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Morphological and mechanical characterization of a PMMA/CdS nanocomposite

Vishal MATHUR, Manasvi DIXIT, K.S. RATHORE, N. S. SAXENA, K.B. SHARMA

《化学科学与工程前沿(英文)》 2011年 第5卷 第2期   页码 258-263 doi: 10.1007/s11705-010-1014-7

摘要: Thick film of poly(methyl methacrylate) (PMMA)/CdS nanocomposite have been synthesized by the solution casting process. The nanostructure of the CdS particles has been ascertained through the small angle X-ray scattering (SAXS) technique. The surface morphological characterization of the PMMA/CdS nanocomposite has been done through scanning electron microscopy (SEM) analysis. The variation of mechanical loss factor (Tan ) with temperature and tensile properties of prepared samples have been studied using Dynamic Mechanical Analyzer (DMA). This study reveals that the glass transition temperature ( ), Young’s modulus, and fracture energy of the PMMA/CdS nanocomposite are greatly influenced by the existence of interfacial energetic interaction between dispersed CdS nanoparticles and the matrix of PMMA.

关键词: poly(methyl methacrylate) (PMMA)     filler nanoparticles     polymer semiconducting nanocomposite     tensile properties     glass transition temperature    

Phenolic rigid organic filler/isotactic polypropylene composites. III. Impact resistance property

Heming LIN, Dongming QI, Jian HAN, Zhiqi CAI, Minghua WU

《化学科学与工程前沿(英文)》 2009年 第3卷 第2期   页码 176-181 doi: 10.1007/s11705-009-0203-8

摘要: A novel phenolic rigid organic filler (KT) was used to modify isotactic polypropylene (iPP). The influence of KT particles on the impact resistance property of PP/KT specimens (with similar interparticles distance, 1.8 μm) was studied by notched izod impact tests. It was found that the brittle-ductile transition (BDT) of the PP/KT microcomposites took place at the filler content of about 4%, and the impact strength attains the maximum at 5% (with filler particles size of 1.5 μm), which is about 2.5 times that of unfilled iPP specimens. The impact fracture morphology was investigated by scanning electron microscopy (SEM). For the PP/KT specimens and the high-density polyethylene/KT (HDPE/KT) specimens in ductile fracture mode, many microfibers could be found on the whole impact fracture surface. It was the filler particles that induced the plastic deformation of interparticles ligament and hence improved the capability of iPP matrix on absorbing impact energy dramatically. The determinants on the BDT were further discussed on the basis of stress concentration and debonding resistance. It can be concluded that aside from the interparticle distance, the filler particles size also plays an important role in semicrystalline polymer toughening.

关键词: rigid organic filler     polypropylene     impact resistance    

Dispersion of a novel phenolic rigid organic filler in isotactic polypropylene matrix by solution-mixing

Dongming QI, Xiaoli ZHAO, Zhijie CHEN, Peng HUANG, Jun CAO

《化学科学与工程前沿(英文)》 2012年 第6卷 第4期   页码 395-402 doi: 10.1007/s11705-012-1269-2

摘要: A novel phenolic rigid organic filler (named KD) with a high melting point was dispersed in an isotactic polypropylene (iPP) matrix by solution-mixing and/or melt-mixing. A series of KD/iPP blends was prepared with or without addition of maleic anhydride-grafted polypropylene (MAPP) as a compatibilizer. Influences of MAPP and mixing methods on the filler dispersion were studied using polaried optical microscope (POM), scanning electron microscope (SEM) and tensile test. The filler particles are always inclined to form large irregular aggregates in the iPP matrix due to their significant differences in polarity and solubility in solvent. However, an iPP/MAPP/KD (PMK) blend containing filler particles with a quasi-spherical shape (~97.8 nm in diameter) and narrow particle size distribution (polydispersity index= 1.076) was successfully prepared by incorporating MAPP to reduce the interfacial tension and surface free energy between the dispersion phase and the continuous phase, and adopting a spray-drying method after solution-mixing to suppress the increase of the size of the dispersed phase during the removal of solvent.

