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## Caracterização e utilização do resíduo da borracha de pneus inservíveis em compósitos aplicáveis na construção civil; Caracterization and utilization of the waste rubber from scrap tires in composites to use in the civil construction

Rodrigues, Mara Regina Pagliuso
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Relevância na Pesquisa
36.36%

## Influence of the surface treatment of tire rubber residues added in mortars

Marques, A. C.; Akasaki, J. L.; Trigo, A. P. M.; Marques, M. L.
Fonte: IBRACON - Instituto Brasileiro do Concreto Publicador: IBRACON - Instituto Brasileiro do Concreto
Tipo: Artigo de Revista Científica Formato: 113-120
ENG
Relevância na Pesquisa
36.54%
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); In this work it was evaluated the influence tire rubber addition in mortars in order to replace part of the sand (12% by volume). It was also intended to verify if the tire rubber treatment with NaOH saturated aqueous solution causes interference on the mechanical properties of the mixture. Compressive strength, splitting tensile strength, water absorption, modulus of elasticity, and flow test were made in specimens of 5cmx10cm and the tests were carried out to 7, 28, 56, 90, and 180 days. The results show reduction on mechanical properties values after addition of tire rubber and decrease of the workability. It was also observed that the tire rubber treatment does not cause any alteration on the results compared to the rubber without treatment.; Neste trabalho foi avaliada a influência da adição de borracha de pneus em argamassas substituindo parte da areia (12% em volume). O trabalho também tem como objetivo verificar se o tratamento da superfície da borracha com solução aquosa saturada de NaOH, causa interferência nas propriedades mecânicas das misturas. Foram feitos ensaios de trabalhabilidade...

## Aplicação do método dos elementos de contorno à elasticidade não-linear; Boundary element method applied to nonlinear elasticity

Borges, Ricardo Vendrame
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Relevância na Pesquisa
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A presente dissertação concentra-se no estudo da elasticidade não-linear através do Método dos Elementos de Contorno. A elasticidade não-linear possui um importante campo de aplicações, da simulação de materiais que se comportam como a borracha a novas aplicações como a simulação de tecidos biológicos. A dissertação apresenta como resultado principal a elaboração de um código computacional em Matlab ®, o qual é capaz de modelar materiais elásticos, não-lineares, sujeitos à deformações não-lineares, incrementais. O programa de elementos de contorno foi utilizado na simulação da resposta quasi-estática em materiais incompressíveis como a borracha, aproximados através do modelo constitutivo de Mooney-Rivlin.; The present work focuses on the modelling of non-linear elastic problems via the Boundary Element Method. Non-linear elasticity has several important applications, from the modelling of rubber-like materials to new areas of research such as the study of biological tissues. The work´s main result is the construction of a computer code (in Matlab ®) which can model non-linear elastic materials subjected to incremental non-linear deformations. The code was used within the realm of quasi-static simulations of incompressible rubber-like materials...

## NHL 3.5 mortars with scrap tire rubber

Faria, Paulina; Piteira, Rui
Fonte: European Mortar Organization (EMO) Publicador: European Mortar Organization (EMO)
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
36.51%
The use of wastes and industrial by-products as building materials is an important issue in order to decrease costs with waste management and the embodied energy of building products. Scrap tire rubber has been studied as aggregate for cementitious materials. Natural hydraulic limes are natural binders with particular characteristics of both air and hydraulic binders. Their specifications became stricter with the last version of EN 459-1:2010. In this study scrap tire rubber was used as additional aggregate of mortars, based on NHL3.5 and natural sand. Different particle size fractions and proportions of scrap tire rubber were used: a mix obtained almost directly from industry (only after sieving for preparation of particle sizes similar to mortar aggregate) and separated fine, medium and coarse fractions; 0%, 18%, 36% and 54% weight of binder, corresponding to 2.5%, 5% and 7.5% weight of sand. The influence of the rubbers´ additions on the mortars´ fresh state, mechanical and physical performance is presented, namely by flow table consistency, water retention, fresh bulk density, dynamic elasticity modulus, flexural and compressive strength, open porosity and bulk density, capillary absorption, drying and thermal conductivity. The use of the rubber mix coming from the waste tire industry seems advantageous and may open possibilities for use as raw material by the mortars industry.

