Co-reporter:Chengshuang Wang, Qicheng Jin, Yuting Wang, Haiyan Yin, Hongfeng Xie, Rongshi Cheng
Materials Letters 2012 Volume 68() pp:280-282
Publication Date(Web):1 February 2012
DOI:10.1016/j.matlet.2011.10.088
Co-reporter:Hu Yang, Qiang Zheng, Rongshi Cheng
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2012 Volume 407() pp:1-8
Publication Date(Web):5 August 2012
DOI:10.1016/j.colsurfa.2012.05.031
A new insight into “polyelectrolyte effect” which referred to the reduced viscosity of polyelectrolyte upon dilution resulting from the intra-molecular electrostatic repulsion was proposed, depending on the results by the authors concerning the viscosity theory of polymer solutions through theoretical and experimental methods. The results reveal that the abnormal viscosity behaviors of polyelectrolytes as well as neutral polymers in dilute solution region are ascribed to the interface effects. The polymeric solutes are readily adsorbed on the viscometer capillary wall surface, which greatly influences the viscosity measurement of polymer solutions, and results in apparent abnormal viscosity behavior. It is suggested that the so-called “abnormal” viscosity data, difficult to deal with and ignored by previous researchers, are not actually abnormal, but contain a lot of structural information on polymer both on the capillary wall and in solutions. In the present article, recent progresses in the studies on the viscosity behaviors of various polyelectrolytes are summarized, mainly depending on the findings of the authors and their collaborators involving synthetic polyelectrolytes, natural polyelectrolytes and amphoteric proteins.Graphical abstractHighlights► A new insight into “polyelectrolyte effect” is proposed. ► The interface effect results in the abnormal viscosity of polyelectrolyte. ► The “abnormal” viscosity data contain a lot of structural information on polymer.
Co-reporter:Jian-qiang Chen;Yu-fang Shao;Zhen Yang;Hu Yang 杨琥
Chinese Journal of Polymer Science 2011 Volume 29( Issue 6) pp:
Publication Date(Web):2011 November
DOI:10.1007/s10118-011-1088-9
It was found that the interface effects in viscous capillary flow influenced the process of viscosity measurement greatly, and the abnormal viscosity behaviors of polyelectrolytes as well as neutral polymers in dilute solution region were ascribed to interface effect. According to this theory, we have reviewed the previous viscosity data of derivatives of poly-2-vinylpyridine reported by Maclay and Fuoss first. Then, the abnormal viscosity behaviors of a series of sodium polystyrene sulfonate samples with various molecular weights in dilute aqueous solutions were studied further. The solute adsorption behaviors and structural information of polymers have been discussed carefully.
Co-reporter:Cheng-guo Liu;Hong-feng Xie;Zhi-liu Wang;Hu Yang
Chinese Journal of Polymer Science 2011 Volume 29( Issue 2) pp:203-213
Publication Date(Web):2011 March
DOI:10.1007/s10118-010-1010-x
The response factors of refractive index (RI) and ultraviolet (UV) detectors of size exclusion chromatography (SEC) defined as the ratio of area of output signal to the mass of injected sample are studied and analyzed by using five narrowly distributed polystyrene (PS) standard samples with known molar masses. It is found that the individual response factor for a given sample varies with the concentration of the injected solution within a limited range bounded by an upper and a lower limiting response factor values. This variation reveals the conformational change of the polymer chains with the concentration of the injected solution. The dynamic contact concentrations cs of the PS samples derived from the response factor data are in good accordance with those reported earlier by other methods. The physical meanings of the signals of the two detectors are further analyzed and theoretically formulated. The solvation of the polymer chain and the conformation changes play an important role in these detecting systems. Both of the solvation number of the structural repeating unit and the extra embedded solvent due to cluster forming in higher concentrations could be deduced from the variation of response factor with the concentration of the injected solution.
Co-reporter:Chengshuang Wang, Xiaoyu Chen, Hongfeng Xie, Rongshi Cheng
Composites Part A: Applied Science and Manufacturing 2011 Volume 42(Issue 11) pp:1620-1626
Publication Date(Web):November 2011
DOI:10.1016/j.compositesa.2011.07.010
Soy polyol-based polyurethane (PU) nanocomposites (PUNCs) with 1 wt.% hydroxyl-functionalized multi-wall carbon nanotubes (CNT-OH) were prepared via in situ polymerization. CNT-OH increased the glass transition temperature as well as significantly improved the thermal stability and conductivity of the PUNCs. The PUNC Young’s modulus was much lower than that of neat PU. The tensile strength of the PUNCs with large CNT-OH diameters was slightly higher than that of neat PU. Compared with neat PU, the elongation at break of the PUNCs improved by 30%, 39%, and 45% with increased CNT-OH diameters. Scanning and transmission electron microscopic methods revealed CNT-OH relatively homogeneous dispersion in the PU matrix.
