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Article
Publication date: 22 May 2009

A.K. Khan, B.C. Ray, J. Maiti and S.K. Dolui

The purpose of this paper is to study the effect of monomer composition in core‐shell latex prepared from co‐polymer of styrene‐butylacrylate (BA)‐methyl methacrylate…

Abstract

Purpose

The purpose of this paper is to study the effect of monomer composition in core‐shell latex prepared from co‐polymer of styrene‐butylacrylate (BA)‐methyl methacrylate (MMA) and their paint properties.

Design/methodology/approach

The core‐shell latex was prepared by a stepwise semi‐batch emulsion polymerisation. A set of dispersion was made with the different core‐shell compositions. The core phase consists of a copolymer of styrene‐BA‐acrylic acid (AA) and the shell phase consists of a copolymer of MMA‐AA. The properties of latex were determined by solid content, viscosity, pH and particle size. Subsequently, emulsion paint (PVC‐37 per cent and NVM‐53 per cent) was prepared using core‐shell latex. The paint properties were determined by block resistance, gloss, elongation at break, etc. The particle morphology was characterised with transmission electron microscope (TEM).

Findings

Core‐shell structure of latex was confirmed by TEM. The performance of core‐shell latex has been optimised and the best combination achieved with 25‐40 per cent of hard phase in core‐shell latex.

Research limitations/implications

Although the core‐shell structured latex was prepared from co‐polymer of styrene‐BA‐MMA monomer, the system could be extended with other monomers depending on the end use of surface coating.

Practical implications

The paint industry may use this method to improve paint properties.

Originality/value

The paper shows that, by use of core‐shell latex, it is possible to achieve high‐block resistance, hardness, elasticity and gloss.

Details

Pigment & Resin Technology, vol. 38 no. 3
Type: Research Article
ISSN: 0369-9420

Keywords

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Article
Publication date: 2 November 2012

Q. Song, P. Yan, H. Wang, X. Zhu and Y. Xu

The purpose of this paper is to prepare a kind of novel multi‐layer core‐shell latex, and to evaluate the effect of the preparation methodology.

Abstract

Purpose

The purpose of this paper is to prepare a kind of novel multi‐layer core‐shell latex, and to evaluate the effect of the preparation methodology.

Design/methodology/approach

Core‐shell poly(siloxane)/polystyrene/polymethyl methacrylate (PSi/PSt/PMMA) latex particles were prepared by seeded‐emulsion polymerisation with three stages. The core of cured PSi was prepared with octamethyl cyclotetrasiloxane (D4) and tetraethoxysilane (TEOS) by co‐condensation. Using vinyltriethoxysilane (VTEOS) as coupling agent, functional PSi particles with vinyl groups on surfaces were prepared by hydrolysis and condensation of VTEOS in core formation stage. Then, the functional PSi particles were used as seeds to copolymerise with styrene and methyl methacrylate sequentially in shell stage I and stage II to form PSi/PSt/PMMA latex particles.

Findings

FTIR, TEM, DSC and XPS showed that the PSi/PSt/PMMA latex particles had multi‐layer core‐shell structure with cured PSi as core, PSt as shell I and PMMA as shell II.

Research limitations/implications

In the present work, PSi/PSt/PMMA latex particles having multi‐layer core‐shell structure with cured PSi as core, PSt as shell I and PMMA as shell II were prepared. This methodology can be employed to prepare new functional materials for various applications.

Practical implications

Multi‐layer core‐shell particles offer a new area of material science that has wide applications in coatings or modified polymer materials production.

Originality/value

The method developed in the study reported in this paper provides a new strategy to develop new types of core‐shell materials with multi‐layer structure.

Details

Pigment & Resin Technology, vol. 41 no. 6
Type: Research Article
ISSN: 0369-9420

Keywords

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Article
Publication date: 1 May 2003

Neri Volpato and Thomas H.C. Childs

Selective laser sintering can be used to manufacture injection mould inserts using an indirect metal laser sintering process, such as the RapidTool™ process commercialised…

Abstract

Selective laser sintering can be used to manufacture injection mould inserts using an indirect metal laser sintering process, such as the RapidTool™ process commercialised by 3D Systems. The volume of material to be laser processed for insert manufacturing is very high when compared to that for plastic prototype manufacturing. Consequently, the time involved in the laser processing is also very long. This paper describes the development and assessment of shelling strategies to be applied in an indirect rapid tooling process aimed at reducing time in the process. The feasibility of the shelling idea has been confirmed and although the scanning system offers some limitations to the idea two strategies are presented as successful, open shell and closed shell, with a great potential to save time.

Details

Rapid Prototyping Journal, vol. 9 no. 2
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 4 November 2013

Alan Elliott Richardson and Thomas Fuller

The purpose of this paper is to examine the use of a waste marine sea shell product incorporated into a concrete mix as an aggregate replacement. Utilising shells reduces…

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Abstract

Purpose

The purpose of this paper is to examine the use of a waste marine sea shell product incorporated into a concrete mix as an aggregate replacement. Utilising shells reduces the storage of shell waste, also reducing the need for quarried aggregate and has potential benefits of adding a different material to a design mix concrete mix design for improved performance.

Design/methodology/approach

The test methods used to evaluate the concrete were, British Standard tests for compressive strength (BS EN 12390-3:2002) and porosity (BS EN 12390-8:2009). A paired comparison test was carried out examining two different partial replacement shell aggregate mixes against a plain concrete control sample.

Findings

The results showed a reduction in compressive strength when 50 per cent of sea shells were used as an aggregate replacement, for both sand and gravel, compared to the control sample. Crushed and graded sea shells used in concrete displayed a lower porosity/permeability than plain concrete.

