84 results on '"Yancun Yu"'
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2. Miscibility, crystallization, mechanical, and rheological properties of poly (L-lactic acid)/poly(vinyl acetate) blends
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Yi Li, Hongda Cheng, Changyu Han, Yancun Yu, Hechang Shi, Ye Zhang, and Shilong Yao
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Colloid and Surface Chemistry ,Polymers and Plastics ,Materials Chemistry ,Physical and Theoretical Chemistry - Published
- 2022
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Catalog
3. Ternary blends from biodegradable poly(L-lactic acid), poly(ε-caprolactone) and poly(vinyl acetate) with balanced properties
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Hongda Cheng, Yi Li, Ye Zhang, Yancun Yu, Mengdie Yu, Changyu Han, and Hechang Shi
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Polymers and Plastics ,Organic Chemistry ,Materials Chemistry - Published
- 2023
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4. Crystallization, rheological and mechanical properties of poly(butylene succinate)/poly(propylene carbonate)/poly(vinyl acetate) ternary blends
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Yancun Yu, Yi Li, and Han Xu
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Materials science ,Polymers and Plastics ,Scanning electron microscope ,Dynamic mechanical analysis ,Miscibility ,Polybutylene succinate ,law.invention ,chemistry.chemical_compound ,Colloid and Surface Chemistry ,Chemical engineering ,chemistry ,law ,Propylene carbonate ,Materials Chemistry ,Vinyl acetate ,Physical and Theoretical Chemistry ,Crystallization ,Ternary operation - Abstract
Herein, a ternary blend from poly(butylene succinate) (PBS), poly(propylene carbonate) (PPC), and poly(vinyl acetate) (PVAc) with improved crystallization rate, stiffness, and toughness was initially prepared via melt compounded. The influence of PVAc content on morphology, miscibility, thermal behavior, and rheological and mechanical properties was investigated. Scanning electron microscopy observation showed phase morphology of PBS/PPC/PVAc ternary blends evolved from sea-island dispersion to co-continuous structure. Dynamic mechanical analysis revealed that PBS and PPC were immiscible. The presence of PPC inhibited the crystallization of PBS, while simultaneous incorporation of PVAc and PPC promoted the crystallization. Furthermore, the introduction of PPC and PVAc enhanced the rheological properties of PBS. Unexpectedly, prominent improvement in tensile modulus, yield strength, and elongation was obtained for the PBS/PPC/PVAc ternary blend with 10 wt% PVAc due to the morphological evolution from sea-island to co-continuous structure, which was respectively increased by 93%, 52%, and 26% compared with neat PBS. more...
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- 2021
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5. Ternary blends from biological poly(3-hydroxybutyrate-co-4-hydroxyvalerate), poly(L-lactic acid), and poly(vinyl acetate) with balanced properties
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Yancun Yu, Yi Li, Liguang Xiao, Shuangna Yao, and Changyu Han
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Materials science ,Morphology (linguistics) ,Scanning electron microscope ,Polyesters ,Proton Magnetic Resonance Spectroscopy ,Hydroxybutyrates ,02 engineering and technology ,Biochemistry ,Miscibility ,law.invention ,03 medical and health sciences ,chemistry.chemical_compound ,Structural Biology ,law ,Tensile Strength ,Phase (matter) ,Vinyl acetate ,Transition Temperature ,Crystallization ,Molecular Biology ,030304 developmental biology ,0303 health sciences ,Calorimetry, Differential Scanning ,Viscosity ,General Medicine ,Dynamic mechanical analysis ,021001 nanoscience & nanotechnology ,Elasticity ,Kinetics ,Chemical engineering ,chemistry ,Polyvinyls ,Stress, Mechanical ,Rheology ,0210 nano-technology ,Ternary operation - Abstract
Herein, poly(3-hydroxybutyrate-co-4-hydroxyvalerate) (P34HB), poly (L-lactic acid) (PLA), and poly(vinyl acetate) (PVAc) were initially melt compounded to prepare a ternary blend with balanced properties. Further, the miscibility, phase morphology, thermal and crystallization behaviors, and rheological and mechanical properties of the blends were studied. The dynamic mechanical analysis (DMA) results indicated that P34HB and PLA were partially miscible; however, PVAc showed full miscibility with PLA and P34HB. PVAc would selectively disperse in the PLA phase when considering low content, whereas it would gradually diffuse into the P34HB phase with the increasing PVAc concentration. A phase-separated morphology was observed for all the blends using scanning electron microscopy (SEM), and the diameters of the dispersed phases increased with the increasing PVAc concentration. The crystallization of P34HB was enhanced by the presence of PLA alone and was restrained by the simultaneous incorporation of PVAc and PLA. The rheological properties of P34HB were significantly improved because of the PVAc phase. Unexpectedly, the toughness and stiffness of the P34HB in ternary blends clearly improved because of the incorporation of PLA and PVAc. more...
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- 2021
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6. Effect of the molecular weight of poly(vinyl acetate) on the polymorphism and thermomechanical properties of poly(L-lactic acid)/poly(D-lactic acid) blends
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Liguang Xiao, Yancun Yu, Lijia Zhao, Changyu Han, Guangbin Zhou, Yi Li, and Mingzhi Xu
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Poly l lactic acid ,Materials science ,Crystal structure ,Condensed Matter Physics ,law.invention ,Lactic acid ,chemistry.chemical_compound ,chemistry ,Polymorphism (materials science) ,Chemical engineering ,law ,Vinyl acetate ,Crystallite ,Physical and Theoretical Chemistry ,Crystallization - Abstract
The effects of molecular weight (Mw) and content of poly(vinyl acetate) (PVAc) on the crystallization behaviors, competing crystallization of homocrystallites and stereocomplex crystallites (SCs), crystalline structure, and mechanical properties of poly(L-lactic acid) (PLLA)/poly(D-lactic acid) (PDLA) blends were investigated. The crystallization of PLLA/PDLA component is accelerated after the addition of low-Mw PVAc and is suppressed with high-Mw PVAc. The ability of SC formation is enhanced via blending with PVAc, irrespective of its Mw, and becomes prominent with low-Mw PVAc. The exclusive SCs are obtained in the blends with 30 mass % low-Mw PVAc. The improvement in thermomechanical property above 170 °C is ascribed to the enhancement of SC content. This work presents guidance for achieving the melt processability of SC-PLA, thus proving their potential as a high-performance substitute for conventional plastics. more...
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- 2021
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7. Improving the stereocomplexation and toughness of poly(<scp>L</scp>-lactic acid)/poly(<scp>D</scp>-lactic acid) blends via melt blending with ethylene/methyl acrylate/glycidyl methacrylate terpolymer
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Huan Liu, Mingzhi Xu, Hongwei Zhao, Yancun Yu, Changyu Han, Guangbin Zhou, and Qingquan Liu
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Poly l lactic acid ,Toughness ,Glycidyl methacrylate ,Ethylene ,Materials science ,Polymers and Plastics ,food and beverages ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Elastomer ,01 natural sciences ,0104 chemical sciences ,Lactic acid ,chemistry.chemical_compound ,stomatognathic system ,chemistry ,Chemical engineering ,Materials Chemistry ,Ceramics and Composites ,Copolymer ,0210 nano-technology ,Methyl acrylate - Abstract
In this study, the ethylene/methyl acrylate/glycidyl methacrylate (EGA) terpolymer was performed to improve the stereocomplexation and toughness of poly(L-lactic acid)/poly(D-lactic acid) (PLLA/PDL... more...
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- 2021
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8. Miscibility, morphology, and properties of poly(butylene succinate)/poly(vinyl acetate) blends
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Yi Li, Changyu Han, Guangbin Zhou, Liguang Xiao, Yancun Yu, and Mingzhi Xu
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Toughness ,Materials science ,Polymers and Plastics ,Nucleation ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Miscibility ,0104 chemical sciences ,Polybutylene succinate ,law.invention ,chemistry.chemical_compound ,Crystallinity ,Colloid and Surface Chemistry ,chemistry ,Chemical engineering ,Rheology ,law ,Materials Chemistry ,Vinyl acetate ,Physical and Theoretical Chemistry ,Crystallization ,0210 nano-technology - Abstract
Poly(butylene succinate) (PBS)/poly(vinyl acetate) (PVAc) blends were prepared by melt mixing. The miscibility, morphology, non-isothermal and isothermal crystallization, and rheological and mechanical properties of PBS/PVAc blends were investigated. The blends were a partial miscible two-phase system with PVAc evenly dispersed in the PBS matrix. The incorporation of PVAc accelerated the crystallization rate of PBS due to the heterogeneous nucleation, but decreased the degree of crystallinity. The rheological properties of PBS were greatly improved by the incorporation of PVAc, because of the high viscosity of PVAc in melt state. The most intriguing result was that the stiffness, strength, and toughness could be improved simultaneously by the addition of PVAc. The modulus, breaking strength, and elongation at break of PBS containing 10 wt% PVAc increased by 3.5%, 15.7%, and 43.4%, respectively. The synergetic improvement in the crystallization, rheological, and mechanical properties may be of much importance for widening the application of PBS. more...
