Characterization of polymeric shape memory materials

Wu, Xiaomo; Huang, Wei Min; Lu, Hai; Wang, Chang Chun; Cui, Hai Po

doi:10.1515/polyeng-2015-0370

Cited by 58 publications

(31 citation statements)

References 85 publications

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“…In many real engineering applications, the shape/dimension change is of more to us. As such, instead of following the conventional definitions based on strain as in, for instance [57], we use length to characterize the shape memory performance. Hence, the shape fixity ratio (R f ) is defined by,…”

Section: Shape Memory Performancementioning

confidence: 99%

Influence of Long-Term Storage on Shape Memory Performance and Mechanical Behavior of Pre-stretched Commercial Poly(methyl methacrylate) (PMMA)

et al. 2019

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In this paper, we experimentally investigate the influence of storage at 40 • C on the shape memory performance and mechanical behavior of a pre-stretched commercial poly(methyl methacrylate) (PMMA). This is to simulate the scenario in many applications. Although this is a very important topic in engineering practice, it has rarely been touched upon so far. The shape memory performance is characterized in terms of the shape fixity ratio (after up to one year of storage) and shape recovery ratio (upon heating to previous programming temperature). Programming in the mode of uniaxial tension is carried out at a temperature within the glass transition range to one of four prescribed programming strains (namely 10%, 20%, 40% and 80%). Also investigated is the residual strain after heating for shape recovery. The characterization of the mechanical behavior of programmed samples after storage for up to three months is via cyclic uniaxial tensile test. It is concluded that from an engineering application point view, for this particular PMMA, programming should be done at higher temperatures (i.e., above its T g of 110 • C) in order to not only achieve reliable and better shape memory performance, but also minimize the influence of storage on the shape memory performance and mechanical behavior of the programmed material. This finding provides a useful guide for engineering applications of shape memory polymers, in particular based on the multiple-shape memory effect, temperature memory effect, and/or low temperature programming.2 of 12 applications [34][35][36][37][38][39][40], activation of the SME may not be carried out right after programming, but after a period of storage. As such, we need to consider the influence of aging at around room temperature after programming [41], which is a topic that has been less explored so far [42,43], but that is utterly important from an engineering application point of view.The purpose of this paper is to experimentally investigate the influence of storage at 40 • C on the shape memory performance and mechanical behavior of a commercial poly(methyl methacrylate) (PMMA), which is a typical engineering polymer, used in many applications, including optical lens [44,45] and plastic screw. This particular PMMA has been verified to have excellent heating-responsive SME in our previous studies (e.g., in [46,47]), and unlike some moisture/water-responsive SMPs (e.g., the polyurethane reported in [48]), it appears to be non-sensitive to moisture in air. PMMA and polycarbonates (PC) are typical amorphous polymer, and their SME was reported over 20 years ago [49,50]. Both experimental investigation and simulation on the SME of amorphous polymers (without chemical cross-linking, but via physical cross-linking) have been well documented in the literature (e.g., in [41,51-53]). Different programming temperatures (all within the glass transition range) and programming strains (up to 80%, in the mode of uniaxial tension) are applied in this study, as they have been identified to be influential para...

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Section: Shape Memory Performancementioning

confidence: 99%

Influence of Long-Term Storage on Shape Memory Performance and Mechanical Behavior of Pre-stretched Commercial Poly(methyl methacrylate) (PMMA)

et al. 2019

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“…A standard thermo-responsive SME cycle, programmed by means of, for instance, uni-axial tension in this study, includes two processes, namely programming and shape recovery, with three major steps as illustrated in Figure 5 [28]. Dog-bone shaped samples (refer to Figure 4 for dimensions) for uni-axial tensile test were cut out from the PC sheets.…”

