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Three-dimensional boron nitride network/polyvinyl alcohol composite hydrogel with solid-liquid interpenetrating heat conduction network for thermal management

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Journal of Materials Science & Technology 2022年第32期127卷 183-191页

作者： Mengmeng Qin Yajie Huo Guoying Han Junwei Yue Xueying Zhou Yiyu Feng Wei Feng School of Materials Science and Engineering Tianjin UniversityTianjin 300072China Key Laboratory of Advanced Ceramics and Machining Technology Ministry of EducationTianjin 300072China School of Materials Science and Engineering Tianjin University of TechnologyTianjin 300084China

polyvinyl alcohol hydrogels have been used in wearable devices due to their good flexibility and ***,due to the low thermal conductivity(κ)of pure hydrogel,its further application in high power devices is *** solve this problem,melamine sponge(MS)was used as the skeleton to wrap boron nitride nanosheets(BNNS)through repeated layering assembly,successfully preparing a three-dimensional(3D)boron nitride network(BNNS@MS),and PVA hydrogels were formed in the pores of the *** to the existence of the continuous phonon conduction network,the BNNS@MS/PVA exhibited an improvedκ.When the content of BNNS is about 6 wt.%,κof the hydrogel was increased to 1.12 W m^(-1)K^(-1),about two times higher than that of pure *** solid heat conduction network and liquid convection network cooperate to achieve good thermal management *** with its high specific heat capacity,the composites have an important application prospect in the field of wearable flexible electronic thermal management.

关键词： Thermal conductivity polyvinyl alcohol Three-dimensional network Composite hydrogel

In situ construction of BiVO_(4)(-)cellulose fibers@CDs(-)polyvinyl alcohol composites for tetracycline photocatalytic degradation

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Science China(Technological Sciences) 2021年第3期64卷 548-558页

作者： WANG Tao LIU XiQing MA ChangChang WEI MaoBin HUO PengWei YAN YongSheng School of Chemistry and Chemical Engineering Jiangsu UniversityZhenjiang 212013China Institute of Green Chemistry and Chemical Technology Jiangsu UniversityZhenjiang 212013China School of Materials Science and Engineering Jiangsu UniversityZhenjiang 212013China Department of Chemistry Dongguk UniversitySeoul 04620Republic of Korea College of Physics Jilin Normal UniversitySiping 136000China

Non-biodegradable and toxic photocatalysts pose as secondary threats to the environmental *** this work,non-toxic biocomposites were prepared using natural bamboo cellulose fibers(CF),polyvinyl alcohols(PVAs),BiVO_(4),and carbon dots(CDs)from ***,their optical properties,chemical characterizations,and photocatalytic performances were *** novel BiVO_(4)(-)CF@CDs(-)PVA composites were prepared via the combined implementation of in situ and impregnation *** optical properties revealed that the CDs and fibers increased the range and intensity of light *** PVAs were used as the shield and dispersant to enhance stability because they have numerous chemical *** view of the various possible paths of electron migration,the enhanced photocatalytic activity of BiVO_(4)(-)CF@CDs(-)PVA composites for tetracycline degradation was observed under visible light *** origins of the structure,morphology,and optical mechanism in the enhancement of the photocatalytic ability of BiVO_(4)(-)CF@CDs(-)PVA composites were discussed and demonstrated.

关键词： biodegradable bamboo fibers polyvinyl alcohol carbon dots BiVO_(4) mechanism

Starch/polyvinyl alcohol blended materials used as solid carbon source for tertiary denitrification of secondary efuent

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Journal of Environmental Sciences 2013年第10期25卷 1972-1979页

作者： Peng Li Jiane Zuo Wei Xing Lei Tang Xiangyang Ye Zaixing Li Lin Yuan Kaijun Wang Hongtao Zhang State Key Joint Laboratory of Environmental Simulation and Pollution Control School of Environment Tsinghua University School of Environmental Science and Engineering Hebei University of Science and Technology THUNIP Holdings Co. Ltd.

Starch/polyvinyl alcohol （PVA） blended materials for using as a solid carbon source （SCS） were prepared by blending PVA and gelatinized starch in an aqueous solution system, in which PVA served as framework material and starch as carbon source. The optimization of starch content and temperature effects were investigated. It was indicated that higher denitrification efficiency could be achieved with more starch in the materials. The average specific denitrification rates were 0.93, 0.66, 0.37 and 0.36 mg/（g·day） corresponding to starch content of 70%, 60%, 40% and 30% respectively at 37℃. The denitrification rates increased when operating temperature was raised from 23℃ to 30℃ and then 37℃. The mechanism of carbon release was analyzed incorporating the experimental results of abiotic release in deionized water. The organic carbon was mainly hydrolyzed by microbes, and the biological release efficiencies were at the range of 89.2% to 96.0%. A long-term experiment with a continuous flow reactor with SCS material containing 70% starch was conducted to gain some experience for practical application. When the influent nitrate concentration was in the range of 35.2 to 39.1 mg/L, hydraulic retention time of 4 hr, and operating temperature of 30℃, a nitrogen removal efficiency up to 94.6% and denitrification rate of 0.217 kg/（***） was achieved. The starch-based materials developed in this study can be used as a solid carbon source for tertiary nitrogen removal from secondary effluent.

