JOURNAL OF MEMBRANE SCIENCE
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2014
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IF 4.908
Xipeng Li,Yingbo Chen,Xiaoyu Hu,Yufeng Zhang,Linjia Hu
Novel poly(vinyl alcohol) (PVA)/poly(vinylidene fluoride) (PVDF) hollow fiber composite membranes modified with nano-TiO 2 were prepared by a dip-coating method and they are suitable to be utilized in dye desalination and wastewater treatment . Glutaraldehyde (GA) was used as a cross-linker for the composite polymer membrane in order to enhance the chemical, thermal as well as mechanical stabilities. The surface morphologies and chemical structures of modified membranes were observed by scanning electronic microscopy (SEM), energy dispersive spectroscopy (EDS) and FTIR spectroscopy . Zeta potential of the membrane surface was used to analyze the membrane separation performance. Separation efficiency of dye and salts through novel PVA/PVDF composite membrane was dramatically influenced by dye concentration, salts concentration, pH and temperature of feed solution. Fouling and thermal stability of the membrane were also evaluated with CR, NaCl, and Na 2 SO 4 as model compounds. The separation datas showed that the 1 g/L nano-TiO 2 modified membrane presented highest performance in terms of the rejections to CR, MO, and MB being 94±2.57%, 52.1±2.45%, and 92±2.20%, respectively. And all the PVA composite membranes had no rejection to salts (NaCl, Na 2 SO 4 ). Compared with PVA composite membrane, the PVA composite membrane modified with nano-TiO 2 has higher separation efficiency, antifouling and thermal stability.
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JOURNAL OF APPLIED POLYMER SCIENCE
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2013
·Vol. 131
·期 3
·
IF 1.395
Ting Li,Yuan Ren,Chaohai Wei
Polyvinyl alcohol(PVA) bead crosslinked with boric acid has been widely utilized as a microorganism immobilization carrier. However, it has some disadvantages such as drastic cell viability loss, small adsorption capacity and mass transfer limitation. To improve upon these drawbacks, a new method to prepare PVA composite pieces with the addition of activated carbon (AC) and poly-3-hydroxybutyrate(PHB) was explored through a combination of freezing/thawing and the boric acid method and by using Tween-80 to improve the mass transfer performance of hydrophobic organics. m -Cresol and pyrene were used as representative compounds with benzene ring structures to model hydrophilic and hydrophobic organics in order to test the performance of PVA pieces. The results showed that, compared with the boric acid method alone, a combination of freezing/thawing and the boric acid method led to a decrease in total organic carbon(TOC) loss from 0.315 g g −1 to 0.033 g g −1 and increased the oxygen uptake rate(OUR) of microorganisms from 0.03 mg L −1 ·min −1 to 0.22 mg L −1 min −1 . The m -cresol equilibrium adsorption amount of the PVA-SA(sodium alginate)-PHB-AC piece was 2.80 times that of the PVA-SA piece. The diffusion coefficient of pyrene in the PVA-SA-PHB-AC piece increased from 0.53×10 −9 m 2 min −1 to 2.30×10 −9 m 2 min −1 with increasing concentrations of Tween-80 from 1000 mg L −1 to 5000 mg L −1 . The PVA-SA-PHB-AC composite carrier demonstrated great scope for immobilizing microorganisms for practical wastewater bio-treatment. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131 , 39837.
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MICROSYSTEM TECHNOLOGIES-MICRO-AND NANOSYSTEMS-INFORMATION STORAGE AND PROCESSING SYSTEMS
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2024
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IF 1.6
Zhang Yonghua,Kang Ling,Yao Songping,Karthikeyan Sreejith,Wang Chaolun,Zhang Jian
Humidity measurement plays an essential role in industrial and agricultural production, meteorological monitoring, medical services, and people’s comfortable life. Polymer materials-based humidity sensors have gained much research focus due to the good dielectric properties and the compatibility with a variety of coating and pattern processes of polymer materials. In this paper, for the first time, a flexible capacitive humidity sensor is presented based on doped polyvinyl alcohol (PVA)/ cellulose acetate butyrate (CAB) double-layer sensing film and polyimide (PI) substrate. Potassium ions (K + ) are introduced into PVA for high effective capacitance, and CAB is used as protective film for preventing the hydrolysis of the doped PVA layer in high humidity environment. The fabricated novel sensor with a size of 20 × 20mm 2 has a capacitance of 61.84pF at 10% relative humidity (% RH) and 188.42pF at 90% RH. The average sensitivity is 1.414 pF/% RH. The maximum humidity hysteresis is about 5.83% RH at 50% RH. The response and recovery times from room humidity to 75% RH were likewise measured to be 78.71s and 6.19s, respectively. In addition, the long-time measurements for 7 days and bending tests for 5000 cycles demonstrated a good long-time humidity detecting stability and high mechanical flexibility for the capacitive humidity sensor based on potassium ion-doped PVA/CAB double-layer sensing film.
