Search

Your search keyword '"Liu, Guoquan"' showing total 1,137 results
Start Over Author "Liu, Guoquan"
1,137 results on '"Liu, Guoquan"'

4. Interface properties of composites from PBO fibers modified by polyurethane sizing agent

Author

JIANG Lei, XU Renxin, WU Shuguang, LIU Guoquan, DING Anxin, and CHEN Yang

Subjects
pbo fiber, waterborne polyurethane, sizing agent, interface property, shear strength, Materials of engineering and construction. Mechanics of materials, TA401-492
Abstract

To improve the interfacial properties of poly-p-phenylenebenzobisoxazole(PBO) fiber/epoxy resin (EP)composites, the surfaces of acidified PBO fibers were coated with the sizing agents of waterborne polyurethane modified using γ-aminopropyltriethoxysilane(KH550). The surface chemical composition of PBO fibers was characterized by X-ray photoelectron spectroscopy (XPS) and energy dispersive spectroscopy (EDS). Scanning electron microscopy (SEM)was employed to characterize the surface morphology of PBO fibers and the tear surface morphology of PBO/EP composites. Furthermore, the mechanical properties of single PBO fibers and PBO/EP composites were analyzed. The results show that the active groups on the surfaces of PBO fibers increase significantly with the values of O/C(atomic ratio)from 0.16 to 0.25 after being coated with the sizing agents, and the defects on the surfaces of PBO fibers can be repaired effectively. By adjusting the contents and structure of the sizing agents on the fibers, the interlaminar shear strength and tensile strength of PBO/EP unidirectional composites reach 41.3 MPa and 1.70 GPa, respectively. In contrast to the untreated ones, the interlaminar shear strength and tensile strength of modified composites increase by 44.9% and 15.6%, respectively.

Published
2024
Full Text
View/download PDF

5. Tailoring Luminescent Properties of SrS:Ce by Modulating Defects: Sr-Deficiency and Na+ Doping

Author

Chang, Shuqin, Fu, Jipeng, Sun, Xuan, Bai, Guangcan, Liu, Guoquan, Wang, Kaina, Xu, Ligang, Wei, Qi, Meier, Thomas, and Tang, Mingxue

Subjects
Condensed Matter - Materials Science, C.1.1
Abstract

Ce3+ doped SrS phosphors with a charge-compensating Na+ for light-emitting diode (LED) applications have been successfully synthesized via a solid-state reaction method, which can be indexed to rock-salt-like crystal structures of Fm-3m space group. SrS:(Ce3+)x(x=0.005-0.05) and SrS:(Ce3+)0.01,(Na+)y(y=0.005-0.030) phosphors were excited by 430nm UV-VIS light, associated to the 5d1-4f1 transition of Ce3+. The composition-optimized SrS:(Ce3+)0.01,(Na+)0.015 phosphors showed an intense broad emission band at 430-700nm. The doping of Na+ was probed by solid-state nuclear magnetic resonance. The 430 nm pumped with white LED (w-LED) combining SrS:(Ce3+)0.01,(Na+)0.015 phosphors and Sr2Si5N8:Eu2+ phosphors shows a color-rendering index (Ra) of 89.7. The proposed strategy provides new avenues for design and realization of novel high color quality solid-state lighting emitting diodes (SS-LEDS)., Comment: 22 pages, 8figures

Published
2021

33. Non-Invasive Imaging Method of Microwave Near Field Based on Solid State Quantum Sensing

Author

Yang, Bo, Du, Guanxiang, Dong, Yue, Liu, Guoquan, Hu, Zhenzhong, and Wang, Yongjin

Subjects
Physics - Instrumentation and Detectors, Physics - Optics
Abstract

In this paper, we propose a non-invasive imaging method of microwave near field using a diamond containing nitrogen-vacancy centers. We applied synchronous pulsed sequence combined with charge coupled device camera to measure the amplitude of the microwave magnetic field. A full reconstruction formulation of the local field vector, including the amplitude and phase, is developed by measuring both left and right circular polarizations along the four nitrogen-vacancy axes. Compared to the raster scanning approach, the two dimensional imaging method is promising for application to circuit failure analysis. A diamond film with micrometer thinness enables high-resolution near field imaging. The proposed method is expected to have applications in monolithic-microwave-integrated circuit chip local diagnosis, antenna characterization, and field mode imaging of microwave cavities and waveguides.

