Co-reporter:Mengjin Jiang, Jiadeng Zhu, Chen Chen, Yao Lu, Yeqian Ge, and Xiangwu Zhang
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 5) pp:3473
Publication Date(Web):January 20, 2016
DOI:10.1021/acsami.5b11984
Gel polymer electrolytes (GPEs) have been studied for preparing flexible and compact electrochemical energy storage devices. However, the preparation and use of GPEs are complex, and most GPEs prepared through traditional methods do not have good wettability with the electrodes, which retard them from achieving their performance potential. In this study, these problems are addressed by conceiving and implementing a simple, but effective, method of electrodepositing poly(vinyl alcohol) potassium borate (PVAPB) GPEs directly onto the surfaces of active carbon electrodes for electrochemical supercapacitors. PVAPB GPEs serve as both the electrolyte and the separator in the assembled supercapacitors, and their scale and shape are determined solely by the geometry of the electrodes. PVAPB GPEs have good bonding to the active electrode materials, leading to excellent and stable electrochemical performance of the supercapacitors. The electrochemical performance of PVAPB GPEs and supercapacitors can be manipulated simply by adjusting the concentration of KCl salt used during the electrodeposition process. With a 0.9 M KCl concentration, the as-prepared supercapacitors deliver a specific capacitance of 65.9 F g–1 at a current density of 0.1 A g–1 and retain more than 95% capacitance after 2000 charge/discharge cycles at a current density of 1 A g–1. These supercapacitors also exhibit intelligent high voltage self-protection function due to the electrolysis-induced cross-linking effect of PVAPB GPEs.Keywords: electrodeposition; gel polymer electrolyte; poly(vinyl alcohol); potassium chloride; supercapacitor
Co-reporter:Weixing Xu;Cihang Yu;Xiangsen Zhao;Jianjun Xu
Journal of Applied Polymer Science 2016 Volume 133( Issue 4) pp:
Publication Date(Web):
DOI:10.1002/app.42918
ABSTRACT
Melamine−formaldehyde resin (MF)/polyvinyl alcohol (PVA) composite fibers with different phase structures and properties were prepared through reaction induced phase separation by wet spinning. Raman spectroscopy, rotary viscometer, and miscibility index were used to characterize the MF resins with different reaction degrees (RD). The phase structures of composite spinning dopes and composite fibers were observed by optical microscope (OM) and scanning electron microscope (SEM). Mechanical properties, flame retardant properties, and thermal stability of the composite fibers were also tested. Results show that the composite fibers made from MF resins with different RD have different phase structures and properties; when the miscibility index (MI) of MF resin is 1.60, the obtained MF/PVA composite fiber shows a sea-island phase structure, which endues the fiber with the best comprehensive properties: the breaking strength, breaking elongation, rupture work and limiting oxygen index (LOI) are 4.29 cN/dtex, 13.55%, 8.46 × 10−5 J/dtex and 43.1%, respectively. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 42918.
Co-reporter:Yongjiao Song, Junfan Li, Guangdou Ye, Jianjun Xu, and Mengjin Jiang
Industrial & Engineering Chemistry Research 2015 Volume 54(Issue 49) pp:12367-12373
Publication Date(Web):November 23, 2015
DOI:10.1021/acs.iecr.5b03250
The precursor polyacrylonitrile/poly(vinyl alcohol) (PAN/PVA) fibers were prepared by emulsion spinning of PAN emulsion with PVA solution. The precursor fibers were then amidoximated to get the polyamidoxime (PAO)/PVA composite chelating fibers. The structures of PAN emulsion particles and composite fiber were studied with a laser mastersizer, scan electronic microscope, Fourier transform infrared spectra, auto-Kjeldahl determination, and X-ray diffraction analysis. Results show that nanosized PAN particles were well-dispersed in PVA fiber matrix through emulsion spinning. Almost all of the PAN particles were amidoximated after treatment. The PAO/PVA fiber has good selectivity to silver ions in a multiple metal ions solution. Its maximum amount of adsorption of silver ions and copper ions were calculated to be 518 and 146 mg g–1 according to the Langmuir model. It also has good mechanical performance with breaking strength, 392.10 MPa, and elongation at break, 30.19%.
