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Article
Publication date: 8 November 2011

Galal Nawwar, Sayed Yakout, M.S.A El‐Sadiek and Salwa El‐Sabbagh

The purpose of this paper is to study the effect of new heterocyclic compounds on styrene butadiene rubber (SBR) mixes.

450

Abstract

Purpose

The purpose of this paper is to study the effect of new heterocyclic compounds on styrene butadiene rubber (SBR) mixes.

Design/methodology/approach

It has been found that the starting material 1 could react with cyromazine (2) and/or 4‐aminoantipyriene (4) as amino compounds in the presence of triethylorthoformate and in the boiling dioxane to yield triazine‐3 and/or pyrazolo 5 derivatives, respectively. The chemical structures of the new products 3 and 5 have been established by their elemental analyses spectroscopic data IR, Ms and 1H, 13C NMR. These two compounds were evaluated as antioxidants in SBR, and this evaluation was confirmed by physico‐mechanical properties of vulcanizates, IR spectra and scanning electron microscope.

Findings

The difference between maximum torque MH and minimum torque ML (ΔM), tensile strength, modulus and elongation at break increases in the presence of prepared antioxidants while the equilibrium swelling decreased. The rubber vulcanizates were subjected to thermal oxidative aging at 90°C for up to seven days. It has been found that new compounds 3 and 5 can protect SBR vulcanizates against oxidative deterioration.

Research limitations/implications

The solubility of the prepared compounds 3 and 5 is very poor and they are only soluble in dimethyl formamide (DMF) or dimethyl sulphoxide (DMSO) which have high boiling points. Also, new compounds 3 and 5 have melting points (above 300°C).

Practical implications

Triazine and antipyrine derivatives have many medical and industrial applications.

Originality/value

The new synthesized compounds revealed excellent antioxidant behaviour in comparison with the commercial antioxidant phenyl‐β‐naphthyl amine (PβN) which is used in industry.

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Article
Publication date: 10 July 2007

E.M.A. Yakout and S.H. El‐Sabbagh

Evaluation of uracil and/or benzothiazol derivatives as antioxidants in natural rubber mixes.

597

Abstract

Purpose

Evaluation of uracil and/or benzothiazol derivatives as antioxidants in natural rubber mixes.

Design/methodology/approach

Cyanoacetylurea 1, as a precursor, was prepared at a good yield from widely available, low‐cost chemicals. Compound 1 was treated with triethylorthoformate and amine derivatives in one pot reaction affording the target uracil derivative 3. Replacement of the cyano group in 1 by benzothiazol led to obtaining the interesting N‐hydroxy uracils containing benzothiazole moiety 5 at a good yield. Some of the compounds prepared was selected and were evaluated as antioxidants in natural rubber mixes. The rheometric characteristic of the compounded rubber and the physico‐mechanical properties of the vulcanizates were determined.

Findings

The cure rate index, tensile strength and modulus increased while the equilibrium swelling decreased, i.e. compound 5 behaved as a secondary accelerator. The rubber vulcanizates were subjected to thermal oxidative ageing at 90°C for up to seven days. It has been found that uracil and/or benzothiazol derivatives can protect natural rubber vulcanizates against oxidative deterioration.

Research limitations/implications

The compounds prepareds were difficult to dissolve, they needed solvents with high boiling points, e.g. DMF, DMSO to be dissolved and even then they are not completely dissolved.

Practical implications

Uracil and or benzothiazol derivatives have many industrial applications.

Originality/value

The new compounds were prepared from very cheap and widely available chemicals. The compounds synthesised showed good antioxidant behaviour in comparison with the commercial antioxidant (phenyl‐β‐naphthyl amine) industrially used.

Details

Pigment & Resin Technology, vol. 36 no. 4
Type: Research Article
ISSN: 0369-9420

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Article
Publication date: 1 April 1997

M.A. Abd El‐Ghaffar, E.M. Yakout and E.A.M. Youssef

Highly coloured, thermally stable metal free, copper, cobalt and nickel of the hexadecachloro‐ and hexadecabromo‐phthalocyanine were synthesized by the urea fusion technique in…

587

Abstract

Highly coloured, thermally stable metal free, copper, cobalt and nickel of the hexadecachloro‐ and hexadecabromo‐phthalocyanine were synthesized by the urea fusion technique in the dry method. The structure of these compounds was confirmed via spectrophotometric measurements such as ultraviolet‐visible, nuclear magnetic resonance and infrared spectra. Evaluates the pigmentary properties of these compounds according to standard international methods. From the results reveals that these compounds have outstanding properties which allow them to be excellent pigments for various applications.