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BIOMACROMOLECULES
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2024
·
IF 5.5
Kai Liu,Zhipeng Zhao,Siyu Zheng,Afei Liu,Yingyue Wang,Lihui Chen,Qingxian Miao
Traditional hydrogel-based wearable sensors with flexibility, biocompatibility, and mechanical compliance exhibit potential applications in flexible wearable electronics. However, the low sensitivity and poor environmental resistance of traditional hydrogels severely limit their practical application. Herein, high-ion-conducting poly(vinyl alcohol) (PVA) nanocomposite hydrogels were fabricated and applied for harsh environments. MXene ion-conducting microchannels and poly(sodium 4-styrenesulfonate) ion sources contributed to the directional transport of abundant free ions in the hydrogel, which significantly improved the sensitivity and mechanical–electric conversion of the nanocomposite hydrogel-based piezoelectric and triboelectric sensors. More importantly, the glycerol as an antifreezing agent enabled the hydrogel-based sensors to function in harsh environments. Therefore, the nanocomposite hydrogel exhibited high gauge factor (GF) at −20 °C (GF = 3.37) and 60 °C (GF = 3.62), enabling the hydrogel-based sensor to distinguish different writing letters and sounding words. Meanwhile, the hydrogel-based piezoelectric and triboelectric generators showed excellent mechanical–electric conversion performance regardless of low- (−20 °C) or high- (60 °C) temperature environments, which can be applied as a visual feedback system for information transmission without external power sources. This work provides self-powered nanocomposite hydrogel-based sensors that exhibit potential applications in flexible wearable electronics under harsh environmental conditions.
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Advanced Composites and Hybrid Materials
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2024
·Vol. 7
·期 6
·1-9
·
IF 23.2
Dai Xiaokang,Wang Longxiang,Fallatah Ahmed M.,Wang Xing,Almalki Abdulraheem S. A.,Qi Yiyu,Jin Xiaoyu,Yang Shengxiang,Yuan Bingnan
Translucent materials are widely used in indoor lighting, electronic display devices, photovoltaic devices, and other aspects of daily life. Developing materials with high transparency that can effectively manage the transmitted light spectrum is of significant practical importance. This study focuses on constructing a flexible composite film matrix using biomass nanocellulose fibrils (CNF) and polyvinyl alcohol (PVA) as raw materials. Based on the down-conversion luminescence principle, we use carbon nitride nanosheets (CNNs) as the core for light management, filtering UV rays from sunlight while converting them into visible light for light compensation. The transparency test results show that the prepared CNNs@CNF/PVA flexible composite film has a total transmittance of about 90% in the visible light range, with a haze greater than 60%. Three-dimensional fluorescence test results indicate that CNNs@CNF/PVA can convert UV light in the range of 250–375 nm into visible light in the range of 420–550 nm. Simulated outdoor lighting results show that the composite film material performs better than ordinary glass and PMMA in light transmission. This biomass-based flexible film material is expected to have broad applications in indoor lighting, flexible photovoltaic devices, and high-quality fruit and vegetable cultivation.
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SOLAR ENERGY MATERIALS AND SOLAR CELLS
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2025
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IF 6.3
Yuzhen Zhao,Yongle Wu,Xiangke Jiao,Yang Zhao,Ruijuan Yao,Zhun Guo,Dong Wang,Yi Luan
The bilayer broadband reflective films with a PSCLC-PVA-PSCLC structure were achieved by stacking two monolayer polymer-stabilized cholesteric liquid crystal (PSCLC) films with different reflection centers. Ultraviolet (UV) light irradiation in the thickness direction of the broadband reflective film induced an intensity gradient, leading to a pitch gradient distribution. By fine-tuning the substance ratios and polymerization conditions, the performance of the bilayer broadband reflective film was significantly optimized. Under the optimal conditions, the reflective bandwidth (Δλ) of the bilayer film was expanded by approximately 80 % compared to the original sample. The preparation of these bilayer broadband reflective films demonstrates significant potential for applications in the field of anti-infrared devices, owing to their excellent infrared (IR) shielding effect.