Co-reporter:Dan Zhong, Xin Huang, Hu Yang, Rongshi Cheng
Carbohydrate Polymers 2010 Volume 81(Issue 4) pp:948-952
Publication Date(Web):23 July 2010
DOI:10.1016/j.carbpol.2010.04.012
The viscosities of dilute sodium alginate aqueous solutions have been measured at various temperatures. The upward bending phenomenon of the reduced viscosity of sodium alginate solution in the dilute concentration region resulted from the adsorption of polymer on the glass capillary wall. Experimental viscosity data satisfactorily coincided with the recent theory regarding the adsorption effect of polyelectrolyte. The theory predicted that the second term of reduced viscosity would vanish due to the presence of inter-chain Coulombic repulsion interaction, which prevents self-association or cluster formation in the experimental concentration regime. Furthermore, temperature dependence of the hydrodynamic diffusion constants of sodium alginate in aqueous solution was measured by dynamic light scattering (DLS). The morphologies of sodium alginate on the glass surface were also investigated by atomic force microscope (AFM). A self-consistent result was obtained quantitatively by different experimental means.
Co-reporter:Cheng-guo Liu;Hong-feng Xie;Zhi-liu Wang;Hu Yang
Chinese Journal of Polymer Science 2010 Volume 28( Issue 3) pp:291-297
Publication Date(Web):2010 May
DOI:10.1007/s10118-010-0017-7
Base on the principle of absolute quantification of size exclusion chromatography (SEC), a light scattering (LS) detector coupled with a concentration detector (refractive index detector) is utilized to determine the compositions of complicated binary mixtures. A theoretical analysis predicts that the response factors for both LS and RI detectors are linear functions with the composition of any specified polymer mixtures in the binary polymer mixtures. Two pairs of complicated binary mixtures were used to test the theory mentioned in the present paper, and the experimental results show an excellent accordance with the theory.
Co-reporter:Zhengchun Cai, Jie Dai, Hu Yang, Rongshi Cheng
Carbohydrate Polymers 2009 Volume 78(Issue 3) pp:488-491
Publication Date(Web):15 October 2009
DOI:10.1016/j.carbpol.2009.05.009
The relative viscosities of acetic acid solutions of chitosan at varied temperatures were measured in a common glass capillary Ubbelohde viscometer in the range from dilute down to extremely dilute concentration. With the aid of the newly proposed theory related to the effect of solute adsorption on the relative viscosity measurement, the experimental data was analyzed, and some interesting parameters describing the interfacial properties of viscous capillary flow were deduced. The change of the conformation of the chitosan chains both free dissolved in solution and adsorbed on the glass capillary surface were discussed in detail. Furthermore, the morphologies of the adsorbed chitosan was also observed by AFM.
Co-reporter:Zhengnian Chen;Hongfeng Xie;Hu Yang;Zhiliu Wang
Frontiers of Chemistry in China 2008 Volume 3( Issue 3) pp:344-347
Publication Date(Web):2008 September
DOI:10.1007/s11458-008-0057-5
The analyses of the composition of a binary mixture composed of two kinds of industrial complicated materials have great importance for formulation in practice. The present paper provides a quantitative size exclusion chromatography (SEC) method based on the principle of absolute quantification of SEC to solve the problem. The conventional data treatment procedure for the differential refractive index (DRI) signal of SEC H(V) is improved first by dividing it with the injected sample weight and leads to a novel defined weight normalized distribution Hw(V) and its integral Iw(V). These two distributions reflect the response constant of the sample in addition to the conventional normalized distribution F(V). The difference of the average response constants of the composing components provides a sensitive method to compute the composition of their mixture from its Hw(V) or Iw(V). The method was applied to mixtures of a kind of industrial asphalt and paraffin diluents as an example, and successful results are obtained.