Details

Pigment & Resin Technology, vol. 26 no. 2
Type: Research Article
ISSN: 0369-9420

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Article
Publication date: 13 September 2021

Hoda Sabry Othman, Salwa H. El-Sabbagh and Galal A. Nawwar

In continuation to the previous work on copper (lignin/silica/fatty acids) (Cu-LSF) complex as a natural antioxidant/electrical conductivity agent for nitrile-butadiene rubber…

107

Abstract

Purpose

In continuation to the previous work on copper (lignin/silica/fatty acids) (Cu-LSF) complex as a natural antioxidant/electrical conductivity agent for nitrile-butadiene rubber (NBR), this study aims to perform further investigations for NBR vulcanizates loaded with different concentrations of Cu-LSF complex, including swelling behavior and hardness properties, as well as evaluating their thermal stability via thermogravimetric analysis.

Design/methodology/approach

The behavior of Cu-LSF complex in NBR matrix was compared with that of the standard commercial antioxidants (2,2,4-trimethyl-1,2-dihydroquinoline/N-isopropyl-N′-phenyl-p-phenylenediamine [TMQ/IPPD]).

Findings

Results revealed that Cu-LSF complex can act as an effective reinforcing and hardening agent, with exhibiting fluid resistance, even when compared with the commercial antioxidants. In comparison with the previous studies on its Zn and Ca analogues and their behavior in different rubber matrixes, Cu-LSF complex showed higher values of hardness and less susceptibility for swelling, respectively. Moreover, Cu-LSF antioxidant activity becomes in accordance with the previous work.

Originality/value

The new Cu-LSF complex could be used as a green alternative to the commercial antioxidants (TMQ/IPPD) with introducing further advantages to the rubber matrix, such as hardening, fluid resistance and thermal stability.

Details

Pigment & Resin Technology, vol. 51 no. 5
Type: Research Article
ISSN: 0369-9420

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Article
Publication date: 6 September 2019

Mostafa Yakout, M.A. Elbestawi, S.C. Veldhuis and S. Nangle-Smith

Residual stresses are induced during selective laser melting (SLM) because of rapid melting, solidification and build plate removal. This paper aims to examine the thermal cycle…

1233

Abstract

Purpose

Residual stresses are induced during selective laser melting (SLM) because of rapid melting, solidification and build plate removal. This paper aims to examine the thermal cycle, residual stresses and part distortions for selected aerospace materials (i.e. Ti-6Al-4V, stainless steel 316L and Invar 36) using a thermo-mechanical finite element model. The numerical results are validated and compared to experimental data.

Design/methodology/approach

The model predicts the residual stress and part distortion after build plate removal. The residual stress field is validated using X-ray diffraction method and the part distortion is validated using dimensional measurements.

Findings

The trends found in the numerical results agree with those found experimentally. Invar 36 had the lowest tensile residual stresses because of its lowest coefficient of thermal expansion. The residual stresses of stainless steel 316L were lower than those of Ti-6Al-4V because of its high thermal diffusivity.

Research limitations/implications

The model predicts residual stresses at the optimal SLM process parameters. However, using any other process conditions could cause void formation and/or alloying element vaporization, which would require the inclusion of melt pool physics in the model.

Originality/value

The paper explains the influence of the coefficient of thermal expansion and thermal diffusivity on the induced thermal stresses using experimental and numerical results. The methodology can be used to predict the part distortions and residual stresses in complex designs of any of the three materials under optimal SLM process parameters.

Details

Rapid Prototyping Journal, vol. 26 no. 1
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 5 April 2021

Hoda Sabry Othman, Maher A. El-Hashash, S.H. El-Sabbagh, A.A. Ward and Galal A.M. Nawwar

Calcium and Zinc lignates were proven to be good antioxidants for rubber composites. The purpose of this paper is to evaluate the copper lignate antioxidant activity along with…

193

Abstract

Purpose

Calcium and Zinc lignates were proven to be good antioxidants for rubber composites. The purpose of this paper is to evaluate the copper lignate antioxidant activity along with evaluating its electrical conductivity in rubber composites.

