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
Polymers
·
2021
·Vol. 13
·期 11
·1754
·
IF 4.329
Huishi Pi,Weiping Li,Zhiwei Shi,Haining Chen,Xiaoyu Jiang
N-vinylpyrrolidone (NVP) has a large molecular structure, so it is difficult to diffuse during holographic recording, especially at low spatial frequencies. We used glycerol to promote the diffusion of NVP, and successfully improved the holographic performance of the photopolymer at low spatial frequencies. As the concentration of glycerol increases, the holographic performance first increases and then remains stable. The optimal concentration of glycerol is 0.21 mol/L. At this concentration, the maximum diffraction efficiency of the photopolymer is 84%, the refractive index modulation is 1.95 × 10−3, and the photosensitive sensitivity is 7.91 × 10−4cm2/mJ. Compared with the control group, the maximum diffraction efficiency, maximum refractive index modulation and photosensitivity at low spatial frequencies (800 lp/mm) have increased by 11.19 times, 4.69 times and 1.71 times, respectively. Using the optimized photopolymer for transmission holographic recording and reproduction, we have obtained a clear and bright transmission hologram. The photopolymer modified with glycerol is expected to be applied to the fields of holography, diffractive optics, and so on.Keywords:transmission holography;photopolymer;polymerization rate;diffusion rate;diffraction efficiency
研究领域:
光学材料
·
全息技术
✓ 已验证
DOI
PubMed
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2019
·
IF 5.107
Yifu Li,Li'ao Wang,Zhongchao Tan,Zhien Zhang,Xinyue Hu
Absorption and desorption of CO 2 using K 2 CO 3 solutions promoted by three amino acid salts (AASs), potassium glycinate (PG), potassium lysinate (PL) and potassium L-argininate (PA), were evaluated using 40% CO 2 at 40 °C and with pure N 2 at 80 °C, respectively. The addition of all 3 AASs clearly enhanced both absorption and desorption of CO 2 compared to single K 2 CO 3 solution. PA + K 2 CO 3 solution showed the highest CO 2 cyclic capacity of 0.678 mol CO 2 /mol absorbent, while the highest CO 2 absorption and desorption rates of 39.8 and 17.6 mol CO 2 L −1 s −1 were achieved by PG + K 2 CO 3 solution. Finally, simulated biogas containing 40% of CO 2 and 60% of CH 4 was used as test gas in a hollow fiber membrane contactor. PG and PA promoters presented higher CO 2 absorption flux and removal efficiency than PL promoters in K 2 CO 3 solution within low Gas/Liquid ratio region. Stable CO 2 removal performances for all three promoters were observed at elevated temperature and pressure for 60 min operation.
研究领域:
化学工程
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
ULTRASONICS SONOCHEMISTRY
·
2024
·
IF 8.7
Jie Li,Shichun Li,Shiliang Huang,Jinjiang Xu,Qilong Yan,Shaohua Jin,Yu Liu
Low sensitivity octahydro-1,3,4,7-tetranitro-1,3,5,7-tetrazocine (HMX) has garnered significant attention from researchers due to its reduced shock sensitivity. However, the crystallization process poses challenges due to the high solidity and viscosity of the metastable α phase. Despite efforts to address this with additional energy sources like ultrasonic irradiation, prolonged exposure duration often results in small particle sizes, hindering the production of HMX with a consistent particle size distribution, thus limiting its applicability. To overcome these challenges, a method combining ultrasonic irradiation and trace H + additive was proposed and investigated for their impact on the polymorphic transformation of HMX. The H + additive was found to modify barriers, thus there was a lack of competitive driving force for the nucleation or growth of the metastable α form, thereby shortening the transformation pathway and duration. Moreover, the H + additive significantly accelerated the nucleation rate of the β form (67.7 orders of magnitude faster with 0.10 wt ‰ H + ) and the growth rate of β form HMX (5.8 orders of magnitude faster with 0.10 wt ‰ H + ). While H + additive alone was insufficient to induce spontaneous nucleation of the β form, combining it with short-duration ultrasonic irradiation further promoted β nucleation and shortened the polymorphic transformation duration (almost 20 orders of magnitude shorter). This rational approach led to effective control of the transformation process. The resulting low sensitivity HMX crystals exhibited varying mean sizes ranging from 20 to 340 μm, with purity exceeding 99.6 %, an apparent density greater than 1.8994 g/cm 3 , and few internal defects, fully meeting the requirements of low-sensitivity HMX, thus significantly expanding its potential applications. Our study sheds light on the mechanisms governing HMX polymorphic transformation in the presence of additives and ultrasonic irradiation, offering guidance for the rational control of this complex transformation.