Co-reporter:Zhao Li, Wei He, Jianjun Xu, Mengjin Jiang
Solar Energy Materials and Solar Cells 2015 140() pp: 193-201
Publication Date(Web):
DOI:10.1016/j.solmat.2015.04.014
Co-reporter:Wanlu Chen, Xingwei Fu, Weibing Ge, Jianjun Xu, Mengjin Jiang
Polymer Degradation and Stability 2014 Volume 102() pp:81-87
Publication Date(Web):April 2014
DOI:10.1016/j.polymdegradstab.2014.02.004
Bisneopentyl glycol dithiopyrophosphate (DDPS) has been successfully microencapsulated with melamine formaldehyde (MF) resin as a shell material by in-situ polymerization process in this study. Chemical structures of DDPS and microencapsulated DDPS (MDDPS) were characterized by Fourier-transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). Morphologies were investigated by scanning electron microscopy (SEM), while particle size and distribution were investigated by granulometry. The results show that microencapsulation can make DDPS particles be coated by MF resin entirely. After microencapsulation, the mean diameter of DDPS increased slightly from 1.405 μm to 2.757 μm, DDPS and MDDPS both were applied in polyvinyl alcohol (PVA) films to compare their flame retardancy. The flame retardation property was evaluated by limiting oxygen index (LOI). Decomposition mechanism was investigated by TG-FTIR, FTIR and SEM. The results indicated that MDDPS has better flame retardancy to PVA, and the LOI of MDDPS/PVA composite is 31.8%. As a fire retardant for PVA, DDPS mainly functions in the gaseous phase rather than in the condensed phase, while MDDPS works in both the gaseous and condensed phase.
Co-reporter:Weixing Xu;Shujuan Dong;Cihang Yu;Xiang Yan;Jianjun Xu
Journal of Applied Polymer Science 2014 Volume 131( Issue 17) pp:
Publication Date(Web):
DOI:10.1002/app.40678
ABSTRACT
Composite fibers made of different hydroxymethylation degree (HMD) melamine formaldehyde (MF) resins and polyvinyl alcohol were prepared by wet spinning. The structures of MF resins and composite fibers were studied using Fourier transform infrared spectrometer, optical microscope, scanning electron microscope, differential scanning calorimetry, X-ray diffraction, and Kjeldahl. The fibers' mechanical properties, fire retardant properties, softening point in hot water, and thermal stability were also tested. Results show that with the increase of HMD, the compatibility between MF and PVA gets better; the breaking strength and thermal stability of the fibers increase, while the nitrogen-loss rate, the elongation at break, and SP decrease. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40678.
Co-reporter:Cihang Yu;Weixing Xu;Xiangsen Zhao;Jianjun Xu
Fibers and Polymers 2014 Volume 15( Issue 9) pp:1828-1834
Publication Date(Web):2014 September
DOI:10.1007/s12221-014-1828-x
Composite fibers made of polyvinyl alcohol (PVA) and melamine-formaldehyde (MF) resins with different reaction degrees were prepared by wet spinning. The phase structures of MF/PVA spinning dopes and composite fibers were observed by using optical microscope (OM) and scanning electron microscope with energy-dispersive X-ray spetroscopy (SEM-EDS). Crystal structures of composite fibers were studied by X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The loss of MF resins in the spinning process was calculated by using Kjeldahl. The mechanical properties, the flame retardant property, the water resistant property, and the thermal stability of composite fibers were also tested. Results show that with an increase in the reaction degree of MF resin, the phase separation degrees of spinning dopes and composite fibers rise up, the size of MF microphase grows larger, and the loss of MF resin diminishes; consequently, the hot water resistance and the flame retardancy of the fiber ameliorate while the tensile strength and the thermal stability perform a tendency of dropping after rising.
Co-reporter:Jiajia Li;Bin Wang;Guangdou Ye;Jianjun Xu
Fibers and Polymers 2013 Volume 14( Issue 4) pp:537-541
Publication Date(Web):2013/04/01
DOI:10.1007/s12221-013-0537-1
Thermal regulating fiber has been a research hotspot worldwide recently. In this paper, the energy storage microcapsules composed of silicon dioxide (SiO2) as shell and paraffin as core were synthesized in the spinning solution of polyvinyl alcohol (PVA). This solution was used to prepare thermal regulating PVA fibers by wet spinning directly. Orthogonal experiment was conducted to optimize the synthetic conditions of the microcapsules. Chemical structure and morphology of the fibers were characterized by Fourier transform infrared-attenuated total reflectance (FTIR-ATR) and scanning electron microscope (SEM) respectively. The thermal properties of the fibers were studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Results present that energy storage microcapsules are successfully synthesized in PVA spinning solution with a mean particle size of 1.39 µm. The fibers containing such microcapsules show a high latent heat storage density of 45.39 J g−1, which also achieve a relatively better thermal stability.