Design/methodology/approach

The antioxidant activity of the Cu-LSF complex was compared with that of standard commercial antioxidant additives as a green alternative. The rheological characteristics, thermal aging and mechanical and electrical properties were evaluated for the NBR vulcanizates containing the different antioxidants in the presence or absence of coupling agents.

Findings

Results revealed that the Cu-LSF complex (5 phr) can function as a compatibilizing, antioxidant and electrical conductivity agent.

Originality/value

The new copper complex prepared from paper-pulping black liquor of wastes could be used as a green antioxidant and electrical conductivity agent in rubber composites.

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Article
Publication date: 28 February 2023

O.A. Elhefnawy and A.A. Elabd

The purpose of this study is to prepare a new adsorbent activated carbon immobilized on polystyrene (ACPS) for uranium (VI) and thorium (IV) removal from an aqueous solution…

129

Abstract

Purpose

The purpose of this study is to prepare a new adsorbent activated carbon immobilized on polystyrene (ACPS) for uranium (VI) and thorium (IV) removal from an aqueous solution. Activated carbon (AC) was derived from biochar material by chemical activation to increase the active sites on its surface and enhance the adsorption capacity. Activated carbon (AC) was immobilized on polystyrene (PS) to improve the physical properties and facilitate separation from the working solution. A feasibility study for the adsorption of uranium (VI) and thorium (IV) on the new adsorbent (ACPS) has been achieved. Adsorption kinetics, isotherms, and thermodynamics models of the adsorption process were used to describe the reaction mechanism.

Design/methodology/approach

Activated carbon was synthesized from biochar charcoal by 2 M H2SO4. Activated carbon was immobilized on the pretreatment polystyrene by hydrothermal process forming new adsorbent (ACPS). Characterization studies were carried out by scanning electron microscope, energy-dispersive X-ray spectrometer, infrared spectroscopy and X-ray diffraction techniques. Different factors affect the adsorption process as pH, contact time, solid/liquid ratio, initial concentration and temperature. The adsorption mechanism was explained according to kinetic, isothermal and thermodynamic studies. Also, the regeneration of spent ACPS was studied.

Findings

The experimental results showed that pH and equilibrium time of the best adsorption were 6.0 and 60 min for U(VI), 4.0 and 90 min for Th(IV), (pHPZC = 3.4). The experimental results fit well with pseudo-second order, Freundlich and Dubinin–Radushkevich models proving the chemisorption and heterogenous adsorption reaction. Adsorption thermodynamics demonstrated that the adsorption process is exothermic and has random nature of the solid/liquid interface. In addition, the regeneration of spent ACPS research showed that the adsorbent has good chemical stability. According to the comparative study, ACPS shows higher adsorption capacities of U(VI) and Th(IV) than other previous bio-adsorbents.

Originality/value

This study was conducted to improve the chemical and physical properties of bio-charcoal purchased from the local market to activated carbon by hydrothermal method. Activated carbon was immobilized on polystyrene forming new adsorbent ACPS for eliminating U(VI) and Th(IV) from aqueous solutions.

Details

Pigment & Resin Technology, vol. 53 no. 5
Type: Research Article
ISSN: 0369-9420

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Article
Publication date: 2 February 2023

Mahyar Khorasani, Ian Gibson, Amir Hossein Ghasemi, Elahe Hadavi and Bernard Rolfe

The purpose of this study is, to compare laser-based additive manufacturing and subtractive methods. Laser-based manufacturing is a widely used, noncontact, advanced manufacturing…

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Abstract

Purpose

The purpose of this study is, to compare laser-based additive manufacturing and subtractive methods. Laser-based manufacturing is a widely used, noncontact, advanced manufacturing technique, which can be applied to a very wide range of materials, with particular emphasis on metals. In this paper, the governing principles of both laser-based subtractive of metals (LB-SM) and laser-based powder bed fusion (LB-PBF) of metallic materials are discussed and evaluated in terms of performance and capabilities. Using the principles of both laser-based methods, some new potential hybrid additive manufacturing options are discussed.

Design methodology approach

Production characteristics, such as surface quality, dimensional accuracy, material range, mechanical properties and applications, are reviewed and discussed. The process parameters for both LB-PBF and LB-SM were identified, and different factors that caused defects in both processes are explored. Advantages, disadvantages and limitations are explained and analyzed to shed light on the process selection for both additive and subtractive processes.

