On the evolution law for the frozen fraction in linear theories of shape memory polymers

Kazakevičiūtė-Makovska, Rasa; Steeb, Holger

doi:10.1007/s00419-012-0615-7

Cited by 14 publications

(13 citation statements)

References 21 publications

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“…The next model was introduced by Kazakeviciute-Makovska et al [40]. They have analyzed different FVF functions (sans-serifϕ(ξ)) and suggested a modified general function based on a reduced, i.e., dimensionless temperature sans-serifξ, depicted by the following equation:sans-serifϕ(ξ)=11+exp[c0(sans-serifξ−(1−b0))].…”

Section: Methodsmentioning

confidence: 99%

Demonstrating the Influence of Physical Aging on the Functional Properties of Shape-Memory Polymers

et al. 2018

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Abstract:Polymers that allow the adjustment of Shape-Memory properties by the variation of physical parameters during programming are advantageous compared with their counterparts requiring synthesis of new material. Here, we explored the influence of hydrolytic (physical) aging on the Shape-Memory properties of the polyetherurethane system Estane, programmed in repeated thermomechanical cycles under torsional load. We were able to demonstrate that physical aging occurred through water adsorption influencing the existing free volume of the samples as well as the functional properties of Estane. Dynamic Mechanical Thermal Analysis determined the glass transition temperatures of dry and hydrolytically aged samples. According to our results, Estane takes up to 3 wt % water for two weeks (at an ambient temperature of θ = 20 • C). The glass transition temperatures of dry samples decreased within this period from 55 to 48 • C as a consequence of a plasticization effect. Next, for both samples, six subsequent thermomechanical cycles under torsional loading conditions were performed. We were able to confirm that hydrolytically aged samples showed higher shape recovery ratios of R r ≥ 97%, although dry samples revealed better shape fixity values of about 98%. Moreover, it was observed that the shape fixity ratio of both dry and hydrolytically (physically) aged samples remained almost unchanged even after six successive cycles. Besides this, the shape recovery ratio values of the aged samples were nearly unaltered, although the shape recovery values of the dry samples increased from R r = 81% in the first cycle to 96% at the end of six repeated cycles. Further, the evolution of the free volume as a function of temperature was studied using Positron Annihilation Lifetime Spectroscopy. It was shown that the uptake of two other organic solvents (acetone and ethanol) resulted in much higher specific free volume inside the samples and, consequently, a softening effect was observed. We anticipate that the presented approach will assist in defining design criteria for self-sufficiently moving scaffolds within a knowledge-based development process.

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Section: Methodsmentioning

confidence: 99%

Demonstrating the Influence of Physical Aging on the Functional Properties of Shape-Memory Polymers

et al. 2018

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“…In addition to this dominated thermoviscoelastic approach, in recent years, SMP modeling methods have even incorporated molecular dynamic simulation (Diani and Gall, 2007), quantum mechanics (Zhang et al, 2010), multi-scale modeling (Shojaei and Li, 2013), and statistical mechanics (Shojaei and Li, 2014), etc. Of all these methods, the phase evolution approach, first proposed by Liu et al (Liu et al, 2006) and further developed by other researchers (Baghani et al, 2012;Chen and Lagoudas, 2008a, b;Gilormini and Diani, 2012;Guo et al, 2015;Kafka, 2008;Kazakevic̆iūtė-Makovska et al, 2012;Kim et al, 2010;Long et al, 2010;Pieczyska et al, 2015;Qi et al, 2008;Reese et al, 2010;Scalet et al, 2015;Volk et al, 2011;Wang et al, 2009;Xu and Li, 2010) has become another widely used modeling approach due to its ease of application in design.…”

Section: Accepted Manuscriptmentioning

confidence: 99%

Temperature and rate dependent thermomechanical modeling of shape memory polymers with physics based phase evolution law

Yang

2016

International Journal of Plasticity

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“…1), the glass transition develops from a high temperature h θ , where (and above which) ( ) 0 φ θ = , to a low temperature l θ , where (and below which) ( ) 1 φ θ = . Discussion of various special forms of ( ) φ θ proposed in the literature has been presented in [31]. All LTE models generalizing the original formulation of Liu et al [18,19] are based on the temperature-dependent frozen volume fraction ( ) φ θ , which is used for evaluation the overall elastic behavior of two-phase SMPs defining their overall thermal expansion and describing the shape memory effect.…”

Section: Two-phase Lte Modelsmentioning

confidence: 99%

Universal relations in linear thermoelastic theories of thermally-responsive shape memory polymers

Kazakevičiūtė-Makovska

Heuchel

Kratz

et al. 2014

International Journal of Engineering Science

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In this paper we formulate an one-dimensional linear thermo-elastic (LTE) model in integral form for describing the behavior of thermally-responsive shape memory polymers (SMPs), which unifies and slightly generalizes numerous theories proposed in the literature starting with the seminal approach proposed by Liu et al. (2006). The presented model in its most general form requires the calibration of three response functions. Detailed analysis of four types of shape memory cycles (SMCs) used to quantify the shape memory effect in thermally-responsive SMPs and the corresponding forms of constitutive relations derived within LTE model display a number of critical properties. In particular, two of three response functions may be determined in many different ways from strain and stress storage/recovery profiles measured in SMCs (the third response function may be determined from an independent test). As implication of this fact, we show that the LTE model predicts a number of interrelations between the measured strain and stress storage/recovery profiles. All these relations are universal in the sense that for any shape memory polymer, which may be correctly described by LTE model, the strain/stress storage/recovery profiles measured in SMCs must satisfy (at least approximately) these relations. Their role within the LTE model is analogous to the role of universal relations in the theory of finite deformation elasticity. In particular, these universal relationships provide a theoretical basis for the validation of any model within the LTE class. The basic theoretical results derived in this paper are illustrated using data obtained by Liu et al. (2006)

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On the evolution law for the frozen fraction in linear theories of shape memory polymers

Cited by 14 publications

References 21 publications

Demonstrating the Influence of Physical Aging on the Functional Properties of Shape-Memory Polymers

Demonstrating the Influence of Physical Aging on the Functional Properties of Shape-Memory Polymers

Temperature and rate dependent thermomechanical modeling of shape memory polymers with physics based phase evolution law

Universal relations in linear thermoelastic theories of thermally-responsive shape memory polymers

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