关键词： solid carbon source tertiary denitrification blends polyvinyl alcohol starch organics residue

Vortex fluidic mediated one-step fabrication of polyvinyl alcohol hydrogel films with tunable surface morphologies and enhanced self-healing properties

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Science China Materials 2020年第7期63卷 1310-1317页

作者： Javad Tavakoli Colin LRaston Yong Ma Youhong Tang School of Biomedical Engineering University of Technology SydneyNew South Wales 2007Australia Institute for NanoScale Science and Technology College of Science and EngineeringFlinders UniversitySouth Australia 5042Australia School of Sports Engineering and Information Technology Wuhan Sports UniversityHubei 430079China

Previous strategies for controlling the surface morphologies of polyvinyl alcohol(PVA)-based hydrogels,including freeze-drying and electrospinning,require a posttreatment process,which can affect the final textures and properties of the *** particular interest,it is almost impossible to control the surface morphology during the formation of PVA hydrogels using these *** strategy reported in this study used the novel vortex fluidic device(VFD)technology,which for the first time provided an opportunity for one-step fabrication of PVA hydrogel *** hydrogels with different surface morphologies could be readily fabricated using a *** also reducing the crosslinking agent concentration,a self-healing gel with enhanced fracture stress(60%greater than that of traditionally made hydrogel)was ***,the associated selfhealing property remained unchanged during the 260-s mechanical testing performed with the strain rate of 5%*** VFD can effectively tune the surface morphologies of the PVA-based hydrogels and their associated properties,particularly the self-healing property.

关键词： polyvinyl alcohol vortex fluidic device one-step fabrication self-healing surface morphology manipulation

Low-temperature-cured highly conductive composite of Ag nanowires & polyvinyl alcohol

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Chinese Physics B 2017年第7期26卷 426-432页

作者：何松张祥杨兵初徐晓梅陈辉周聪华 Hunan Key Laboratory of Super-microstructure and Ultrafast Process School of Physics and ElectronicsCentral South University

Flexible conductive films were fabricated from a low-temperature-cured, highly conductive composite of silver nanowires （as conducting filler） and polyvinyl alcohol （PVA, as binder）. Sheet resistance of 0.12 Ω/sq, conductivity of 2.63 ×10^4 S/cm, and contact resistance of 1.0Ω/cm^2 were measured in the films, along with excellent resistance to scratch- ing and good flexibility, making them suitable electrical contact materials for flexible optoelectronic devices. Effects of curing temperature, curing duration, film thickness, and nanowire length on the film＇s electrical properties were studied. Due to the abundance of hydroxyl groups on its molecular chains, the addition of PVA improves the film＇s flexibility and resistance to scratching. Increased nanowire density and nanowire length benefit film conductance. Monte Carlo simulation was used to further explore the impact of these two parameters on the conductivity. It was observed that longer nanowires produce a higher length-ratio of conducting routes in the networks, giving better film conductivity.

关键词： conductive composite polyvinyl alcohol silver nanowires Monte Carlo simulation

DEHYDRATION KINETICS OF polyvinyl alcohol HYDROGEL WOUND DRESSINGS DURING WOUND HEALING PROCESS

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Chinese Journal of Polymer Science 2010年第4期28卷 573-580页

作者： Mohammad Sirousazar Mortaza Yari Faculty of Chemical Engineering Urmia University of TechnologyP.O.Box 57166-93187UrmiaIran Polymer Engineering Group Faculty of EngineeringTarbiat Modares UniversityP.O.Box 14115-143TehranIran Mechanical Engineering Group Faculty of EngineeringUniversity of Mohaghegh ArdabiliP.O.Box 56199-11367ArdabilIran

The hydrogel wound dressing based on polyvinyl alcohol （PVA） was prepared by the freezing-thawing cyclic method. The dehydration kinetics of prepared hydrogels was determined using the experimental method and mathematical modeling based on diffusion mechanism. The results show that the dehydration rate of PVA hydrogel wound dressing inversely depends on the hydrogel thickness as well as water content of the wound. On the other hand, the initial water content of hydrogel and the atmospheric humidity have little direct effect on the dehydration rate. The good agreement between experimental and mathematical modeling results in early stages of dehydration process shows that the predominate factor determining the dehydration of these wound dressings is diffusion.

