Changlei Xia | University of Science and Technology of China (original) (raw)
Address: Denton, Texas, United States
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Papers by Changlei Xia
Journal of Polymer Science Part A: Polymer Chemistry, 2010
Novel amphiphilic hyperbranched-upon-dendritic polymers with a dendritic polyester core, a linear... more Novel amphiphilic hyperbranched-upon-dendritic polymers with a dendritic polyester core, a linear poly(e-caprolactone) (PCL) inner shell, and a hyperbranched polyglycerol outer shell have been prepared. The structures of the hyperbranchedupon-dendritic polymers were characterized by using NMR spectra. The critical aggregating concentrations (CACs) of those amphiphilic hyperbranched-upon-dendritic polymers were measured by using pyrene as the polarity probe. To study the encapsulation performances of those hyperbranched-upon-dendritic polymers as unimolecular hosts, inter-molecular encapsulation was carefully prevented by controlling the host concentrations below their CACs and by washing with good organic solvents. The study on encapsulation of two model guest molecules, pyrene and indomethacin, was performed. The amounts of encapsu-lated molecules were dependent mainly on the size of inner linear shells. About three pyrene molecules or five indomethacin molecules were encapsulated in hyperbranched-upon-dendritic polymers with average PCL repeating units of two but different hyperbranched polyglycerol outer shells, whereas about five pyrene molecules or about 12 indomethacin molecules were encapsulated in those with PCL repeating units of nine. The encapsulated molecules could be released in a controlled manner. Thus, the hyperbranched-upon-dendritic polymers could be used as unimolecular nanocarriers with controllable molecular encapsulation dosage for controlled release. V C 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 4013-4019, 2010
Holzforschung, 2014
This work was aimed at applying vacuumassisted resin transfer molding (VARTM) technique to reinfo... more This work was aimed at applying vacuumassisted resin transfer molding (VARTM) technique to reinforced polymer molding products made of vegetable fibers. Kenaf ( Hibiscus cannabinus L. Malvaceae) bast fibers were preformed into mat by means of a cold press. The unsaturated polyester resin was infused into the preforms at a vacuum pressure of 1.3 -1.6 kPa. The examination of the mechanical properties and microstructure of the prepared composites indicated that the modulus of elasticity (MOE), modulus of rapture (MOR), and tensile strength (TS) of the VARTM composites were increased by 65.5%, 30.7%, and 41.7%, respectively, compared to the traditional hot-pressing composites. The dynamic mechanical analysis (DMA) revealed that the VARTM composite moduli in the temperature range of -50 ° C -200 ° C were doubled. The observations by scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and mercury porosimetry confirmed that the interfacial compatibility between the kenaf fibers and the polyester resin was substantially improved.
Journal of Polymer Science Part A: Polymer Chemistry, 2010
Novel amphiphilic hyperbranched-upon-dendritic polymers with a dendritic polyester core, a linear... more Novel amphiphilic hyperbranched-upon-dendritic polymers with a dendritic polyester core, a linear poly(e-caprolactone) (PCL) inner shell, and a hyperbranched polyglycerol outer shell have been prepared. The structures of the hyperbranchedupon-dendritic polymers were characterized by using NMR spectra. The critical aggregating concentrations (CACs) of those amphiphilic hyperbranched-upon-dendritic polymers were measured by using pyrene as the polarity probe. To study the encapsulation performances of those hyperbranched-upon-dendritic polymers as unimolecular hosts, inter-molecular encapsulation was carefully prevented by controlling the host concentrations below their CACs and by washing with good organic solvents. The study on encapsulation of two model guest molecules, pyrene and indomethacin, was performed. The amounts of encapsu-lated molecules were dependent mainly on the size of inner linear shells. About three pyrene molecules or five indomethacin molecules were encapsulated in hyperbranched-upon-dendritic polymers with average PCL repeating units of two but different hyperbranched polyglycerol outer shells, whereas about five pyrene molecules or about 12 indomethacin molecules were encapsulated in those with PCL repeating units of nine. The encapsulated molecules could be released in a controlled manner. Thus, the hyperbranched-upon-dendritic polymers could be used as unimolecular nanocarriers with controllable molecular encapsulation dosage for controlled release. V C 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 4013-4019, 2010
Holzforschung, 2014
This work was aimed at applying vacuumassisted resin transfer molding (VARTM) technique to reinfo... more This work was aimed at applying vacuumassisted resin transfer molding (VARTM) technique to reinforced polymer molding products made of vegetable fibers. Kenaf ( Hibiscus cannabinus L. Malvaceae) bast fibers were preformed into mat by means of a cold press. The unsaturated polyester resin was infused into the preforms at a vacuum pressure of 1.3 -1.6 kPa. The examination of the mechanical properties and microstructure of the prepared composites indicated that the modulus of elasticity (MOE), modulus of rapture (MOR), and tensile strength (TS) of the VARTM composites were increased by 65.5%, 30.7%, and 41.7%, respectively, compared to the traditional hot-pressing composites. The dynamic mechanical analysis (DMA) revealed that the VARTM composite moduli in the temperature range of -50 ° C -200 ° C were doubled. The observations by scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and mercury porosimetry confirmed that the interfacial compatibility between the kenaf fibers and the polyester resin was substantially improved.