POLYMERS FOR ADVANCED TECHNOLOGIES
·
2023
·Vol. 34
·期 6
·1948-1958
·
IF 3.4
Huajun Wang,Junwei He,Liming Zou,Chao Wang,Yan Vivian Li
Different vinyl acetate (VAc) and vinyl benzoate (VBz) monomer ratios have been chosen as monomers to create high polymerization degree ( P n ) and high syndiotacticity-diad content ( S-diad ) poly(vinyl alcohol) (PVA) polymers via emulsifier-free polymerization in order to address the problem of limited mechanical capabilities of PVA fibers prepared with low P n and low S-diad polymer. The variations in hydrogen bonding, P n , S-diad , and viscosity of different PVA polymers were investigated and evaluated using Fourier transform infrared spectroscopy, proton nuclear magnetic resonance, gel permeation chromatography, and a viscosity tester. Moreover, various PVA fibers with high strength and modulus have been manufactured using a synthetic polymer as the raw material for dry-wet spinning. The effect of P n and S-diad on the mechanical and thermal characteristics of PVA fibers is evaluated using a variety of characterization techniques, such as the scanning electron microscope, differential scanning calorimetry, thermogravimetric analyzer, X-ray diffraction, and tensile tester. As the ratio of VBz monomer increased, the results suggested that VBz may have a considerable impact on the P n and S-diad of PVA polymers, the OH vibration absorption peak reduced from 3491 to 3442 cm −1 ; the P n increased from 2112 to 17,704; and the S-diad rose from 51.2% to 60.1%. In addition to the fact that P n and S-diad significantly increased the fibers' strength and modulus, the crystallinity increased from 41.8% to 51.7%, and the orientation degree rose from 87.5% to 91.7%, as P n and S-diad increased; the tensile strength and highest elastic modulus increased from 9.71 ± 0.3 cN/dtex to 12.74 ± 0.5 cN/dtex (increased of 31.2%) and 264.52 ± 9.3 cN/dtex to 338.41 ± 8.6 cN/dtex (increased of 27.9%); the elongation at break decreased from 5.63 ± 0.3% to 2.92 ± 0.2%.
研究领域:
材料科学
·
高分子化学
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产品关联
DOI
高影响因子
Journal of Industrial Textiles
·
2019
·
IF 1.884
Hongbin Li,Wenying Shi,Haixia Zhang,Xiaohong Qin
The rigid-rod-like poly(p-phenylene terephthalamide) (PPTA), as the raw material of aramid 1414, has the characteristics of high modulus and hydrophilicity. The flat sheet poly(vinylidene fluoride) (PVDF)/PPTA blend separation membranes with improved hydrophilicity and enhanced modulus have been successfully prepared using in situ polycondensation method in our previous study. In this study, PPTA/PVDF hollow fiber blend separation membranes with enhanced hydrophilicity and mechanical strength were fabricated through the dry–wet spinning technique. Monomers of PPTA were polymerized in the PVDF solution, and the polymerization system was directly used as the spinning solution to fabricate the hollow fiber blend membrane. The effects of spinning conditions including the air-gap distance; the composition of core fluid; and composition of coagulation bath on the structure and properties including the separation properties, surface hydrophilicity, and mechanical properties of PPTA/PVDF hollow fiber blend membranes were well investigated. Membrane surface and cross-sectional morphologies were observed through scanning electron microscope. The enhancements of these spinning conditions weakened the phase separation process as a result of the formation of a small pore structure. The pore size distribution, water flux, and solute rejection varied accordingly. Different spinning conditions have different effects on the mechanical and hydrophilic properties of the hollow fiber blend membranes. Compared with pure PVDF hollow fiber membrane, blend membranes fabricated under different spinning conditions exhibited enhanced surface hydrophilicity and tensile properties. Finally, the change rates of the pure water flux and the solute rejection with different spinning conditions were calculated to further analyze and compare the statistically significant effects.
研究领域:
材料科学
·
分离技术
·
高分子化学
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DOI
高影响因子
ACS Omega
·
2019
·
IF 2.584
Zeming Jiang,Lan Tang,Xin Gao,Wentao Zhang,Jiwei Ma,Liping Zhang
An electrolyte and aprotic solvent mixture were used to prepare cellulose solutions containing cellulose nanocrystals (CNCs). All-cellulose composite fibers were then produced by dry–wet spinning these solutions. The presence of CNC in the all-cellulose fibers was demonstrated, and the effects of the CNC on the fiber properties were investigated. The all-cellulose fibers were characterized by scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis, and electronic tensile measurements. These results showed that CNCs were present in the mixture and that their structure was maintained in the all-cellulose fibers. No compatibility problems between the CNC and cellulose II matrix were observed. Introducing CNC enhanced the crystallinity, thermal stability, and mechanical properties of the composite fibers.
研究领域:
材料科学
·
高分子化学
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产品关联
DOI
PubMed
高影响因子
JOURNAL OF MEMBRANE SCIENCE
·
2013
·
IF 4.093
Huyan Shi,Fu Liu,Lixin Xue
This work describes the fabrication and characterization of antibacterial poly(vinylidene fluoride) (PVDF) hollow fibre membranes via phase inversion using dry-jet wet-spinning technique. Ag-loaded NaY zeolites were particularly synthesized and then doped with PVDF spinning solution to produce a novel antibacterial hollow fibre with enhanced antibacterial efficiency. The morphologies, crystal structures, and Ag + loading of synthesized Ag-loaded NaY zeolites were analyzed by field emission scanning electron microscope (FE-SEM), X-ray diffraction (XRD) and inductively coupled plasma-atomic emission spectrometry (ICP-AES), respectively. The antibacterial efficiencies of the prepared hollow fibre membranes against Escherichia coli ( E. coli ) were evaluated by halo zone test, E. coli suspension filtration test and adhesion test. The surface morphologies , pure water flux, hydrophilicity, tensile strength , through-pore size, resistance to BSA of antibacterial PVDF hollow fibre membrane were also investigated. All results demonstrated that PVDF hollow fibre fabricated by doping Ag-loaded zeolites showed excellent antibacterial property, high permeability and mechanical strength , indicating the promising application as the antibacterial ultra-filtration membranes.
研究领域:
材料科学
·
化学工程
·
环境工程
·
生物技术
✓ 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）