Temperature memory effect and its stability revealed via differential scanning calorimetry in ethylene‐vinyl acetate within glass transition range

Wang, Tao Xi; Huang, Wei Min; Chen, Hongmei; Lu, Hai Bo; Kang, Shu Feng

doi:10.1002/polb.24076

Cited by 7 publications

(10 citation statements)

References 39 publications

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“…Other than T m , TME within T g is found in a commercial ethylene‐vinyl acetate copolymer (EVA) (Figure 1(b)), which is also reported with excellent shape memory performance 23,38 . As revealed, the T s in first cycle is around its T g area and an apparent turning point in second cycle appears near the T s .…”

Section: Introductionmentioning

confidence: 62%

“…Additionally, although SME has been already confirmed to be able to be triggered by both T m and T g in a certain SMP 39 when the material possesses an adequate degree of amorphous and crystalline domains in its molecular structure, 40–42 research about TME in SMPs so far are still focused on a particular transition (either T m or T g ), it seems still unclear whether one single SMP could behave TME at both T g and T m . Therefore, in this study, we expand the investigation of TME via DSC tests from below T g to up to T m using the same EVA as reported in Reference 38. The relationship between the corresponding T t and T s is also revealed.…”

Section: Introductionmentioning

confidence: 81%

“…As revealed, the T s in first cycle is around its T g area and an apparent turning point in second cycle appears near the T s . Besides, it is also observed in 38 that the turning step becomes more remarkable with the increase of the holding time at T s .…”

Section: Introductionmentioning

confidence: 82%

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Temperature memory effect from below glass transition to up to melting range in an ethylene‐vinyl acetate copolymer

Wang

Song

Geng

et al. 2021

J of Applied Polymer Sci

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In this paper, the temperature memory effect (TME) in a commercial ethylenevinyl acetate copolymer (EVA) is characterized via differential scanning calorimetry (DSC) tests. Three temperatures, which are 35, 60, and 85 C representing temperatures below glass transition (T g), within T g and within melting (T m), respectively, are included for the investigation. It is found that TME in polymers is not as reported to be limited at around either T g or T m only, the effective temperature range for TME could be actually much wider that covers from below T g to up to T m. In addition, it is concluded that higher heating stop temperature (T s) erases the memory of previous lower ones in this EVA. Hysteresis (described by ΔT) between the temperature of turning points

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Section: Introductionmentioning

confidence: 62%

Section: Introductionmentioning

confidence: 81%

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Temperature memory effect from below glass transition to up to melting range in an ethylene‐vinyl acetate copolymer

Wang

Song

Geng

et al. 2021

J of Applied Polymer Sci

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“…In the early stage of materials selection for sensor applications of SMPs, we may reveal the stability of a particular polymer via differential scanning calorimetry (DSC) test without introducing any macroscopic shape change [56,57]. The equivalent time-temperature effect (the time-temperature superposition principle), which considers the accumulation of both heating/cooling temperature and heating/cooling time, may be used in temperature-time accumulation sensors after careful and extensive calibration.…”

Section: Working Mechanisms and Shape Memory Phenomenamentioning

confidence: 99%

A Brief Review of the Shape Memory Phenomena in Polymers and Their Typical Sensor Applications

et al. 2019

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In this brief review, an introduction of the underlying mechanisms for the shape memory effect (SME) and various shape memory phenomena in polymers is presented first. After that, a summary of typical applications in sensors based on either heating or wetting activated shape recovery using largely commercial engineering polymers, which are programmed by means of in-plane pre-deformation (load applied in the length/width direction) or out-of-plane pre-deformation (load applied in the thickness direction), is presented. As demonstrated by a number of examples, many low-cost engineering polymers are well suited to, for instance, anti-counterfeit and over-heating/wetting monitoring applications via visual sensation and/or tactual sensation, and many existing technologies and products (e.g., holography, 3D printing, nano-imprinting, electro-spinning, lenticular lens, Fresnel lens, QR/bar code, Moiré pattern, FRID, structural coloring, etc.) can be integrated with the shape memory feature.

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“…Inset: zoom-in view of the glass transition range upon heating. (Reproduced from(Wang et al, 2016b)) Two types of TME tests were carried out. In the first type, there was only one stop temperature (single-stop test); and in the second type, there were three stop temperatures (triple-stop test), i.e., there were three thermal cycles (all started from 0 o C and finished at 0 o C) before final heating (also started at 0 o C).…”

mentioning

confidence: 99%

Elastic shape memory polymeric materials for comfort fitting footwear

Wang¹

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Nowadays consumers demand more and more comfort and functionality from their footwear, making these characteristics very important considerations in footwear design and evaluation. Both are the results between the nature of human body and different elements of the footwear. Although there are quite many different methods or ways to achieve better comfort fitting, for instance, via 3D printing, disadvantages are still quite obvious in available products in the market. Thus, in order to improve comfort fitting and provide a better solution to consumers, shape memory polymers are introduced. First, a commercially available polymer, namely ethylene-vinyl acetate (EVA) foam is investigated in terms of its shape memory effect (SME). It is concluded that this EVA foam can satisfy some but not all of the requirements for comfort fitting shoes. Since it is difficult to find an existing shape memory material that meets the requirements for comfort fitting footwear, both thermoset and thermoplastic shape memory hybrids (SMHs) programmable at around human body temperature with tailorable elasticity and stretchability are developed. The fitting time window for the thermoset version is over 10 minutes, while it is less than two minutes for the thermoplastic version. No similar materials have been reported so far. Additionally, some possible shoe designs are proposed and the enhanced stretchability via local structural design is investigated by finite element method (FEM). Subsequently, a few prototypes are fabricated and the feasibility to actualize comfort vi fitting shoes using developed materials is demonstrated. Although the shoe prototypes are only for the purpose of proof-of-concept, the demonstration successfully shows that the prototypes are deformable to fit different sized feet at around human body temperature. Such a kind of comfort fitting approach has yet been achieved using any other existing materials and technologies.

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Temperature memory effect and its stability revealed via differential scanning calorimetry in ethylene‐vinyl acetate within glass transition range

Cited by 7 publications

References 39 publications

Temperature memory effect from below glass transition to up to melting range in an ethylene‐vinyl acetate copolymer

Temperature memory effect from below glass transition to up to melting range in an ethylene‐vinyl acetate copolymer

A Brief Review of the Shape Memory Phenomena in Polymers and Their Typical Sensor Applications

Elastic shape memory polymeric materials for comfort fitting footwear

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