研究领域:
材料科学
·
化学工程
·
炸药科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Russian Journal of Physical Chemistry A
·
2024
·Vol. 98
·期 4
·568-576
·
IF 0.7
Yayuan Zheng
This paper discusses the crystallization kinetics of potassium sulfate in a stirred bed crystallizer through experimental investigation. Using classical nucleation theory, the homogeneous and heterogeneous nucleation mechanisms of potassium sulfate are studied. The induction time and critical nucleation parameters, including surface tension (γ), critical nucleation radius ( r *), critical nucleation free energy (Δ G *), and critical nucleation molecule number ( i *), are measured under different temperatures and supersaturation ratios. Experimental results show that as temperature and supersaturation ratio increase, induction time, critical nucleation free energy, critical nucleation radius, and critical molecule number decrease while nucleation rate increases. The crystal shape remains relatively unchanged with temperature and supersaturation ratio, but the average particle size increases with increasing supersaturation and temperature. Changes in measured nucleation parameters are consistent with classical nucleation theory. In addition, the kinetic equations of crystal nucleation and growth rate in a stirred crystallization system are fitted using population balance equations, and the results show that the growth rate increases with increasing supersaturation and stirring speed. In addition, the effects of the parameters in the nucleation rate equation suggest that suspension density has the greatest impact, followed by supersaturation ratio and stirring speed.
研究领域:
化学工程
·
材料科学
·
物理化学
·
过程工程
✓ 已验证
DOI
高影响因子
Metals
·
2022
·Vol. 12
·期 9
·1419
·
IF 2.695
Jie Wang,Hongtao Yang,Long Cheng,Pin Gao,Yanchun Li,Dongming Song
To improve the combustion stability and ignition performance of thermite, B/NC/CuO micro particles were prepared from boron (B), nano copper oxide (CuO), and nitrocellulose (NC) as an energetic binder through the electrospray technique. The burning rate dependency on boron content, ambient temperature, and pressure was estimated by compressing B/NC/CuO micro particles into columns. Scanning electron microscopy results show that the sizes of these particles mostly lie in the range of 3–4 μm. The particles are ignitable and burn consistently with minor variations in the conditions: B content (8.3–17%), ambient temperature (−50–55 °C), and ambient pressure (0.02–0.1 MPa). The optimum formula was observed for micro particles with 11 wt% B content. Compared with the ball milling sample, the standard deviation of the burning rate of the electrosprayed sample was reduced by 32%. Combustion is barely affected by ambient pressure. Between −50 °C to 55 °C, the burning rate of B/NC/CuO increases by 14.16% from an initial rate of 13.35 mm⋅s−1. In addition, the laser ignition energy required for B/NC/CuO microparticles was also reduced from 70 to 45 mJ.Keywords:boron;thermite;burning rate;combustion performance
研究领域:
材料科学
·
燃烧学
✓ 已验证
产品关联
DOI
高影响因子
Thermal Science and Engineering Progress
·
2025
·
IF 5.4
Yunpeng Yang,Lilong Nie,Yongkang Guo,Zhuoxuan Li,Sicheng Xu,Linlin Yi,Kaiyuan Li
To address the environmental risks posed by PFOS-containing fire extinguishing agents, the development of highly efficient and environmentally friendly fluorine-free foam extinguishing agents has become a forefront research area in the firefighting community. In this study, a novel foam extinguishing agent was prepared using the nonionic silicone surfactant SiCare2238 and the amphoteric hydrocarbon surfactant LAMC as core components, with hydrophilic nano-SiO₂ particles (NPs) introduced to construct a gas–liquid-solid three-phase fluorine-free foam system. By regulating the NP concentration, the interactions of NPs and surfactants and the resulting effects on the foam performance were investigated. The results indicate that when the NP concentration is < 1 wt%, the charge interactions between particles and surfactants weaken the interfacial adsorption, leading to accelerated drainage and coarsening, thereby reducing the foam stability. In contrast, when the NP concentration is ≥ 1 wt%, the particles form a dense network in the Plateau borders, blocking the Plateau channels, resulting in a 47.4 % reduction in drainage within 30 min and a 30 % decrease in coarsening rate, significantly enhancing the foam stability. Moreover, the fire extinguishing and burn-back experiments demonstrated that the SN-7# system with 5 wt% NPs achieved a 90 % flame control time of 17 s and an extinguishing time of 26 s, outperforming the commercial AFFF and the NP-free SN-0#. The addition of NPs significantly enhances fire suppression efficiency, as they interact with surfactants in foam films and Plateau borders to form aggregated network structures, effectively delaying the drainage and coarsening, thereby improving the foam’s thermal stability and burn-back resistance. The findings of this study provide theoretical guidance for the development and application of NPs in fluorine-free foam extinguishing agents.
研究领域:
消防工程
·
材料科学
·
界面化学
·
燃烧学
·
环境友好材料
✓ 已验证
产品关联
DOI
高影响因子
Defence Technology
·
2024
·
IF 5
Chao Deng,Huihui Liu,Yongping Bai,Zhen Hu
Herein, the effect of fluoropolymer binders on the properties of polymer-bonded explosives (PBXs) was comprehensively investigated. To this end, fluorinated semi-interpenetrating polymer networks (semi-IPNs) were prepared using different catalyst amounts (denoted as F23-CLF-30-D). The involved curing and phase separation processes were monitored using Fourier-transform infrared spectroscopy, differential scanning calorimetry, a haze meter and a rheometer. Curing rate constant and activation energy were calculated using a theoretical model and numerical method, respectively. Results revealed that owing to its co-continuous micro-phase separation structure, the F23-CLF-30-D3 semi-IPN exhibited considerably higher tensile strength and elongation at break than pure fluororubber F2314 and the F23-CLF-30-D0 semi-IPN because the phase separation and curing rates matched in the initial stage of curing. An arc Brazilian test revealed that F23-CLF-30-D-based composites used as mock materials for PBXs exhibited excellent mechanical performance and storage stability. Thus, the matched curing and phase separation rates play a crucial role during the fabrication of high-performance semi-IPNs; these factors can be feasibly controlled using an appropriate catalyst amount.
