Co-reporter:Yang Xiang, Xudong Ru, Jinguo Shi, Jiang Song, Haidong Zhao, Yaqing Liu, Dongdong Guo, and Xin Lu
Journal of Agricultural and Food Chemistry December 20, 2017 Volume 65(Issue 50) pp:10851-10851
Publication Date(Web):November 27, 2017
DOI:10.1021/acs.jafc.7b03827
A new semi-interpenetrating polymer network (semi-IPN) slow-release fertilizer (SISRF) with water absorbency, based on the kaolin-g-poly(acrylic acid-co-acrylic amide) (kaolin-g-P(AA-co-AM)) network and linear urea–formaldehyde oligomers (UF), was prepared by solution polymerization. Nutrients phosphorus and potassium were supplied by adding dipotassium hydrogen phosphate during the preparation process. The structure and properties of SISRF were characterized by various characterization methods. SISRF showed excellent water absorbency of 68 g g–1 in tap water. The slow-release behavior of nutrients and water-retention capacity of SISRF were also measured. Meanwhile, the swelling kinetics was well described by a pseudo-second-order kinetics model. Results suggested the formation of SISRF with simultaneously good slow-release and water-retention capacity, which was expected to apply in modern agriculture and horticulture.Keywords: kaolin-g-poly(acrylic acid-co-acrylic amide); semi-IPN; slow-release fertilizer; urea−formaldehyde; water retention;
Co-reporter:Wen-jun Liang, Bin Zhao, Pei-hua Zhao, Cong-yun Zhang, Ya-qing Liu
Polymer Degradation and Stability 2017 Volume 135() pp:140-151
Publication Date(Web):January 2017
DOI:10.1016/j.polymdegradstab.2016.11.023
A novel bridged-cyclotriphosphazene flame retardant, named bisphenol-S bridged penta(anilino)cyclotriphosphazene (BPS-BPP), was synthesized and characterized by fourier transform infrared (FTIR), 1H NMR and 31P NMR and mass spectroscopy (MS). Then, BPS-BPP was used to flame retard epoxy resin (EP, diglycidyl ether of bisphenol-A type). The curing behavior and glass-transition temperature (Tg) of EP/BPS-BPP were investigated by differential scanning calorimetry (DSC). The thermogravimetric analysis (TGA) results showed that the incorporation of BPS-BPP improved the thermal stability of EP at high temperature region. Limiting oxygen index (LOI) value of EP sample increased to 29.7% with limited amount of 9 wt% BPS-BPP. The peak of heat release rate (PHRR), total heat release (THR), total smoke production (TSP) values of the same sample, obtained from cone calorimetry, were declined conspicuously, indicating good flame-retardant and smoke suppression efficiency of BPS-BPP. The flame-retardant mechanism of EP/BPS-BPP thermosets was investigated via analyses of gaseous products and char residues. Based on the aforementioned studies, BPS-BPP was demonstrated as an effective flame retardant for EP due to temperature-dependent and bi-phase flame retardant mechanism.
Co-reporter:Cong-yun Zhang, Rui Hao, Bin Zhao, Yao-wu Hao, Ya-qing Liu
Applied Surface Science 2017 Volume 409(Volume 409) pp:
Publication Date(Web):1 July 2017
DOI:10.1016/j.apsusc.2017.03.023
•A novel sandwiched hybrid (Ag@GO@Au) with graphene oxide (GO) films embedded between hierarchically flower-like Ag particles and Au nanoparticles was successfully fabricated.•The Ag@GO@Au sandwiched structures exhibited ultrasensitive SERS response by multi-dimensional coupling.•The GO interlayer as an isolating shell endowed the sandwiched hybrids good signal reproducibility and prolonged stability.The graphene-mediated surface enhanced Raman scattering (SERS) substrates by virtues of plasmonic metal nanostructures and graphene or its derivatives have attracted tremendous interests which are expected to make up the deficiency of traditional plasmonic metal substrates. Herein, we designed and fabricated a novel ternary Ag@GO@Au sandwich hybrid wherein the ultrathin graphene oxide (GO) films were seamlessly wrapped around the hierarchical flower-like Ag particle core and meanwhile provided two-dimensional anchoring scaffold for the coating of Au nanoparticles (NPs). The surface coverage density of loading Au NPs could be readily controlled by tuning the dosage amount of Au particle solutions. These features endowed the sandwiched structures high enrichment capability for analytes such as aromatic molecules and astonishing SERS performance. The Raman signals were enormously enhanced with an ultrasensitive detection limit of rhodamine-6G (R6G) as low as 10−13 M based on the chemical enhancement from GO and multi-dimensional plasmonic coupling between the metal nanoparticles. In addition, the GO interlayer as an isolating shell could effectively prevent the metal–molecule direct interaction and suppress the oxidation of Ag after exposure at ambient condition which enabled the substrates excellent reproducibility with less than 6% signal variations and prolonged life-time. To evaluate the feasibility and the practical application for SERS detection in real-world samples based on GO sandwiched hybrid as SERS-active substrate, three different prohibited colorants with a series of concentrations were measured with a minimum detected concentration down to 10−9 M. Furthermore, the prepared GO sandwiched nanostructures can be used to identify different types of colorants existing in red wine, implying the great potential applications for single-particle SERS sensing of biotechnology and on-site monitoring in food security.The GO embedded sandwich nanoparticles are capable of serving as an ultrasensitive, highly reproducible and stable SERS platform.Download high-res image (158KB)Download full-size imageDownload high-res image (158KB)Download full-size image