Findings

The performance of subtractive and additive processes is highly related to the material properties, such as diffusivity, reflectivity, thermal conductivity as well as laser parameters. LB-PBF has more influential factors affecting the quality of produced parts and is a more complex process. Both LB-SM and LB-PBF are flexible manufacturing methods that can be applied to a wide range of materials; however, they both suffer from low energy efficiency and production rate. These may be useful when producing highly innovative parts detailed, hollow products, such as medical implants.

Originality value

This paper reviews the literature for both LB-PBF and LB-SM; nevertheless, the main contributions of this paper are twofold. To the best of the authors’ knowledge, this paper is one of the first to discuss the effect of the production process (both additive and subtractive) on the quality of the produced components. Also, some options for the hybrid capability of both LB-PBF and LB-SM are suggested to produce complex components with the desired macro- and microscale features.

Details

Rapid Prototyping Journal, vol. 29 no. 5
Type: Research Article
ISSN: 1355-2546

Keywords

Available. Open Access. Open Access
Article
Publication date: 15 February 2022

Martin Nečaský, Petr Škoda, David Bernhauer, Jakub Klímek and Tomáš Skopal

Semantic retrieval and discovery of datasets published as open data remains a challenging task. The datasets inherently originate in the globally distributed web jungle, lacking…

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Abstract

Purpose

Semantic retrieval and discovery of datasets published as open data remains a challenging task. The datasets inherently originate in the globally distributed web jungle, lacking the luxury of centralized database administration, database schemes, shared attributes, vocabulary, structure and semantics. The existing dataset catalogs provide basic search functionality relying on keyword search in brief, incomplete or misleading textual metadata attached to the datasets. The search results are thus often insufficient. However, there exist many ways of improving the dataset discovery by employing content-based retrieval, machine learning tools, third-party (external) knowledge bases, countless feature extraction methods and description models and so forth.

Design/methodology/approach

In this paper, the authors propose a modular framework for rapid experimentation with methods for similarity-based dataset discovery. The framework consists of an extensible catalog of components prepared to form custom pipelines for dataset representation and discovery.

Findings

The study proposes several proof-of-concept pipelines including experimental evaluation, which showcase the usage of the framework.

Originality/value

To the best of authors’ knowledge, there is no similar formal framework for experimentation with various similarity methods in the context of dataset discovery. The framework has the ambition to establish a platform for reproducible and comparable research in the area of dataset discovery. The prototype implementation of the framework is available on GitHub.

Details

Data Technologies and Applications, vol. 56 no. 4
Type: Research Article
ISSN: 2514-9288

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Article
Publication date: 2 May 2023

Chang Zhang, Jiyin Tian and Dan Guo

Fix-position preloading, centrifugal force and higher temperatures cause the bearing units in angular contact ball bearings to expand, changing the contact load and affecting…

133

Abstract

Purpose

Fix-position preloading, centrifugal force and higher temperatures cause the bearing units in angular contact ball bearings to expand, changing the contact load and affecting bearing life. This study aims to examine the effect of thermal and centrifugal expansion on the fatigue life of fix-position preloaded angular contact ball bearings in high-speed operating conditions.

Design/methodology/approach

The contact loads on the inner and outer bearing rings were resolved according to the thermal and centrifugal expansion factors in the quasi-static position preloading model. The pressure and frictional stress distribution were used to calculate the subsurface stress in the contact area, while the Zaretsky model was used to determine the relative fatigue life of the inner and outer bearing rings.

Findings

Under fix-position bearing preloading, thermal and centrifugal expansion significantly affected the contact load and relative fatigue life. At the same axial preload, the inner ring contact load was higher than the outer ring contact load, with a maximum difference of 132.3%. The decrease in the inner ring relative life exceeded the outer ring contact load, with a maximum difference of 7.5%, compared to the absence of thermal and centrifugal expansion.

Originality/value

This study revealed the influence of thermal and centrifugal expansion on the fatigue life of angular contact ball bearings in high-speed service conditions.

Peer review

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-03-2023-0065/

Details

Industrial Lubrication and Tribology, vol. 75 no. 4
Type: Research Article
ISSN: 0036-8792

Keywords

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