Section: Characterization Of Heating-responsive Smementioning

confidence: 99%

“…A standard thermo-responsive SME cycle, programmed by means of, for instance, uni-axial tension in this study, includes two processes, namely programming and shape recovery, with three major steps as illustrated in Figure 5 [28]. Differential scanning calorimetric (DSC) (DSC Q200, Coppell, TX, USA) tests were carried out between 25 °C and 380 °C at a ramp rate of 10 °C/min for two cycles.…”

Section: Characterization Of Heating-responsive Smementioning

confidence: 99%

“…A standard thermo-responsive SME cycle, programmed by means of, for instance, uni-axial tension in this study, includes two processes, namely programming and shape recovery, with three major steps as illustrated in Figure 5 [28]. Step 1 Loading: at a prescribed programming temperature, stretching the sample to the required maximum strain of ε m at a prescribed strain rate;…”

Section: Characterization Of Heating-responsive Smementioning

confidence: 99%

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Thermo-Responsive Shape-Memory Effect and Surface Features in Polycarbonate (PC)

Wang

Huang

et al. 2017

Applied Sciences

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The influence of programming strain and temperature on the shape memory effect and surface morphology in programmed polycarbonate (PC) samples via uni-axial stretching is investigated. It is found that the samples programmed at around the glass transition start temperature not only have micro-cracks on their surface, but also show a necking phenomenon. Furthermore, the surface of the necked area is concave, but the surface of the non-necked area is convex. On the other hand, despite the samples programmed at high temperatures being able to deform in a uniform manner at macroscopic scale, their surfaces are still uneven, either concave or convex. While the samples programmed at low temperatures are able to achieve full shape recovery, stretching at higher temperatures over the glass transition range to a higher strain may result in non-recoverable deformation.

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“…Right now, the family of SMM has expended significantly, and covers a range of different types of materials, including alloy, polymer and ceramic etc [2][3][4][5]. In general, the SME process includes two steps [6]. The first step is to program the piece of SMM into a temporary shape (known as the programming process); and the second step is to apply the right stimulus for recovery (called the recovery process) with or without constraint applied.…”

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confidence: 99%

Stimulus Activated Shape Switching in Shape Memory Materials with Tailor Able Start/Finish Temperature/ Time

Huang¹

2017

RMES

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EditorialThe shape memory effect (SME) refers to the phenomenon of shape recovery in a severely pre-deformed material, but only when a right stimulus is applied. The materials with the SME are called shape memory material (SMM), and typical stimuli include heat, chemical (including water/moisture), light, etc [1]. Right now, the family of SMM has expended significantly, and covers a range of different types of materials, including alloy, polymer and ceramic etc [2][3][4][5]. In general, the SME process includes two steps [6]. The first step is to program the piece of SMM into a temporary shape (known as the programming process); and the second step is to apply the right stimulus for recovery (called the recovery process) with or without constraint applied. However, the start and finish of recovery is normally dependent on the material itself. For instance, in Figure 1, a piece of heat shrink polymeric film starts to shrink upon heating to its glass transition start temperature, which is about 50 oC. Hence, traditionally, in order to meet the recovery temperature requirement of a particular application, we have to search for a polymeric material with the required glass transition start temperature or melting start temperature. Although most of polymeric materials are heat/chemo-responsive SMM, it is still a tedious process to find the right material, since there are many other requirements, such as biodegradability, shape recovery ratio etc, in the application as well.

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Characterization of polymeric shape memory materials

Cited by 58 publications

References 85 publications

Influence of Long-Term Storage on Shape Memory Performance and Mechanical Behavior of Pre-stretched Commercial Poly(methyl methacrylate) (PMMA)

Influence of Long-Term Storage on Shape Memory Performance and Mechanical Behavior of Pre-stretched Commercial Poly(methyl methacrylate) (PMMA)

Thermo-Responsive Shape-Memory Effect and Surface Features in Polycarbonate (PC)

Stimulus Activated Shape Switching in Shape Memory Materials with Tailor Able Start/Finish Temperature/ Time

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