Co-reporter:Wen-Jun Liang, Bin Zhao, Cong-Yun Zhang, Rong-Kun Jian, Dong-Yue Liu, Ya-Qing Liu
Polymer Degradation and Stability 2017 Volume 144(Volume 144) pp:
Publication Date(Web):1 October 2017
DOI:10.1016/j.polymdegradstab.2017.08.027
A novel flame retardant, namely bisphenol-A bridged penta(phenoxy)cyclotriphosphazene (A-BP), was synthesized and characterized successfully. Obtained A-BP was mixed in different proportions with diglycidyl ether of bisphenol-A (DGEBA) in order to prepare a series of flame retardant epoxy resins (EP). The differential scanning calorimeter (DSC) results indicated that the glass transition temperatures (Tg) of EPs containing A-BP had only a slight decrease in comparison to EP. Thermogravimetric analysis (TGA) showed that the incorporation of A-BP improves the thermal stability of EP at a high temperature. Moreover, an increase of LOI value (33.9%) was achieved for EP contained with 9 wt% of A-BP. Furthermore, such sample passed UL-94 V-0 rating. Additionally, according to the cone calorimeter tests, in the whole combustion, the EP/9% A-BP material showed lower heat release and smoke production than neat EP. To elucidate the flame retardant actions of A-BP for EP, comprehensive measurement including Fourier transform infrared (FTIR), Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), pyrolysis gas chromatography/mass spectrometry (Py-GC/MS) and TG-FTIR techniques were adopted to analyze the char layers and gaseous products. As a result, a bi-phase flame retardant mechanism was proposed showing the efficiency of inert gas dilution and quenching of existed free radicals in gaseous phase and char formation action in a condensed phase, respectively.
Co-reporter:Lu Bai, Zhaodong Yan, Lu Jia, Zhicheng Liu, Yaqing Liu
Materials & Design 2017 Volume 135(Volume 135) pp:
Publication Date(Web):5 December 2017
DOI:10.1016/j.matdes.2017.09.010
•Morphological changes of the gold Nanorods-decorated electrospun nanofibers were controlled by applying thermal treatment.•The decorated nanorods became short, and finally round with the increasing thermal treating time.•The SERS activity of the changing nanostructure firstly increased and then decreased with the thermal treating time.•The catalytic property of the changing nanostructure monotonously decreased with the thermal treating time.Understanding the structure-property relationships of functional materials with changing nanostructures is essential for their practical applications. In this work, the nanorods-decorated electrospun nanofibers underwent a morphology evolution upon simple thermal treatment. The nanorods became short, and finally round with the increasing thermal treating time. As results of the morphology evolution, the SERS properties and the catalytic properties of the changing nanostructures showed different trends. The SERS activity firstly increased and then decreased with the thermal treating time. However, the catalytic property decreased with the thermal treating time. The revealed connections between the practical performance and the morphology evolution might be helpful for the control of functionality of nanomaterials under certain conditions.Download high-res image (129KB)Download full-size image
Co-reporter:Cong-yun Zhang;Rui Hao;Bin Zhao;Yi-zheng Fu;Yao-wu Hao
Journal of Materials Science 2017 Volume 52( Issue 19) pp:11391-11401
Publication Date(Web):21 June 2017
DOI:10.1007/s10853-017-1292-2
Using ascorbic acid as reducing agent and different organic acids (e.g., oxalic acid, DL-malic acid and citric acid) as structure-directing agents, a novel class of hierarchical flower-like silver mesoparticles with tunable size and shape were synthesized in high yield. The chemical structures of organic acids with different carbon chain length and functional groups have been found to play critical roles in the process of assembling metal nanoparticles into hierarchical complex structures. The anisotropic morphologies of as-synthesized silver structures could readily be tuned by simply varying the concentrations of reagents and the growth temperature. This synthesis method provides a new synthetic strategy for the anisotropic growth and morphology control of metallic particles. The textured flower-like Ag mesoparticles with hierarchical three-dimensional structures could generate abundant surface plasmon resonance hot spots and exhibit an excellent surface-enhanced Raman scattering (SERS) activity, revealing the promising potential for practical applications in single-particle and particle-array SERS sensing.
