Mechanics of soft active materials with phase evolution

Long, Kevin Nicholas; Dunn, Martin L.; Hu, Qi

doi:10.1016/j.ijplas.2009.10.005

Cited by 76 publications

(41 citation statements)

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“…In general, the polymer's shape memory (SM) effect is described and evaluated in a thermo-temporal SM cycle, where the SMP is firstly deformed at a high temperature (usually above the glass transition or melting point) and subsequently frozen upon cooling to fix the programmed temporary shape. When an environmental stimulus is applied, the SMP could either provide recovery stresses or return to their permanent shapes, depending on whether or not the external loads still exist, namely the constrained or free recovery condition [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] . Since SMPs can sense the environmental changes and then take reactions in a predetermined sequence with deformation, they are considered as a promising alternative for the future's spontaneous shape changing and tunable components in various applications such as microelectromechanical systems, surface patterning, biomedical devices, aerospace deployable structures and morphing structures [31][32][33][34][35][36][37][38][39] .…”

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confidence: 99%

Reduced time as a unified parameter determining fixity and free recovery of shape memory polymers

2014

Nat Commun

231

179

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Shape memory polymers are at the forefront of recent materials research. Although the basic concept has been known for decades, recent advances in the research of shape memory polymers demand a unified approach to predict the shape memory performance under different thermo-temporal conditions. Here we report such an approach to predict the shape fixity and free recovery of thermo-rheologically simple shape memory polymers. The results show that the influence of programming conditions to free recovery can be unified by a reduced programming time that uniquely determines shape fixity, which consequently uniquely determines the shape recovery with a reduced recovery time. Furthermore, using the time-temperature superposition principle, shape recoveries under different thermo-temporal conditions can be extracted from the shape recovery under the reduced recovery time. Finally, a shape memory performance map is constructed based on a few simple standard polymer rheology tests to characterize the shape memory performance of the polymer.

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confidence: 99%

Reduced time as a unified parameter determining fixity and free recovery of shape memory polymers

2014

Nat Commun

231

179

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“…At the continuum level, different constitutive models for the bulk material have also been developed. For example, photoinduced BERs [39][40][41][42] have been modeled as a phase evolution process where the chain addition-fragmentation process was considered as a phase transformation between stressed phases and newly-born phases [43]. Such a modeling scheme exhibits reasonable fidelity but is computationally expensive.…”

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confidence: 99%

Interfacial welding of dynamic covalent network polymers

Shi

et al. 2016

Journal of the Mechanics and Physics of Solids

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120

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Dynamic covalent network (or covalent adaptable network) polymers can rearrange their macromolecular chain network by bond exchange reactions (BERs) where an active unit can replace a unit in an existing bond to form a new bond. Such macromolecular events, when they occur in large amounts, can attribute to unusual properties that are not seen in conventional covalent network polymers, such as shape reforming and surface welding; the latter further enables the important attributes of material malleability and 2 powder-based reprocessing. In this paper, a multiscale modeling framework is developed to study surface welding of thermally induced dynamic covalent network polymers. At the macromolecular network level, a lattice model is developed to describe the chain density evolution across the interface and its connection to bulk stress relaxation due to BERs. The chain density evolution rule then feeds in to a continuum level interfacial model that takes into account surface roughness and applied pressure during welding to predict the effective elastic modulus and interfacial fracture energy of welded dynamic covalent network polymers. The model yields particularly accessible results where the moduli and interfacial strength of the welded samples as a function of temperature and pressure can be predicted with three parameters, two of which can be measured directly.The model identifies the dependency of surface welding efficiency on the applied thermal and mechanical fields: the pressure will affect the real contact area under the consideration of surface roughness of dynamic covalent network polymers; the chain density increment on the real contact area of interface is only dependent on the welding time and temperature. The modeling approach shows good agreement with experiments and can be extended to other types of dynamic covalent network polymers using different stimuli for BERs, such as light and moisture etc.

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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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Mechanics of soft active materials with phase evolution

Cited by 76 publications

References 47 publications

Reduced time as a unified parameter determining fixity and free recovery of shape memory polymers

Reduced time as a unified parameter determining fixity and free recovery of shape memory polymers

Interfacial welding of dynamic covalent network polymers

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

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