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Article
Publication date: 16 March 2012

Xugang Zhang, Bin Zhang, Mingming Sun, Jianhui Li, Lei Wang and Chuanli Qin

The purpose of this paper is to obtain liquid acrylate oligomers containing carboxyl groups as excellent toughening agents for epoxy resins.

Abstract

Purpose

The purpose of this paper is to obtain liquid acrylate oligomers containing carboxyl groups as excellent toughening agents for epoxy resins.

Design/methodology/approach

Liquid acrylate oligomers containing carboxyl groups were synthesised by the solution polymerisation of butyl acrylate (BA), acrylic acid (AA) and acrylonitrile (AN) as monomers. The liquid acrylate oligomers were used as the toughening agents for epoxy resins. The chemical structure of the oligomers was characterised by 13C nuclear magnetic resonance (NMR) spectroscope. The morphology of modified epoxy networks was analysed by scanning electron microscope (SEM). The mechanical and thermodynamic properties were measured by universal testing machine and dynamic mechanical analyser (DMA).

Findings

The results show that AA and oligomer concentrations have great influence on the morphology, mechanical and thermodynamic properties of the modified epoxy networks. When the 10 wt percent oligomer containing BA and AN and AA in the ratio of 75/20/5 is used to modify the epoxy resin, the increase in impact strength of the modified epoxy network is 291.5 percent over the unmodified epoxy network due to addition of the oligomers without a sacrifice in heat‐resistance properties. Fracture surface analysis by SEM indicates the presence of a two‐phase microstructure.

Practical implications

The modified epoxy networks can be used as high performance materials such as adhesives, sealants and matrices of composites.

Originality/value

The liquid acrylate oligomers containing carboxyl and nitrile groups which were synthesised with BA, AA and AN as monomers by the solution polymerisation are novel and can greatly increase the toughness of epoxy resins without loss of thermal resistance.

Details

Pigment & Resin Technology, vol. 41 no. 2
Type: Research Article
ISSN: 0369-9420

Keywords

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Article
Publication date: 1 January 2014

Xugang Zhang, Bin Zhang, Mingming Sun, Jianhui Li, Lei Wang and Chuanli Qin

– In order to obtain functionalized core-shell nanoparticles (CSNPs) as excellent toughening agents for epoxy resins. The paper aims to discuss these issues.

Abstract

Purpose

In order to obtain functionalized core-shell nanoparticles (CSNPs) as excellent toughening agents for epoxy resins. The paper aims to discuss these issues.

Design/methodology/approach

Functionalized CSNPs containing epoxy groups on the surface were synthesized by emulsion polymerization with butyl acrylate as the core and methyl methacrylate copolymerizing with glycidyl methacrylate (GMA) as the shell. CSNPs were used as toughening agents for epoxy resins and their chemical structure was characterized by FT-IR. The morphology of modified epoxy networks (MEPN) was analyzed by SEM and TEM. Both the mechanical properties and thermodynamic properties were studied.

Findings

The results show that nearly spherical CSNPs with the particle size of 50-100 nm are obtained. A certain amount of CSNPs are uniformly dispersed in epoxy resins by the grinding method and the MEPN shows the ductile fracture feature. The miscibility between CSNPs and epoxy matrix increases with the increase of GMA concentration which makes more bonds form between them. Epoxy resins toughened with 10 wt% CSNPs containing 10 wt% GMA show the best mechanical properties and the increase in tensile strength and impact strength of the MEPN is 13.5 and 59.7 percent, respectively, over the unmodified epoxy networks. And the improvement in impact strength is not accompanied with loss of thermal resistance.

Practical implications

The MEPN can be used as high-performance materials such as adhesives, sealants and matrixes of composites.

Originality/value

The functionalized CSNPs are novel and it can greatly increase the toughness of epoxy resins without loss of thermal resistance.

Details

Pigment & Resin Technology, vol. 43 no. 1
Type: Research Article
ISSN: 0369-9420

Keywords

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Article
Publication date: 22 February 2013

Ignacio G. Tejada and Rafael Jimenez

The purpose of this paper is to show that there are some underlying principles of granular media that can be derived from statistical mechanics and that could be useful…

Abstract

Purpose

The purpose of this paper is to show that there are some underlying principles of granular media that can be derived from statistical mechanics and that could be useful when considered in the context of computer simulations.

