Modeling the glass transition of amorphous networks for shape-memory behavior

Xiao, Rui; Choi, Jin‐Woo; Lakhera, Nishant; Yakacki, Christopher M.; Frick, Carl P.; Nguyen, Thao D.

doi:10.1016/j.jmps.2013.02.005

Cited by 112 publications

(118 citation statements)

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“…Therefore, a time-temperature superposition does apply at finite strain, at least in the temperature and strain rate ranges considered. Moreover, this superposition requires a mere shift factor to be applied to the strain rate, which is in favour of thermorheologically simple (TRS) models [5,17,18], where the material free energy is written in terms of strain history using a reduced time that depends on temperature history through the shift factor. Using the same definition as in Eq.…”

Section: Methodsmentioning

confidence: 99%

“…Therefore, the acrylate network shows the same time-temperature superposition property at infinitesimal strain as at finite strain. As a consequence, standard small-strain DMA tests may be enough to identify easily the time-temperature superposition that applies at finite strain, which was already used for shape memory modelling for instance [5,17] but without experimental evidences supporting it. Note that this conclusion was reached at moderate strain rates, further work would be necessary to investigate the case of high strain rate conditions, which has interested several authors [2][3][19][20].…”

Section: Methodsmentioning

confidence: 99%

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Direct experimental evidence of time-temperature superposition at finite strain for an amorphous polymer network

Diani

Pierre²,

Arrieta³

2015

Polymer

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experimental evidence of timetemperature superposition at finite strain for an amorphous polymer network. Polymer, Elsevier, 2015, 58, pp.107-112. hal-01102768 Science Arts & Métiers (SAM)is an open access repository that collects the work of Arts et Métiers ParisTech researchers and makes it freely available over the web where possible. AbstractThe time-temperature superposition property of an amorphous polymer acrylate network is characterized at infinitesimal strain by standard dynamic mechanical analysis tests. Comparison of the shift factors determined in uniaxial tension and in torsion shows that both tests provide equivalent time-temperature superposition properties. More interestingly, finite strain uniaxial tension tests run until break at constant strain rate show that the acrylate network exhibits the same time-temperature superposition property at finite strain as at infinitesimal strain. Such original experimental evidence provides new insight for finite strain constitutive modelling of polymer amorphous networks.Keywords: amorphous network; time-temperature superposition; finite strain IntroductionThe mechanical behaviour of amorphous polymers at finite strain is very sensitive to temperature and strain rate, especially in the glass transition temperature range, where a change of temperature affects greatly the molecular mobility. Various studies have reported experimental evidences supporting this fact ([1-7] among others), and several viscohyperelastic models with an account of temperature have been proposed for the representation of the mechanical behaviour of amorphous polymers at finite strain ([1,4-5,8-11] for instance). Despite interesting features, the models of the literature show difficulties to represent accurately the mechanical behaviour of amorphous polymers over a wide range of temperature and strain rate, let alone to predict it. In order to better model the time and temperature dependent behaviour of amorphous polymer networks, useful for shape memory applications for instance, it is proposed to explore the time-temperature superposition property at finite strain. Time-temperature superposition at infinitesimal strain in amorphous polymers is well known [12]. Such a property formulates the idea that time and temperature are dependent parameters. In other words, exposing the material to a high temperature and a short duration is the same as exposing it to a lower temperature over a longer span of time. When looking at the change of the stress-strain responses of amorphous polymers when the temperature or the strain rate varies, such a property seems also true at finite strain. Some authors showed that master curves could be built for finite strain behaviour quantities such as reduced yield stress [2][3]6] or stretch at break [13]. Nonetheless, finite strain time-temperature equivalence remains to be tested on the entire stress-strain response and its quantitative estimate to be compared to the time-

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Direct experimental evidence of time-temperature superposition at finite strain for an amorphous polymer network

