Liting Yang

Find an error

Name: 杨丽庭; LiTing Yang
Organization: Hebei University , China
Department: College of Chemical and Environmental Science
Title: Professor(PhD)

TOPICS

Co-reporter:Li-jun Ma, Weiguang Cao, Jialun Liu, Dayi Deng, Yuqing Wu, Yuhua Yan, Liting Yang
Sensors and Actuators B: Chemical 2012 Volume 169() pp:243-247
Publication Date(Web):5 July 2012
DOI:10.1016/j.snb.2012.04.076
A structurally simple fluorescence probe, dansyl acid (DA), was reported in the present study. The probe could selectively and sensitively respond to pH from 7.00 to 2.00 in aqueous solution with fluorescence “turn-off” and “turn-on” dual-responses under two different excitation wavelengths. The mechanism of response was further clarified by NMR, UV–vis spectrometry and single crystal X-ray crystallography, which revealed that the pH-induced changes of fluorescence and UV–vis absorption were due to the protonation of nitrogen atom in the dimethylamino group. The fluorescent imaging of NIH 3T3 cells were also provided, which demonstrated the probe was applicable in monitoring intracellular H+.A structurally simple fluorescence probe, dansyl acid (DA), was reported in the present study. The probe could selectively and sensitively respond to pH from 7.00 to 2.00 in aqueous solution with fluorescence “turn-off” and “turn-on” dual-responses under two different excitation wavelengths. The mechanism of response was further clarified by NMR, UV–vis spectrometry and single crystal X-ray crystallography, which revealed that the pH-induced changes of fluorescence and UV–vis absorption were due to the protonation of nitrogen atom in the dimethylamino group. The fluorescent imaging of NIH 3T3 cells were also provided, which demonstrated the probe was applicable in monitoring intracellular H+.
Co-reporter:Liyu Fu;Chunlan Dai;Chengshan Zhao ;Lijun Ma
Journal of Applied Polymer Science 2010 Volume 117( Issue 4) pp:2220-2225
Publication Date(Web):
DOI:10.1002/app.32126

Abstract

A series of epoxidized-soybean oil (ESO) with different epoxyl content were synthesized by in situ epoxidation of soybean oil (SBO). The acrylated epoxidized-soybean oil (AESO) was obtained by the reaction of ring opening of ESO using acrylic acid as ring opener. The acrylated expoxidized-soybean oil-based thermosets have been synthesized by bulk radical polymerization of these AESOs and styrene. The thermal properties of the resins were characterized by differential scanning calorimetry (DSC) and thermo-gravimetric analysis (TG). The results showed that these resins possess high thermal stability. There were two glass transition temperature of each resin due to the triglycerides structure of the resins. The tensile strength and impact strength of the resins were also recorded, and the tensile strength and impact strength increased as the iodine value of ESO decreased. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Co-reporter:Yantao Li;Liyu Fu;Shufen Lai;Xinchao Cai
European Journal of Lipid Science and Technology 2010 Volume 112( Issue 4) pp:511-516
Publication Date(Web):
DOI:10.1002/ejlt.200900191

Abstract

Acrylated epoxidized soybean oils (AESOs) with different level of saturation were obtained by the ring opening of different saturation epoxidized soybean oils using acrylic acid as the ring opener. AESO-based thermosets have been synthesized by free radical polymerization of these AESOs and methyl methacrylate. The thermal properties of these resins were studied by differential scanning calorimetry and thermo-gravimetric analysis. The results indicated that the thermal stability of these resins depends upon the epoxy value; the glass transition temperature increases with increasing of epoxy value. The tensile and impact strength of the resins were also studied, and indicated that tensile strength increases with increasing epoxy value, whereas impact strength decreases. The resulting thermosets ranged from elastomers to glassy polymers.