Co-reporter:Bin Zhao, Yan-Ting Liu, Cong-Yun Zhang, Dong-Yue Liu, Fei Li, Ya-Qing Liu
Journal of Analytical and Applied Pyrolysis 2017 Volume 125(Volume 125) pp:
Publication Date(Web):1 May 2017
DOI:10.1016/j.jaap.2017.04.011
•A Novel phosphoramidate named 2,2-dimethyl-1,3-propanediol-N,N-bis(2-hydroxyethyl) (DPDA) was synthesized successfully.•The flame retardancy of cotton fabric was enhanced by flame retardant finishing with DPDA.•The phosphorylation of DPDA promoted forming phosphorus-rich compact char layer and inhibited flammable gases released.A novel phosphoramidate named 2,2-dimethyl-1,3-propanediol-N,N-bis(2-hydroxyethyl) (DPDA) was successfully synthesized and used to reduce the flammability of cotton fabrics through flame retardant finishing method. Fourier transform infrared spectroscopy (FTIR), 1H-, and 31P-nuclear magnetic resonance (NMR) were adopted to characterize the chemical structure of DPDA. The flame retardancy and fire behavior of neat and treated cotton fabrics were evaluated by vertical burning, limiting oxygen index (LOI) and cone calorimetric tests. To further investigate the flame retardant action of DPDA for cotton, the char layers of treated and controlled cotton fabrics after combustion were analyzed by scanning electron microscopy coupled with an energy dispersive X-ray spectroscopy (SEM-EDX); then the pyrolysis products released from DPDA and cotton fabric samples were characterized using thermogravimetric analysis coupled with Fourier transform infrared spectrometry (TG-FTIR). The enhanced fire retardancy for cotton fabrics by the introduction of DPDA was mainly due to the phosphorylation which promoted the formation of phosphorus-rich compact char layer and restrained release of flammable gases in the condensed and gaseous phase, respectively.
Co-reporter:Shao-Feng Zhou, Jun-Jie Wang, Lin Gan, Xiao-Juan Han, Hong-Lei Fan, Lin-Yu Mei, Jin Huang, Ya-Qing Liu
Journal of Alloys and Compounds 2017 Volume 721(Volume 721) pp:
Publication Date(Web):15 October 2017
DOI:10.1016/j.jallcom.2017.05.321
•Heavy metal ions sensor based on L-cysteine functionalized mesoporous MnFe2O4.•Realized individual and simultaneous detection toward four target ions.•Good selectivity and sensitivity toward Pb(II).•Satisfying anti-interference, reproducibility, stability, repeatability and applicability.In order to improve the electrochemical sensing performance toward heavy metal ions, this work presents a novel L-cysteine functionalized mesoporous MnFe2O4 hybrid nanospheres (MnFe2O4@Cys) applied as electrochemical sensor for determination of Pb(II), Hg(II), Cu(II) and Cd(II) based on square wave anodic stripping voltammetry (SWASV) technique. Combined the excellent adsorption capacity toward heavy metal ions of mesoporous MnFe2O4 nanocluster with Lewis acid-base interaction supported by L-cysteine, the MnFe2O4@Cys modified glass carbon electrode (GCE) successfully realized individual and simultaneous detection toward four target ions. In particular, the L-cysteine modified Mn and Fe bimetal oxides nanoparticles displayed good selectivity toward Pb(II) with high sensitivity of 57.0 μA/μM and 35.3 μA/μM under the individual and simultaneous determination conditions, respectively. Meanwhile, this fabricated sensor showed satisfying anti-interference, reproducibility, stability, repeatability and applicability for detecting heavy metal ions. It provides a promising platform for developing new and high performance electrochemical sensors applied in individual and simultaneous determination of various of heavy metal ions.Download high-res image (161KB)Download full-size image
Co-reporter:Bin Zhao, Dong-Yue Liu, Wen-Jun Liang, Fei Li, Jun-Sheng Wang, Ya-Qing Liu
Journal of Analytical and Applied Pyrolysis 2017 Volume 124(Volume 124) pp:
Publication Date(Web):1 March 2017
DOI:10.1016/j.jaap.2016.12.032
•The complex system EG/DEPA greatly enhanced the LOI values of RPUFs from 19.5% to 30.4%.•EG and DEPA jointly acted inhibitive effects on the combustion intensity and smoke production according to cone tests.•Bi-phase flame retardant mechanism of EG/DEPA in RPUF were investigated in detail.Flame-retardant water-blown rigid polyurethane foams (RPUFs) with a reactive-type phosphoramidate named diethyl-N,N-bis(2-hydroxyethyl) phosphoramide (DEPA) and expandable graphite (EG) were fabricated through free foaming technique. The flame retardancy and fire behaviors of RPUFs were characterized using limiting oxygen index (LOI), microscale combustion calorimeter (MCC) and cone calorimetric tests. Compared to the effects of individual flame retardant agent (DEPA or EG), the complex system (EG/DEPA) endowed RPUFs enhanced LOI values (28.8%–30.4%), higher protective char yields, lower heat release and smoke production. EG and DEPA jointly acted to remarkably inhibit the combustion intensity and smoke production through their addition or synergistic flame-retardant effects. To further validate the flame-retardant mechanism of EG/DEPA in RPUF, thermogravimetric analysis connected with Fourier transform infrared spectrometry (TG–FTIR), scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDX) tests were conducted. These results demonstrated that DEPA decomposed potential free radical scavenger (PO) and promoted generating more H2O and CO2 in gaseous phase. Furthermore, DEPA facilitated the formation of phosphorus-rich residue, which was combined with worm-like expanded graphite to constitute protective char layers. On the basis of these results, a bi-phase flame-retardant mechanism of EG/DEPA in RPUF was proposed.
