree of crosslinking, hard-segment content, crystallinity and hydrophilic group content, on optical properties of waterborne polyurethane (WPU) was investigated. Based on the relationship between structure and properties, a series of self-matting WPUs with excellent transmittance were synthesized. Results demonstrated that refractive index of constituent groups was an important factor to influence the optical properties of coatings. For multiphase polyurethane, aromatic ring, ester bond, NH COO and urea groups with high refractive index could decrease the matting effect and transmittance. Higher hard-segment content resulting in an increase of the number of NH COO or urea bonds also decreased the matting effect and transmittance. The aggregation structure of WPU was another factor to influence the optical properties of coatings. Crystalline soft and hard segment domains could decrease the transmittance and matting effect, whilst non-crystalline segments, pendent groups and crosslinking destroyed the regularity or crystallinity of macromolecules, behaving as an auxiliary function to improve the transmittance. The particle size of WPU was of great importance for the matting effect. Smaller particle size (<5.0 µm) would endow the coating with a smoother surface and higher reflected light ratio, and thus the expected matting effect was hard to be achieved. A larger particle size could improve the matting effect but impart to the coating a coarse surface and hand-feel. When the 2,2-bis(hydroxymethyl)propionic acid content was 1.6 wt%, spherical particles with a size distribution of 7–8 µm were aggregated on the coating surface, giving the coating an excellent matting effect and hand-feel. © 2017 Society of Chemical Industry
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
MATERIALS CHEMISTRY AND PHYSICS
·
2018
·
IF 2.21
Chuanhui Xu,Jianfeng Fan,Daosheng Yuan,Yanpeng Wang,Yukun Chen
Peroxide-induced dynamic vulcanization of poly (vinylidene fluoride)/silicone rubber (PVDF/SR) blends was studied in this paper. We controlled the size of rubber particles by changing the rotor speed , and discussed the influence of shearing on the particle diameter and the particle diameter polydispersity ( d p ). The size of SR particle was confirmed to be decreased with increasing the rotor speed. However, a good matching degree of shearing and crosslinking rate helped the SR phase to achieve a uniform crosslinking, as well as a narrow d p . In this particular PVDF/SR system, the suitable rotor speed was found to be 90 rpm, at which the d p reached a minimum of 1.1981 and 1.1614 for the P9S1 and the P7S3, respectively. At last, we discussed the influences of the macroscopic breaking energy ( E dk ) and the coalescence ( P ) on the number-average particle diameter ( D n ) of the SR. This work is thus devoted to construct a model for predicting the particle size in dynamic vulcanization of PVDF/SR blends.
研究领域:
材料科学
·
高分子化学
✓ 已验证
DOI
高影响因子
DESIGNED MONOMERS AND POLYMERS
·
2015
·
IF 2.78
Jishuai Wang,Botian Li,Qingjun Jin,Xinyi Huang,Jie Shen,Chengyou Kan
A polymerizable red dye 1-(6-acrylamidohexylamino) anthraquinone (AHAQ) was synthesized and used to prepare colored polymer latexes using styrene and butyl acrylate as main monomers. Influences of the initiator and surfactant amounts, oil/aqueous phase ratio, and AHAQ content on the polymerization process, the particle size, and surface tension of the resulted latex were investigated, and the migration resistance and light fastness of the red latex films were determined. Results showed that the polymerization was carried out smoothly, and the miniemulsion polymerization mechanism was confirmed by monitoring the dimensions of oil phase before and after polymerization. The latex particle size can be adjusted by varying the surfactant amount, and when AHAQ content was 0.2–1 wt% of total monomers, the encapsulation efficiency and dye conversion could be achieved to 98.7 and 96.3%, respectively. The UV–vis spectra of AHAQ and its corresponding covalently colored polymer indicated that the maximum absorption peak was the same, meaning that the chemical structure of chromophore in AHAQ maintains unchanged after undergoing polymerization. The migration resistance and light fastness of the covalently colored latex films were much better than that of the correspondingly non-covalently colored ones.
