Search results for "Elastic"
showing 10 items of 2162 documents
Creep and recovery experimental investigation of low oil content food emulsions
2008
Abstract Creep and recovery tests have been performed to study the viscoelastic behavior of low oil content food emulsions. Formulations of salad dressings usually include modified starch (MS) due to its low cost and the special creamy texture if affords. The combination of starch with other natural gums may improve the quality of the product. A reference emulsion containing 4% MS, and four other formulations in which the starch was partially replaced by xanthan gum (XG), locust bean gum (LBG) and two synergistic blends of these gums were formulated. Gels prior to emulsification were studied for comparative purposes. The viscoelastic behavior of all the systems was characterized by means of…
Disorder Classification of the Vibrational Spectra of Modern Glasses
2021
Using the coherent-potential approximation in heterogeneous-elasticity theory with a log-normal distribution of elastic constants for the description of the Raman spectrum and the temperature dependence of the specifi?c heat, we are able to reconstruct the vibrational density of states and characteristic descriptors of the elastic heterogeneity of a wide range of glassy materials. These descriptors are the non-affi?ne contribution to the shear modulus, the mean-square fluctuation of the local elasticity, and its correlation length. They enable a physical classification scheme for disorder in modern, industrially relevant glass materials. We apply our procedure to a broad range of real-world…
Nematic elastomers: From a microscopic model to macroscopic elasticity theory
2008
A Landau theory is constructed for the gelation transition in cross-linked polymer systems possessing spontaneous nematic ordering, based on symmetry principles and the concept of an order parameter for the amorphous solid state. This theory is substantiated with help of a simple microscopic model of cross-linked dimers. Minimization of the Landau free energy in the presence of nematic order yields the neoclassical theory of the elasticity of nematic elastomers and, in the isotropic limit, the classical theory of isotropic elasticity. These phenomenological theories of elasticity are thereby derived from a microscopic model, and it is furthermore demonstrated that they are universal mean-fi…
QENS investigation of filled rubbers
2002
The polymer segmental dynamics is investigated in a series of silica-filled rubbers. The presence of inert fillers in polymers greatly affects the mechanical and physical performance of the final materials. For example, silica has been proposed as a reinforcing agent of elastomers in tire production. Results from quasielastic neutron scattering and Dynamic Mechanical Thermal Analysis (DMTA) measurements are presented on styrene–ran-butadiene rubber filled with silica. A clear indication is obtained of the existence of a bimodal dynamics, which can be rationalized in terms of the relaxation of bulk rubber and the much slower relaxation of the rubber adsorbed on the filler surface.
A Quantitative Analysis of the Thermoelastic Effect in CFRP Composite Materials
2010
: In this study the thermoelastic signal from carbon fibre-reinforced plastic (CFRP) laminates is investigated. A comparison between the theoretical and experimental values of the thermoelastic signal is reported, with the theoretical predictions obtained from two different quantitative models. These models are based on the classic thermoelastic effect law extended to the case of orthotropic materials (by using the mesomechanical or bulk approach), and the modified law assuming that the surface resin-rich layer behaves as a strain witness of the laminate. It is found that the theoretical predictions of the two models can be strongly and differently influenced by the intrinsic orthotropy of…
Elastic Properties of Liquid Crystal Elastomer Balloons
2001
We introduce a method to measure elastic properties of smectic liquid crystalline elastomers. Freely suspended smectic polymer films containing photoreactive groups are inflated to spherical bubbles and crosslinked by UV light irradiation. After crosslinking, the balloon volume is varied and elastic properties of the material are determined from the relation between radius and inner excess pressure. The influence of the network topology on the elastic behaviour is discussed.
Estimation of the elastic constants of highly porous cellular plastics reinforced with fibres embedded in foam struts
2015
In order to enhance the mechanical properties of polymer foams, fillers of different materials and sizes are being applied. Fibrous fillers shorter than the characteristic foam cell dimensions have the potential of efficient reinforcement, due to their high aspect ratio, without detrimentally interfering with foam structure. A theoretical model is developed for evaluation of the effect of filler on foam stiffness. The elastic response of rigid polymer foams filled with short fibres, of length commensurable with that of foam struts, is modelled by using the orientational averaging technique. Explicit expressions for components of the stiffness tensor of composite foams are derived in terms …
Disentangling the Role of Chain Conformation on the Mechanics of Polymer Tethered Particle Materials
2019
[Image: see text] The linear elastic properties of isotropic materials of polymer tethered nanoparticles (NPs) are evaluated using noncontact Brillouin light spectroscopy. While the mechanical properties of dense brush materials follow predicted trends with NP composition, a surprising increase in elastic moduli is observed in the case of sparsely grafted particle systems at approximately equal NP filling ratio. Complementary molecular dynamics simulations reveal that the stiffening is caused by the coil-like conformations of the grafted chains, which lead to stronger polymer–polymer interactions compared to densely grafted NPs with short chains. Our results point to novel opportunities to …
Modeling and stress-strain characteristics of the mechanical properties of carbon-nanotube-reinforced poly(vinyl acetate) nanocomposites
2011
Polymer/carbon nanotube (CNT) composites are one of the most perspective advanced materials developed in recent years. The properties of CNT-reinforced polymer composites, however, strongly depend on structural aspects of the nanostructured filler and on its dispersion quality in a polymer matrix. Consequently, this research was devoted to the investigation of multiwalled-CNT-modified poly(vinyl acetate) (PVAc) composites with respect to the mechanical property dependence on some structural characteristics of CNTs. PVAc/CNT nanocomposites were obtained with a solution casting technique. The amount of CNTs was changed from 0.01 up to 2 wt %. The stress–strain characteristics of PVAc/CNT nano…
Compatibilization of polyethylene/polyamide 6 blend nanocomposite films
2015
Polymer blends of incompatible components need to undergo compatibilization, in order to give rise to a blend with good physical properties. At the same way, polymer/clay nanocomposites show this problem because of different chemical nature of the polymer matrix and of the clay. Compatibilization is therefore more necessary if an incompatible polymer blend is filled with an organomodified clay in order to give a final material with good properties. In this work, a polyethylene/polyamide 6 blend filled with an organomodified clay has been compatibilized with a maleic anhydride grafted SEBS (styrene-ethylene-butylene-styrene) copolymer and a glicidylmethacrylate-ethylene copolymer. The result…