Co-reporter:Hongji Duan, Yadong Xu, Ding-Xiang Yan, Yaqi Yang, Guizhe Zhao, Yaqing Liu
Materials Letters 2017 Volume 209(Volume 209) pp:
Publication Date(Web):15 December 2017
DOI:10.1016/j.matlet.2017.08.053
•Conductive UHMWPE composites with segregated Ni structure were realized.•Ni constructed a well connected 3D conductive network with selective distribution.•High conductivity of composite (2687 S/m) was achieved with very low Ni content.•Remarkable EMI SE of average 55 dB in X band was achieved with only 2.58 vol% Ni.Conductive ultrahigh-molecular-weight polyethylene (UHMWPE) composite with segregated nickel (Ni) structure which exhibited highly efficient electromagnetic interference (EMI) shielding performance was fabricated in this work. By synthesizing nickel coated UHMWPE particles via electroless deposition and then hot compressing, the prearranged thin Ni layer could only selectively locate at the boundary between UHMWPE regions due to the specific high melting viscosity of UHMWPE, and thus constructed a well connected segregate Ni conductive network in UHMWPE matrix. Owing to the advantage of segregated network structure, the UHMWPE/Ni composite shows a low percolation threshold and high conductivity, and exhibits an EMI shielding effectiveness (SE) of average 55 dB with Ni content of only 2.58 vol% in X-band. This result indicates the segregated UHMWPE/Ni composite can serve as an ultra-efficient material for EMI shielding applications.Download high-res image (84KB)Download full-size image
Co-reporter:Yadong Xu;Yaqi Yang;Dingxiang Yan
Journal of Materials Science: Materials in Electronics 2017 Volume 28( Issue 12) pp:9126-9131
Publication Date(Web):02 March 2017
DOI:10.1007/s10854-017-6646-7
In this work, we have reported a facile strategy to prepare an anisotropic conductive polypropylene/nickel coated glass fiber (PP/NCGF) composite with aligned NCGF network, through magnetic-assistant compression molding method. Owing to the high aspect ratio and particular magnetism, the conductive NCGF exhibits significant responsivity to the magnetic field during the molding process and thus aligns automatically in the PP matrix. The resultant PP/NCGF composite shows obvious anisotropy in electrical and electromagnetic interference (EMI) shielding performance. The electrical conductivity parallel to the magnetic field direction (1.46 S/m) is 18 times higher than that of perpendicular direction (8.06 × 10−2 S/m), and the EMI shielding effectiveness shows 8 dB disparity (15 dB in parallel direction and 23 dB in perpendicular direction). The anisotropic PP/NCGF composite would be considered as promising EMI shielding material where discrepant shielding level is required in orthogonal directions.
Co-reporter:Cong-yun Zhang, Rui Hao, Bin Zhao, Yizheng Fu, Huijuan Zhang, Sina Moeendarbari, Christopher S. Pickering, Yao-wu Hao, Ya-qing Liu
Applied Surface Science 2017 Volume 400(Volume 400) pp:
Publication Date(Web):1 April 2017
DOI:10.1016/j.apsusc.2016.12.161
•A novel SERS substrate based on graphene oxide-wrapped flower-like Ag particles was successfully synthesized.•The Ag@GO hybrids exhibit extremely high SERS stability, reproducibility and outstanding sensitivity.•The Ag@GO hybrids are capable of selectively and directly detecting polychlorinated biphenyls.Graphene oxide (GO) serving as an ultrathin, seamless and passivated shell has been intensively investigated in shell-isolated surface-enhanced Raman scattering (shell-isolated SERS) research field. Here we report a novel and effective SERS platform based on GO wrapped flower-like Ag microparticles (Ag@GO). GO layers were efficiently enclosed around cysteamine functionalized Ag particles by electrostatic interactions. The morphology of flower-like Ag microparticles could be optimized by varying the reaction conditions such as growth temperature and the amount of reagents. The prepared Ag@GO SERS-active substrates exhibited much higher stability wherein the SERS intensities of Ag@GO hybrids were only decreased by 16 ± 5% after 50 days exposure under ambient condition, comparing with a 69 ± 10% decrease for bare Ag particles. Furthermore, the SERS sensitivity of rhodamine 6G (R6G) on Ag@GO hybrids was improved 3.5 times due to the chemical enhancement from transparent GO shell. The excellent reproducibility with average intensity variations less than 5% was also achieved. Most importantly, eliminating an extra surface modification steps, Ag@GO composite substrates demonstrated a high enrichment capability and remarkable SERS response toward polychlorinated biphenyls (PCBs), which have weak affinity on noble metal surface. Specifically, GO wrapped Ag particle hybrid could offer spectroscopic identification of two PCB congeners in mixed solution, showing promising potential for practical applications of single-particle SERS-based sensing and on-site monitoring in environment.The Ag@GO hybrids serving as SERS platform exhibit excellent sensitivity, stability and reproducibility, particularly for the selective detection of PCBs.Download high-res image (165KB)Download full-size image
Co-reporter:Hongji Duan;Jianming Yang;Yaqi Yang
Journal of Materials Science: Materials in Electronics 2017 Volume 28( Issue 8) pp:5725-5732
Publication Date(Web):2017 April
DOI:10.1007/s10854-016-6244-0
A highly efficient electromagnetic interference shielding composite based on nickel coated glass fibers (NCGFs) and titanium dioxide (TiO2) filled polypropylene (PP) is fabricated via the simple melt blending method. Superior shielding effectiveness of 44.5 dB can be achieved with only 1.12 vol% Ni and 0.8 vol% TiO2 loadings owning to the well-formed conductive network and interfacial polarization effect of TiO2. The conductive Ni layer coating on the surface of glass fibers constructs an efficient conductive network due to its interfacial distribution between GF and PP. This interconnected Ni network provides fast electron transport channels to absorb the electromagnetic waves. Meanwhile, TiO2 dispersed among the network of NCGFs induces more interfacial polarization, and thus produces a synergistic effect to enhance the shielding effectiveness of composite. Such composite would be considered as a promising electromagnetic shielding material in aerospace and electronics.