Design/methodology/approach

The fundamentals of statistical mechanics are presented and they are revised in order to set up a suitable approach for jammed static granular media. After a conceptual discussion about the entropy of granular matter, some specific statistical mechanics approaches that have been used for granular media are reviewed. Finally, a numerical simulation, conducted using an open source molecular dynamics code, is included as an illustrative example.

Findings

It is shown qualitatively how statistical mechanics can be used to analytically compute the expected statistical distribution of some quantities in numerical simulations.

Research limitations/implications

The computation of entropy from histograms and the establishment of the constraints of the ensembles in simulations are still open issues.

Practical implications

Considering the entropy could set up new computational techniques. Initial arrangements could be analyzed in terms of their probability of occurrence and of their “distance” to the most probable state.

Originality/value

The paper includes the distribution of the mean force‐moment tensor component of a fast cyclic quasi isotropic compression process of a simple granular media. Results show how the system tends to an equilibrium state.

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Article
Publication date: 1 August 1952

J.A.C. Williams

AIRCRAFT performance is dependent upon a number of independent variables such as air density. Any variation in one of these variables, if not allowed for in performance…

Abstract

AIRCRAFT performance is dependent upon a number of independent variables such as air density. Any variation in one of these variables, if not allowed for in performance correction, causes discrepancies in corrected performance figures.

Details

Aircraft Engineering and Aerospace Technology, vol. 24 no. 8
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 12 June 2009

S. Ghasemloo and M. Mani

The purpose of this paper is to present a non‐equilibrium viscous shock layer (VSL) solution procedure that considerably improves computational efficiency, especially for…

Abstract

Purpose

The purpose of this paper is to present a non‐equilibrium viscous shock layer (VSL) solution procedure that considerably improves computational efficiency, especially for long slender bodies.

Design/methodology/approach

The VSL equations are solved in a shock oriented coordinate system. The method of solution is spatial marching, implicit, finite‐difference technique, which includes coupling of the normal momentum and continuity equations. In the nose region, the shock shape is specified from an algebraic expression and corrected through global passes through that region. The shock shape is computed as part of the solution beyond the nose region and requires only a single global pass. For this study, a seven‐species (O2, N2, O, N, NO, NO+, e) air model is used.

Findings

The present approach eliminates the need for initial shock shape, which was required by previous method of solution. This method generates its own shock shape as a part of solution and the input shock shape obtained from a different solution is not required. Therefore, in comparison with the other VSL methods, the present approach dramatically reduces the CPU time of calculations. Moreover, by using the shock oriented coordinate systems the junction point problem in sphere‐cone configurations is solved.

Practical implications

This method is an excellent tool for parametric study and preliminary design of hypersonic vehicles.

Originality/value

The present method provides a computational capability which reduces the CPU time, and expands the range of application for the prediction of hypersonic heating rates.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 19 no. 5
Type: Research Article
ISSN: 0961-5539

Keywords

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Article
Publication date: 1 September 2005

Ghislain Tchuen, Yves Burtschell and David E. Zeitoun

To compute the Navier‐Stokes equations of a non‐equilibrium weakly ionized air flow. This can help to have a better description of the flow‐field and the wall heat…

Abstract

Purpose

To compute the Navier‐Stokes equations of a non‐equilibrium weakly ionized air flow. This can help to have a better description of the flow‐field and the wall heat transfer in hypersonic conditions.

Design/methodology/approach

The numerical approach is based on a multi block finite volume method and using a Riemann's solver based on a MUSCL‐TVD algorithm. In the flux splitting procedure the modified speed of sound, due to the electronic mode, is implemented.

Findings

A good description of the shock standoff distance, of the wall heat fluxes and of the peak of electron density number in the shock layer.

Research limitations/implications

The radiative effects are not included in this paper. For the very high Mach numbers, this can modify the shock layer parameters.

Practical implications

The knowledge of the wall heat transfer in the re‐entry body problems.

Originality/value

The building of a robust numerical code in order to well describe hypersonic air flow in high Mach numbers.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 15 no. 6
Type: Research Article
ISSN: 0961-5539

Keywords

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Article
Publication date: 1 June 2005

J.L. Lin and C.S. Yang

This work experimentally and numerically investigates the aerodynamic heating of the charring‐ablating materials.

Abstract

Purpose

This work experimentally and numerically investigates the aerodynamic heating of the charring‐ablating materials.