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
NEW JOURNAL OF CHEMISTRY
·
2023
·Vol. 47
·期 26
·12279-12286
·
IF 3.3
Chaowen Liu,Mudi Xin,Xuejing Zhang,Chunlu Wang,Limei Qiu,Guangtong Xu
As an alternative to conventional cryogenic distillation, LTA zeolites act as cost-effective adsorbents for the adsorptive separation of ethylene and ethane. In this approach, the thermodynamic and kinetic separation of ethylene and ethane by LTA zeolites with regulated particle sizes and pore structures has been studied. Herein, LTA zeolites, with different particle sizes ranging from 0.82 μm to 4.96 μm and a pore diameter distribution concentrated around 4.16–5.07 Å, were prepared using the hydrothermal method followed by an ion-exchange procedure. The results indicated that variation of the zeolitic particle size and the Ca2+ exchange rate has a great influence on the separation process, including the selectivity of C2H4 and the breakthrough time intervals of C2H4 and C2H6. Several issues, including the intracrystalline diffusion, accessibility of active sites, reinforced interaction between adsorbents and adsorbates, and the confined space in the zeolitic channels, were investigated to explain the altered nature of the separation performance. The optimized separation performance was achieved using LTA zeolites with a particle size of 0.82 μm or with an ion-exchange rate of 69.13% and a pore diameter distribution of 4.94 Å.
研究领域:
化学工程
·
材料科学
·
吸附分离技术
✓ 已验证
DOI
高影响因子
POWDER TECHNOLOGY
·
2023
·
IF 5.2
Yuxiang Cheng,Zhongjie Shen,Feng Lv,Dayang Wan,Yongchuan Gao,Yiru Yang,Haifeng Lu,Zhenghua Dai,Haifeng Liu
During the Ca(OH) 2 /CaO thermochemical energy storage process, the cyclability of reactions and the consolidation properties of powder storage are important issues to consider. In this study, experiments were conducted to assess the evolution of reaction conversion, particle size and penetration resistance of Ca(OH) 2 /CaO powder fixed bed. The results revealed that the final conversions of both the hydration and dehydration reactions stabilized between 70 and 80%. The particle size distributions of Ca(OH) 2 increased initially and then decreased with the increasing cycle number and degree of dehydration. The dehydration conversion was the dominant factor for changing Ca(OH) 2 bed penetration resistance force. The particle size and penetration resistance of the CaO bed remained stable during long-term storage at high temperatures. The theoretical analysis of the inter-particle forces agreed with the trend of the experimental results, with particle size and moisture content being the main factors affecting cohesion.
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 Environmental Sciences
·
2020
·
IF 4.302
Hongyan Sun,Ruyuan Jiao,Guangyu An,Hui Xu,Dongsheng Wang
More and more attention has been paid to the aggregation behavior of nanoparticles , but little research has been done on the effect of particle size. Therefore, this study systematically evaluated the aggregation behavior of nano-silica particles with diameter 130–480 nm at different initial particle concentration, pH, ionic strength, and ionic valence of electrolytes. The modified Smoluchowski theory failed to describe the aggregation kinetics for nano-silica particles with diameters less than 190 nm. Besides, ionic strength, cation species and pH all affected fast aggregation rate coefficients of 130 nm nanoparticles . Through incorporating structural hydration force into the modified Smoluchowski theory, it is found that the reason for all the anomalous aggregation behavior was the different structural hydration layer thickness of nanoparticles with various sizes. The thickness decreased with increasing of particle size, and remained basically unchanged for particles larger than 190 nm. Only when the distance at primary minimum was twice the thickness of structural hydration layer, the structural hydration force dominated, leading to the higher stability of nanoparticles. This study clearly clarified the unique aggregation mechanism of nanoparticles with smaller size, which provided reference for predicting transport and fate of nanoparticles and could help facilitate the evaluation of their environment risks.