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JOURNAL OF ALLOYS AND COMPOUNDS
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2024
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IF 5.8
Zhimin Li,Guanhui Chen,Shuqi Gou,Xiaofang Deng,Zhongai Hu,Xiaoquan Lu
The quasi-solid-state flexible supercapacitor has been successfully built by freezing-thawing method and in-situ polymerization. The high redox activity nickel-iron layered double hydroxide (NiFe-LDH) provides certain pseudocapacitance, interacts with high conductivity reduced graphene oxide (RGO), and avoids the activity structural collapse and agglomeration. Polyvinyl alcohol (PVA) serves as a flexible framework with uniform cross-linking between the components, facilitated by the presence of abundant hydrogen bonds. Polypyrrole (PPy) is further polymerized in-situ into PVA/RGO/NiFe-LDH to improve its electrochemical performance and flexibility. The PVA/RGO/NiFe-LDH 0.40 /PPy hydrogel electrodes exhibit a high area specific capacitance of 729 mF/cm 2 at 1 mA/cm 2 . The elongation at break of the electrodes is up to 749 %, which reflects excellent tensile properties. The quasi-solid-state flexible supercapacitor has been built using PVA/H 2 SO 4 as the gel electrolyte and PVA/RGO/NiFe-LDH 0.40 /PPy as the electrodes. The device exhibits a high energy density of 15.9 µWh/cm 2 at a power density of 0.19 mW/cm 2 and the capacitance retention of 96.7 % after 10,000 charge-discharge cycles.
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JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
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2017
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IF 2.63
Hongjian Wang,Bin Liu,Weilong Huang,Zi Lin,Jie Luo,Yan Li,Lin Zhuang,Wei Wang,Lelun Jiang
A novel approach, continuous needleless electrospinning from the tips of magnetization-induced self-assembling PVA/ferrofluid cone array, was proposed to prepare magnetic nanofibers. A PVA/ferrofluid was synthesized, the needleless electrospinning process was observed, and the morphology and magnetic properties of magnetic nanofibers were investigated. The results showed that the PVA/ferrofluid could remain stable and homogeneous for 21 days under the magnetic field gradient (2.2 mT/mm). “Taylor cone” array of PVA/ferrofluid was self-assembled under both the magnetic and electric fields. As the electric voltage reached 25 kV, the jets were emitted from the “Taylor cone” array, resulting in needleless electrospinning of magnetic nanofibers. Magnetic nanofibers were homogeneous and continuous with an average diameter of 73.6 nm. Magnetic nanofibers showed a good magnetic response property and relatively high saturated magnetization (1.71 emu/g), which is expected to be applied in the biomedical field.
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Petroleum Science
·
2018
·Vol. 15
·期 1
·146-156
·
IF 1.624
Zhang Rui,Xu Xiaoying,Cao Bing,Li Pei
The pyromellitic dianhydride (PMDA) crosslinked poly(vinyl alcohol) (PVA) was coated on top of the PAN ultrafiltration membrane to form a PVA/PAN composite PV membranes for wastewater desalination. The composite membranes have high application value in industrial wastewater treatment. By varying the membrane fabrication parameters including the weight percent (wt%) of the PMDA, the crosslink temperature and duration, membrane with the best desalination performance was obtained. The composite membrane with a 2-μm-thick PVA selective layer containing 20 wt% of PMDA and being crosslinked at 100 °C for 2 h showed the highest NaCl rejection of 99.98% with a water flux of 32.26 L/(m 2 h) at 70 °C using the 35,000 ppm NaCl aqueous solution as feed. FTIR spectroscopy, wide-angle X-ray diffraction, thermogravimetric analysis and scanning electron microscope have been used to characterize the structures and properties of both the crosslinked PVA dense films and PVA/PAN composite membranes. The effects of the concentrations of PMDA, the crosslinking time and temperature to the membrane water contact angle, swelling degree, salt rejection and water flux were systematically studied.