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- 2020
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9. Sustainable Blends of Poly(propylene carbonate) and Stereocomplex Polylactide with Enhanced Rheological Properties and Heat Resistance
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Yi Li, Dexin Huang, Changyu Han, Xianhong Wang, and Yancun Yu
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Vicat softening point ,Materials science ,Polymers and Plastics ,General Chemical Engineering ,Organic Chemistry ,chemistry.chemical_compound ,Differential scanning calorimetry ,Rheology ,Chemical engineering ,chemistry ,Percolation ,Phase (matter) ,Propylene carbonate ,Polymer blend ,Glass transition - Abstract
Sustainable blends of poly(propylene carbonate) (PPC) and stereocomplex polylactide (sc-PLA) were prepared by melt blending equimolar poly(L-lactic acid) (PLLA) and poly(D-lactide acid) (PDLA) with PPC to form sc-PLA crystals in situ in the melt blending process. Differential scanning calorimetry analysis revealed that only sc-PLA, no homo-crystallization of PLLA or PDLA, formed in the PPC matrix as the sc-PLA content was more than 10 wt%. Very intriguingly, scanning electronic microscopy observation showed that sc-PLA was evenly dispersed in the PPC phase as spherical particles and the sizes of sc-PLA particles did not obviously increase with increasing sc-PLA content. As a consequence, the rheological properties of PPC were greatly improved by incorporation of sc-PLA. When the sc-PLA content was 20 wt%, a percolation network structure was formed, and the blends showed solid-like behavior. The sc-PLA particles could reinforce the PPC matrix, especially at a temperature above the glass transition temperature of PPC. Moreover, the Vicat softening temperature of PPC/sc-PLA blends could be increased compared with that of neat PPC. more...
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- 2020
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10. Biodegradable blends of poly(butylene adipate-co-terephthalate) and stereocomplex polylactide with enhanced rheological, mechanical properties and thermal resistance
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Yi Li, Changyu Han, Yancun Yu, and Lijia Zhao
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Materials science ,Polymers and Plastics ,Modulus ,02 engineering and technology ,Biodegradation ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Colloid and Surface Chemistry ,Differential scanning calorimetry ,Rheology ,Chemical engineering ,Percolation ,Adipate ,Ultimate tensile strength ,Materials Chemistry ,Physical and Theoretical Chemistry ,Elongation ,0210 nano-technology - Abstract
The aim of this study was to prepare a new blend system by blending equimolar poly(L-lactic acid) (PLLA) and poly(D-lactide acid) (PDLA) with poly(butylene adipate-co-terephthalate) (PBAT) and to form stereocomplex polylactide (sc-PLA) during blending process. Then, sc-PLA would improve the performance of PBAT without compromising its biodegradability. Torque-time curve, differential scanning calorimetry (DSC), and wide angle X-ray diffraction (WAXD) measurements indicated that only sc-PLA formed in PBAT matrix. The phase morphology showed that sc-PLA particles were uniformly dispersed in PBAT matrix, and the sizes were independent of their contents. The rheological properties of PBAT were significantly enhanced by addition of sc-PLA, especially after the formation of a percolation network structure. With the increase of sc-PLA content, the blends displayed increased yield strength and modulus and decreased elongation at break and tensile strength. The sc-PLA particles could reinforce PBAT matrix. Compared with pure PBAT, the heat resistance of PBAT/sc-PLA blends was improved. more...
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- 2020
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11. Surface interaction between Pd and nitrogen derived from hyperbranched polyamide towards highly effective formic acid dehydrogenation
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Changpeng Liu, Junjie Ge, Wei Xing, Yancun Yu, Xian Wang, and Fateev Vladimir
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Formic acid ,Energy Engineering and Power Technology ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Catalysis ,chemistry.chemical_compound ,Fuel Technology ,chemistry ,Chemical engineering ,Hydrogen fuel ,Polyamide ,Electrochemistry ,medicine ,Dehydrogenation ,In situ polymerization ,0210 nano-technology ,Energy (miscellaneous) ,Activated carbon ,medicine.drug ,Hydrogen production - Abstract
Hydrogen production from formic acid decomposition (FAD) is a promising means of hydrogen energy storage and utilization in fuel cells. Development of efficient catalysts for dehydrogenation of formic acid is a challenging topic. The surface chemical and electronic structure of the active catalysis components is important in formic acid decomposition at room-temperature. Here, the pyrdinic-nitrogen doped catalysts from hyperbranched polyamide were prepared via in situ polymerization reaction process by using activated carbon as a support. Because of the introduction of the polymer, the particles of the catalysts were stabilized, and the average particle diameter was only 1.64 nm. Under mild conditions, the catalysts activities were evaluated for FAD. The optimized Pd-N30/C catalyst exhibited high performance achieving almost full conversion, with a turnover frequency of 3481 h−1 at 30 °C. more...
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- 2020
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12. Enhancement of the properties of biosourced poly(3-hydroxybutyrate-co-4-hydroxybutyrate) by the incorporation of natural orotic acid
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Changyu Han, Yi Li, Liguang Xiao, and Yancun Yu
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Orotic acid ,Polyesters ,Nucleation ,Hydroxybutyrates ,02 engineering and technology ,Biochemistry ,law.invention ,03 medical and health sciences ,Structural Biology ,law ,Tensile Strength ,Enzymatic hydrolysis ,medicine ,Thermal stability ,Crystallization ,Molecular Biology ,030304 developmental biology ,Orotic Acid ,Biological Products ,0303 health sciences ,Chemistry ,Hydrolysis ,Thermal decomposition ,Temperature ,Green Chemistry Technology ,General Medicine ,Biodegradation ,021001 nanoscience & nanotechnology ,Kinetics ,Chemical engineering ,Spherulite ,Rheology ,0210 nano-technology ,medicine.drug - Abstract
The aim of this study is to use natural orotic acid (OA) as a sustainable, environmentally friendly additive to improve the crystallization, rheological, thermal, mechanical, and biodegradation properties of bacterially synthesized poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P34HB). OA was found to be an efficient nucleating agent for P34HB, and dramatically enhanced both non-isothermal and isothermal crystallization rates. The incorporation of OA increased nucleation density and decreased spherulite size, but had little effect on the crystalline structure. The rheological properties of the P34HB were greatly improved by the solid filler OA, particularly when a percolation network structure was formed in the blends. The thermal stability of P34HB was strongly enhanced, as exemplified by the ~23 °C increase in the onset thermal decomposition temperature (To) for the blend loaded with 5 wt% OA compared to that of pure P34HB. Moreover, the yield strength and elongation at break of P34HB containing 0.5 wt% OA increased by 25% and 119%, respectively. The most intriguing result was the clear enhancement in the enzymatic hydrolysis rates of the P34HB/OA blends compared to that of neat P34HB. The synergetic improvement in these properties may be of significant importance for the wider practical application of biosourced P34HB. more...
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- 2019
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13. Uniaxial stretching and properties of fully biodegradable poly(lactic acid)/poly(3-hydroxybutyrate-co-4-hydroxybutyrate) blends
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Changyu Han, Yancun Yu, Yi Li, and Dexin Huang
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Materials science ,Chemical Phenomena ,Scanning electron microscope ,Polyesters ,Hydroxybutyrates ,Modulus ,Biocompatible Materials ,02 engineering and technology ,Biochemistry ,law.invention ,03 medical and health sciences ,chemistry.chemical_compound ,Biopolymers ,Differential scanning calorimetry ,Structural Biology ,law ,Crystallization ,Ductility ,Molecular Biology ,030304 developmental biology ,0303 health sciences ,Spectrum Analysis ,General Medicine ,021001 nanoscience & nanotechnology ,Lactic acid ,chemistry ,Chemical engineering ,Microscopy, Electron, Scanning ,Thermodynamics ,Elongation ,0210 nano-technology ,Glass transition - Abstract
In this work, fully biodegradable poly (lactic acid) (PLA)/poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P(3HB-co-4HB)) blends of various compositions were uniaxially stretched at different stretch ratios above the glass transition temperature (Tg) of PLA. These stretched blends exhibited a closed microvoid structure, as evaluated by scanning electron microscopy. Differential scanning calorimetry and wide-angle X-ray diffraction analyses verified that stretching-induced crystallization in the α-form could be achieved in the PLA matrix. This hierarchical structure could improve the multifunctional performance of PLA blends. The density of drawn blends with a P(3HB-co-4HB) content of 30 wt% and stretch ratio of 6 was reduced by 20% as compared to neat PLA. The excellent combination of strength, modulus, and ductility of drawn blends with a P(3HB-co-4HB) content of 10 wt% and stretch ratio of 6 was demonstrated; compared to neat PLA, these parameters increased by 300%, 320%, and 317%, respectively in breaking strength, modulus, and elongation at break (172.2 MPa, 4200 MPa, and 18.4%), respectively. Meanwhile, control over the degradation rate and thermomechanical-property improvement was achieved by adjusting the stretch ratio and/or blend composition. In practical terms, this processing technique provides a new way to manufacture lightweight and high-performance microvoid-containing biopolymers. more...
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- 2019
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14. Morphology and properties in the binary blends of polypropylene and propylene–ethylene random copolymers
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Yi Li, Changyu Han, Liguang Xiao, Yang Li, and Yancun Yu
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Polypropylene ,Materials science ,Polymers and Plastics ,02 engineering and technology ,General Chemistry ,Dynamic mechanical analysis ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Miscibility ,0104 chemical sciences ,chemistry.chemical_compound ,Crystallinity ,Differential scanning calorimetry ,chemistry ,Chemical engineering ,Phase (matter) ,Tacticity ,Materials Chemistry ,Copolymer ,0210 nano-technology - Abstract
Propylene-based random copolymers copolymerized by propylene and ethylene (PEC) with low degree of crystallinity were used for the modification of isotactic polypropylene (PP) in this work. The phase morphology, miscibility, mechanical properties and rheological properties of the PP/PEC blends were systematically investigated. Dynamic mechanical analysis (DMA) and differential scanning calorimeter (DSC) results verified that the blends were partial miscibility. This may be due to the fact that the PP segments from PEC chains are incorporated into crystal lattice of neat PP, and they together act as a matrix of the PP/PEC blends. The rest of the PEC chains serve as the dispersed phase. The segments from the PEC chains incorporated into pure PP play the role of compatibilizer between the PP matrix and the dispersed phase, which make the dispersed phase to be uniformly dispersed in the PP matrix, resulting in an increase in impact strength from 5 kJ/m2 of neat PP to 40 kJ/m2 of blend with 20 wt% PEC. In addition, the viscosity and modulus of the blends were lower than that of pure PP due to the dilution of PEC in the molten state. more...