Originality/value

Whilst there is existing work relating to the compressive strength of concrete using sea shells, the porosity of concrete using sea shells has not been widely addressed and the paper investigates this aspect of sustainable concrete research.

Details

Structural Survey, vol. 31 no. 5
Type: Research Article
ISSN: 0263-080X

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Article
Publication date: 1 March 1999

W.L. Yao and Ming C. Leu

This paper presents a numerical and experimental investigation of ceramic shell cracking during the burnout process in investment casting with internally webbed laser…

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1341

Abstract

This paper presents a numerical and experimental investigation of ceramic shell cracking during the burnout process in investment casting with internally webbed laser stereolithography patterns. Considered are the cracking temperature of the ceramic shell, the buckling temperature of the web link, and the glass transition temperature of the epoxy resin. Our hypothesis is that shell cracking will occur if the ceramic rupture temperature is lower than the temperature of glass transition and the temperature of web buckling. This hypothesis is validated by a good agreement we obtained between experimental observations and numerical simulations. It is found that the shell cracking and web link buckling are strongly related to the cross‐sectional dimensions and span length of the web structure and the shell thickness, and that shell cracking can be prevented by buckling of the epoxy webbed pattern in early stages of the burnout process.

Details

Rapid Prototyping Journal, vol. 5 no. 1
Type: Research Article
ISSN: 1355-2546

Keywords

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Article
Publication date: 1 April 1993

E. HINTON, S.M.B. AFONSO and N.V.R. RAO

The optimization of variable thickness plates and shells is studied. In particular, three types of shell are considered: hyperbolic paraboloid, conoid and cylindrical shell

Abstract

The optimization of variable thickness plates and shells is studied. In particular, three types of shell are considered: hyperbolic paraboloid, conoid and cylindrical shell. The main objective is to investigate the optimal thickness distributions as the geometric form of the structure changes from a plate to a deep shell. The optimal thickness distribution is found by use of a structural optimization algorithm which integrates the Coons patch technique for thickness definition, structural analysis using 9‐node Huang‐Hinton shell elements, sensitivity evaluation using the global finite difference method and the sequential quadratic programming method. The composition of the strain energy is monitored during the optimization process to obtain insight into the energy distribution for the optimum structures. Several benchmark examples are considered illustrating optimal thickness variations under different loading, boundary and design variable linking conditions.

Details

Engineering Computations, vol. 10 no. 4
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 13 December 2021

Yongliang Wang and Jianhui Wang

This study presents a novel hp-version adaptive finite element method (FEM) to investigate the high-precision eigensolutions of the free vibration of moderately thick…

Abstract

Purpose

This study presents a novel hp-version adaptive finite element method (FEM) to investigate the high-precision eigensolutions of the free vibration of moderately thick circular cylindrical shells, involving the issues of variable geometrical factors, such as the thickness, circumferential wave number, radius and length.

Design/methodology/approach

An hp-version adaptive finite element (FE) algorithm is proposed for determining the eigensolutions of the free vibration of moderately thick circular cylindrical shells via error homogenisation and higher-order interpolation. This algorithm first develops the established h-version mesh refinement method for detecting the non-uniform distributed optimised meshes, where the error estimation and element subdivision approaches based on the superconvergent patch recovery displacement method are introduced to obtain high-precision solutions. The errors in the vibration mode solutions in the global space domain are homogenised and approximately the same. Subsequently, on the refined meshes, the algorithm uses higher-order shape functions for the interpolation of trial displacement functions to reduce the errors quickly, until the solution meets a pre-specified error tolerance condition. In this algorithm, the non-uniform mesh generation and higher-order interpolation of shape functions are suitable for addressing the problem of complex frequencies and modes caused by variable structural geometries.

Findings

Numerical results are presented for moderately thick circular cylindrical shells with different geometrical factors (circumferential wave number, thickness-to-radius ratio, thickness-to-length ratio) to demonstrate the effectiveness, accuracy and reliability of the proposed method. The hp-version refinement uses fewer optimised meshes than h-version mesh refinement, and only one-step interpolation of the higher-order shape function yields the eigensolutions satisfying the accuracy requirement.

Originality/value

The proposed combination of methodologies provides a complete hp-version adaptive FEM for analysing the free vibration of moderately thick circular cylindrical shells. This algorithm can be extended to general eigenproblems and geometric forms of structures to solve for the frequency and mode quickly and efficiently.

Details

Engineering Computations, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0264-4401

Keywords

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Book part
Publication date: 14 March 2017

Kenneth M. Moffett

Abstract

Details

Forming and Centering
Type: Book
ISBN: 978-1-78635-829-5

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Book part
Publication date: 14 March 2017

Kenneth M. Moffett

Abstract

Details

Forming and Centering
Type: Book
ISBN: 978-1-78635-829-5

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Book part
Publication date: 16 August 2010

Alexander J. Martín

Archaeological evidence from the prehistoric Spondylus industry of coastal Ecuador is analyzed here to clarify how craft production was structured and the role that it…

Abstract

Archaeological evidence from the prehistoric Spondylus industry of coastal Ecuador is analyzed here to clarify how craft production was structured and the role that it played in the rise of social complexity. Many models of social development propose that elite cooption of specialized craft production can be a useful avenue through which aspiring elites can gain differential status. Contrary to the expectations of these models, data from coastal Ecuador indicates that craft production of sumptuary goods was an activity primarily carried out by household units for the benefit of the domestic economy. Increased trafficking with northern Peruvian states at ca. 750 seems to have promoted local social stratification by attracting large numbers of households to the restricted locales where they could exploit these resources, which in turn prompted a strengthening of the kinds of political conditions that facilitate orderly interaction and minimize internal social conflict.

Details

Economic Action in Theory and Practice: Anthropological Investigations
Type: Book
ISBN: 978-0-85724-118-4

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