CERAMICS INTERNATIONAL
·
2024
·
IF 5.1
Minhao Shen,Renli Fu,Yi Zhang,Kuang Sun,Wei Xu,Yanlin Jiang,Zhe Zhao,Ming Liu
Vat photopolymerized 3D printing technology can be used to fabricate ceramics with complex shapes. However, the extensive use of photosensitive resins as binders is not conducive to achieving crack-free ceramic green parts, especially the Si 3 N 4 ceramics with the weak interlayer bonding. In this work, the influence of different debinding atmosphere on the pyrolysis process of organics in vat photopolymerization 3D printed Si 3 N 4 green parts was investigated. The results showed that the use of 95 vol% N 2 +5 vol% H 2 atmosphere can effectively inhibit the cracking during the debinding process, especially the wall thickness of the 3D printed defect-free Si 3 N 4 green body was successfully increased to 5 mm, and the obtained sintered Si 3 N 4 ceramics exhibited higher true densities and better mechanical properties. The debinding atmospheres proposed in the current work provided additional options of debinding atmosphere for achieving high-performance 3D printed Si 3 N 4 ceramics and are expected to be expanded to other photosensitive slurry systems, with the potential to enable the production of ceramic components with the larger wall thicknesses.
研究领域:
材料科学
·
陶瓷制造
·
3D打印技术
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MEMBRANE SCIENCE
·
2024
·
IF 8.4
Ziheng Li,Yan Dai,Xuehua Ruan,Xiangcun Li,Miao Yu,Tiantian Li,Xiujuan Zhang,Xiaobin Jiang,Xuemei Wu,Wenji Zheng,Gaohong He
Defect-free MOFs membrane on flexible substrate is challenging and promising for industrial applications. In this work, electrospun nanofiber substrates were employed to construct deep-rooted and defect-free ZIF-8 membranes by a symbiotic layer composed of interpenetrated nanofibers and ZIF-8. Nanofibers provide sufficient nucleation sites to construct an interpenetrated “symbiotic layer”, which further supports ZIF-8 growing to be defect-free. Importantly, benefiting from this symbiotic layer, the rigidity difference between substrate and ZIF-8 is well balanced, resulting in ZIF-8 membrane deep-rooted within the support. Furthermore, tannic acid (TA), was combined to modulate the surface chemistry and inter-crystalline defects of ZIF-8 membranes. Finally, a hierarchical ZIF-8 membrane with nanofibers as flexible substrates were obtained. The prepared PAN/TA 2 -NZIF-8 0.25 membrane exhibits H 2 permeance of 2408 GPU and H 2 /CO 2 selectivity of 21.80. Specifically, compared with the reported MOFs membrane for H 2 separation, the H 2 permeance of this work locates in a very high region, while proper H 2 /CO 2 separation factor is still remained, exceeding the 2008 upper bound of H 2 /CO 2 separation. Importantly, this membrane presents stable microstructures and separation performance after twisting. The proposed deep-rooted and defect-free ZIF-8 membrane on flexible substrate is competitive to achieve industrial application.
研究领域:
材料科学
·
化学工程
·
纳米技术
✓ 已验证
产品关联
DOI
高影响因子
SCIENCE AND ENGINEERING OF COMPOSITE MATERIALS
·
2020
·Vol. 27
·期 1
·28-40
·
IF 0.7
Zhang Wenhua,Wu Peipei,Zhang Yunsheng,Zeng Weizhao,Yang Fenghao
The effect of CNTs on the mechanical and damping properties of macro-defect-free (MDF) cements was studied, and polyvinyl alcohol (PVA) fibers were also studied as a contrast. It was found that the compressive strength of MDF cements was not significantly affected by the two types of fibers. The CNTs enhanced the flexural strength of MDF, while PVA fibers made negative contribution. The strengthening mechanism of flexural strength of MDF cements by CNTs can be summarized as fiber bridging, crack deflection and fiber slippage. For the damping properties, the proper contents of CNTs and PVA fibers improved the loss factor significantly. The interface transition zone (ITZ) between the PVA fibers and matrix was large, which was favorable for fiber slippage. The damping property of MDF cements with CNTs was mainly due to the slippage between the inner tubes of the CNTs rather than the slippage between the CNTs and matrix.
研究领域:
土木工程
·
材料科学
✓ 已验证
DOI
高影响因子
MACROMOLECULES
·
2011
·
IF 4.838
Lianwei Li,Chen He,Weidong He,Chi Wu
Using a facile approach, we successfully made large “defect-free” hyperbranched polystyrene (PSt) chains with uniform subchains between two branching points from the interchain “clicking” of a seesaw-type linear macromonomer [azide∼∼∼alkyne∼∼∼azide] prepared by ATRP with a following conversion of two bromine-ends into two azide-ends, where ∼∼∼ denotes a PSt chain (1.65–31.0 kg/mol). The “click” reaction kinetics monitored by a combination of size exclusion chromatography (SEC) and laser light scattering (LLS) reveals that the degree of self-polycondensation (DP) is related to the reaction time (t) as ln(DP+ 1)/2 = ([A]0kAB,0)/β arctan(βt), where [A]0 and kAB,0 are the initial alkyne concentration and the initial reaction rate between the azide and alkyne groups, respectively; β is a constant and its reciprocal (1/β) represents the time at which kAB = kAB,0/2. The results reveal that 1/β is scaled to the macromonomer’s molar concentration ([C]) and molar mass (M) as 1/β ∼ [C]−0.35M0.55, indicating that 1/β is governed by the interchain distance and diffusion, respectively. Each hyperbranched sample can be further fractionated into a set of narrowly distributed “defect-free” hyperbranched chains with different molar masses by precipitation. The LLS results show, for the first time, that the root-mean-square radius of gyration (⟨Rg⟩) and hydrodynamic radius (⟨Rh⟩) of “defect-free” hyperbranched polystyrenes in toluene at 25 °C are scaled to the weight-average molar mass (Mw) as ⟨Rg⟩ = 5.53 × 10–2Mw0.464 and ⟨Rh⟩ = 2.95 × 10–2Mw0.489, respectively, where the exponents are smaller than the predicted 1/2.