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- 2018
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15. Production and characterization of sustainable poly(lactic acid)/functionalized-eggshell composites plasticized by epoxidized soybean oil
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Changyu Han, Junjun Kong, Yancun Yu, and Lisong Dong
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chemistry.chemical_classification ,Toughness ,Materials science ,Mechanical Engineering ,Nucleation ,Plasticizer ,02 engineering and technology ,Polymer ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,law.invention ,Epoxidized soybean oil ,chemistry.chemical_compound ,chemistry ,Mechanics of Materials ,law ,Ultimate tensile strength ,General Materials Science ,Elongation ,Crystallization ,Composite material ,0210 nano-technology - Abstract
To improve the intrinsic brittleness and crystallization capacity of poly(lactic acid) (PLA), fully sustainable PLA composites were prepared. The biodegradable PLA composites consisted of 10 wt% epoxidized soybean oil (ESO) and different amounts of functional eggshell (FES) with surface modified with calcium phenylphosphonate (PPCa) were prepared by melt blending. Mechanical and crystallization behavior were studied in terms of the weight percentage of FES. ESO-plasticized PLA showed an excellent tensile toughness with the elongation at break increased over than 160% compared to 6% of pure PLA. The elongation at break for PLA composites was still higher than 70% even filled with 30 wt% FES. Besides, the tensile and storage moduli of PLA/ESO/FES composites did not suffer significant deterioration as compared with pure PLA. For cold crystallization behavior, FES with surface modified by PPCa as a good nucleating agent improved the nucleating ability of PLA. The rates of nonisothermal and isothermal cold crystallization of PLA were improved due to the synergistic effect of plasticization and nucleation. The nonisothermal cold crystallization peak temperature (Tcc) of PLA composites decreases considerably from 118.7 °C (for pure PLA) to 90 °C. The crystallization half-time of PLA composites is lower than 10 min compared with 162 min of pure PLA after isothermal crystallized at 75 °C. As a consequence, it is encouraging that ESO and FES exhibit great viability for modifying the mechanical and crystallization properties of PLA matrix, which make PLA a promising sustainable alternative to petroleum-based polymers in conventional fields. more...
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- 2018
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16. Effect of content and particle size of talc on nonisothermal melt crystallization behavior of poly(l-lactide)
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Yancun Yu, Changyu Han, Yi Li, Liguang Xiao, and Yan Shao
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Materials science ,Scanning electron microscope ,Nucleation ,02 engineering and technology ,Activation energy ,Crystal structure ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Talc ,01 natural sciences ,010406 physical chemistry ,0104 chemical sciences ,law.invention ,Chemical engineering ,law ,medicine ,Particle ,Particle size ,Physical and Theoretical Chemistry ,Crystallization ,0210 nano-technology ,medicine.drug - Abstract
This work examined the effect of content and particle size of nucleating agent on nonisothermal melt crystallization behavior of poly(l-lactide) (PLLA). Two different particle sizes of talc were used as the nucleating agents of PLLA. Scanning electron microscopy observation revealed that both big and small particles of talc were homogeneously dispersed in the PLLA matrix. Talc significantly accelerated the nonisothermal melt crystallization rate of PLLA. The effect of smaller particle talc on crystallization was obviously better than that of the bigger one. The activation energy based on Friedman equation was evaluated. Lower activation energy was obtained for nucleated PLLA. Finally, addition of talc did not modify the crystal structure. more...
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- 2018
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17. Crystallization behaviors of poly(lactic acid) composites fabricated using functionalized eggshell powder and poly(ethylene glycol)
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Yan Shao, Liguang Xiao, Changyu Han, Yi Li, and Yancun Yu
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Materials science ,Scanning electron microscope ,macromolecular substances ,02 engineering and technology ,Activation energy ,010402 general chemistry ,01 natural sciences ,Isothermal process ,law.invention ,chemistry.chemical_compound ,Differential scanning calorimetry ,stomatognathic system ,law ,PEG ratio ,Physical and Theoretical Chemistry ,Composite material ,Crystallization ,Instrumentation ,technology, industry, and agriculture ,Plasticizer ,respiratory system ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,0104 chemical sciences ,chemistry ,lipids (amino acids, peptides, and proteins) ,0210 nano-technology ,Ethylene glycol - Abstract
The eggshell power decorated with calcium phenyphosphonate (NES), an effective nucleating agent for poly(lactic acid) (PLA), was introduced into PLA simultaneously with a plasticizer, poly(ethylene glycol) (PEG), via melt blending. The morphology and melt crystallization behaviors of PLA composites were studied by scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). PEG improved compatibility and interfacial adhesion between NES and PLA, which made NES dispersed more evenly in PLA matrix. The isothermal melt crystallization rate of PLA/PEG/NES was fastest in all the composites, indicative of a synergistic effect between PEG and NES. For the nonisothermal melt crystallization, the Avrami and Mo’s model could describe the experiment data successfully. Whereas the Ozawa equation failed to provide an adequate description for the composites. Moreover, the crystallization activation energy was further evaluated based on Friedman equation. more...
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- 2018
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18. Enhancing the crystallization of biodegradable poly(ε-caprolactone) using a polyvinyl alcohol fiber favoring nucleation
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Changyu Han, Yancun Yu, Hechang Shi, Yi Li, Ye Zhang, and Shilong Yao
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Materials science ,Composite number ,Nucleation ,Dynamic mechanical analysis ,Condensed Matter Physics ,Polyvinyl alcohol ,law.invention ,chemistry.chemical_compound ,Differential scanning calorimetry ,chemistry ,Chemical engineering ,law ,Fiber ,Physical and Theoretical Chemistry ,Crystallization ,Instrumentation ,Caprolactone - Abstract
In this study, biodegradable poly(e-caprolactone) (PCL)/polyvinyl alcohol (PVA) fiber composites were prepared using melt processing techniques with different PVA fiber contents. The effect of PVA fiber on the non-isothermal and isothermal melt crystallization kinetics of PCL/PVA fiber composites was studied by using differential scanning calorimetry. Non-isothermal crystallization peak temperatures were enhanced significantly, as exemplified by about 20 K increase for the composite loaded with 5 wt% PVA fiber at a cooling rate of 20 K/min compared to that of neat PCL. The crystallization half-time decreased from 1.67 min for neat PCL to 0.80 min for composite with 5 wt% PVA fiber at a cooling rate of 5 K/min. PVA fiber was also found to dramatically accelerate the isothermal crystallization rate of PCL/PVA fiber composites. The crystallization half-time of composite containing 5 wt% PVA fiber was reduced by more than 10 times compared with neat PCL. Moreover, dynamic mechanical analysis results showed that PVA fiber had a strengthening effect on the PCL. more...
- Published
- 2021
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19. Isothermal and nonisothermal cold crystallization kinetics of poly(l-lactide)/functionalized eggshell powder composites
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Yan Shao, Yancun Yu, Changyu Han, Yi Li, and Liguang Xiao
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Materials science ,Composite number ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Isothermal process ,0104 chemical sciences ,law.invention ,Crystallization kinetics ,Avrami equation ,Differential scanning calorimetry ,law ,Poly-L-lactide ,Physical and Theoretical Chemistry ,Crystallization ,Eggshell ,Composite material ,0210 nano-technology - Abstract
Functionalized eggshell powder (NES) with nucleating surface of calcium phenylphosphonic acid (PPCa) for poly(l-lactide) (PLLA) was compounded with PLLA via melt blending to improve the cold crystallization process of PLLA. The cold crystallization behavior of the PLLA/NES composites was studied by differential scanning calorimetry. The isothermal cold crystallization rates have been enhanced obviously in the PLLA/NES composites than in the neat PLLA, indicative of the excellent nucleating effects of NES on PLLA. For the nonisothermal cold crystallization, the overall crystallization rate of PLLA increased with both increasing NES loadings and heating rate. It was found that the Avrami equation and the combined Ozawa–Avrami model could describe the experiment data successfully. more...
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- 2017
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20. Effect of loadings of nanocellulose on the significantly improved crystallization and mechanical properties of biodegradable poly(ε-caprolactone)
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Changyu Han, Liguang Xiao, Yi Li, and Yancun Yu
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Materials science ,Time Factors ,Polyesters ,Nucleation ,Modulus ,02 engineering and technology ,Crystal structure ,Biochemistry ,Isothermal process ,Nanocellulose ,law.invention ,03 medical and health sciences ,chemistry.chemical_compound ,X-Ray Diffraction ,Structural Biology ,law ,Elastic Modulus ,Tensile Strength ,Materials Testing ,Crystallization ,Cellulose ,Molecular Biology ,030304 developmental biology ,Mechanical Phenomena ,0303 health sciences ,Nanocomposite ,Calorimetry, Differential Scanning ,Temperature ,General Medicine ,021001 nanoscience & nanotechnology ,Kinetics ,Chemical engineering ,chemistry ,Nanoparticles ,Stress, Mechanical ,0210 nano-technology ,Caprolactone - Abstract
Biodegradable poly(e-caprolactone) (PCL)/nanocellulose (NC) nanocomposites were prepared using solvent-free melt processing techniques with various NC contents. Both the nonisothermal and isothermal melt crystallization processes of PCL/NC nanocomposites were significantly accelerated by adding NC. The nonisothermal melt crystallization peak temperature obviously increased from 18.8 °C for neat PCL to 30.9 °C for the PCL/NC nanocomposite with 10 wt% NC content at a cooling rate of 10 °C min−1; moreover, the half-time isothermal crystallization at 40 °C significantly decreased from 12.2 min for neat PCL to 2.0 min. Apparently, NC enhanced PCL's crystallization rate. The crystalline morphology study confirmed the increased nucleation density of PCL spherulites, indicating the role of NC as an efficient nucleating agent. Moreover, the loading of NC did not change the crystal structure of PCL, and with increase in NC content, the Young's modulus and yield strength increased; however, the elongation-at-break and the breaking strength decreased. Compared with pure PCL, the thermomechanical properties of PCL/NC nanocomposites were significantly improved. These biodegradable PCL/NC nanocomposites showed excellent crystallization capabilities and tailored mechanical properties, thus proving their potential as a substitute for traditional commercial plastics. more...
