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ABSTRACT: The thermal degradation of synthetic waterborne polyurethane (PU) based on toluenediisocyanate (TDI) was investigated by pyrolysis-gas
chromatography/mass spectrometry (Py-GC/MS) and thermogravimetry (TG). The degradation profiles of cast films obtained from
dispersions were evaluated. More than 20 characteristic volatile pyrolyzates reflecting the structure and pyrolysis mechanisms
of the polymer have been identified by on-line MS. In helium atmosphere, the synthesized products of polyurethane were pyrolyzed
at 350, 450, 550, 650 and 750 °C respectively, and the thermal decomposition products were analyzed on line using GC/MS. The
product analysis reveals that the pyrolyzates distribution of the polyurethane depends strongly on the pyrolysis temperature.
Based on the Py-GC/MS data, the thermal degradation mechanism of the polyurethane is discussed.
Key wordswaterborne polyurethane-pyrolysis-gas chromatography-mass spectrometry-pyrolysis-thermogravimetry
Journal of Wuhan University of Technology-Mater Sci Ed 04/2012; 25(3):479-483. · 0.35 Impact Factor
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ABSTRACT: Novel self-emulsifying acrylic polymer aqueous dispersions (NPAD) for two component waterborne polyurethane coatings (2K-WPU) were prepared by the emulsification of self-emulsifying polymer blends in water, which the polymer blends typically consist of two acrylic polymers, one is a salt group containing polymer (P1), the other is a polymer without salt groups (P2). The dynamic light scattering (DLS) analysis showed that the NPAD have a bimodal particle size distribution and the particle diameters can be controlled by the amount of salt group containing polymer and the concentration of salt groups in this polymer. Transmission electron microscopy (TEM) images also testified that the NPADs possess small particles consisted of P1 and core-shell structure large particles which are composed of the P1 in the shell parts and the P2 in the core parts. The property comparisons of the NPAD, conventional polyacrylic dispersion (CPAD) and poylacrylic emulsion (PAE) for 2K-WPU disclosed that the NPADs possess higher solid contents up to 45 wt% and much lower carboxy salt contents than those of the CPAD, and the NPAD-based 2K-WPU films display much better performance including 90% of the gloss, 0.81 of the pendulum hardness, much better solvent- and water-resistance than those of the CPAD and PAE. The TGA curves indicated the NPAD-based 2K-WPU films display good thermal stability.
Journal of Macromolecular Science. 04/2010; Part A: Pure and Applied Chemistry(Vol. 47):368-374.
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Macromolecular Chemistry and Physics 01/2010; 211(3):345 - 352. · 2.36 Impact Factor
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Journal of Polymer Science Part A Polymer Chemistry 08/2009; 47(18):4749 - 4761. · 3.92 Impact Factor
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ABSTRACT: Novel chiral methylpropargyl ester monomers containing ferrocene moieties, ferrocenecarbonyl-(R)-1-methylpropargyl ester were synthesized and polymerized with (nbd)Rh+[η 6-C6H5B−(C6H5)3] to give the corresponding polymers with number-average molecular weights ranging from 7600 to 12 000 in 34–78% yields. The polymers were soluble in CHCl3, CH2Cl2, and THF, but insoluble in hexane and diethyl ether. The specific rotation and circular dichroism (CD) spectroscopic studies revealed that polymers took predominantly one-handed helical structures in the solvents, and the helical structure of the polymers was stable to the addition of MeOH and heat. The cyclic voltammograms of the polymers indicated that the polymers exhibit electrochemical properties.
Journal of Macromolecular Science®. 02/2009; 46(2):131-135.
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ABSTRACT: A novel ethyl cellulose derivative [poly(1)] that carries triphenylamine moieties is synthesized with a moderate number-average molecular weight up to 78,200 in 85% yield by the reaction of 4-(diphenylamino)benzoic acid with the residual hydroxy group of ethyl cellulose. Poly(1) is soluble in common organic solvents including toluene, CHCl3, CH2Cl2, and tetrahydrofuran while insoluble in hexane, diethyl ether, and methanol. The polymer emits blue-green fluorescence with quantum yields up to 65% in CHCl3 and displays unique solvatochromism. The cyclic voltammograms of poly(1) indicate that the polymer carrying TPA moieties is electrochemically redox active. The onset temperature of weight loss of the poly(1) is about 177 degrees C according to thermogravimetric analysis in air.