Co-reporter:Jianming Yang;Yaqi Yang;Hongji Duan
Journal of Materials Science: Materials in Electronics 2017 Volume 28( Issue 8) pp:5925-5930
Publication Date(Web):30 December 2016
DOI:10.1007/s10854-016-6266-7
A light-weight and electromagnetic interference (EMI) shielding conductive epoxy resin (EP) composite foam was firstly fabricated by loading nickel coated carbon fibers (NCCFs). The foamed EP/NCCFs composites with a uniform foam cell containing various NCCFs contents (0–5.03 vol%) have been fabricated via chemical foaming. The foams exhibit densities of as low as 0.45 g cm− 3. Owning to the high aspect ratio of carbon fibers and selective distribution of NCCFs in the foam structure, NCCFs could easily connect with each other and construct the conductive network in polymer matrix. As a result, the composite foams exhibit an EMI shielding effectiveness of ~33 dB and a corresponding specific EMI shielding effectiveness of as high as 77.4 dB cm3 g− 1 in the microwave frequency range of 8.2–12.4 GHz. Such composite foam would be considered as a promising lightweight and EMI shielding material in aerospace and electronics.
Co-reporter:Shao-Feng Zhou, Xiao-Juan Han, Ya-Qing Liu
Journal of Alloys and Compounds 2016 Volume 684() pp:1-7
Publication Date(Web):5 November 2016
DOI:10.1016/j.jallcom.2016.05.152
•Fe3O4-chitosan NPs were used to electrochemical detect heavy metal ions.•The sensing material is relatively simple with high response to heavy metal ions.•The modification of chitosan improves the response to Pb(II) 4.8 times than Fe3O4.•It offers good stability and practical applicability in detection of heavy metal ions.A high-activity, eco-friendly and inexpensive magnetic chitosan sensing nanomaterials were introduced for individual electrochemical detection toward Pb(II), Hg(II), Cu(II) and Cd(II) by square wave anodic stripping voltammetry (SWASV). The morphology and structure of Fe3O4-chitosan nanoparticles were characterized by TEM, XRD and FTIR respectively, and their electrochemical behavior based on the sensing materials modified glassy carbon electrode (GCE) was studied by cyclic voltammograms (CV) and electrochemical impedance spectra (EIS). Serving as a heavy metal ions sensor, the chitosan magnetic nanoparticles exhibited much more remarkable electrochemical response toward heavy metal ions. Especially, the introduction of chitosan significantly enhanced the SWASV performance toward Pb(II) with the high sensitivity of 50.6 μA/μM and LOD of 0.0422 μM, which was about 4.8 times than pure Fe3O4 nanoparticles. This result might be due to the strong charge-transfer interaction as well as the chelation and electrostatic interaction existence between Pb(II) and Fe3O4-chitosan unit, which will generate a high concentration region at electrode surface for efficient redox interaction between electrode and Pb(II). Furthermore, the Fe3O4-chitosan modified GCE offers good stability and potential practical applicability in the electrochemical determination of Pb(II). This work provides a potential simple and low cost material for electrochemical detection of toxic metal ions.This is the first report involving high-activity, eco-friendly and inexpensive magnetic chitosan nanomaterials serving as electrochemical sensor for individual determination of heavy metal ion.