关键词: dispersion     rigid organic filler     isotactic polypropylene     mixing    

Influence of the filler materials on flux-free brazing of pure aluminium (1050)

Kirsten BOBZIN, Lidong ZHAO, Thomas SCHLAEFER, Thomas WARDA,

《机械工程前沿(英文)》 2010年 第5卷 第1期   页码 47-51 doi: 10.1007/s11465-009-0079-9

摘要: In the present study, samples of pure aluminium (1050) were deposited by cold spraying with filler materials such as Al12Si, Al7Si, Al12Si-4%Cu, and the Al-Si-based filler material A, which was especially developed for flux-free brazing by the Surface Engineering Institute. Besides, pure Si powder was also sprayed. The coated samples were heat-treated under different conditions and were brazed under an argon atmosphere without fluxes or with the flux Nokolok by an induction heating system. The shear strength of the brazed joints was determined. The results show that the filler materials could be well deposited by cold spraying. A thin layer of brittle Si could also form due to the strong deformation of the substrate surface. The heat treatments showed that a very good metallurgical bond between the filler materials and the substrate could be realized by the deposition by cold spraying. The Al7Si deposited samples could not be brazed without fluxes under the given conditions. The samples deposited with other filler materials could be brazed without fluxes. The in-situ diffusion process made it possible to braze the Si-deposited samples at 580°C. The joints of the samples deposited with the filler material showed the highest shear strength of 41 MPa, whereas the values of the Al12Si and Si deposited samples were less than 20 MPa. The employment of the flux Nikolok significantly increased the shear strength of the Al12Si deposited samples to more than 53 MPa.

关键词: aluminium     flux-free brazing     cold spraying     shear strength    

Phenolic rigid organic filler/isotactic polypropylene composites. I. Preparation

QI Dongming, YANG Lei, WU Minghua, LIN Heming, NITTA Kohhei

《化学科学与工程前沿(英文)》 2008年 第2卷 第3期   页码 236-241 doi: 10.1007/s11705-008-0034-z

摘要: A novel phenolic rigid organic filler (KT) was melt-mixed with an isotactic polypropylene (iPP) to prepare a series of PP/KT composites, with or without maleic anhydride grafted polypropylene (MAPP) as compatilizer. The evolution of filler morphology during melt-mixing and melt-pressure processes was monitored by scanning electron microscope (SEM) and polarized optical microscope (POM). The influences of shear force, pressure time, filler content and MAPP concentration on the final filler dispersion were studied. We found that this rigid organic filler readily melted and dispersed homogenously into the iPP matrix through a fission-fusion process during the melt-mixing process. Thus a balanced dispersion, which was closely related to shear force and MAPP concentration, can be achieved. During the melt-pressure process, parts of the filler particles combined gradually through a coalescence process. However, the incorporation of MAPP can effectively inhibit the tendency to coalesce and refine the filler particles sizes into nanoscale. Thus, a series of PP/KT composites with controllable filler particles size and narrow size distribution can be obtained just by adjusting process conditions and MAPP concentration. In addition, due to the in-situ formation mechanism, the filler phase possessed a typical solid true-spherical shape.

关键词: morphology     concentration     tendency     controllable     addition    

Phenolic rigid organic filler/isotactic polypropylene composites. II. Tensile properties

QI Dongming, SHAO Jianzhong, WU Minghua, NITTA Kohhei

《化学科学与工程前沿(英文)》 2008年 第2卷 第4期   页码 396-401 doi: 10.1007/s11705-008-0077-1

摘要: A novel phenolic rigid organic filler (KT) was used to modify isotactic polypropylene (iPP). The influence of KT particles on the tensile properties of PP/KT microcomposites was studied by uniaxial tensile test and the morphological structures of the stretched specimens were observed by scanning electron microscopy (SEM) and polarized optical microscopy (POM). We found that the Young’s modulus of PP/KT specimens increased with filler content, while the yield and break of the specimens are related to the filler particles size. The yield stress, the breaking stress and the ultimate elongation of PP/KT specimens were close to those of unfilled iPP specimens when the maximal filler particles size is less than a critical value, which is 7 ?m at a crosshead speed of 10 mm/min and 3 ?m at 200 mm/min, close to that of glass bead but far more than those of other rigid inorganic filler particles. The interfacial interaction was further estimated from yield stress, indicating that KT particles have a moderate interfacial interaction with iPP matrix. Thus, the incorporation of small KT particles can reinforce iPP matrix and simultaneously cause few detrimental effects on the other excellent tensile properties of iPP matrix, due to their organic nature, higher specific area, solid true-spherical shape and the homogenous dispersion of the ROF particles in microcomposites.