- Published
- 2019
21. Synthesis of a novel hydrophobic polyurea gel from CO 2 and amino-modified polysiloxane
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Shan Jiang, Minli Lan, Qifan Wu, Yancun Yu, Fengyu Zhao, Bin Zhang, Chao Zhang, Zhong Ying, and Haiyang Cheng
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010405 organic chemistry ,Process Chemistry and Technology ,Carbon-13 NMR ,010402 general chemistry ,01 natural sciences ,Isocyanate ,0104 chemical sciences ,Contact angle ,chemistry.chemical_compound ,chemistry ,Polymer chemistry ,Acetone ,Urea ,Proton NMR ,Chemical Engineering (miscellaneous) ,Organic chemistry ,Solubility ,Waste Management and Disposal ,Polyurea - Abstract
Carbon dioxide, as a carbonyl source to replace the highly toxic isocyanate, was used to prepare a new type of polyurea with amino modified polysiloxane in this work. The formation of both the modified polysiloxane and polyureas were confirmed by FT-IR spectra, 1H NMR spectrum and 13C NMR spectrum. The thermo-stability, solubility as well as the hydrophilicity was examined; the polysiloxane could be soluble in several polar solvents like acetone, THF, ethanol and so on. The polyureas are stable at temperature lower than 150 °C, and the synthesized polyureas are hydrophobic as they have a water contact angles larger than 90°. Moreover, the polyurea containing high urea linkage content presented excellent absorption for some organic solvents, such as C2H3Cl3, thus it is expected to have an application in removing organic pollutants on river. more...
- Published
- 2016
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22. A facile strategy for confining ZnPd nanoparticles into a ZnO@Al2O3 support: A stable catalyst for glycerol hydrogenolysis
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Yan Li, Yancun Yu, Haiyang Cheng, Weiwei Lin, Chao Zhang, Xiaoru Li, Qifan Wu, Fengyu Zhao, and Bin Zhang
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Aqueous solution ,Annealing (metallurgy) ,Chemistry ,Alloy ,Nanoparticle ,02 engineering and technology ,engineering.material ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Catalysis ,0104 chemical sciences ,Metal ,Chemical engineering ,Hydrogenolysis ,visual_art ,visual_art.visual_art_medium ,engineering ,Organic chemistry ,Physical and Theoretical Chemistry ,0210 nano-technology ,Selectivity - Abstract
Stability and reusability are crucial properties for heterogeneous catalysts in view of their industrial applications. Here, we report a very stable catalyst, ZnPd/ZnO@Al2O3, for the aqueous phase hydrogenolysis of glycerol, which was prepared by a facile strategy via pretreatment of ZnO with Al(NO3)3 and conventional impregnation and annealing processes. The as-prepared ZnPd/ZnO@Al2O3 showed excellent stability, and it could be recycled 5 times, retaining high activity and selectivity (92%) to 1,2-propanediol. It was confirmed that the surface porous Al2O3 skin layer could suppress the aggregation and growth of ZnPd alloy particles and protect the imbedded ZnO from etching by water. This work provides a facile method for preparing stable catalysts with metal particles imbedded into a surface Al2O3 layer, and the present ZnPd/ZnO@Al2O3 is expected to have a potential application in other aqueous catalysis reactions. more...
- Published
- 2016
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23. Miscibility, crystallization, rheological and mechanical properties of biodegradable poly(3-hydroxybutyrate-co-4-hydroxybutyrate)/poly(vinyl acetate) blends
- Author
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Changyu Han, Liguang Xiao, Yutong Lei, Yi Li, Yancun Yu, and Shilong Yao
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Materials science ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Miscibility ,010406 physical chemistry ,0104 chemical sciences ,law.invention ,Amorphous solid ,chemistry.chemical_compound ,Crystallinity ,chemistry ,Rheology ,Chemical engineering ,law ,Compounding ,Vinyl acetate ,Physical and Theoretical Chemistry ,Crystallization ,0210 nano-technology ,Glass transition ,Instrumentation - Abstract
Herein, biodegradable poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P34HB) was mixed with amorphous poly(vinyl acetate) (PVAc) to prepare a binary blend system by melt compounding. The miscibility, thermal behavior, isothermal crystallization behaviors, and mechanical and rheological properties of P34HB/PVAc blends were investigated. Only one glass transition temperature of the blends indicated that P34HB and PVAc were miscible. The introduction of PVAc suppressed the cold crystallization of the blends and reduced the degree of crystallinity. The study of isothermal crystallization behaviors revealed that the addition of amorphous PVAc reduced the crystallization rate of blends, but did not change the crystallization mechanism. In addition, the blends showed a remarkable improvement in the rheological properties compared with those of neat P34HB. The most intriguing result was a greatly increased elongation at break, coupled with an only slightly reduced modulus and strength for blends. more...
- Published
- 2020
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24. Hydrogenation of levulinic acid by RuCl2(PPh3)3 in supercritical CO2: the significance of structural changes of Ru complexes via interaction with CO2
- Author
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Masahiko Arai, Shin-ichiro Fujita, Haiyang Cheng, Yan Li, Chao Zhang, Yancun Yu, Weiwei Lin, Bin Zhang, Wenjing Yang, Fengyu Zhao, Mingli Lan, and Tong Liu
- Subjects
Molecular interactions ,010405 organic chemistry ,Chemistry ,010402 general chemistry ,01 natural sciences ,Pollution ,Supercritical fluid ,0104 chemical sciences ,Catalysis ,chemistry.chemical_compound ,Homogeneous ,Phase (matter) ,Levulinic acid ,Environmental Chemistry ,Organic chemistry - Abstract
The hydrogenation of levulinic acid (LA) to γ-valerolactone (GVL) was studied with a homogeneous RuCl2(PPh3)3 catalyst in supercritical CO2 (scCO2). The conversion of LA was observed to increase with CO2 pressure and the possible reasons for this rate acceleration were discussed, including the molecular interactions of CO2 with the reacting and catalytic species as well as the acidity and phase behavior of the reaction mixture. The interaction between CO2 and RuCl2(PPh3)3 was significant, which resulted in the production of an active RuHCl(CO)(PPh3)3 complex and thus enhanced the rate of hydrogenation in the presence of CO2. more...
- Published
- 2016
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25. Carbon dioxide as a sustainable resource for macrocyclic oligourea
- Author
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Zhong Ying, Yancun Yu, Jin Wang, Yu-Bin Dong, Chao Zhang, Yanzhi Sun, Fuhua Zhao, Hui-Ming Cheng, and Yu Zhou
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010405 organic chemistry ,Substrate (chemistry) ,010402 general chemistry ,01 natural sciences ,Pollution ,Oligomer ,0104 chemical sciences ,Solvent ,chemistry.chemical_compound ,chemistry ,Carbon dioxide ,Environmental Chemistry ,Organic chemistry ,Molecule ,Polyurea - Abstract
As carbon dioxide is an inexpensive, abundant, sustainable and green carbonyl resource, its utilization to produce value-added chemicals and polymeric materials has attracted much more attention. In this work, novel macrocyclic oligourea were synthesized and it is the first time to produce macrocyclic oligourea from a sustainable substrate of CO2. The chemical composition and molecular structure of oligourea have been confirmed by FTIR, MALDI-TOF and tandem mass spectrometry. The formation of macrocyclic polyurea largely depends on the kind of solvent chosen and the reaction duration, which has been discussed according to the reaction phase behavior observation. The synthesized novel macrocyclic oligourea is expected to have important and special applications in the pharmaceutical industry. The present work provides a green and renewable process for the synthesis of a macrocyclic oligomer, which opens a new route for carbon dioxide utilization. more...
- Published
- 2016
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26. Synthesis of Ni/mesoporous ZSM-5 for direct catalytic conversion of cellulose to hexitols: modulating the pore structure and acidic sites via a nanocrystalline cellulose template
- Author
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Qifan Wu, Chao Zhang, Tong Liu, Xiaoru Li, Bin Zhang, Xing Wei, Fengyu Zhao, Guanfeng Liang, Zhong Ying, Mingli Lan, and Yancun Yu
- Subjects
010405 organic chemistry ,Chemistry ,Inorganic chemistry ,010402 general chemistry ,01 natural sciences ,Pollution ,Nanocrystalline material ,0104 chemical sciences ,Catalysis ,Microcrystalline cellulose ,chemistry.chemical_compound ,Chemical engineering ,Yield (chemistry) ,Environmental Chemistry ,Metal catalyst ,Cellulose ,ZSM-5 ,Mesoporous material - Abstract
Efficient utilization of cellulose is of scientific significance and a great challenge for both fundamental and industrial studies. Herein, we synthesized MesoZSM-5 zeolites by using nanocrystalline cellulose as a template for the first time, and reported the exciting performance of the corresponding non-noble metal catalysts (Ni/MesoZSM-5) for efficient conversion of cellulose to hexitols. By modulating the ratio of the template to precursor, MesoZSM-5 supports were produced with tunable pore structure and acidic sites. With the cooperation of active Ni sites and acidic sites of MesoZSM-5, hexitols were obtained with a high yield of around 60% in the direct conversion of commercial microcrystalline cellulose (MCC). The corresponding correlation between the structural characteristics and catalytic performance was established. This work provides a new approach for efficient utilization of cellulose, as well as gives rise to a sustainable templating method for the synthesis of mesoporous zeolites. more...