Co-reporter:Bin Zhao, Wen-Jun Liang, Jun-Sheng Wang, Fei Li, Ya-Qing Liu
Polymer Degradation and Stability 2016 Volume 133() pp:162-173
Publication Date(Web):November 2016
DOI:10.1016/j.polymdegradstab.2016.08.013
A novel flame retardant, named bisphenol-A bridged penta(anilino)cyclotriphosphazene (BPA-BPP), was successfully synthesized. Its chemical structure was characterized by Fourier transform infrared (FTIR), 1H NMR and 31P NMR. Then, different amounts of BPA-BPP were mixed with diglycidyl ether of bisphenol-A (DGEBA) to fabricate flame retardant epoxy resin (EP). Nonisothermal differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) tests were used to study the curing kinetics and thermal degradation behaviors of flame retardant EPs. The results of limiting oxygen index (LOI), vertical burning tests (UL-94) suggested that BPA-BPP exhibited good flame-retarded efficiency on the EP loaded with low phosphorus content. Compared with the neat EP, the LOI value of EP/9%BPA-BPP increased from 21.0 vol% to 28.7 vol%. Furthermore, the peak of heat release rate (PHRR), total heat release (THR), total smoke production (TSP) of the same sample, obtained from cone calorimetry, were declined obviously, suggesting excellent flame retardancy and smoke inhibition. The morphology and chemical structures of the char layers were analyzed by SEM, Raman and FTIR. The Py-GC/MS was used to investigate the pyrolysis behavior and flame-retardant mechanism of BPA-BPP. In the process of heating, aniline, diphenylamine and NH3 were released from BPA-BPP in gaseous phase, and phosphorus-rich carbonaceous chars were left in condensed phase. BPA-BPP could promote EP to form intumencent protective char layers, enhancing flame retardancy of EP effectively.
Co-reporter:Bin Zhao, Ya Lu, Congyun Zhang, Yizheng Fu, Sina Moeendarbari, Sandesh R. Shelke, Yaqing Liu, Yaowu Hao
Applied Surface Science 2016 Volume 387() pp:431-436
Publication Date(Web):30 November 2016
DOI:10.1016/j.apsusc.2016.06.128
Highlights
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We report a novel and flexible SERS substrate based on filter membranes decorated with silver dendrites.
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The filter membrane-based substrate exhibits high SERS sensitivity, excellent reproducibility and stability.
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The 3D SERS substrate has the potential for rapid, direct and sensitive detection for trace organic pollutants.
Co-reporter:Cong-yun Zhang, Ya Lu, Bin Zhao, Yao-wu Hao, Ya-qing Liu
Applied Surface Science 2016 Volume 377() pp:167-173
Publication Date(Web):30 July 2016
DOI:10.1016/j.apsusc.2016.03.132
Highlights
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The 3D SERS-active substrate, with Ag-dendrites within and on top of AAO membrane has been synthesized.
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The Ag dendrite-integrated AAO membrane substrate exhibits high SERS sensitivity, excellent reproducibility and tunability.
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Without any surface modification, the substrate shows an outstanding SERS response for the molecules with weak affinity for noble metal surfaces.
Co-reporter:Zhiyi Zhang;Huan Zhang;Ye Li;Haixiang Jia;Jinquan Shou;Kai Wen;Pengguang Bai;Yi Xue;Lizhong Bai
Polymer Composites 2016 Volume 37( Issue 5) pp:1318-1322
Publication Date(Web):
DOI:10.1002/pc.23298
Elastomeric polyurethane (PU) was mixed with 0, 10, 15, 20, 25, and 30 wt% of graphite to obtain PUE-based composites. The structure of PU/graphite elastomer was characterized by scanning electron microscopy. It was found that the polyurethane elastomer (PUE) molecular chains were intercalated into the graphite layers and evenly distributed in the matrix. When the graphite content was lower it could make full use of its strength with some loss of plasticity; when the graphite content was too high, the friction between graphite and PUE increased and hence it is more difficult for the macromolecular chain reaction. The polymer was more unstable as a whole. Furthermore, the thermal and mechanical properties of the obtained products were investigated in detail. The result showed that the thermal stability of PUE was improved by the introduction of the graphite. The softening temperature of the PUE/graphite containing 10% graphite was 11°C higher than that of pure PUE. At the same time, the hardness, tensile strength, elongation, 300% tensile modulus, tearing strength of PU/graphite elastomer were also investigated. POLYM. COMPOS., 37:1318–1322, 2016. © 2014 Society of Plastics Engineers
Co-reporter:Yaqi Yang;Tingting Hou;Chunyu Dong;Hongji Duan
Journal of Polymer Research 2016 Volume 23( Issue 8) pp:
Publication Date(Web):2016 August
DOI:10.1007/s10965-016-1065-7
A highly conductive and reinforced polypropylene/nickel coated glass fiber (PP/NCGF) composite is fabricated via a simple and efficient strategy. Nucleating agent induced crystallization leads to the sharp volume excluded effect and drives NCGFs into the amorphous region of PP matrix, thus the formation of conductive network connected by NCGFs is promoted remarkably. The incorporation of nucleating agent dibenzylidene sorbitol (DBS) improves the strength of composites simultaneously due to the enhanced crystallinity and the reinforced interfacial interaction. Accordingly, the percolation threshold of PP/NCGF composites is decreased to 0.35 vol% (Ni content) by loading DBS, and the conductivity increases by four order of magnitude around the percolation threshold which exceeds 70 S/m with the Ni content of only 0.47 vol%. The tensile strength of PP/NCGF composites is increased by about 30–40 % in all range of NCGF content. This exciting result provides a strategy to prepare high-performance conductive composites by crystallization-induced enhancement.