关键词: maximal     uniaxial tensile     unfilled     excellent tensile     influence    

Translocation and biotoxicity of metal (oxide) nanoparticles in the wetland-plant system

《环境科学与工程前沿(英文)》 2021年 第15卷 第6期 doi: 10.1007/s11783-021-1432-4

摘要:

• Aquatic plants are more likely to absorb TiO2 NPs that are beneficial to them.

关键词: Constructed wetlands     Aquatic plants     Nanoparticles     Physiological activity     Biomass    

Enhanced 4-chlorophenol biodegradation by integrating FeO nanoparticles into an anaerobic reactor: Long-term

《环境科学与工程前沿(英文)》 2022年 第16卷 第8期 doi: 10.1007/s11783-022-1519-6

摘要:

• 4-chlorophenol biodegradation could be enhanced in Fe2O3 coupled anaerobic system.

关键词: Dechlorination     Fe2O3 nanoparticles     Electron transfer     Microbial community    

Gold nanoparticles/single-stranded DNA-reduced graphene oxide nanocomposites based electrochemical biosensor

《化学科学与工程前沿(英文)》 2021年 第15卷 第6期   页码 1572-1582 doi: 10.1007/s11705-021-2112-4

摘要: High density and uniform distribution of the gold nanoparticles functionalized single-stranded DNA modified reduced graphene oxide nanocomposites were obtained by non-covalent interaction. The positive gold nanoparticles prepared by phase inversion method exhibited good dimensional homogeneity and dispersibility, which could readily combine with single-stranded DNA modified reduced graphene oxide nanocomposites by electrostatic interactions. The modification of single-stranded DNA endowed the reduced graphene oxide with favorable biocompatibility and provided the preferable surface with negative charge for further assembling of gold nanoparticles to obtain gold nanoparticles/single-stranded DNA modified reduced graphene oxide nanocomposites with better conductivity, larger specific surface area, biocompatibility and electrocatalytic characteristics. The as-prepared nanocomposites were applied as substrates for the construction of cholesterol oxidase modified electrode and well realized the direct electron transfer between the enzyme and electrode. The modified gold nanoparticles could further catalyze the products of cholesterol oxidation catalyzed by cholesterol oxidase, which was beneficial to the enzyme-catalyzed reaction. The as-fabricated bioelectrode exhibited excellent electrocatalytic performance for the cholesterol with a linear range of 7.5‒280.5 μmol·L‒1, a low detection limit of 2.1 μmol·L‒1, good stability and reproducibility. Moreover, the electrochemical biosensor showed good selectivity and acceptable accuracy for the detection of cholesterol in human serum samples.

关键词: reduced graphene oxide     gold nanoparticles     electrochemical biosensor     cholesterol oxidase     cholesterol    

polymeric substances from activated sludge on the aggregation kinetics of silver and silver sulfide nanoparticles

《环境科学与工程前沿(英文)》 2022年 第16卷 第2期 doi: 10.1007/s11783-021-1450-2

摘要:

• The NPs aggregation in the electrolyte solution is consistent with the DLVO theory.

关键词: Silver nanoparticles     Silver sulfide nanoparticles     Extracellular polymeric substances     Aggregation kinetics     Influence mechanisms    

Size and shape effects of MnFeO nanoparticles as catalysts for reductive degradation of dye pollutants

《环境科学与工程前沿(英文)》 2021年 第15卷 第5期   页码 108-171 doi: 10.1007/s11783-021-1396-4

摘要: The magnetic nanoparticles that are easy to recycle have tremendous potential as a suitable catalyst for environmental toxic dye pollutant degradation. Rationally engineering shapes and tailoring the size of nanocatalysts are regarded as an effective manner for enhancing performances. Herein, we successfully synthesized three kinds of MnFe2O4 NPs with distinctive sizes and shapes as catalysts for reductive degradation of methylene blue, rhodamine 6G, rhodamine B, and methylene orange. It was found that the catalytic activities were dependent on the size and shape of the MnFe2O4 NPs and highly related to the surface-to-volume ratio and atom arrangements. Besides, all these nanocatalysts exhibit selectivity to different organic dyes, which is beneficial for their practical application in dye pollutant treatment. Furthermore, the MnFe2O4 NPs could be readily recovered by a magnet and reused more than ten times without appreciable loss of activity. The size and shape effects of MnFe2O4 nanoparticles demonstrated in this work not only accelerate further understanding the nature of nanocatalysts but also contribute to the precise design of nanoparticles catalyst for pollutant degradation.