- Published
- 2016
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27. A Study on the Oxygen Vacancies in ZnPd/ZnO-Al and their Promoting Role in Glycerol Hydrogenolysis
- Author
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Chao Zhang, Xiaoru Li, Haiyang Cheng, Fengyu Zhao, Bin Zhang, Qifan Wu, Yancun Yu, Weiwei Lin, and Pingjing Chang
- Subjects
Organic Chemistry ,chemistry.chemical_element ,Zinc ,Heterogeneous catalysis ,Photochemistry ,Oxygen ,Catalysis ,law.invention ,Inorganic Chemistry ,chemistry.chemical_compound ,chemistry ,Hydrogenolysis ,law ,Glycerol ,Physical and Theoretical Chemistry ,Electron paramagnetic resonance ,Palladium - Abstract
the relationship between catalyst structure and catalytic activity is an important and challenging topic for researchers in the field of catalysis. in this work, the effect of oxygen vacancies on the activity of znpd/zno-al catalysts was studied in an important reaction-glycerol hydrogenolysis. interestingly, the catalytic activity improved significantly with the addition of a small amount of al, and high selectivity to 1,2-propanediol (>90%) was achieved in glycerol hydrogenolysis over znpd/zno-al catalysts. importantly, the formation of oxygen vacancies benefits from the substitution of al atoms, and the al content in the zno lattice is related to the oxygen vacancies density and catalytic activity. moreover, the important role played by oxygen vacancies in glycerol hydrogenolysis has been discussed in detail. more...
- Published
- 2015
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28. Utilization of carbon dioxide to build a basic block for polymeric materials: an isocyanate-free route to synthesize a soluble oligourea
- Author
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Zhong Ying, Tong Liu, Lijun Zhao, Fengyu Zhao, Haiyang Cheng, Chao Zhang, and Yancun Yu
- Subjects
chemistry.chemical_classification ,Chemistry ,General Chemical Engineering ,Chemical structure ,Thermal decomposition ,General Chemistry ,Polymer ,Isocyanate ,Oligomer ,chemistry.chemical_compound ,End-group ,Diamine ,Polymer chemistry ,Molar mass distribution - Abstract
A water soluble oligourea was synthesized by an isocyanate-free route from carbon dioxide and diamine in the absence of any organic solvents or additives. The chemical structure of the product was confirmed by FTIR and 13C NMR analysis, and the average molecular weight was estimated with MALDI-TOF MS. The weight average molecular weight of the obtained oligourea is about 2210 Da reacting under 180 °C and 11 MPa for 12 h. Moreover, the prepared oligourea has a moderate thermo-stability, it has an initial decomposition temperature at ∼220 °C and a melting temperature of 110 °C, as confirmed by TGA and DSC. As a soluble oligomer, it could be used as a building block to synthesize CO2-based polymeric materials due to it possessing a chemically active amino end group. For example, foaming plastics, greases, spun fibers and high strength polymer materials may be fabricated by reaction of the oligomer with a chain extender like a diisocyanate, diester or diacid. more...
- Published
- 2015
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29. High-performance biodegradable polylactide composites fabricated using a novel plasticizer and functionalized eggshell powder
- Author
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Zengwen Cao, Junjun Kong, Zonglin Li, Changyu Han, Yungang Bai, Yi Li, Lisong Dong, and Yancun Yu
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Materials science ,Polyesters ,02 engineering and technology ,Biodegradable Plastics ,010402 general chemistry ,01 natural sciences ,Biochemistry ,Miscibility ,Isothermal process ,law.invention ,chemistry.chemical_compound ,Egg Shell ,Structural Biology ,law ,Plasticizers ,Animals ,Crystallization ,Composite material ,Molecular Biology ,Diethylene glycol ,Plasticizer ,General Medicine ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Polyester ,chemistry ,Elongation ,Powders ,0210 nano-technology ,Macromolecule - Abstract
A novel polyester poly(diethylene glycol succinate) (PDEGS) was synthesized and evaluated as a plasticizer for polylactide (PLA) in this study. Meanwhile, an effective sustainable filler, functionalized eggshell powder (FES) with a surface layer of calcium phenyphosphonate was also prepared. Then, PLA biocomposites were prepared from FES and PDEGS using a facile melt blending process. The addition of 15 wt% PDEGS as plasticizer showed good miscibility with PLA macromolecules and increased the chain mobility of PLA. The crystallization kinetics of PLA composites revealed that the highly effective nucleating FES significantly improved the crystallization ability of PLA at both of non-isothermal and isothermal conditions. In addition, the effective plasticizer and well-dispersed FES increased the elongation at break from 6% of pure PLA to over 200% for all of the plasticized PLA composites. These biodegradable PLA biocomposites, coupled with excellent crystallization ability and tunable mechanical properties, demonstrate their potential as alternatives to traditional commodity plastics. more...
- Published
- 2017
30. Effect of Zn doping on the hydrogenolysis of glycerol over ZnNiAl catalyst
- Author
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Chao Zhang, Yancun Yu, Fengyu Zhao, Haiyang Cheng, Xiaoru Li, Limin He, and Weiwei Lin
- Subjects
inorganic chemicals ,Nial ,Dopant ,Process Chemistry and Technology ,Inorganic chemistry ,Doping ,chemistry.chemical_element ,Catalysis ,chemistry.chemical_compound ,Nickel ,chemistry ,Hydrogenolysis ,Glycerol ,Physical and Theoretical Chemistry ,Selectivity ,computer ,computer.programming_language - Abstract
Nickel based catalyst is of interest in the industrial catalytic processes, and it is always modified by doping a second element to improve its catalytic properties. Understanding the role of dopant is extremely helpful in tailoring the active centers. In this work, Zn could induce a significant improvement of the catalytic performance of NiAl for the hydrogenolysis of glycerol. The Zn doped ZnNiAl catalysts exhibited high activity and the improved selectivity to 1,2-propanediol, it was about 2 times higher than the original ones. The ZnNi alloy formed in ZnNiAl was responsible for the noticeable catalytic performance. They preferred to coordinate with the end hydroxyl group of glycerol, promoted the cleavage of C O bond in glycerol, and resulted in the dominant formation of 1,2-propanediol. The findings described here will provide a useful knowledge for rational design of nickel-based catalysts, as well as reveal a new reaction model for the hydrogenolysis of glycerol. more...
- Published
- 2014
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31. Structure variation and properties enhancement of uniaxial stretching poly( <scp>l</scp> ‐lactic acid)/eggshell powder composites
- Author
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Dexin Huang, Yi Li, Changyu Han, and Yancun Yu
- Subjects
Poly l lactic acid ,Materials science ,Polymers and Plastics ,Composite number ,Materials Chemistry ,General Chemistry ,Composite material ,Eggshell ,Surfaces, Coatings and Films - Published
- 2019
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32. The hydrogenation/dehydrogenation activity of supported Ni catalysts and their effect on hexitols selectivity in hydrolytic hydrogenation of cellulose
- Author
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Wei Li, Limin He, Yancun Yu, Haiyang Cheng, Xiaoru Li, Fengyu Zhao, Guanfeng Liang, and Chao Zhang
- Subjects
Microcrystalline cellulose ,chemistry.chemical_compound ,Hydrolysis ,Chemistry ,Organic chemistry ,Dehydrogenation ,Cellobiose ,Physical and Theoretical Chemistry ,Cellulose ,Selectivity ,Catalysis ,Propanediol - Abstract
A series of Ni catalysts were prepared with various supports (ZSM-5, Al2O3, SiO2, bentonite, TiO2, and kieselguhr) and their catalytic properties were investigated for the hydrogenation of cellobiose and glucose, the reaction intermediates of cellulose hydrolysis in hot-compressed water, in order to elucidate the key factors to control the hexitols selectivity in the hydrolytic hydrogenation of cellulose. For the hydrogenation of cellobiose, hexitols were produced with a selectivity above 82% over Ni/ZSM-5, but the other checked Ni catalysts produced large amount of glycerol, ethylene glycol, and propanediol, and the product distribution strikingly depended on the catalysts used. On the basis of kinetic experiments, it was the hydrogenation/dehydrogenation ability of Ni catalyst that played a critical role in controlling hexitols selectivity. High hydrogenation and inferior dehydrogenation activity of Ni catalysts were essential for obtaining high yield of hexitols in the hydrolytic hydrogenation of cellulose. The synergistic effect of Ni active species and acid–base sites was proposed to accelerate the dehydrogenation of sorbitol and thus reducing the yield of hexitols. more...
- Published
- 2014
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33. Simultaneous surface coating and chemical activation of the Li-rich solid solution lithium rechargeable cathode and its improved performance
- Author
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Linhai Zhuo, Yancun Yu, Fengyu Zhao, Jun Ming, and Yingqiang Wu
- Subjects
Materials science ,General Chemical Engineering ,Composite number ,Thermal decomposition ,chemistry.chemical_element ,Cathode ,law.invention ,Surface coating ,Chemical engineering ,chemistry ,law ,Electrode ,Electrochemistry ,Lithium ,Faraday efficiency ,Solid solution - Abstract
In this study, highly dispersive spherical Li-rich solid solution (Li1.2Mn0.54Ni0.13Co0.13O2) particles are successfully synthesized by a co-precipitation method. Then these particles are treated with aluminum nitrates ethanol solution at 80 degrees C. The treatment can extract lithium (Li2O) from the Li2MnO3 component in the composite of Li1.2Mn0.54Ni0.13Co0.13O2. Simultaneously, a thin layer of Al2O3 can be precipitated on the surface of the electrode particles via direct thermal decomposition of aluminum nitrates. After treatment, the first-cycle coulombic efficiency of the electrode increases from 72.1% to 93.6%, meanwhile it shows a superior cycling stability at 100 mAg(-1) with a discharge capacity of around 220 mAh g(-1) and retention of 92.5% after 100 cycles, which is much higher than that of the pristine electrode (83.2%). Even at a high current density of 2 A g(-1) (10 C), the discharge capacity could still achieve and well maintain as high as 140 mAh g(-1). (C) 2013 Elsevier Ltd. All rights reserved. more...