Co-reporter:Neng Wang;Enyong Ding
Frontiers of Chemical Science and Engineering 2007 Volume 1( Issue 3) pp:228-232
Publication Date(Web):2007 July
DOI:10.1007/s11705-007-0041-5
In order to improve the dispersibility of cellulose nanocrystal (CNC) particles, three different grafted reactions of acetylation, hydroxyethylation and hydroxypropylation were introduced to modify the CNC surface. The main advantages of these methods were the simple and easily controlled reaction conditions, and the dispersibility of the resulting products was distinctly improved. The properties of the modified CNC were characterized by means of Fourier transform infrared spectroscopy (FT-IR), 13C nuclear magnetic resonance (NMR), transmission electron microscopy (TEM) and thermogravimetric analyses (TGA). The results indicated that after desiccation, the modification products could be dispersed again in the proper solvents by ultrasonic treatments, and the diameter of their particles had no obvious changes. However, their thermal degradation behaviors were quite different. The initial decomposition temperature of the modified products via hydroxyethylation or hydroxypropylation was lower than that of modified products via acetylation.
Co-reporter:Rongshi Cheng;Hu Yang
Journal of Applied Polymer Science 2006 Volume 99(Issue 4) pp:1767-1772
Publication Date(Web):7 DEC 2005
DOI:10.1002/app.22706
The time–temperature equivalence equation is deduced simply in view of the transition kinetics of a polymer. The independent variables time and temperature are separated in the two sides of the resulting equation. Thus, a physical property of the polymer, which is temperature dependent, can be matched with the theoretical calculated curve from a supposed model of transition kinetics in which only time is involved as the independent variable. By comparing different models, one may judge which model is probably more correct. The procedure of data fitting is described. As an application example, the measured viscosity data at different temperatures for the coil–globule transition of poly(N-isopropylacrylamide) in aqueous solution is tested to judge its transition mechanism. A transition mechanism involving a two-stage reversible reaction fits the experimental data in a satisfactory way. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1767–1772, 2006
Co-reporter:Hongfeng Xie;Binghua Liu;Hu Yang;Jianyi Shen;Zhiliu Wang
Journal of Applied Polymer Science 2006 Volume 100(Issue 1) pp:295-298
Publication Date(Web):26 JAN 2006
DOI:10.1002/app.23106
The thermal properties of carbon nanofibers (CNF)/epoxy composites, composed of tetraglycidyl-4,4′-diaminodiphenylmethane (TGDDM) resin and 4,4′-diaminodiphenylsulfone (DDS) as a curing agent, were investigated with differential scanning calorimetry (DSC), thermogravimetric analysis, and dynamic mechanical thermal analysis. DSC results showed that the presence of CNF had no pronounced influence on the heat of the cure reaction. However, the incorporation of CNF slightly improved the thermal stability of the epoxy. Furthermore, the storage modulus of the TGDDM/DDS epoxy was significantly enhanced, whereas the glass-transition temperature was not significantly affected, upon the incorporation of CNFs. The storage modulus of 5 wt % CNF/epoxy composites at 25°C was increased by 35% in comparison with that of the pure epoxy. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 295–298, 2006
Co-reporter:Yi Li
Journal of Polymer Science Part B: Polymer Physics 2006 Volume 44(Issue 13) pp:1804-1812
Publication Date(Web):19 MAY 2006
DOI:10.1002/polb.20847
The viscosities of aqueous solutions of gelatin at different temperatures were carefully measured in a common glass-capillary Ubbelohde viscometer at dilute to extremely dilute concentrations. The adsorption effect that occurred in the viscosity measurements was theoretically analyzed and discussed. A theory based on Langmuir isotherms could adequately describe the existing data. Some structural information was obtained by the use of an iterative fitting procedure to treat the reduced viscosity data, which disclosed that individual gelatin chains underwent a coil-to-helix transition as the solution cooled from 40 to 15 °C. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1804–1812, 2006
Co-reporter:Hongfeng Xie;Binghua Liu;Qing Sun;Zuanru Yuan;Jianyi Shen
Journal of Applied Polymer Science 2005 Volume 96(Issue 2) pp:329-335
Publication Date(Web):7 FEB 2005
DOI:10.1002/app.21415
An investigation was carried out into the cure kinetics of carbon nanofibers (CNF)/epoxy composites, composed of tetraglycidyl-4,4′-diaminodiphenylmethane (TGDDM) resin and 4,4′-diaminodiphenylsulfone (DDS) as a curing agent. The experimental data for both neat system and CNF/epoxy composites revealed an autocatalytic behavior. Analysis of DSC data indicated that the presence of carbon nanofibers had only a negligible effect on the cure kinetics of the epoxy. Kinetic analysis was performed using the phenomenological model of Kamal and two diffusion factors were introduced to describe the cure reaction in the latter stage. Activation energies and kinetic parameters were determined by fitting experimental data. Comparison between the two diffusion factors was performed, showing that the modified factor was successfully applied to the experimental data over the whole curing temperature range. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 329–335, 2005