## Investigations on cementitious composites based on rubber particle waste additions

Nacif,Glaucio Laun; Panzera,Túlio Hallak; Strecker,Kurt; Christoforo,André Luis; Paine,Kevin
Fonte: ABM, ABC, ABPol Publicador: ABM, ABC, ABPol
Tipo: Artigo de Revista Científica Formato: text/html
Relevância na Pesquisa
36.8%
The amount of waste rubber has gradually increased over recent years because of over-growing use of rubber products. The disposal of waste rubber has caused serious environmental problems. The incorporation of recycled materials into cementitious composites is a feasible alternative that has gained ground in civil construction. The performance of such materials is much affected not only by the rubber addition, but also the particle size which has been controversially reported in the literature. In order to investigate the single effect of rubber particles into cement based materials, rubber cementitious composites were prepared with no silica particle additions. A full factorial design has been conducted to assess the influence of the rubber particle size (0.84/0.58 mm and 0.28/0.18 mm); mass fraction used (5, 15 and 30%); and water/cement ratio (0.35 and 0.50) on the physic-mechanical properties of the composites. The materials were characterized through apparent density, porosity, compressive strength, flexural strength, modulus of elasticity and microstructural analysis. The interactions of rubber particle size, rubber fraction and water/cement ratio affected significantly the density and compressive strength of the composites. The apparent porosity was influenced mainly by the rubber particle size. The flexural strength was affected by the main factors and the modulus of elasticity was affected by the interaction factors rubber particle size and fraction...

## The influence of handling on the elasticity of addition silicone putties

Rodrigues Filho,Leonardo Eloy; Muench,Antonio; Francci,Carlos; Luebke,Angelika Katia; Traina,Andréia Aparecida
Tipo: Artigo de Revista Científica Formato: text/html
Relevância na Pesquisa
36.62%
The handling of vinyl polysiloxane (addition silicone) impression putties with latex gloves is said to interfere with the setting of these impression materials. The aim of this study is to evaluate the effect of handling techniques on the setting of vinyl polysiloxane impression putties using several types of gloves. The setting of these materials was evaluated by means of an elasticimeter. Four vinyl polysiloxane putty impression materials and five brands of gloves (one made of vinyl, one of synthetic rubber, and three of natural rubber) were studied. Based on the type of glove, they were previously washed or not, and a spatula was used or not for initial mixing (before handmixing). The vinyl, the synthetic and one of the natural rubber gloves did not require the previous washing procedure and/or the use of a spatula for initial mixing. Two other natural rubber gloves - depending on the silicone -, showed satisfactory results only when the initial mixing was performed with a spatula. It was concluded that setting inhibition depends on the kind of vinyl polysiloxane impression material and the kind of gloves used, but when the initial mixing was performed with the spatula this setting inhibition was overcome. The results of this study also showed that it is possible to associate cross-contamination control and satisfactory performance of addition silicone putty materials. When doubts arise from the compatibility between vinyl polysiloxane impression putties and gloves...

## Influence of the surface treatment of tire rubber residues added in mortars

Marques,A. C.; Akasaki,J. L.; Trigo,A. P. M.; Marques,M. L.
Fonte: IBRACON - Instituto Brasileiro do Concreto Publicador: IBRACON - Instituto Brasileiro do Concreto
Tipo: Artigo de Revista Científica Formato: text/html
Relevância na Pesquisa
36.54%
In this work it was evaluated the influence tire rubber addition in mortars in order to replace part of the sand (12% by volume). It was also intended to verify if the tire rubber treatment with NaOH saturated aqueous solution causes interference on the mechanical properties of the mixture. Compressive strength, splitting tensile strength, water absorption, modulus of elasticity, and flow test were made in specimens of 5cmx10cm and the tests were carried out to 7, 28, 56, 90, and 180 days. The results show reduction on mechanical properties values after addition of tire rubber and decrease of the workability. It was also observed that the tire rubber treatment does not cause any alteration on the results compared to the rubber without treatment.

## Rubber-like elasticity and volume changes in the isolated spasmoneme of giant Zoothamnium sp. under Ca2+-induced contraction.

Moriyama, Y; Okamoto, H; Asai, H
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
36.44%
Using glycerinated spasmoneme of giant Zoothamnium sp., the physical properties of spasmoneme before and after Ca2+-induced contraction (pCa 4.5) were investigated. The volume change of spasmoneme contraction was measured under zero tension. The length and diameter decreased by about 50% of their initial value as a result of contraction, which means that contraction is nearly isotropic. Thus the volume of spasmoneme decreased drastically by 86% of its original value. The swollen ratio of extended and contracted spasmoneme were 0.07 and 0.37, respectively. Tension-extension relationships of extended and contracted spasmonemes were measured. By applying the theory of rubber elasticity, the number of segments of a chain in originally extended spasmoneme was only 3.3, i.e., the chain was almost a straight one. On the other hand, the number of segments of a chain in contracted spasmoneme was more than 100, i.e., the chain was essentially a random one. Furthermore, the total number of chains in single spasmoneme was the same in extended and contracted spasmoneme. This means that the interchain cross-links of chains were not influenced by addition or removal of Ca2+. Moreover, the molecular weight of a chain is estimated to be at most about 50 kd. By considering all these results...