研究领域:
环境科学
·
胶体化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
APPLIED SURFACE SCIENCE
·
2017
·
IF 3.387
Ting-Ting Zhang,Jian-Dong Song,Jia-Xi Chen,Ai-Ping Jia,Meng-Fei Luo,Ji-Qing Lu
A series of supported CoCr 2 O 4 /TUD-1 catalysts with different loadings were prepared and tested for catalytic combustion of dichloromethane, in order to investigate the effect of particle size on the catalyst properties and related catalytic behaviors. It was found that the supported catalyst with low content of CoCr 2 O 4 had smaller CoCr 2 O 4 particles compared to that with high content, as revealed by the XRD results. Consequently, the changes in particle size altered the surface composition of the catalyst, as the small particles contained higher content of surface Cr 6+ species compared to the large ones. The enrichment of Cr 6+ species improved catalyst reducibility and surface acidity, which synergistically governed the observed catalytic behaviors. As a reuslt, the 5CoCr 2 O 4 /TUD-1 catalyst had the highest reaction rate of 64.8 × 10 −7 molDCM g −1 CoCr2o4s −1 , due to its best reducibility and highest surface acidity.
研究领域:
化学工程
·
环境科学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
ELECTROANALYSIS
·
2019
·Vol. 31
·期 7
·1316-1323
·
IF 2.691
Mengying Wang,Zixiang Cui,Yongqiang Xue,Aijie Yan,Xing Yu,Xinru Song,Hongxing Li
Nano-bismuth has excellent electrochemical properties. However, it is still unclear how the particle size of nano-bismuth influences its electrochemical thermodynamic properties. In this paper, spherical bismuth nanoparticles with different particle sizes were prepared by solvothermal method; the electrode potentials, the temperature coefficients of the electrode potentials and the thermodynamic functions of reaction for nano-bismuth electrodes with different particle sizes at different temperatures were determined; and the effects of particle size on the electrode potential, the temperature coefficient and the thermodynamic functions were discussed. The experimental results show that particle size of bismuth nanoparticles has a significant influences on the electrochemical thermodynamic properties. The standard electrode potential of the nano-bismuth electrode with a diameter of 39.9 nm was 0.009 V lower than that of the ordinary standard electrode (0.308 V); the temperature coefficient of the electrode potential with a diameter of 39.9 nm was nearly double that of 85.9 nm. With the particle sizes decrease, the standard molar Gibbs energy of reaction, the standard molar enthalpy of reaction, the standard molar entropy of reaction, the molar reversible reaction heat and the temperature coefficient increase; and these quantities are linearly related to the reciprocal of the particle diameter.
研究领域:
材料科学
·
电化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF POLYMER SCIENCE
·
2024
·
IF 3.9
Li Zhao,Shulai Lu,Ming Chen,Yuchao Wang,Shicheng Zhao
Polymer agglomeration is a useful way to enlarge the particle size of polybutadiene latex (PBL). However, the agglomeration process is very complex and is affected by many factors. Therefore, it is difficult to predict the mean particle size and distribution of agglomerated PBL. This study proposed a novel simulation method based on the artificial neural network (ANN) model. Firstly, the influence of agglomeration conditions on the particle size of agglomerated PBL were investigated, including the particle size of pre-agglomerate PBL, the amount, the α-methacrylic acid (α-MAA) content, the solid content and the particle size of agglomerating agent. It is found that these factors have a close nonlinear relationship with the mean particle size and polydispersion index (PDI) of agglomerated PBL. Then, a model containing 236 data points was built using ANN including these properties as input with mean particle size and PDI of agglomerated PBL as output. The coefficient of determination ( R 2 ) values predicted by ANN for training, validation, test and total data are 0.9879, 0.9964, 0.9930, and 0.9902, respectively. It indicates that there is a good agreement between experimental data and predicted results by ANN. This study demonstrates that a simple machine learning method has good performance in predicting the particle size of agglomerated PBL, which further improves the development efficiency of PBL polymer agglomeration. Graphical
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
危险品化学品经营许可证（带存储）