- Published
- 2013
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34. Selective hydrogenation of benzonitrile in multiphase reaction systems including compressed carbon dioxide over Ni/Al2O3 catalyst
- Author
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Yancun Yu, Fengyu Zhao, Xiaoyu Shan, Chaoyong Wu, Haiyang Cheng, and Xiangchun Meng
- Subjects
Nucleophilic addition ,Process Chemistry and Technology ,Medicinal chemistry ,Catalysis ,Solvent ,Hexane ,Reaction rate ,Benzonitrile ,chemistry.chemical_compound ,Benzylamine ,chemistry ,Yield (chemistry) ,Organic chemistry ,Physical and Theoretical Chemistry - Abstract
a b s t r a c t Selective hydrogenation of benzonitrile was studied with Ni/Al2O3 in compressed CO2, hexane-CO2, ethanol-CO2 and H2O-CO2 systems. The phase behavior and the effect of CO2 on the conversion of ben- zonitrile and the yield of benzylamine were discussed. The reaction rate was retarded in solventless, hexane and ethanol, but accelerated in water in the presence of compressed CO2. The decrease in reac- tion rate was mainly ascribed to the formation of carbamate from benzylamine and the intermediate 1-aminodibenzylamine reacting with CO2, and it precipitated out to coat on the surface of catalyst in solventless and hexane, and the dilution effect of compressed CO2 in ethanol. But the yield of benzy- lamine was increased in solventless, hexane and ethanol due to the following nucleophilic addition of benzylamine and benzylimine to N-benzylidenebenzylamine was inhibited. Although, the reaction rate increased in water for the enhanced solubility of H2 and benzonitrile in H2O and decreased mass-transfer resistance in the presence of compressed CO2, the yield of benzylamine decreased because of the acidic nature of H2O-CO2 favorites the elimination of NH3 and the formation of NH4HCO3. Accordingly, the possible reaction pathway of benzonitrile hydrogenation was proposed for all the studied systems. © 2013 Elsevier B.V. All rights reserved. more...
- Published
- 2013
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35. Comparisons among six strains of Tetrahymena by microcalorimetry
- Author
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Yancun Yu, Xi Chen, and Weisong Feng
- Subjects
Isothermal microcalorimetry ,biology ,Chemistry ,Tetrahymena pyriformis ,Metabolic rate ,Heat output ,Tetrahymena ,Analytical chemistry ,Physical and Theoretical Chemistry ,Condensed Matter Physics ,biology.organism_classification ,Tetrahymena pigmentosa - Abstract
The typical power–time curves of six strains of Tetrahymena were determined by microcalorimetry at 28 °C. Metabolic characteristics were obtained including metabolic rate constant (r), heat output in the log phase (Q log), total heat production (Q T), peak time, and measured and potential maximum power output (P m and P max). The power–time curves and metabolic characteristics show the differences among Tetrahymena strains. Euclidean distances and a clustering analysis diagram were obtained by metabolic properties. The smaller distances are between the four strains of Tetrahymena thermophila and the largest distance exists between Tetrahymena pyriformis GL and Tetrahymena pigmentosa HG2. These results are consistent with those obtained by first internal transcriptional spacer sequences. Therefore, the power–time curves and metabolic properties can be noticeable characteristics in distinguishing the different strains of Tetrahymena. And, the heat output in the log phase (Q log) is probably the most specific characteristic in distinguishing the different Tetrahymena strains and studying their relationships. more...
- Published
- 2013
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36. Studies on the nongrowth metabolism of the different strains of Tetrahymena cells by isothermal microcalorimetry
- Author
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Xi Chen, Yancun Yu, and Weisong Feng
- Subjects
Isothermal microcalorimetry ,biology ,Strain (chemistry) ,Cell ,Tetrahymena ,chemistry.chemical_element ,Metabolism ,Condensed Matter Physics ,biology.organism_classification ,Oxygen ,medicine.anatomical_structure ,Reaction rate constant ,Biochemistry ,chemistry ,Tetrahymena pyriformis ,medicine ,Physical and Theoretical Chemistry - Abstract
The nongrowth metabolic processes of Tetrahymena strains with the different cell densities were monitored by isothermal microcalorimetry, including Tetrahymena thermophila BF1, Tetrahymena thermophila SB210, Tetrahymena pyriformis GL, the mixed cells of T. thermophila BF1 and T. thermophila SB210, and the mixed cells of T. thermophila BF1 and T. pyriformis GL. All the typical power-time curves showed a decreasing trend on the whole. It was found that total heat production (Q (t)) and maximum heat output (P (m)) decreased significantly with the decrease of cell density. Cell density did not influence significantly the maximum heat output per cell (P (cell)) of Tetrahymena cells, which was probably due to enough oxygen. The P (cell) and metabolic decrease rate constant (K) values for the mixture of T. thermophila BF1 and T. pyriformis GL, and that of T. thermophila BF1 and T. thermophila SB210 were similar to the mean values of P (cell) and K for the corresponding single Tetrahymena strain, respectively. It was speculated that the cell mixing did not possibly influence significantly their P (cell) and K values because of no competition for nutrition, oxygen, and room, and the low conjunction percentages. more...
- Published
- 2013
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37. Trace Amounts of Water-Induced Distinct Growth Behaviors of NiO Nanostructures on Graphene in CO2-Expanded Ethanol and Their Applications in Lithium-Ion Batteries
- Author
-
Xin-Bo Zhang, Wei Zhou, Fengyu Zhao, Lingyan Wang, Linhai Zhuo, Yingqiang Wu, and Yancun Yu
- Subjects
Materials science ,Trace Amounts ,Graphene ,Inorganic chemistry ,Non-blocking I/O ,Oxide ,chemistry.chemical_element ,Nanoparticle ,law.invention ,Nanomaterials ,chemistry.chemical_compound ,Nickel ,chemistry ,law ,General Materials Science ,Lithium - Abstract
In this work, we have developed a new method to grow NiO nanomaterials on the surface of graphene nanosheets (GNSs). The morphologies of NiO nanomaterials grown on GNSs could be tailored by trace amounts of water introduced into the mixed solvents of CO2-expanded ethanol (CE). Small and uniform Ni-salt nanoparticles (Ni-salt-NPs) were grown on the surface of graphene oxide (GO) through the decomposition of nickel nitrate directly in CE. However, when trace amounts of water were introduced into the mixed solvents, Ni-salt nanoflakes arrays (Ni-salt-NFAs) were grown on the surface of GO with almost perpendicular direction. After thermal treatment in N2 atmosphere, these Ni-salt @GO composites were converted to NiO@GNSs composites. The forming mechanisms of the NiO-NPs@GNSs and NiO-NFAs@GNSs were discussed by series comparative experiments. The presence of the trace amounts of water affected the chemical composition and structure of the precursors formed in CE and the growth behaviors on the surface of GNSs. When used as anode materials for lithium-ion batteries, the NiO-NPs@GNSs composite exhibited better cycle and rate performance compared with the NiO-NFAs@GNSs. more...
- Published
- 2013
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38. High performance of Ir-promoted Ni/TiO2 catalyst toward the selective hydrogenation of cinnamaldehyde
- Author
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Yancun Yu, Haiyang Cheng, Weiwei Lin, Fengyu Zhao, and Limin He
- Subjects
Hydrogen ,Inorganic chemistry ,chemistry.chemical_element ,Electronic structure ,Catalysis ,Cinnamaldehyde ,chemistry.chemical_compound ,chemistry ,X-ray photoelectron spectroscopy ,Transmission electron microscopy ,Desorption ,Physical and Theoretical Chemistry ,Hydrogen spillover ,Nuclear chemistry - Abstract
The catalytic performance of Ni/TiO2 and Ni-Ir/TiO2 catalysts in the selective hydrogenation of cinnamaldehyde (CAL) has been investigated. The Ni-Ir/TiO2 presented higher activity than the Ni/TiO2. Here, we studied and gave some insights into the interaction between Ni and Ir species and the role of Ir using X-ray diffraction (XRD), transmission electron microscope (TEM), hydrogen temperature-programmed reduction (H-2 TPR), hydrogen temperature-programmed desorption (H-2 TPD), and X-ray photoelectron spectroscopy (XPS). The size of Ni particles on the Ni-Ir/TiO2 was 10.1 nm, smaller than that (12.7 nm) on the Ni/TiO2. The reducibility of Ni was improved by addition of a small amount of Ir, as confirmed with the H-2 TPR analysis. The Ni-Ir/TiO2 could be reduced at a temperature of 352 degrees C, which is lower than the temperature for Ni/TiO2 (385 degrees C); moreover, a new reduction peak appeared at 240 degrees C due to the stronger interaction of Ni-Ir species, which was certified by XPS analysis. The H-2 TPD results indicate that the hydrogen spillover effect may occur in Ni-Ir/TiO2. The electronic structure of the surface Ni atoms was modified upon addition of Ir, resulting in an enhanced activity of the Ni-Ir/TiO2 catalyst, about four times as high as that of the Ni/TiO2 catalyst. (c) 2013 Elsevier Inc. All rights reserved. more...