关键词: Dye degradation     MnFe2O4 nanoparticles     Size and shape-control    

Functional magnetic nanoparticles for facile viable but nonculturable bacteria separation and purification

Chunming Wang, Huirong Lin, Chengsong Ye

《环境科学与工程前沿(英文)》 2016年 第10卷 第6期 doi: 10.1007/s11783-016-0874-6

摘要: The functional surface-modified MNPs were capable of capture with high efficiency. After induced to VBNC state by chlorination, cells could be separated by MNPs with an additional incubation process. This study provides a facile and economic method for VBNC cell enrichment and purification. GRAPHIC ABSTRACT Viable But Nonculturable (VBNC) Bacteria, which represent a unique population of microorganisms in drinking water systems, have become a potential threat to human health. Current studies on VBNC cells usually fail to obtain pure VBNC state bacteria, which may lead to inaccurate results. We therefore introduce a novel method of VBNC cell separation and purification in this paper. PAH-coated magnetic nanoparticles (MNPs) were synthesized and found to be capable of capturing and releasing bacterial cells with high efficiency. With the aid of an additional incubation step, VBNC cells were easily isolated and purified from normal bacteria using functional MNPs. Our method represents a new technique that can be utilized in studies of VBNCs.

关键词: Drinking water biosafety     VBNC     Nanoparticles     Magnetic separation and purification    

Size-controlled green synthesis of silver nanoparticles assisted by L-cysteine

Wenchao Zhang,Lin Zhang,Yan Sun

《化学科学与工程前沿(英文)》 2015年 第9卷 第4期   页码 494-500 doi: 10.1007/s11705-015-1527-1

摘要: A green and size-controlled synthesis of silver nanoparticles (Ag NPs) in aqueous solution with the assistance of L-cysteine is presented. The size of Ag NPs decreases with the increase of L-cysteine concentration, and thus can be controlled by adjusting L-cysteine concentration. TEM analysis shows that Ag NPs with an average size of 3 nm can be produced in the presence of 1.0 mmol/L L-cysteine, about one sixth of the size of Ag NPs obtained in the absence of L-cysteine (17 nm). The as-synthesized silver colloidal solution is stable and can be stored at room temperature for at least two months without any precipitation. This L-cysteine assisted method is simple, feasible and efficient, and would facilitate the production and application of Ag NPs.

关键词: nanoparticles     silver     L-cysteine     size distribution     synthesis    

Catalytic decomposition of low level ozone with gold nanoparticles supported on activated carbon

Pengyi ZHANG , Bo ZHANG , Rui SHI ,

《环境科学与工程前沿(英文)》 2009年 第3卷 第3期   页码 281-288 doi: 10.1007/s11783-009-0032-5

摘要: Highly dispersed gold nanoparticles were supported on coal-based activated carbon (AC) by a sol immobilization method and were used to investigate their catalytic activity for low-level ozone decomposition at ambient temperature. Nitrogen adsorption-desorption, scanning electron microscope (SEM), and X-ray photoelectron spectroscopy (XPS) were used to characterize the catalysts before and after ozone decomposition. The results showed that the supported gold nanoparticles prepared with microwave heating were much smaller and more uniformly dispersed on the activated carbon than those prepared with traditional conduction heating, exhibiting higher catalytic activity for ozone decomposition. The pH values of gold precursor solution significantly influenced the catalytic activity of supported gold for ozone decomposition, and the best pH value was 8. In the case of space velocity of 120000h, inlet ozone concentration of 50mg/m, and relative humidity of 45%, the Au/AC catalyst maintained the ozone removal ratio at 90.7% after 2500min. After being used for ozone decomposition, the surface carbon of the catalyst was partly oxidized and the oxygen content increased accordingly, while its specific surface area and pore volume only decreased a little. Ozone was mainly catalytically decomposed by the gold nanoparticles supported on the activated carbon.