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
JOM
·
2022
·Vol. 74
·期 5
·1958-1968
·
IF 2.597
Luo Yinbo,He Dongfeng
Indirect carbonation as an efficient CO 2 sequestration strategy has received extensive attention in recent years. This study proposes a two-step leaching indirect carbonation process using NH 4 Cl and CH 3 COOH in order to combine the advantages of the two leaching agents to obtain a better experimental outcome. The experimental results show that NH 4 Cl has a high pH buffering capacity, which can increase the pH of the mixed leachate to an alkaline level. Among the 21 groups of mixed leachate, 17 were alkaline (pH > 7). The mixed leachate has a high Ca 2+ ions carbonation rate under low CH 3 COOH concentration conditions, and the carbonation rate of steel slag with a particle size of < 38 μm can reach 60% when the CH 3 COOH concentration is 0.1 M. SEM imaging showed that the CaCO 3 formed by the reaction exists in a hexagonal calcite crystal form.
研究领域:
环境科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2022
·
IF 4.326
Qiu-Yu Zhu,Liu-Kun Wu,Lan-Qian Li,Li-Wei Zhuang,Shuang-Mei Xue,Zhen-Liang Xu,Yong-Jian Tang
The monomer concentration is a key factor affecting the diffusion rate and reaction rate of the monomers and determines the physicochemical property of polyamide nanofiltration membranes. However, the mechanism of the monomer concentration effect on the polyamide nanofiltration membrane remains unclear. The properties of nascent membranes fabricated with different monomer concentrations with a fixed ratio presented completely new results in the absence of heat treatment. The results reveal that the polyamide layer thickness increases linearly with the monomer concentration when the concentration is high. The nanofiltration membranes prepared at a low concentration have a larger pore size and a lower cross-linking degree, which contributed to high water permeability. The optimal membrane presented a high pure water permeability of 36.1 L h–1 m–2 bar–1, with the Na2SO4 rejection maintained at 98.4%. This work provides a novel insight into the relationship between the properties of the nanofiltration membrane and monomer concentration.
研究领域:
材料科学
·
化学工程
·
膜技术
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING SCIENCE
·
2024
·
IF 4.1
Shikun Tong,Kele Yan,Jianbo Zhang,Zhiyuan Wang
Hydrate and wax phase transitions are typical flow risks during oil and gas development. The wax on hydrate formation was systematically studied based on dual-scale experimental platform. The sensitivity analysis on hydrate growth illustrates that the wax inhibits hydrate growth and the maximum reduction of hydrate growth rate is 79.6 % in waxy emulsions, and the wax on hydrate conversion ratio decreased the most by 27.2 %. The promoting effect of water content, subcooling, and stirring rate on hydrate growth increased by more than 10 times, 2 times, and 7 times, respectively. The droplet size first decreases and then increases as the wax concentration increases in emulsions. The mechanism of hydrate growth in waxy emulsions considers bidirectional growth and pores renewal of hydrate particles, and the mean error of the prediction model is 8.4 %. This work provides data basis and theoretical foundation for flow assurance management in oil and gas filed.
研究领域:
石油工程
·
化学工程
✓ 已验证
DOI
高影响因子
Crystals
·
2019
·Vol. 9
·期 12
·675
·
IF 2.061
Jinbo Ouyang,Jian Chen,Limin Zhou,Fangze Han,Xin Huang
To improve the physicochemical properties of valnemulin (VLM), different solid forms formed by VLM and organic acids, including tartaric acid (TAR), fumaric acid (FUM), and oxalic acid (OXA), were successfully prepared and characterized by using differential scanning calorimetry (DSC), scanning electron microscope (SEM), X-ray powder diffraction (XRPD), and Fourier-transform infrared spectroscopy (FT-IR). The excess enthalpyHexbetween VLM and other organic acids was calculated by COSMOthermXsoftware and was used to evaluate the probability of forming multi-component solids between VLM and organic acids. By thermal analysis, it was confirmed that multi-component solid forms of VLM were thermodynamically more stable than VLM itself. Through dynamic vapor sorption (DVS) experiments, it was found that three multi-component solid forms of VLM had lower hygroscopicity than VLM itself. Furthermore, the intrinsic dissolution rate of VLM and its multi-component forms was determined in one kind of acidic aqueous medium by using UV-vis spectrometry. It was found that the three multi-component solid forms of VLM dissolved faster than VLM itself.Keywords:valnemulin;solid forms;dissolution rate;hygroscopicity
研究领域:
药学
·
物理化学
✓ 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）