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INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
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2024
·
IF 7.7
Yumeng Wang,Boyu Du,Qian Zheng,Xiaohong Chen
Poly (vinyl alcohol) (PVA), as an excellent degradable plastic feedstock , is limited by its diminishing stability in wet environment, low strength , thermal instability and nonopaque properties. In response to these concerns, a PVA/demethylated lignin-based supramolecular plastic (DPVA-HA-Fe-5) was designed and produced from PVA, demethylated lignin (DL), humic acid (HA) and Fe 3+ ions via a simple casting method. As compared with pure PVA plastic, the tensile strength of DPVA-HA-Fe-5 were increased by 411 % to 410.61 MPa, and the breaking strain was increased by 149 % to 239.47 %. Notably, the hydrophobicity of DPVA-HA-Fe-5 was also significantly improved. Although in highly humid environment (stored in RH = 100 % for 10 days) or in alkaline organic solvent (stored in pyridine for 3 h), DPVA-HA-Fe-5 also showed excellent mechanical strengths of 302.9 and 222.99 MPa, respectively, which are equivalent or even superior to the most of commercial petroleum-based plastics. Moreover, the prepared plastics showed an outstanding UV resistance and shading performance, and about 98.3 % protection against ultraviolet radiation B rays and 90.7 % protection against visible light were obtained. In short, the introduction of lignin to improve the performance of PVA-based plastic is a feasible method, and it could facilitate the development of high-value utilization of lignin.
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ACS Applied Polymer Materials
·
2024
·
IF 4.4
Shunyang Li,Yaping Wang,Juan Xia,Chengyao Zhuge,Wangyang Lu,Nan Li
The excellent conductivity of flexible hydrogel sensors endows them with a wide application range. However, traditional flexible hydrogel sensors lack mechanical strength, which greatly limits their usage. In this study, fabrics were used to improve mechanical properties. Particularly knitted ones, characterized by good mechanical stability, breathability and a soft texture. This combination can fit well on the skin and provide an ideal platform for flexible sensing. We utilize brocade nylon-spandex knitted fabrics to reinforce poly(vinyl alcohol) (PVA) hydrogels. The results show that the elongation at break of the conductive hydrogels increases by 1.57 times compared to the original, while their tensile stress is enhanced 7.2-fold. The hydrogels can lift a bucket with 19 L of water with no obvious damage. We employ polyaniline (PANI) and calcium chloride (CaCl2) as conductive materials, which give the hydrogels high conductivity. Ethylene glycol and water serve as solvents for preparing the PVA/PANI conductive hydrogels. Due to the presence of ethylene glycol, the hydrogels are resistant to frost and can maintain their conductivity even at −18 °C. These are subsequently coated on nylon-spandex fabrics. The direct coating can be mass produced using a simple and cost-effective method. The PVA/PANI hydrogel fabric sensor demonstrates high sensitivity, excellent linearity, fast response and recovery times, remarkable durability and the ability to detect various levels of human motion. These findings indicate significant potential for flexible sensor applications.
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Advanced Science
·
2024
·
IF 14.3
Yichang Quan,Engui Wang,Han Ouyang,Lingling Xu,Lu Jiang,Lijing Teng,Jiaxuan Li,Lin Luo,Xujie Wu,Zhu Zeng,Zhou Li,Qiang Zheng
Triboelectric nanogenerators (TENGs) are highly promising as implantable, degradable energy sources and self-powered sensors. However, the degradable triboelectric materials are often limited in terms of contact electrification and mechanical properties. Here, a bio-macromolecule-assisted toughening strategy for PVA aerogel-based triboelectric materials is proposed. By introducing β-lactoglobulin fibrils (BF) into the PVA aerogel network, the material's mechanical properties while preserving its swelling resistance is significantly enhanced. Compared to pure PVA porous film, the BF-PVA porous film exhibits an eightfold increase in fracture strength (from 1.92 to 15.48 J) and a fourfold increase in flexibility (from 10.956 to 39.36 MPa). Additionally, the electrical output of BF-PVA in triboelectric performance tests increased nearly fivefold (from 45 to 203 V). Leveraging these enhanced properties, a biodegradable TENG (bi-TENG) for implantable muscle activity sensing is developed, achieving real-time monitoring of neuromuscular processes. This innovation holds significant potential for advancing implantable medical devices and promoting new applications in bio-integrated electronics.
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