## An experimental and analytical study of the elasticity of model polyurethane networks crosslinked by tri- and quadriisocyanate

FAYOLLE, Bruno; GILORMINI, Pierre; DIANI, Julie
EN
Relevância na Pesquisa
56.54%
The original publication is available at www.springerlink.com : http://link.springer.com/article/10.1007%2Fs00396-009-2145-6?LI=true; Polyurethane networks have been prepared from a mix of tri- and quadriisocyanate and from two types of diols, polyether-based (with molar masses of 1,000, 2,000, and 4,000 g/mol) and polyester-based (1,035 g/mol). The weight fraction of sol has been measured, as well as the elastic shear modulus of the gels. It has been found that the statistical theory of network formation predicts a weight fraction of sol in agreement with the experimental results, but its standard combination with the theory of rubber elasticity disagrees significantly with the elastic modulus measured. This suggests a discrepancy between theory and experiment in terms of elastically active chains. In contrast, the assumption that all nodes in the gel, or even in the system, are elastically active gives much better predictions for the system considered.; ANR JCJC MELAC

## Symmetries and Elasticity of Nematic Gels

Tipo: Artigo de Revista Científica
Relevância na Pesquisa
36.33%
A nematic liquid-crystal gel is a macroscopically homogeneous elastic medium with the rotational symmetry of a nematic liquid crystal. In this paper, we develop a general approach to the study of these gels that incorporates all underlying symmetries. After reviewing traditional elasticity and clarifying the role of broken rotational symmetries in both the reference space of points in the undistorted medium and the target space into which these points are mapped, we explore the unusual properties of nematic gels from a number of perspectives. We show how symmetries of nematic gels formed via spontaneous symmetry breaking from an isotropic gel enforce soft elastic response characterized by the vanishing of a shear modulus and the vanishing of stress up to a critical value of strain along certain directions. We also study the phase transition from isotropic to nematic gels. In addition to being fully consistent with approaches to nematic gels based on rubber elasticity, our description has the important advantages of being independent of a microscopic model, of emphasizing and clarifying the role of broken symmetries in determining elastic response, and of permitting easy incorporation of spatial variations, thermal fluctuations, and gel heterogeneity...

## To grow or to shrink: A tale of two rubber balloons

Levin, Yan; da Silveira, Fernando L.
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
36.36%
Two identical rubber balloons are partially inflated with air (to different extent) and connected by a hose with a valve. It is found that depending on balloon volumes, when the valve is opened the air will flow either from the larger (fuller) balloon to the smaller (emptier) balloon, or from the smaller balloon to the larger one. The phenomenon is explained in terms of the non-ideal rubber elasticity of balloons. The full phase diagram for the air flow dynamics is constructed.

## Topological Interaction between Loop Structures in Polymer Networks and the Nonlinear Rubber Elasticity

Hirayama, Naomi; Tsurusaki, Kyoichi
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
46.44%
We numerically examine the nonlinear rubber elasticity of topologically constrained polymer networks. We propose a simple and effective model based on Graessley and Pearson's topological model (GP model) for describing the topological effect. The main point is to take account of a nonequilibrium effect in the synthesis process of the polymer network. We introduce a new parameter $\gamma$ to describe entropic contributions from the entanglement of polymer loops, which may be determined from the structural characteristics of the sample. The model is evaluated in the light of experimental data under uniaxial and biaxial deformations. As a result, our model exhibits uniaxial behaviors which are common to many elastomers in various deformation regimes such as Mooney-Rivlin's relation in small extension, stress divergence in the elongation limit and the declined stress in compression. Furthermore, it is also qualitatively consistent with biaxial experiments, which can be explained by few theoretical models.; Comment: 7 pages

## A Hybrid Model of Rubber Elasticity in Simple Extension

Tipo: Artigo de Revista Científica
Relevância na Pesquisa
36.44%
A thermodynamically related model is developed for describing elastic rubber-like behavior of amorphous and crystallizing polymers and demonstrated on example of simple extension. Both the “entropic” and “energetic” motions of polymer chains that contribute in macroscopic elastic deformation are taken into account. The model displays a continuous transition from entropy to energetic elasticity, without common singularity caused by finite extensibility of polymer chains. A multi-scale molecular approach, based on recent literature concepts has been employed for evaluations of continuum parameters. For crystallizing polymers, a simple model is developed for the stress-induced crystallization, which describes the stress reinforcement caused by the formation of long, needle-like polymer crystals.; Comment: 21 pages, 4 figures

## Non-entropic theory of rubber elasticity: flexible chains grafted on a rigid surface

Drozdov, A. D.
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
46.44%
The elastic response is studied of a single flexible chain grafted on a rigid plane and an ensemble of non-interacting tethered chains. It is demonstrated that the entropic theory of rubber elasticity leads to conclusions that disagree with experimental data. A modification of the conventional approach is proposed, where the end-to-end distribution function (treated as the governing parameter) is replaced by the average energy of a chain. It is revealed that this refinement ensures an adequate description of the mechanical behavior of flexible chains. Results of numerical simulation are compared with observations on uniaxial compression of a layer of grafted chains, and an acceptable agreement is shown between the model predictions and the experimental data. Based on the analysis of combined compression and shear, a novel micro-mechanism is proposed for the reduction of friction of polymer melts at rigid walls.; Comment: 16 pages, 2 figures