Macromolecular Bioscience 01/2009; 9(6):563-7. · 3.89 Impact Factor
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ABSTRACT: In this paper, we introduce an approach to compress gray image using deterministic generalized finite automata (GFA). By detecting the self-similarity inside an input digitized gray image, a GFA can be constructed to describe the image. The decode algorithm can restore the image from the deterministic generalized finite automata efficiently. This method has a smaller number of states than an equivalent classical finite automaton. Meanwhile it also has an advantage of higher compression without further degradation of quality.
Audio, Language and Image Processing, 2008. ICALIP 2008. International Conference on; 08/2008
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ABSTRACT: Thermal degradation of pyrolysis of waste circuit boards was investigated by high-resolution pyrolysis gas chromatography-mass spectrometry (PyGC-MS) and thermogravimetry (TG). In helium atmosphere, the products of FR-4 waste printed circuit board were pyrolyzed at 350, 450, 550, 650, and 750 degrees degrees C, separately, and the pyrolysis products were identified by online MS. The results indicated that the pyrolysis products of the FR-4 waste circuit board were three kinds of substances, such as the low boiling point products, phenol, bisphenol and their related products. Moreover, under 300 degrees degrees C, only observed less pyrolysis products. As the increase of pyrolysis temperature, the relative content of the low boiling point products increased. In the range of 450-650 degrees degrees C, the qualitative analysis and character were similar, and the relative contents of phenol and bisphenol were higher. The influence of pyrolysis temperature on pyrolyzate yields was studied. On the basis of the pyrolyzate profile and the dependence of pyrolyzate yields on pyrolysis temperature, the thermal degradation mechanism of brominated epoxy resin was proposed.
Se pu = Chinese journal of chromatography / Zhongguo hua xue hui 08/2008; 26(4):519-22.
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ABSTRACT: Novel DNA-lipid complexes carrying azobenzene moieties were prepared by substituting sodium counter cations with cationic amphiphilic lipids, namely lipid(AZO) and lipid(diAZO), in which the actual molar ratios of phosphate to lipid were 1:1.05 and 1:1.02, respectively. DNA-lipid(AZO) and DNA-lipid(diAZO) complexes were soluble in common organic solvents including CHCl3, CH2Cl2, methanol, and ethanol, while insoluble in THF, toluene, and water. CD spectroscopy revealed that DNA-lipid(AZO) and DNA-lipid(diAZO) complexes took a predominantly double helical structure in methanol and CHCl3 and that the helical structure was fairly stable against heating. The trans-azobenzene of the DNA-lipid complexes in the side chain isomerized into cis upon UV irradiation, while the helical conformation of DNA backbone hardly changed. The cis-azobenzene moiety reisomerized into trans upon visible-light irradiation, but they did not recover completely the original geometry of azobenzene moieties in the side chain. Both DNA-lipid(AZO) and DNA-lipid(diAZO) exhibited lyotropic LC properties. The onset temperatures of weight loss of DNA-lipid(AZO) and DNA-lipid(diAZO) were both 226 °C according to TGA in air.Graphical abstract•Novel DNA-lipid complexes carrying azobenzene were prepared by substituting sodium counter cations with cationic amphiphilic lipid(AZO) and lipid(diAZO); the actual molar ratios of phosphate to lipid in the products were 1:1.05 and 1:1.02. CD spectroscopic studies revealed that DNA-lipid(AZO) and DNA-lipid(diAZO) took predominantly double helical structure in methanol, and the helical structure was very stable against heating. The trans-azobenzene of the DNA-lipid complexes in the side chain isomerized into cis upon UV irradiation, and reisomerized into trans upon visible-light irradiation, but they did not recover completely the original geometry of azobenzene moieties in the side chain. Both DNA-lipid(AZO) and DNA-lipid(diAZO) exhibited lyotropic liquid crystalline properties.
Polymer. 50(23):5398-5405.
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ABSTRACT: The thermal degradation of synthetic waterborne polyurethane (PU) based on toluenediisocyanate (TDI) was investigated by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) and thermogravimetry (TG). The degradation profiles of cast films obtained from dispersions were evaluated. More than 20 characteristic volatile pyrolyzates reflecting the structure and pyrolysis mechanisms of the polymer have been identified by on-line MS. The synthesized products of polyurethane were pyrolyzed at 350, 450, 550, 650 and 750 °C respectively, and the analysis results revealed that the pyrolyzates distribution of the polyurethane depends strongly on the pyrolysis temperature. The aqueous polyurethane thermogravimetric measurements were used to study the kinetics of thermal degradation.
Polymer Testing 28(3):264-269. · 1.61 Impact Factor