Co-reporter:Youyi Sun, Wenhui Zhang, Diansen Li, Li Gao, Chunlin Hou, Yinghe Zhang, Yaqing Liu
Electrochimica Acta 2015 Volume 178() pp:823-828
Publication Date(Web):1 October 2015
DOI:10.1016/j.electacta.2015.08.092
Here, a novel three dimensional Ni foam-supported porous MnO2 film (porous MnO2/Ni composite foam) was successfully synthesized by the simple hydrothermal method using Ni foam as substrate. The porous MnO2 film had closely coated on the backbones of the Ni foam without assistant of surfactant at mild conditions. At the same time, the pore size of porous MnO2/Ni composite foam was easily controlled by the reaction temperature. Furthermore, it was found that the capacitive properties of porous MnO2/Ni composite foam were related to the pore size of MnO2 film. It showed smaller pore size, and it exhibited better capacitive behavior for the electrode, in which the porous MnO2/Ni composite foam with pore size of ca.50.0∼150.0 nm showed high rate capability of 1086.0 F/g at 10.0 A/g and good cycle stability with capacitance retention of 98.0% after 500 cycles. The high capacitive properties was due to the active materials MnO2 grown on the the backbone of the Ni foam and porous structure of MnO2 materials, resulting in the reduce of resistance and enhancement of active surface area. Our work not only demonstrates the controlled synthesis of high-quality porous MnO2/Ni composite foam at mild conditions on a large scale, but also provides a universal route for the rational design of supercapacitors with high performance.
Co-reporter:Xiao-Juan Han, Shao-Feng Zhou, Hong-Lei Fan, Qiao-Xin Zhang, Ya-Qing Liu
Journal of Electroanalytical Chemistry 2015 Volume 755() pp:203-209
Publication Date(Web):15 October 2015
DOI:10.1016/j.jelechem.2015.07.054
•Mesoporous MnFe2O4 nanocrystal clusters were modified on GCE.•Favorable sensitivity (19.9 μA μM− 1) and LOD (0.054 μM) for Pb2 + were achieved.•The modified GCE exhibits high selectivity and good anti-interference.•It offered excellent stability and practical applicability for detection of Pb2 +.High-adsorption MnFe2O4 nanocrystal clusters (MnFe2O4 NC) with mesoporous structure were used for selective analysis of Pb2 + by square wave anodic stripping voltammetry (SWASV) in this work. The as-prepared MnFe2O4 NCs with diameter of 200–400 nm and mesoporous structure composed of nanocrystals with a size of about 8–12 nm were characterized using SEM, HRTEM and XRD. Electrochemical properties were characterized by cyclic voltammetry and electrochemical impedance spectroscopy. The chemical and electrochemical parameters influencing on deposition and stripping of metal ions, such as supporting electrolytes, pH value, deposition potential, and deposition time, were also studied. The MnFe2O4 NC modified GCE has a high selectivity toward Pb2 + with a favorable sensitivity (19.9 μA μM− 1) and LOD (0.054 μM) for Pb2 + under the optimized conditions while the response to Cd2 +, Hg2 +, Cu2 + and Zn2 + is poor. No interference from Cd2 +, Zn2 + and Hg2 +, favorable stability and potential practical applicability were recognized in the electrochemical determination of Pb2 +. The above results provided a potential material for the design of new sensing materials in the application field of electrochemical detection toward toxic metal ions.
Co-reporter:Chao Guo, Hongji Duan, Chunyu Dong, Guizhe Zhao, Yaqing Liu, Yaqi Yang
Materials Letters 2015 Volume 143() pp:124-127
Publication Date(Web):15 March 2015
DOI:10.1016/j.matlet.2014.12.091
•Conductive PP/Ni coated glass fibers composites were prepared successfully.•Ni coating on the surface of glass fibers formed a continuous conductive network.•Electrical conductivity of composite (8.7 S/cm) was achieved with low content of Ni.•Electrical percolation threshold of conductive composite was as low as 0.46 vol%.In this work, conductive polypropylene composites with a low percolation threshold were fabricated by loading nickel coated glass fibers which were prepared via electroless plating by our group. The incorporation of nickel coated glass fibers could greatly improve the electrical conductivity of polypropylene. Owning to the high aspect ratio of glass fibers, they could easily connect with each other and construct the network structure in polymer matrix. Thus the conductive Ni layer coating on the surface of glass fibers formed a continuous conductive network successfully, attributing to its well distribution at the interface between glass fiber and polypropylene. As a result, the superior electrical conductivity of the composite (8.7 S/cm) was achieved with a relatively low content of Ni (1.17 vol%), and the electrical percolation threshold of the conductive composite was as low as 0.46 vol%.