- Published
- 2013
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39. Coating of Al2O3 on layered Li(Mn1/3Ni1/3Co1/3)O2 using CO2 as green precipitant and their improved electrochemical performance for lithium ion batteries
- Author
-
Linhai Zhuo, Fengyu Zhao, Yancun Yu, Yingqiang Wu, and Jun Ming
- Subjects
Materials science ,Coprecipitation ,Intercalation (chemistry) ,Inorganic chemistry ,Energy Engineering and Power Technology ,chemistry.chemical_element ,engineering.material ,Electrochemistry ,Cathode ,law.invention ,chemistry.chemical_compound ,Fuel Technology ,Coating ,chemistry ,law ,Electrode ,engineering ,Hydroxide ,Lithium ,Energy (miscellaneous) ,Nuclear chemistry - Abstract
Li(Mn 1/3 Ni 1/3 Co 1/3 )O 2 cathode materials were fabricated by a hydroxide precursor method. Al 2 O 3 was coated on the surface of the Li(Mn 1/3 Ni 1/3 Co 1/3 )O 2 through a simple and effective one-step electrostatic self-assembly method. In the coating process, a NHCO 3 -H 2 CO 3 buffer was formed spontaneously when CO 2 was introduced into the NaAlO 2 solution. Compared with bare Li(Mn 1/3 M 1/3 Co 1/3 )O 2 , the surface-modified samples exhibited better cycling performance, rate capability and rate capability retention. The Al 2 O 3 -coated Li(Mn 1/3 Ni 1/3 Co 1/3 )O 2 electrodes delivered a discharge capacity of about 115 mAh·g −1 at 2 A·g −1 , but only 84 mAh·g −1 for the bare one. The capacity retention of the Al 2 O 3 -coated Li(Mn 1/3 Ni 1/3 Co 1/3 )O 2 was 90.7% after 50 cycles, about 30% higher than that of the pristine one. more...
- Published
- 2013
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40. The effect of water on the hydrogenation of o-chloronitrobenzene in ethanol, n-heptane and compressed carbon dioxide
- Author
-
Fengyu Zhao, Yancun Yu, Xiangchun Meng, and Haiyang Cheng
- Subjects
Heptane ,Hydrogen ,Hydrogen bond ,Process Chemistry and Technology ,Inorganic chemistry ,chemistry.chemical_element ,Catalysis ,Solvent ,Reaction rate ,chemistry.chemical_compound ,chemistry ,Phase (matter) ,Solubility - Abstract
Water as a clean solvent and promoter in the organic synthesis have attracted more attention, herein the effect of water was studied for the hydrogenation of o-chloronitrobenzene (o-CNB) over Pt/C and Pd/C catalysts in ethanol, n-heptane and compressed CO2. Very interesting, the reaction rate decreased in ethanol, but increased in n-heptane and compressed CO2 with the addition of water. The role of water in the reaction was mainly discussed from the experimental data and phase behavior analysis, one is to activate the functional group of NO2 through the interactions via a hydrogen bonding, and the other is to affect the solubility of hydrogen in ethanol and n-heptane. The positive effect of the interaction between water and reactants may be counteracted by the negative effect of hydrogen solubility in ethanol. However, the concentration of o-CNB and hydrogen changed slightly in n-heptane with the addition of water, so the interaction of water with reactants may play a main role in improving the TOF. The combination of H2O and CO2 is more efficient than the pure H2O, CO2 and H2O-n-heptane systems. The phase behavior may play important role also for the improved activity except for the interactions of H2O and CO2 with the reactants. o-CNB phase was expanded in the compressed CO2 and so the concentration of H-2 in o-CNB phase increased due to the miscible of CO2 and H-2, resulting in the enhancement of reaction rate and the maximum conversion at pressure of 9 MPa CO2, at which the volume was expanded to the largest one. The similar results were also obtained in the compressed CO2 system without H2O. In addition, the stability of Pt/C and Pd/C was studied in H2O-n-heptane and H2O-CO2. As a result, the H2O-CO2 media and Pt/C catalyst is one of the most effective systems for the hydrogenation of o-CNB. (c) 2013 Elsevier B.V. All rights reserved. more...
- Published
- 2013
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41. Polycaprolactone nanocomposite reinforced by bioresource starch-based nanoparticles
- Author
-
Junjun Kong, Lisong Dong, XiaoPeng Pei, Ying Tan, Changyu Han, and Yancun Yu
- Subjects
Materials science ,Starch ,Scanning electron microscope ,Polyesters ,Nanoparticle ,macromolecular substances ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,Biochemistry ,Nanocomposites ,chemistry.chemical_compound ,Hydrolysis ,Structural Biology ,Enzymatic hydrolysis ,Tensile Strength ,Polymer chemistry ,Molecular Biology ,Nanocomposite ,technology, industry, and agriculture ,Temperature ,General Medicine ,equipment and supplies ,musculoskeletal system ,021001 nanoscience & nanotechnology ,Biodegradable polymer ,0104 chemical sciences ,chemistry ,Chemical engineering ,Polycaprolactone ,Nanoparticles ,0210 nano-technology ,Rheology - Abstract
Biodegradable polymer nanocomposites with bioresource starch-based nanoparticles (SNPs) as reinforcing fillers for polycaprolactone (PCL) were prepared by melt blending. Scanning electron microscopy observation revealed that SNPs as spherical particles were evenly dispersed in the PCL matrix without any aggregation even with the content of SNPs increasing to 10wt% in the nanocomposite. Consequently, the rheological performances of PCL have been improved efficaciously after incorporation with SNPs as well as mechanical properties, especially with a percolation network structure of SNPs in the PCL matrix formed. In addition, the enzymatic hydrolysis experiments showed a more interesting behavior that the hydrolysis rates had been accelerated apparently in the nanocomposites than that in the neat PCL as observed. Such high performance nanocomposites may have great potential in expanding the utilization of starch from sustainable resources and the practical application of PCL-based biodegradable materials. more...
- Published
- 2017
42. Effect of structure of CuO/ZnO/Al2O3 composites on catalytic performance for hydrogenation of fatty acid ester
- Author
-
Limin He, Fengyu Zhao, Guanfeng Liang, Haiyang Cheng, and Yancun Yu
- Subjects
biology ,Process Chemistry and Technology ,Inorganic chemistry ,Layered double hydroxides ,Active site ,Fatty alcohol ,Nanoparticle ,chemistry.chemical_element ,Fatty acid ester ,engineering.material ,Microstructure ,Copper ,Catalysis ,chemistry.chemical_compound ,chemistry ,biology.protein ,engineering - Abstract
In this work, CuO/ZnO/Al2O3 catalysts were prepared by adjusting the initial alkali concentration in the process of co-precipitation. The correlation between the structure and catalytic activity was studied, and the catalyst derived from LDHs (layered double hydroxides) structure exhibited the highest activity in the hydrogenation of fatty esters as well as high selectivity to fatty alcohol, producing fatty alcohol with a yield above 98%. The high catalytic performance was attributed to relatively high dispersion (small crystal size) and the high reducibility of copper species. In addition, the active species was discussed and the Cu+/Cu-0 were supposed to be the active site for the present hydrogenation. (c) 2012 Elsevier B.V. All rights reserved. more...
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- 2013
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43. Facile synthesis of a Co3O4–carbon nanotube composite and its superior performance as an anode material for Li-ion batteries
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Linhai Zhuo, Fengyu Zhao, Yancun Yu, Lingyan Wang, Xin-Bo Zhang, Yingqiang Wu, and Jun Ming
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Nanocomposite ,Nanostructure ,Materials science ,Renewable Energy, Sustainability and the Environment ,Composite number ,Oxide ,chemistry.chemical_element ,Nanoparticle ,Nanotechnology ,General Chemistry ,Carbon nanotube ,Anode ,law.invention ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,law ,General Materials Science ,Lithium - Abstract
In this work, we report a facile method for the synthesis of a Co3O4–functionalized carbon nanotube (Co3O4–f-CNT) composite via the growth of Co3O4 nanoparticles on the surface of functionalized carbon nanotubes (f-CNTs) by thermal decomposition of cobalt nitrate hexahydrate in ethanol. The composite consists of 13% carbon nanotubes and 87% Co3O4 nanoparticles by weight, and all the Co3O4 particles grew compactly along the carbon nanotube axis with a highly uniform dispersion. When used as an anode material for rechargeable lithium ion batteries, the composite manifested high capacities and excellent cycling performance at high and low current rates. The discharge capacity was 719 mA h g−1 at the 2nd cycle and 776 mA h g−1 at the 100th cycle. Even at a current density of 1 A g−1, the specific capacity still remained at about 600 mA h g−1. This superior electrochemical performance was attributed to the unique nanostructure of the composite. Because almost all of the Co3O4 nanoparticles were immobilized on the surface of f-CNTs, physical aggregation of nanoparticles was avoided during the charge–discharge processes. Furthermore, the good mechanical flexibility of f-CNTs can readily alleviate the massive volume expansion/shrinkage associated with a conversion reaction electrode. Finally, f-CNTs are highly conductive matrices for electrons due to their high conductivity, which can shorten the diffusion path for electrons. more...
- Published
- 2013
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44. Fabrication of Co(OH)2 coated Pt nanoparticles as an efficient catalyst for chemoselective hydrogenation of halonitrobenzenes
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Jun Ming, Haiyang Cheng, Xiangchun Meng, Qiang Wang, Yancun Yu, and Fengyu Zhao
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Materials science ,Surface Properties ,Scanning electron microscope ,Inorganic chemistry ,Metal Nanoparticles ,Platinum nanoparticles ,Catalysis ,Biomaterials ,chemistry.chemical_compound ,Colloid and Surface Chemistry ,X-ray photoelectron spectroscopy ,Hydroxides ,Particle Size ,Microwaves ,Nitrobenzenes ,Platinum ,Aniline Compounds ,Temperature ,Halogenation ,Cobalt ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,chemistry ,Transmission electron microscopy ,Hydroxide ,Hydrogenation ,Selectivity - Abstract
Co(OH)(2) coated platinum nanoparticles Pt/Co(OH)(2) were prepared by microwave assistance and hydrothermal method, and the prepared samples were composed of Pt nanoparticles with an average size of 1.8 nm coated uniformly in the thin Co(OH)(2) leaves based on the results of X-ray diffraction, transmission electron microscopy, scanning electron microscopy and X-ray photoelectron spectroscopy. The Pt/Co(OH)(2) presented excellent catalytic performance in the chemoselective hydrogenation of halonitrobenzenes such as chloronitrobenzenes, bromonitrobenzene and iodonitrobenzene, and above 99.6% selectivity to haloanilines was achieved at complete conversion irrespective of the substrates used, even for iodonitrobenzene to which the dehalogenation is more easily to occur. Co(OH)(2) was confirmed to prohibit the dehalogenation effectively, and the Pt/Co(OH)(2) catalyst could be recycled for several times. (C) 2012 Elsevier Inc. All rights reserved. more...