Published
2018
Full Text
View/download PDF

43. Mechanically Interlocked Polyrotaxane Networks with Collective Motions of Multiple Main‐Chain Mechanical Bonds.

Author

Yang, Li, Wang, Yuanhao, Liu, Guoquan, Zhao, Jun, Cheng, Lin, Zhang, Zhaoming, Bai, Ruixue, Liu, Yuhang, Yang, Mengling, Yu, Wei, and Yan, Xuzhou

Subjects
TENSILE tests, POLYMERS, MOLECULAR dynamics, AXLES, DEFORMATIONS (Mechanics), THREAD (Textiles)
Abstract

Type I main‐chain polyrotaxanes (PRs) with multiple wheels threaded onto the axle are widely employed to design slide‐ring materials. However, Type II main‐chain PRs with axles threading into the macrocycles on the polymer backbones have rarely been studied, although they feature special topological structures and dynamic characteristics. Herein, we report the design and preparation of Type II main‐chain PR‐based mechanically interlocked networks (PRMINs), based on which the relationship between microscopic motion of mechanical bonds on the PRs and macroscopic mechanical performance of materials has been revealed. The representative PRMIN‐2 exhibits a robust feature in tensile tests with high stretchability (1680 %) and toughness (47.5 MJ/m3). Moreover, it also has good puncture performance with puncture energy of 22.0 mJ. Detailed rheological measurements and coarse‐grained molecular dynamics (CGMD) simulation reveal that the embedded multiple [2]rotaxane mechanical bonds on the PR backbones of PRMINs could undergo a synergistic long‐range sliding motion under external force, with the introduction of collective dangling chains into the network. As a result, the synchronized motions of coherent PR chains can be readily activated to accommodate network deformation and efficiently dissipate energy, thereby leading to enhanced mechanical performances of PRMINs. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

44. Mechanically Interlocked [an]Daisy Chain Adhesives with Simultaneously Enhanced Interfacial Adhesion and Cohesion.

Author

Wang, Yongming, Liu, Guoquan, Zhao, Jun, Zhang, Zhaoming, Zhang, Hao, Ding, Yi, Zhang, Xinhai, Liu, Zhu, Yu, Wei, and Yan, Xuzhou

Subjects
*SUPRAMOLECULAR polymers, *INTERFACIAL bonding, *SUBSTRATES (Materials science), *DAISIES, *MOIETIES (Chemistry)
Abstract

Adhesives have been widely used to splice and repair materials to meet practical needs of humanity for thousands of years. However, developing robust adhesives with balanced adhesive and cohesive properties still remains a challenging task. Herein, we report the design and preparation of a robust mechanically interlocked [an]daisy chain network (DCMIN) adhesive by orthogonal integration of mechanical bonds and 2‐ureido‐4[1H]‐pyrimidone (UPy) H‐bonding in a single system. Specifically, the UPy moiety plays a dual role: it allows the formation of a cross‐linked network and engages in multivalent interactions with the substrate for strong interfacial bonding. The mechanically interlocked [an]daisy chain, serving as the polymeric backbone of the adhesive, is able to effectively alleviate applied stress and uphold network integrity through synergistic intramolecular motions, and thus significantly improves the cohesive performance. Comparative analysis with the control made of the same quadruple H‐bonding network but with non‐interlocked [an]daisy chain backbones demonstrates that our DCMIN possesses superior adhesion properties over a wide temperature range. These findings not only contribute to a deep understanding of the structure‐property relationship between microscopic mechanical bond motions and macroscopic adhesive properties but also provide a valuable guide for optimizing design principles of robust adhesives. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

45. Trajectory Control of Mobile Robot Based on Novel Gesture Detection

Author

Liu, Shubo, Liu, Guoquan, Cao, Shun’an, Cheng, Liyu, Zou, Hang, Ceccarelli, Marco, Series Editor, Hernandez, Alfonso, Editorial Board Member, Huang, Tian, Editorial Board Member, Takeda, Yukio, Editorial Board Member, Corves, Burkhard, Editorial Board Member, Agrawal, Sunil, Editorial Board Member, Zheng, Lifang, editor, Sun, Chaoyang, editor, and Goh, Kheng-Lim, editor

Published
2021
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results