Co-reporter:Cheng-Shuang Wang;Li-Ting Yang;Bao-Lian Ni ;Guang Shi
Journal of Applied Polymer Science 2009 Volume 114( Issue 1) pp:125-131
Publication Date(Web):
DOI:10.1002/app.30493

Abstract

A series of polyols with a range of hydroxyl (OH) numbers based on soybean oil and epoxidized soybean oil were prepared by oxirane ring opening with methanol, glycol, and 1,2-propanediol. The polyols, with average functionalities varying from 2.6 to 4.9, were characterized. Novel cast polyurethane resins were synthesized from these polyols and 2,4-toluene diisocyanate. The sol fraction of the network decreased as the OH number of the polyol from which it was synthesized increased. None of the samples were completely soluble. The crosslinking density of the polyurethanes correlated directly with the functionality of the polyols. The thermal and mechanical properties of the cast resins were characterized with differential scanning calorimetry and thermogravimetry. The glass-transition temperature increased with the OH number increasing, and the thermal stability of the resins was slightly decreased with the OH number increasing. The tensile strength at break increased with the OH number increasing. Polyurethanes prepared from polyols with OH numbers higher than 170 mg of KOH/g were glassy, whereas those with OH numbers below that value were rubbery. Glassy polyurethanes displayed decent mechanical strength, whereas rubbery samples showed relatively poor elastic properties and were characterized by lower strength. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Co-reporter:Chengshuang Wang;Baolian Ni ;Linyun Wang
Journal of Applied Polymer Science 2009 Volume 112( Issue 3) pp:1122-1127
Publication Date(Web):
DOI:10.1002/app.29537

Abstract

The soy polyols were prepared from epoxidation of soybean oil followed by ring opening of oxirane obtained by using methanol as the ring opener. Polyols of hydroxyl (OH) numbers ranging from 128 to 174 mg of KOH/g were obtained by the variation of epoxidation time of soybean oil. A novel cast polyurethane resin has been synthesized by these polyols and 2,4-toluene diisocyanate. Swelling of networks in toluene showed that the sol fraction varies from 1.13 to 72.06%. The thermal and mechanical properties of cast resins were characterized by differential scanning calorimetry and thermogravimetric analysis. The results showed that the glass transition temperature increases with the increase of OH number and that the thermal stability of the resins was slightly decreased with the increasing OH number. The tensile strength at break increases with the increase of OH number. Polyols with OH number of 174 mg of KOH/g gave glassy polymers, whereas those below this value gave rubbers. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Co-reporter:Honghai Dai;Bo Lin
Journal of the American Oil Chemists' Society 2009 Volume 86( Issue 3) pp:261-267
Publication Date(Web):2009 March
DOI:10.1007/s11746-008-1342-7
Three soy-based polyols intended for application in polyurethanes were prepared by ring opening the epoxy groups in epoxidized soybean oil (ESO, 0.385 mol/100 g epoxy rings) with methanol, 1,2-ethanediol and 1,2-propanediol in the presence of tetrafluoroboric acid catalyst. The effect of the different opening reaction reagents, different low molecular weight alcohols, on the polyols was investigated by spectroscopic, chemical and physical methods. The viscosities, viscous-flow activation energies, molecular weight and melting point of the samples increased in the following order: polyol (3) > polyol (2) > polyol (1) > ESO [polyol (1); polyol (2) and polyol (3) represented the samples synthesized from the same epoxidized soybean oil generated by opening reactions with methanol, 1,2-ethanediol and 1,2-propanediol, respectively]. All the samples were crystalline solids below their melting temperature, displaying multiple melting point peaks. Compared with polyol (1), polyol (2) had a primary hydroxyl group, promoting the reactive activity of the polyol with isocyanates; polyol (3) contained large numbers of hydroxy groups, improving the properties of polyurethanes.
Co-reporter:Chuanshang Cai;Honghai Dai;Rongsheng Chen;Caixia Su;Xiaoya Xu;Shi Zhang
European Journal of Lipid Science and Technology 2008 Volume 110( Issue 4) pp:341-346
Publication Date(Web):
DOI:10.1002/ejlt.200700104