研究领域:
高分子化学
·
材料科学
·
物理化学
✓ 已验证
产品关联
DOI
高影响因子
ACS Applied Materials & Interfaces
·
2016
·
IF 7.145
Yong Du,Wen-Ze Qiu,Yan Lv,Jian Wu,Zhi-Kang Xu
Nanofiltration membranes (NFMs) are widely used in saline water desalination, wastewater treatment, and chemical product purification. However, conventional NFMs suffer from broad pore size distribution, which limits their applications for fine separation, especially in complete separation of molecules with slight differences in molecular size. Herein, defect-free composite NFMs with narrow pore size distribution are fabricated using a contra-diffusion method, with dopamine/polyethylenimine solution on the skin side and ammonium persulfate solution on the other side of the ultrafiltration substrate. Persulfate ions can diffuse through the ultrafiltration substrate into the other side and in situ trigger dopamine to form a codeposited coating with polyethylenimine. The codeposition is hindered on those sites completely covered by the polydopamine/polyethylenimine coating, although it is promoted at the defects or highly permeable regions because it is induced by the diffused persulfate ions. Such a “self-completion” process results in NFMs with highly uniform structures and narrow pore size distribution, as determined by their rejection of neutral solutes. These near electrically neutral NFMs show a high rejection of divalent ions with a low rejection of monovalent ions (MgCl2 rejection = 96%, NaCl rejection = 23%), majorly based on a steric hindrance effect. The as-prepared NFMs can be applied in molecular separation such as isolating cellulose hydrogenation products.
研究领域:
材料科学
·
化学工程
·
环境工程
·
水处理
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF MEMBRANE SCIENCE
·
2022
·
IF 10.53
Siyu Pang,Zhihao Si,Guozhen Li,Hanzhu Wu,Yuhui Cui,Changwei Zhang,Cong Ren,Shuai Yang,Shusheng Pang,Peiyong Qin
A high-quality mixed matrix membrane (MMM) with high flux and separation factor is fostered to enhance ethanol pervaporation . In this study, a fluorinated and defect-free ZIF-8/PDMS membrane was prepared by the covalent bonding among fluoromonomer, ZIF-8 particles and PDMS using a one-pot method. ZIF-8 is first modified with 3-amino-1,2,4-triazole (Atz) to graft –NH 2 groups, and then modified with glycidyl methacrylate (GMA). This was achieved by the amine-epoxide addition reaction (named GZIF-8) to facilitate covalent bonding with methacrylate-functionalized PDMS, where the interfacial compatibility ZIF-8 and PDMS is improved. Moreover, 1H,1H,2H,2H-perfluorooctyl methacrylate (13F) as F-monomer is introduced into the membrane formation process by the polymerization of methacrylate groups among 13F, ZIF-8 and PDMS, where a fluorinated structure with high hydrophobicity and low surface energy is formed. The pervaporation performance for a 5 wt% ethanol solution at 60 °C shows that the resulting MMM has a high separation factor of 9.5 and total flux of 1681 g m −2 h −1 under the optimized parameters of 3 wt% GZIF-8 loading and 12 wt% 13F amounts.
研究领域:
材料科学
·
化学工程
·
膜技术
✓ 已验证
DOI
高影响因子
Materials Horizons
·
2019
·Vol. 6
·期 7
·1416-1424
·
IF 14.356
Yuanqing Xu,Shulin Chen,Zhipeng Dou,Yanhong Ma,Yang Mi,Wenna Du,Yin Liu,Jianqi Zhang,Jinquan Chang,Cheng Liang,Jin Zhou,Hongbo Guo,Peng Gao,Xinfeng Liu,Yanke Che,Yong Zhang
The production of two-dimensional quantum sheets (2D QSs) from bulk layered materials is highly desired but far from satisfactory. Herein, we report a unified top-down method capable of producing a range of 2D QSs in high yields. The method combines silica-assisted ball-milling and sonication-assisted solvent exfoliation and thus enables production of graphene QSs (GQSs), boron nitride QSs (BNQSs), molybdenum disulfide QSs (MoS2 QSs), and tungsten disulfide QSs (WS2 QSs) in exceedingly high yields of 35.5, 33.6, 30.2, and 28.2 wt%, respectively. The as-produced 2D QSs are confirmed as intrinsic and defect-free by multiple characterization techniques. Such 2D QSs can be collected as powders and then redispersed in a wide range of solvents with high concentration up to 5 mg mL−1. Both (re)dispersions and solid thin films of the 2D QSs exhibit extraordinarily high performance in linear and nonlinear optics. Specifically, the QS (re)dispersions show prominent exciton-, solvent-, and concentration-dependent photoluminescence, while the QS solid thin films demonstrate exciting solid-state fluorescence (with lifetimes up to 3.0 ns) and remarkable nonlinear absorption saturation (with absolute modulation depths up to 59% and saturation intensities down to 6.70 kW cm−2 (0.67 nJ cm−2)). Our method could be applicable to any bulk layered materials and therefore paves the way for mass production and full exploration of 2D QSs.
研究领域:
材料科学
·
纳米技术
·
光学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）