关键词： Polymer gels Wound dressing polyvinyl alcohol Dehydration kinetics

Extraordinary thermal conductivity of polyvinyl alcohol composite by aligning densified carbon fiber via magnetic field

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Nano Research 2023年第2期16卷 2572-2578页

作者： Xiaoxiao Guo Shujian Cheng Bo Yan Yile Li Yinghui Zhou Weiwei Cai Yufeng Zhang Xue-ao Zhang College of Physical Science and Technology Xiamen UniversityXiamen 361005China Jiujiang research institute of Xiamen University Jiujiang 360404China

Thermal interface materials(TIMs)with high through-plane thermal conductivity are urgently desired to avoid overheating of high-power density *** and aligning fillers in polymer matrixes via magnetic field is a promising method to improve the thermal conductivity of the ***,either the fillers need to be modified with magnetic particles or a strong magnetic field is needed for good alignment in high filler *** prevents further improvement of the through-plane thermal ***,mesophase pitch-based carbon fibers(MPCFs)with a content as high as 76 wt.%are aligned vertically in water-soluble polyvinyl alcohol(PVA)under a low magnetic field(~0.4 T),forming a vertically aligned MPCF(VAMPCF)/PVA composite with an extraordinary through-plane thermal conductivity of 86 W/(m·K),which is higher than that of many *** addition,both theoretical and experimental results demonstrate that the critical intensity of the magnetic field needed for good alignment of the fillers depends on their size and magnetic ***,the water solubility of PVA makes it easy to recycle *** study offers an inspired venue to develop excellent and eco-friendly TIMs to meet ever increasing demand in heat dissipation for electronics.

关键词： polyvinyl alcohol carbon fiber thermal conductivity Landau diamagnetism magnetic field

Supercritical water oxidation of polyvinyl alcohol and desizing wastewater: Influence of NaOH on the organic decomposition

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Journal of Environmental Sciences 2013年第8期25卷 1583-1591页

作者： Jie Zhang Shuzhong Wang Yang Guo Donghai Xu Yanmeng Gong Xingying Tang Key Laboratory of Thermo-Fluid Science and Engineering of MOE School of Energy and Power Engineering Xi'an Jiaotong University

polyvinyl alcohol is a refractory compound widely used in industry. Here we report supercritical water oxidation of polyvinyl alcohol solution and desizing wastewater with and without sodium hydroxide addition. However, it is difficult to implement complete degradation of organics even though polyvinyl alcohol can readily crack under supercritical water treatment. Sodium hydroxide had a significant catalytic effect during the supercritical water oxidation of polyvinyl alcohol. It appears that the OH ion participated in the C-C bond cleavage of polyvinyl alcohol molecules, the CO2-capture reaction and the neutralization of intermediate organic acids, promoting the overall reactions moving in the forward direction. Acetaldehyde was a typical intermediate product during reaction. For supercritical water oxidation of desizing wastewater, a high destruction rate （98.25%） based on total organic carbon was achieved. In addition, cases where initial wastewater was alkaline were favorable for supercritical water oxidation treatment, but salt precipitation and blockage issues arising during the process need to be taken into account seriously.

关键词： supercritical water oxidation polyvinyl alcohol sodium hydroxide catalysis desizing wastewater

Study on photodegradation of Azo dye by polyoxometalates/polyvinyl alcohol

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Journal of Rare Earths 2009年第5期27卷 717-722页

作者：冯长根卓晓曦刘霞 State Key Laboratory of Explosion Science and Technology Beijing Institute of Technology College of Science China Agricultural University

A series of photocatalysts, K11[Ln(PW11O39)2]/PVA (Ln=La, Ce, Pr, Nd, Sm) were prepared by K11[Ln(PW11O39)2] (Ln=La, Ce, Pr, Nd, Sm) containing five kinds of lanthanides and polyvinyl alcohol as the support. The catalysts obtained were characterized by Fourier transform infrared spectra, UV-vis spectra, powder X-ray diffraction, and scanning electron microscopy, indicating that the structure of K11[Ln(PW11O39)2] and polyvinyl alcohol remained intact, respectively. The photocatalysts exhibited efficient catalytic activity to degrade methyl orange, Congo Red, Ponceau 2R. The maximal degradation conversions of the three kinds of dyes were 99.58%, 47.61%, 72.42%, respectively.

关键词： polyoxometalates polyvinyl alcohol degradation azo dye rare earths