Abstract

In the present work, the kinetics of the epoxidation of soybean oil (SBO) by peroxyacetic acid (PAA) generated in situ in the presence of sulfuric acid as the catalyst was studied at various temperatures (45, 65 and 75 °C). It was found that epoxidation with almost complete conversion of unsaturated carbon and negligible oxirane cleavage can be attained by the in situ technique. The rate constant for epoxidation of SBO was found to be of the order of 10–6 mol–1s–1 and the activation energy of epoxidation is 43.11 kJ/mol. Some thermodynamic parameters: enthalpy, entropy and free activation energy of 40.63 kJ/mol, –208.80 J/mol and 102.88 kJ/mol, respectively, were obtained for the epoxidation of SBO. The kinetic and thermodynamic parameters of epoxidation obtained from this study indicate that an increase in the process temperature would increase the rate of epoxide formation. The epoxidation of corn oil and sunflower oil were also investigated under the same conditions. The results show that the reaction rate is in the order of soybean oil > corn oil > sunflower oil.

Co-reporter:Bo Lin;Honghai Dai;Aihua Yi
Journal of the American Oil Chemists' Society 2008 Volume 85( Issue 2) pp:113-117
Publication Date(Web):2008 February
DOI:10.1007/s11746-007-1187-5
The kinetics of the oxirane cleavage of epoxidized soybean oil (ESO) by methanol (Me) without a catalyst was studied at 50, 60, 65, 70 °C. The rate of oxirane ring opening is given by k[Ep][Me]2, where [Ep] and [Me] are the concentrations of oxiranes in ESO and methanol, respectively and k is a rate constant. From the temperature dependence of the kinetics thermodynamic parameters such as enthalpy (ΔH), entropy (ΔS), free energy of activation (ΔF) and activation energy (ΔEa) were found to be 76.08 (±1.06) kJ mol−1, −118.42 (±3.12) J mol−1 k−1, 111.39 (±2.86) kJ mol−1, and 78.56 (±1.63) kJ mol−1, respectively. The methoxylated polyols formed from the oxirane cleavage reaction , were liquid at room temperature and had three low temperature melting peaks. The results of chemical analysis via titration for residual oxiranes in the reaction system showed good agreement with IR spectroscopy especially the disappearance of epoxy groups at 825, 843 cm−1 and the emergence of hydroxy groups at the OH characteristic absorption peak from 3,100 to 3,800 cm−1.
Co-reporter:Liting Yang;Donghai Sun
Journal of Applied Polymer Science 2007 Volume 104(Issue 2) pp:
Publication Date(Web):25 JAN 2007
DOI:10.1002/app.25559

Terpolymers of N-cyclohexylmaleimide, methylmethacrylate, and acrylonitrile (AN) at different AN feed content were synthesized by suspension polymerization. The thermal properties of the terpolymers such as glass transition temperature (Tg) and Vicat softening temperature (TVicat) were determined by torsion braid analysis and Vicat softening temperature tester, respectively. The value of Tg and TVicat decreased with increasing AN feed content. Thermogravimetric analyses were carried out with the results that the incorporated AN units enhanced the thermal stability of the resulting polymers and a second degradation step appeared with the addition of AN. The mechanical properties (tensile strength and impact strength) of the terpolymers were also detected and the results show that the tensile strength and impact strength of terpolymers increase with increasing AN feed content. The rheological results illustrated that the terpolymers showed rheological behavior similar to that of pseudoplastic liquid. The apparent shear viscosity decreased with the increasing of AN feed content. The flow power index n increased with increasing AN feed content. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 792–796, 2007

Co-reporter:Liting Yang;Donghai Sun
Journal of Applied Polymer Science 2006 Volume 100(Issue 2) pp:918-922
Publication Date(Web):11 JAN 2006
DOI:10.1002/app.22635

