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Viscoelastic Properties of Polymer-Based Bionanocomposites Reinforced with Inorganic Fillers
Published in Senthil Muthu Kumar Thiagamani, Md Enamul Hoque, Senthilkumar Krishnasamy, Chandrasekar Muthukumar, Suchart Siengchin, Vibration and Damping Behavior of Biocomposites, 2022
Polymer is a viscoelastic material, and its viscoelasticity is related to time, frequency, and temperature (Lakes, 2004). Viscoelasticity refers to a combination of “visco” behavior (associates with the spring-like behavior) and “elastic” behavior (associates with the flow-like behavior) of a material (Kulik and Boiko, 2018). Viscoelasticity is an essential feature that can be used to understand the phase transformation and molecular mobility of polymeric materials, and further, it can be used to develop and design functional devices (e.g., instrument mounts, vibration isolation, and shock absorber). The viscoelastic properties of polymeric materials can be illustrated using the Maxwell model and Kelvin-Voigt model (Delgado-Reyes et al., 2013; Chen et al., 2015). According to Yuya and Patel (2014), in a dynamic nano-indentation analysis, tan δ < 1 indicates a predominantly solid-like behavior, while tan δ > 1 indicates a predominantly viscous or fluid-like response.
Thermal Properties of Recycled Polymer Composites
Published in R.A. Ilyas, S.M. Sapuan, Emin Bayraktar, Recycling of Plastics, Metals, and Their Composites, 2021
Marwah Rayung, Min Min Aung, Hiroshi Uyama
In the case of recycled polymer composites, one of the most frequently used thermal characterization methods is TGA. For TGA, the main information from this analysis is the thermal stability and compositional analysis such as matrix and filler content. Another important analysis is DSC, which can be used to determine the heat capacity and various structural transition temperatures of polymeric materials. DMA is used for measuring the viscoelasticity of the materials, glass transition and modulus values. The following section will discuss the thermal behavior of different types of recycled polymer composite systems. To date, most of the reported thermal analysis for recycled polymer composites is based on TGA and DSC methods of characterization, and some studies report on DMA analysis.
Theoretical Aspects of Dynamic Mechanical Analysis
Published in Jose James, K.P. Pramoda, Sabu Thomas, Polymers and Multicomponent Polymeric Systems, 2019
DMA is used to study viscoelasticity, where oscillatory forces (stresses) are applied to a material and the resulting displacement (strain) is measured [1]. The response for all temperature and frequency combinations can then be used to determine the dynamic modulus of the material for a wide range of frequencies and temperatures using the principle of time–temperature superposition (TTS) [2]. This range of frequencies and temperatures can exceed the testable range if the material is thermorheologically simple, meaning regardless of the initial stress, the stress relaxation times share the same dependence on changes in temperature [3].
Impact of fractional strain on medium containing spherical cavity in the framework of generalized thermoviscoelastic diffusion
Published in Journal of Thermal Stresses, 2023
Geetanjali Geetanjali, Pawan Kumar Sharma
The study of viscoelasticity is spurred in different areas of science due to its immense applications in the field of engineering, polymer industry, medical diagnostic tools, and even in NASA space programs. Due to their rheological property, viscoelastic materials have become the best alternatives for neoteric multifunctional materials. Frudenthal [11] discovered that at elevated temperature, majority of solids exhibit viscous effects when exposed to mechanical loadings. Thus while studying thermoelastic interactions of the medium, its viscous effects cannot be neglected. Various models have evolved to study deformation process in viscoelastic materials, among which Kelvin–Voigt [12] model is generally adopted. This model explicates the delayed elastic response due to stress when deformation is time-dependent. Ilioushin and Pobedria [13] formulated the mathematical theory of thermoviscoelasticity and solved some boundary value problems in this regard. Ezzat and Elkaramany [14] proved the uniqueness and reciprocity theorems of the generalized thermoviscoelasticity. Sherief et al. [15] formulated generalization of thermoviscoelasticity and solved half-space problem in this regard. Deswal and Kalkal [16] studied responses of thermoviscoelastic half-space with two temperature TPL model of generalized thermoelasticity.
Investigating the free vibration of viscoelastic FGM Timoshenko nanobeams resting on viscoelastic foundations with the shear correction factor using finite element method
Published in Mechanics Based Design of Structures and Machines, 2022
Ghali Drici, Ismail Mechab, Hichem Abbad, Noureddine Elmeiche, Belaid Mechab
Viscoelasticity is generally defined as the property possessed by materials which exhibit both viscous and elastic characteristics when undergoing deformation. It should be noted that viscous materials resist shear flow and exhibit deformation that increases linearly with time when stress is applied to them (creep and relaxation). In addition, elastic materials deform when subjected to stresses, but quickly return to their original state once those stresses are removed. Moreover, in rheology a viscoelastic material presents an intermediate linear behavior between that of an ideal elastic solid that can be symbolized by a spring having a particular stiffness and that of a Newtonian viscous liquid that can be symbolized by a viscous damping coefficient. It is worth recalling that the viscosity of a material reflects its ability to dissipate energy. Different models can be used to describe the linear viscoelasticity of a material. One may mention Maxwell’s model which is well suited to viscoelastic liquids. The Kelvin–Voigt model is an elementary model that applies to viscoelastic solids. In addition, the models of Zener and Burgers, which fit the two previous cases equally well, are also worth mentioning (Maxwell 1867; Chen and Chen 2014; Chaillat and Bui 2007; Zou et al. 2021) .
Two-dimensional problem for thermoviscoelastic materials with fractional order heat transfer
Published in Journal of Thermal Stresses, 2019
Mohamed H. Hendy, Magdy M. Amin, Magdy A. Ezzat
Viscoelasticity is the property of materials that exhibit both viscous and elastic characteristics when undergoing deformation. Viscous materials, like honey, resist shear flow and strain linearly with time when a stress is applied. Elastic materials strain when stretched and quickly return to their original state once the stress is removed. Viscoelastic materials have elements of both of these properties and, as such, exhibit time-dependent strain. Whereas elasticity is usually the result of bond stretching along crystallographic planes in an ordered solid, viscosity is the result of the diffusion of atoms or molecules inside an amorphous material [1]. Linear viscoelastic materials are rheological materials that exhibit time temperature rate-of-loading dependence. When their response is not only a function of the current input, but also of the current and past input history, the characterization of the viscoelastic response can be expressed using the convolution (hereditary) integral. The mechanical-model representation of linear viscoelastic behavior results was investigated by Gross [2]. One can refer to Atkinson and Craster [3] for a review of fracture mechanics and generalizations to the viscoelastic materials. A general review of time-dependent material properties has been exhibited in Refs. [4–7].