Design/methodology/approach

The experimental model is a stainless steel cone with an attached charring ablator, in which supersonic hot flow impinges. The initial numerical simulation is based on physical and mathematical models, including one‐dimensional, unsteady energy transport and mass conservation equations, coupled with calculations of aerodynamic heating, thermal degradation, heat transfer of the ablating surface and the ablation model. The problem is solved by an efficient numerical method.

Findings

The numerical calculations involve the time history of the temperature distribution inside the charring material and the backup structure. The results are consistent with the experimental data.

Originality/value

This study proposes an effective method to correlate one's own ablation rate equation, by a method of trial and error to find the correlation constants, and the corresponding time histories of the ablation rate or temperature that are closest to one's own experimental data. Then the correlation of the surface ablation rate can be applied with confidence in the numerical calculation of other cases.

Details

Aircraft Engineering and Aerospace Technology, vol. 77 no. 3
Type: Research Article
ISSN: 0002-2667

Keywords

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Article
Publication date: 1 May 1988

David J. Huddart

The Chemical Information System (CIS) is a system of approximately 30 databanks available as a dial‐up online source of interactively available information for chemical…

Abstract

The Chemical Information System (CIS) is a system of approximately 30 databanks available as a dial‐up online source of interactively available information for chemical compounds and their properties. The system was formerly known as the NIH/EPA Chemical Information System on account of its inception and development by two US Government agencies — The National Institutes of Health and Environmental Protection Agency. It is in particular the involvement by the EPA that explains the emphasis of the system on environmental information and the importance of the CIS as a source of data in this area. The databanks are by and large numeric and text databanks containing actual values and observations (quantitative and qualitative results), in contrast to bibliographic databases which, in general, contain only references to the sources of information. The data is compiled by many different producers and ranges widely in terms of applications. The information available can be broadly categorised as:

Details

Aslib Proceedings, vol. 40 no. 5
Type: Research Article
ISSN: 0001-253X

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Article
Publication date: 26 August 2014

B.P. Markhali, R. Naderi, M. Sayebani and M. Mahdavian

The purpose of this paper is investigate the inhibition efficiency of three similar bi-cyclic organic compounds, namely, benzimidazole (BI), benzotriazole (BTAH) and…

Abstract

Purpose

The purpose of this paper is investigate the inhibition efficiency of three similar bi-cyclic organic compounds, namely, benzimidazole (BI), benzotriazole (BTAH) and benzothiazole (BTH) on carbon steel in 1 M hydrochloric acid (HCl) solution. Organic inhibitors are widely used to protect metals in acidic media. Among abundant suggestions for acid corrosion inhibitors, azole compounds have gained attention.

Design/methodology/approach

The inhibition efficiency of the three organic compounds was investigated using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS).

Findings

Superiorities of BTH and BTAH corrosion inhibitors were shown by EIS data and polarization curves. Moreover, the results revealed that BTAH and BTH can function as effective mixed-type adsorptive inhibitors, whereas no inhibition behavior was observed for BI. Both BTAH and BTH obeyed Longmuir adsorption isotherm. The results obtained from this isotherm showed that both inhibitors adsorbed on the specimen surface physically and chemically. The difference in inhibition efficiencies of BTAH, BTH and BI was related to the presence of nitrogen and sulfur hetero atoms on their molecular structures.

Originality/value

This study evaluated inhibition efficiency of BI, BTAH and BTH using electrochemical methods. In addition, the study attempted to find inhibition mechanism of the inhibitors and to find modes of adsorption of the inhibitors, correlating effects of heteroatoms and inhibition efficiency.

Details

Anti-Corrosion Methods and Materials, vol. 61 no. 5
Type: Research Article
ISSN: 0003-5599

Keywords

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Article
Publication date: 1 November 1962

This is the third volume of the series directed specifically to the field of aeronautical sciences, but exclu‐ding propulsion and combustion. The present four papers arc…

Abstract

This is the third volume of the series directed specifically to the field of aeronautical sciences, but exclu‐ding propulsion and combustion. The present four papers arc concerned with advances in aerodynamics, the first of which ‘Some Aerodynamic Principles for the Design of Swept Wings’ is by J. A. Bagley of the Royal Aircraft Establishment, Farnborough, summarizing the aerodynamic principles and methods for designing wings of high efficiency at subsonic and, subsequently, supersonic speeds.

Details

Aircraft Engineering and Aerospace Technology, vol. 34 no. 11
Type: Research Article
ISSN: 0002-2667

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