- Published
- 2012
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45. Deactivation of Ni/TiO2 catalyst in the hydrogenation of nitrobenzene in water and improvement in its stability by coating a layer of hydrophobic carbon
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Weiwei Lin, Yancun Yu, Haiyang Cheng, Jun Ming, and Fengyu Zhao
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inorganic chemicals ,Inorganic chemistry ,chemistry.chemical_element ,Catalysis ,Solvent ,Nitrobenzene ,Nickel ,chemistry.chemical_compound ,chemistry ,Hydroxide ,Reactivity (chemistry) ,Physical and Theoretical Chemistry ,Cobalt ,Carbon - Abstract
Water as a green solvent to replace the conventional organic solvent presents many advantages in the organic synthesis. The hydrogenation of nitrobenzene in water has been investigated by using Ni/TiO2 catalyst in this work, and our main purpose was focused on the Ni/TiO2 catalyst activity and its stability improvement. The experimental results and analysis from the data of XRD, XPS, ICP revealed that the formation of nickel hydroxide from metallic nickel reacting with water caused a rapid deactivation of Nil TiO2 catalyst. Based on these, we designed a catalyst with hydrophobic property to prevent the nickel active species to contact with water: thus, a hydrophobic carbon layer was coated on the surface of Ni/TiO2. As expected, the hydrophobic carbon was successfully coated on Ni/TiO2 catalysts by a hydrothermal method and they presented higher reactivity and improved stability in the present aqueous reaction system; nickel hydroxide was not detected on the used and water treated carbon-coated Ni/TiO2 samples. The improved abilities were attributed to the increased hydrophobicity of catalysts modified by carbon, which not only prevents water to contact with nickel catalytic species, but also protects the metallic nickel to be oxidized as it exposed to air. (C) 2012 Elsevier Inc. All rights reserved. more...
- Published
- 2012
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46. Polyureas from diamines and carbon dioxide: synthesis, structures and properties
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Chaoyong Wu, Yancun Yu, Dewen Dong, Pingjing Chang, Fengyu Zhao, Zhijian Wu, Haiyang Cheng, and Jinyao Wang
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Hydrogen bond ,Small-angle X-ray scattering ,General Physics and Astronomy ,Catalysis ,Solvent ,chemistry.chemical_compound ,chemistry ,Polymer chemistry ,Urea ,Copolymer ,Organic chemistry ,Thermal stability ,Physical and Theoretical Chemistry ,Fourier transform infrared spectroscopy - Abstract
Polyureas were synthesized from diamines and carbon dioxide in the absence of any catalyst or solvent, analogous to the synthesis of urea from condensation of ammonia with carbon dioxide. The method used carbon dioxide as a carbonyl source to substitute highly toxic isocyanates for the synthesis of polyureas. FTIR and DFT calculations confirmed that strong bidentate hydrogen bonds were formed between urea motifs, and XRD patterns showed that the PUas were highly crystalline and formed a network structure through hydrogen bonds, which served as physical cross-links. The long chain PUas presented a microphase separated morphology as characterized by SAXS and showed a high melting temperature above 200 °C. The PUas showed high resistance to solvents and excellent thermal stability, which benefitted from their special network structures. The PUas synthesized by this method are a new kind of functional material and could serve some areas where their analogues with similar functional groups could not be applied. more...
- Published
- 2012
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47. Reaction of hydrous inorganic metal salts in CO2 expanded ethanol: Fabrication of nanostructured materials via supercritical technology
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Haiyang Cheng, Jun Ming, Yancun Yu, Fengyu Zhao, and Chaoyong Wu
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chemistry.chemical_classification ,Reaction mechanism ,Nanocomposite ,Precipitation (chemistry) ,General Chemical Engineering ,Inorganic chemistry ,Salt (chemistry) ,Nanoparticle ,Condensed Matter Physics ,Supercritical fluid ,Reaction rate ,Solvent ,chemistry ,Physical and Theoretical Chemistry - Abstract
The fabrication of nanostructured materials from hydrous inorganic metal salt processed in supercritical CO2 (scCO2) expanded liquids has advantages to obtain good results. However, the behavior of the inorganic salts and the detailed reaction mechanism are still unknown up to now. In this work, the actual behavior of hydrous inorganic metal salts in CO2 expanded ethanol at the temperature of 50–200 °C, including the phase behavior, deposition mechanism, reaction rate and the effect of templates on the deposition were systematically investigated by using XRD, FTIR, CHN-analysis, TGA, ICP-AES. A series of experimental parameters such as CO2 flow rate, expand procedure, reaction temperature and time have been discussed, as well as the roles of CO2 and H2O (often originated from salts and/or solvent but always neglected) were studied in this contribution. Significantly, a coordination–decomposition (C–D) was proved to be the converting mechanism for the precipitation of the hydrous inorganic metal salts, rather than the fuzzy decomposition. more...
- Published
- 2011
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48. Transfer hydrogenation of citral to citronellol with Ru complexes in the mixed solvent of water and polyethylene glycol
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Shuxia Cai, Ruixia Liu, Jianmin Hao, Haiyang Cheng, Yancun Yu, Fengyu Zhao, and Qiang Wang
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Inorganic Chemistry ,Solvent ,Citronellol ,chemistry.chemical_compound ,chemistry ,Organic chemistry ,General Chemistry ,Polyethylene glycol ,Citral ,Selectivity ,Transfer hydrogenation ,Benzene ,Catalysis - Abstract
The transfer hydrogenation of citral to citronellol was studied with [RuCl2(benzene)](2) catalyst in a mixed solvent of water and polyethylene glycol (H2O-PEG). The influence of several important factors including hydrogen source, solvent, temperature and active species is discussed. Under the present conditions, citronellol was produced with an extremely high selectivity above 90%. The Ru complexes could be immobilized in the H2O-PEG phase well and separated from organic products successfully. Moreover, a stable catalytic activity was obtained after the first run, although the decomposition of Ru complexes occurred during the recycling processes. The selectivity to citronellol decreased but kept a stable level about 60% in the recycling runs. Copyright (C) 2010 John Wiley & Sons, Ltd. more...
- Published
- 2010
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49. Physically and chemically mixed TiO2-supported Pd and Au catalysts: unexpected synergistic effects on selective hydrogenation of citral in supercritical CO2
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Ruixia Liu, Kazuki Yoshida, Masahiko Arai, Haoxi Jiang, Minhua Zhang, Guiming Li, Yancun Yu, Shin-ichiro Fujita, and Fengyu Zhao
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chemistry.chemical_compound ,Chemistry ,Citronellal ,Organic chemistry ,Physical and Theoretical Chemistry ,Hydrogen spillover ,Selectivity ,Heterogeneous catalysis ,Citral ,Bimetallic strip ,Catalysis ,Supercritical fluid - Abstract
The selective hydrogenation of citral was studied with various TiO2-supported monometallic and bimetallic Pd and Au catalysts and their physical mixtures in supercritical CO2 (scCO2). Significant synergistic effects appeared when active Pd species was chemically or physically mixed with less active Au species. The total rate of conversion was greatly enhanced and the selectivity to citronellal (CAL) was improved. The physical properties of those catalysts were characterized by TEM, HRTEM-EDS, XPS, and UV/Vis and their features of H2 desorption were examined by TPD. The physical and chemical characterization results were used to discuss the reasons for the unexpected synergistic effects observed. The same selective hydrogenation was also conducted in a conventional non-polar organic solvent of n-hexane to examine the roles of scCO2. The use of scCO2 was effective for accelerating the hydrogenation of citral and improving the selectivity to CAL. more...
- Published
- 2010
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50. Selective hydrogenation of chloronitrobenzene to chloroaniline in supercritical carbon dioxide over Ni/TiO2: Significance of molecular interactions
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Yufen Hao, Yanjiao Shang, Masahiko Arai, Shuxia Cai, Haiyang Cheng, Xiangchun Meng, Yancun Yu, Fengyu Zhao, and Shin-ichiro Fujita
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Reaction rate ,Supercritical carbon dioxide ,Chemistry ,Inorganic chemistry ,Reactivity (chemistry) ,Reaction intermediate ,Physical and Theoretical Chemistry ,Chemoselectivity ,Chloronitrobenzene ,Catalysis ,Supercritical fluid - Abstract
The hydrogenation of chloronitrobenzene to chloroaniline was investigated over Ni/TiO2 at 35 degrees C in supercritical CO2 (scCO(2)), ethanol, and n-hexane. The reaction rate followed the order of scCO(2) > n-hexane > ethanol. In scCO(2), the selectivity to chloroaniline and to aniline over Ni/TiO2 were 97-99.5% and < 1%, respectively, in the conversion range of 9-100%. The high chemoselectivity to chloroaniline cannot be achieved over Ni/TiO2 in ethanol and n-hexane. In situ high-pressure Fourier transform infrared measurements were made to study the molecular interactions of CO2 with the following reactant and reaction intermediates: chloronitrobenzene, chloronitrosobenzene, and N-chlorophenylhydroxylamine. The molecular interaction modifies the reactivity of each species and accordingly the reaction rate and the selectivity. The influence of Cl substituent on the interaction modes of CO2 with these reacting species is discussed. Possible reaction pathways for the hydrogenation of chloronitrobenzene in scCO(2) over Ni/TiO2 are also proposed. (c) 2009 Elsevier Inc. All rights reserved more...
- Published
- 2010
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