Co-reporter:Denghui Wu;Peihua Zhao
Polymer Engineering & Science 2013 Volume 53( Issue 11) pp:2478-2485
Publication Date(Web):
DOI:10.1002/pen.23710
The novel intumescent flame retardant rigid polyurethane foams ((PEPS-RPUF) were prepared based on a P-N containing intumescent flame retardant, poly ethanediamine spirocyclic pentaerythritol bisphosphonate (PEPS). The flammability, thermal, and mechanical properties of PEPS-RPUF were discussed. Scanning electron microscopy (SEM) and compression strength tests showed PEPS exhibited favorable compatibility with polyurethane matrix and smaller negative influence on the mechanical properties of PEPS-RPUF. Cone calorimeter, vertical burning test (UL-94) and limiting oxygen index (LOI) showed when the content of PEPS was 25 pph, the peak heat release rate (PHRR) and total heat release (THR) decrease, respectively, from 75.2 to 52.2 kW m−2 and from 5.7 to 4.1 MJ m−2. The LOI of PEPS-RPUF could reach 27%, and a UL-94 V-0 rating was achieved. The PEPS-RPUF exhibited an outstanding water resistance that it could still obtain a V-0 rating after water soaking. Thermogravimetric analysis (TGA) showed the charring ability of PEPS-RPUF was improved greatly compared to RPUF. SEM and Fourier transform-infrared spectroscopy (FT-IR) were utilized to characterize the surface morphology and chemical structure of the intumescent chars formed from PEPS-RPUF. The results indicated the chars were compact and smooth, which was a critical factor for protecting the substrate material from burning. POLYM. ENG. SCI., 53:2478–2485, 2013. © 2013 Society of Plastics Engineers
Co-reporter:Ye Tian, Yaqing Liu, Minhong He, Guizhe Zhao, Youyi Sun
Materials Research Bulletin 2013 48(5) pp: 2002-2005
Publication Date(Web):
DOI:10.1016/j.materresbull.2013.01.035
Co-reporter:Jianchao Chen;Peihua Zhao;Hua Liu
Korean Journal of Chemical Engineering 2012 Volume 29( Issue 3) pp:288-290
Publication Date(Web):2012 March
DOI:10.1007/s11814-011-0172-8
Triuret has been successfully synthesized by the reaction of urea with dimethyl carbonate (DMC) under mild conditions in the presence of potassium methoxide as a catalyst. It has been fully characterized by FT-IR, 1H-NMR, 13C-NMR, and MS. Effects of the catalyst, the molar ratio of starting materials, and the reaction time on the obtained product were examined in detail. It was found that when n (urea): n (DMC)=1.2: 1, 6 h, and 0.8% catalyst, the yield of triuret can reach 98.1%. Especially, this novel procedure is reported for the first time and has many significant advantages such as easy and clean synthesis, simple work up, and high yields.
Co-reporter:Gui-zhe Zhao;Ya-qing Liu;Yu Tian;You-yi Sun;Yang Cao
Journal of Polymer Research 2010 Volume 17( Issue 1) pp:119-125
Publication Date(Web):2010 January
DOI:10.1007/s10965-009-9297-4
A new kind of macromelecular slow-release fertilizer containing nitrogen, phosphorus and potassium (MSF) was prepared. The structures of the fertilizer were characterized by the FTIR spectrum and the gel permeation chromatography, which shows the uron rings structure and the average molecular weight of 13,500. And the N, P and K contents of the fertilizer are 24.2 wt%, 20.2 wt% (showed by P2O5) and 13.5 wt%( shown by K2O), respectively by an element analysis experiment. The slow-release properties of the fertilizer in water and soil were further investigated, which shows the release of 39.5%, 91.8% and 98.9% for 30 days in soil corresponding to the N, P and K elements, respectively. The result is believed to come from the decomposition of the macromolecular fertilizer. Moreover, the effect of macromolecular fertilizer on the soil and water is environmentally friendly, which is expected to apply in modern agriculture.
Co-reporter:Youyi Sun, Xing Zhou, Yaqing Liu, Guizhe Zhao, Yong Jiang
Materials Research Bulletin 2010 45(7) pp: 878-881
Publication Date(Web):
DOI:10.1016/j.materresbull.2010.01.017
Co-reporter:Ya-qing Liu;Xiao-ying Li;Fa-xing Zhang
Journal of Coatings Technology and Research 2009 Volume 6( Issue 3) pp:377-382
Publication Date(Web):2009 September
DOI:10.1007/s11998-008-9145-1
A new nozzle was designed for the technology of making microencapsulated particles by rapid expansion of supercritical solution (RESS). The design is based on the theory of gas dynamics in which the potential energy of high stagnation pressure is converted totally into effective velocity energy. Therefore, a high momentum of the exit jet can be obtained for improving the capability of removing molten debris quickly. Furthermore, the microencapsulated red phosphorus particles were prepared by RESS with the new nozzle, and the structure and property of the microencapsulated red phosphorus particles were characterized by the SEM images, droplet concentration distributions, and moisture absorption ratio. The results show that the process can effectively encapsulate the red phosphorus particles with the paraffin.
![1H-Phenanthro[9,10-d]imidazole](http://img.cochemist.com/ccimg/300/236-02-2.png)
![1H-Phenanthro[9,10-d]imidazole](http://img.cochemist.com/ccimg/300/236-02-2_b.png)