N-cyclohexylmaleimide (ChMI) and styrene (St) were polymerized with methyl methacrylate (MMA) at different St feed content by suspension polymerization method. The glass transition temperatures (Tg) of the terpolymers were detected by torsional braid analysis (TBA). Two transition peaks in TBA curves of the terpolymers with a high St content illustrated that these terpolymers have a heterogeneous chain structure and the phase separation occurred. The lower transition temperature, Tg1, was assigned to the random St-MMA components, and the higher transition temperature, Tg2, was assigned to the St-ChMI units-rich segments. Thermogravimetric analyses (TGA) revealed that all the terpolymers showed a two-step degradation process. The tensile strength of the terpolymers decrease with increasing St content while the impact strength tended to increase slightly. The rheological behavior of the terpolymers was also detected. The result illustrated that the terpolymers showed rheological behavior similar to that of pseudoplastic liquid. The apparent shear viscosity decreased with the increasing of St content. All terpolymers have a higher value of flow n than the poly(MMA-co-ChMI). © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 918–922, 2006

Co-reporter:Liting Yang;Yanhong Liu;Yanfang Li;Jungang Gao;Riguang Jin;Liucheng Zhang
Journal of Applied Polymer Science 2004 Volume 91(Issue 2) pp:867-870
Publication Date(Web):18 NOV 2003
DOI:10.1002/app.13237

The free-radical copolymerization of methyl methacrylate (MMA) with N-P-tolylmalemide (NPTMI) at 77°C in cyclohexanone solution initiated by AIBN was studied. The copolymer composition was calculated from the nitrogen content estimated by the Mico–Kijedldahl's method and by elemental analysis. The reactivity ratios have been calculated by Fineman and Ross method. The monomer reactivity ratios were rNPTMI = 1.24, rMMA = 2.1. The glass transition temperature (Tg) of the copolymers were determined by torsion braid analysis (TBA). The thermal stability was determined by thermogravimetric analysis (TGA). T50, temperature at which the weight loss reaches 50%, was abstained. The results showed that the Mn and Mw increased, whereas the NPTMI feed content increased. The Tg and T50 increased dramatically. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 867–870, 2004

Co-reporter:Guodong Liu;Yanfang Li;Donghai Sun;Jungang Gao
Journal of Applied Polymer Science 2003 Volume 88(Issue 1) pp:201-205
Publication Date(Web):24 JAN 2003
DOI:10.1002/app.11646

Emulsion-polymerized copolymers of methyl methacrylate and N-cyclohexylmaleimide were synthesized and used for blending with poly(vinyl chloride) (PVC) to improve the heat resistance of PVC. The thermal stabilities of the blends with different copolymer contents were characterized by thermogravimetric analysis, torsional braid analysis, and the Vicat softening temperature. The mechanical properties and rheological behavior of the blends were also determined. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 201–205, 2003

Spiro[1H-isoindole-1,9'-[9H]xanthen]-3(2H)-one, 2-[2-[(2-aminoethyl)amino]ethyl]-3',6'-bis(diethylamino)-
Thiourea, N-[3',6'-bis(diethylamino)-3-oxospiro[1H-isoindole-1,9'-[9H]xanthene]-2(2H)-yl]-N'-1-naphthalenyl-
L-Ornithine, N2,N5-bis(2,2-di-1-pyrenylacetyl)-
L-Ornithine, N2,N5-bis(2,2-di-1-pyrenylacetyl)-, methyl ester
4aH-Xanthene-3,6-diamine, N3,N3,N6,N6-tetraethyl-9-[2-[5-(1-naphthalenylamino)-1,3,4-oxadiazol-2-yl]phenyl]-
Poly[oxy(1,4-dioxo-1,4-butanediyl)oxy-1,4-butanediyl]
1,4-Butanediol-succinic acid copolymer
1H-Benzimidazole, 2-(1-pyrenyl)-