## From Vulcanization to Isotropic and Nematic Rubber Elasticity

Xing, Xiangjun; Mukhopadhyay, Swagatam; Goldbart, Paul M.; Zippelius, Annette
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
46.6%
A Landau theory is constructed for the vulcanization transition in cross-linked polymer systems with spontaneous nematic ordering. The neo-classical theory of the elasticity of nematic elastomers is derived via the minimization of this Landau free energy; this neo-classical theory contains the classical theory of rubber elasticity as its isotropic limit. Our work not only reveals the statistical-mechanical roots of these elasticity theories, but also demonstrates that they are applicable to a wide class of random solids. It also constitutes a starting-point for the investigation of sample-to-sample fluctuations in various forms of vulcanized matter.; Comment: 7 pages, 1 eps figure, submited to Europhys. Lett

## Influence of Chain Structure and Swelling on the Elasticity of Rubbery Materials: Localization Model Description

Douglas, Jack F.
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
36.5%
Classical network elasticity theories are based on the concept of flexible volumeless polymers fixed into a network in which there are no excluded volume, or even topological interactions, and where the chains explore accessible configurations by Brownian motion. In this type of model, the elasticity of the network derives from the entropic changes arising from a displacement of the network junction positions. The shortcoming of this approach is clear from the observation that unswollen rubbery materials are nearly incompressible, reflecting the existence of strong intermolecular interactions that restrict the polymer chains to an exploration of their local tube-like molecular environments. The imposition of a deformation of these solid rubbery materials then necessitates a consideration of how the local molecular packing constraints become modified under deformation and the impact of these changes on the macroscopic elasticity of the material as a whole. Many researchers have struggled with this difficult problem, in the present paper we focus on the simple localization model of rubber elasticity of Gaylord and Douglas, which provides a simple minimal model for the network elasticity of rubbers having strong intermolecular interactions in the dense polymer state. Particular emphasis is given in the implications of this model in describing how network elasticity changes with swelling by a solvent...

## Random parking, Euclidean functionals, and rubber elasticity

Gloria, Antoine; Penrose, Mathew D.
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
46.55%
We study subadditive functions of the random parking model previously analyzed by the second author. In particular, we consider local functions $S$ of subsets of $\mathbb{R}^d$ and of point sets that are (almost) subadditive in their first variable. Denoting by $\xi$ the random parking measure in $\mathbb{R}^d$, and by $\xi^R$ the random parking measure in the cube $Q_R=(-R,R)^d$, we show, under some natural assumptions on $S$, that there exists a constant $\bar{S}\in \mathbb{R}$ such that % $$\lim_{R\to +\infty} \frac{S(Q_R,\xi)}{|Q_R|}\,=\,\lim_{R\to +\infty}\frac{S(Q_R,\xi^R)}{|Q_R|}\,=\,\bar{S}$$ % almost surely. If $\zeta \mapsto S(Q_R,\zeta)$ is the counting measure of $\zeta$ in $Q_R$, then we retrieve the result by the second author on the existence of the jamming limit. The present work generalizes this result to a wide class of (almost) subadditive functions. In particular, classical Euclidean optimization problems as well as the discrete model for rubber previously studied by Alicandro, Cicalese, and the first author enter this class of functions. In the case of rubber elasticity, this yields an approximation result for the continuous energy density associated with the discrete model at the thermodynamic limit, as well as a generalization to stochastic networks generated on bounded sets.; Comment: 28 pages

## Biaxial Deformations of Rubber: Entanglements or Elastic Fluctuations?

Xing, Xiangjun
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
36.44%
The classical theory of rubber elasticity fails in the regime of large deformation. The un- derlying physical mechanism has been under debate for long time. In this work, we test the recently proposed mechanism of thermal elastic fluctuations by Xing, Goldbart and Radzi- hovsky1 against the biaxial stress-strain data of three distinct polymer networks with very different network structures, synthesized by Urayama2 and Kawabata3 respectively. We find that both the two parameters version and the one-parameter version of the XGR theory provide satisfactory description of the elasticity in whole deformation range. For comparison, we also fit the same sets of data using the slip-link model by Edwards and Vilgis with four parameters. The fitting qualities of two theories are found to be comparable.; Comment: 19 pages, 15 eps figures

## Thermal Fluctuations and Rubber Elasticity

Xing, Xiangjun; Goldbart, Paul M.; Radzihovsky, Leo
Tipo: Artigo de Revista Científica