关键词: ozone decomposition     activated carbon     gold nanoparticles     catalysis     sodium citrate     microwave    

Ecotoxicological effect of zinc oxide nanoparticles on soil microorganisms

Zhaoyi SHEN,Zhuo CHEN,Zhen HOU,Tingting LI,Xiaoxia LU

《环境科学与工程前沿(英文)》 2015年 第9卷 第5期   页码 912-918 doi: 10.1007/s11783-015-0789-7

摘要: The widespread production and use of zinc oxide nanoparticles (ZnO-NPs) in recent years have posed potential threat to the ecosystem. This study aimed to investigate the ecotoxicological effect of ZnO-NPs on soil microorganisms using laboratory microcosm test. Respiration, ammonification, dehydrogenase (DH) activity, and fluorescent diacetate hydrolase (FDAH) activity were used as ecotoxicological parameters. The results showed that in the neutral soil treated with 1 mg ZnO-NPs per g soil (fresh, neutral), ammonification was significantly inhibited during the study period of three months, but the inhibition rate decreased over increasing time. Inhibition in respiration was observed in the first month of the test. In various ZnO-NPs treatments (1 mg, 5 mg, and 10 mg ZnO-NPs per g soil), DH activity and FDAH activity were inhibited during the study period of one month. For both enzyme activities, there were positive dose–response relationships between the concentration of ZnO-NPs and the inhibition rates, but the curves changed over time due to changes of ZnO-NPs toxicity. Soil type affected the toxicity of ZnO-NPs in soil. The toxicity was highest in the acid soil, followed by the neutral soil. The toxicity was relatively low in the alkaline soil. The toxicity was not accounted for by the Zn released from the ZnO-NPs. Direct interaction of ZnO-NPs with biologic targets might be one of the reasons. The adverse effect of ZnO-NPs on soil microorganisms in neutral and acid soils is worthy of attention.

关键词: zinc oxide nanoparticles (ZnO-NPs)     soil microorganisms     respiration     ammonification     dehydrogenase (DH) activity     fluorescent diacetate hydrolase (FDAH) activity    

标题 作者 时间 类型 操作

Morphological and mechanical characterization of a PMMA/CdS nanocomposite

Vishal MATHUR, Manasvi DIXIT, K.S. RATHORE, N. S. SAXENA, K.B. SHARMA

期刊论文

Phenolic rigid organic filler/isotactic polypropylene composites. III. Impact resistance property

Heming LIN, Dongming QI, Jian HAN, Zhiqi CAI, Minghua WU

期刊论文

Dispersion of a novel phenolic rigid organic filler in isotactic polypropylene matrix by solution-mixing

Dongming QI, Xiaoli ZHAO, Zhijie CHEN, Peng HUANG, Jun CAO

期刊论文

Influence of the filler materials on flux-free brazing of pure aluminium (1050)

Kirsten BOBZIN, Lidong ZHAO, Thomas SCHLAEFER, Thomas WARDA,

期刊论文

Phenolic rigid organic filler/isotactic polypropylene composites. I. Preparation

QI Dongming, YANG Lei, WU Minghua, LIN Heming, NITTA Kohhei

期刊论文

Phenolic rigid organic filler/isotactic polypropylene composites. II. Tensile properties

QI Dongming, SHAO Jianzhong, WU Minghua, NITTA Kohhei

期刊论文

Translocation and biotoxicity of metal (oxide) nanoparticles in the wetland-plant system

期刊论文

Enhanced 4-chlorophenol biodegradation by integrating FeO nanoparticles into an anaerobic reactor: Long-term

期刊论文

Gold nanoparticles/single-stranded DNA-reduced graphene oxide nanocomposites based electrochemical biosensor

期刊论文

polymeric substances from activated sludge on the aggregation kinetics of silver and silver sulfide nanoparticles

期刊论文

Size and shape effects of MnFeO nanoparticles as catalysts for reductive degradation of dye pollutants

期刊论文

Functional magnetic nanoparticles for facile viable but nonculturable bacteria separation and purification

Chunming Wang, Huirong Lin, Chengsong Ye

期刊论文

Size-controlled green synthesis of silver nanoparticles assisted by L-cysteine

Wenchao Zhang,Lin Zhang,Yan Sun

期刊论文

Catalytic decomposition of low level ozone with gold nanoparticles supported on activated carbon

Pengyi ZHANG , Bo ZHANG , Rui SHI ,

期刊论文

Ecotoxicological effect of zinc oxide nanoparticles on soil microorganisms

Zhaoyi SHEN,Zhuo CHEN,Zhen HOU,Tingting LI,Xiaoxia LU

期刊论文