Diani

Pierre²,

Arrieta³

2015

Polymer

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“…This technique provides also information about relaxation 2 Smart Materials Research processes in polymers, specifically, the glass transition and subglass processes [14][15][16]. This makes DMTA particularly useful for the characterization of SMPs and it becomes an indispensable experimental method in study of these smart materials.…”

Section: Introductionmentioning

confidence: 99%

Characterization of Shape Memory Polymer Estane by Means of Dynamic Mechanical Thermal Analysis Technique

Kazakevičiūtė-Makovska

Özarmut

Steeb

2014

Smart Materials Research

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Commercially available shape memory polymer (SMP) Estane (designation: ETE75DT3 NAT022) is investigated by means of dynamic mechanical thermal analysis (DMTA) technique in torsion mode using the Modular Compact Rheometer MCR-301 (Anton Paar GmbH). Amplitude sweep tests have been run below and above the glass transition temperature to establish the linear viscoelastic range (LVR) in glassy and rubbery phase of this SMP for the correct physical interpretation of DMTA data. Temperature sweep tests were performed at various frequencies to study the influence of this parameter on values of the storage and loss moduli and the storage and loss compliances as well as the viscosities. These tests have been carried out in heating mode with different rates and at different strain amplitudes. The short-and long-term behavior of SMP Estane have been studied by frequency sweep tests performed at different temperatures and data have been transformed into time-domain properties by applying time-temperature superposition principles. All these DMTA data provide the experimental basis for the study of relaxation processes, propertystructure relationships, and the shape memory effect in this little-known SMP.

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“…The model is also formulated within the finite deformation kinematics and is able to describe the SMP loading conditions, where the applied strain level may reach several tens of per cent. It is worthwhile to mention that most of the up to date viscoplatic models for polymers are designed for a specific type of polymer, such as amorphous or semicrystalline, and a large number of material parameters need to be found from curve fitting techniques [24,36]. One of the major contributions of the presented viscoplasticity theory is that the rateand temperature-dependent responses of a wide range of polymers can be simulated regardless of their morphology.…”

Section: Discussionmentioning

confidence: 99%

“…Thermomechanical modelling of SMPs has been extensively studied in the literature [4,5,[8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24]. Most recently Qi and co-workers [25] reported the influence of programming conditions on shape fixity and free shape recovery and developed a unified model for shape memory behaviours.…”

Section: Introductionmentioning

confidence: 99%

Thermomechanical constitutive modelling of shape memory polymer including continuum functional and mechanical damage effects

Shojaei

2014

Proc. R. Soc. A.

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A multi-mechanism-based phenomenological model is developed within the finite deformation kinematics framework for capturing the thermomechanical behaviour of shape memory polymers (SMPs) both during programming and in service. Particularly, the damage mechanisms in SMPs are studied within the continuum damage mechanics (CDMs) framework in which they are classified into mechanical or physical damage, induced during service condition, e.g. fatigue and functional damage induced during thermomechanical cycles, e.g. shape recovery loss. Statistical mechanics is incorporated to describe the initiation and saturation of these deformation mechanisms. The main advantage of the presented viscoplastic model, comparing to the existing counterparts, is its simplicity by minimizing the need for curve fitting, and capability in simulating the nonlinear stress-strain behaviour of amorphous, crystalline or semicrystalline SMPs. The developed viscoplastic CDM model takes into account several distinctive deformation mechanisms involved in the thermomechanical cycle of SMPs, including glass transition loss events, temperature-dependent material properties, stress relaxation, shape recovery transient events and damage effects. The established model correlates well with the experimental results and its computational capabilities provide material designers with a powerful design tool for future SMP applications.

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Modeling the glass transition of amorphous networks for shape-memory behavior

Cited by 112 publications

References 50 publications

Direct experimental evidence of time-temperature superposition at finite strain for an amorphous polymer network

Direct experimental evidence of time-temperature superposition at finite strain for an amorphous polymer network

Characterization of Shape Memory Polymer Estane by Means of Dynamic Mechanical Thermal Analysis Technique

Thermomechanical constitutive modelling of shape memory polymer including continuum functional and mechanical damage effects

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