Giant room-temperature barocaloric effects in PDMS rubber at low pressures

Carvalho, A. Magnus G.; Imamura, William; Usuda, E. O.; Bom, Nicolau Molina

doi:10.1016/j.eurpolymj.2017.12.007

Cited by 50 publications

(45 citation statements)

References 48 publications

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“…Unlike ELVAX, the NRC for all other materials varies nearly linearly with ΔT h−c since they do not undergo any phase transformation. Overall, the TPE NRC values are comparable to those for pure elastomers reported earlier (≈10 kJ kg −1 GPa −1 for ΔT h−c = 25 °C (Carvalho et al, 2018;Usuda et al, 2019), but higher values are measured for ELVAX while lower values are measured for the less compressible EVCA and the thermoplastic ZYTEL.…”

Section: Barocaloric Propertiessupporting

confidence: 86%

“…A higher ΔS T up to 250 J kg −1 K −1 and ΔT s up to 25 °C were measured for natural rubber, albeit at a higher applied pressure (Δp ≈ 500 MPa) (Miliante et al, 2020). Comparable BC properties were also demonstrated in polyurethane rubber (Bocca et al, 2021)-achieving NRC ≈11 kJ kg −1 GPa −1 (Δp = 174 MPa)-and PDMS rubber (Carvalho et al, 2018)-achieving NRC ≈9 kJ kg −1 GPa −1 (Δp = 193 MPa)-for ΔT h−c = 25 °C. The BC properties of these materials were evaluated by pressuredependent differential scanning calorimetry, indirect methods based on Maxwell's relations, or quasi-adiabatic direct measurements (Li et al, 2019;Lloveras et al, 2019;Usuda et al, 2019;Bocca et al, 2021).…”

Section: Introductionmentioning

confidence: 84%

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Barocaloric Properties of Thermoplastic Elastomers

et al. 2022

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Solid-state refrigeration represents a promising alternative to vapor compression refrigeration systems which are inefficient, unreliable, and have a high global warming potential. However, several solid-state cooling technologies—including those relying on a temperature change induced by an applied electric field (electrocaloric effect), magnetic field (magnetocaloric effect), and uniaxial stress (elastocaloric effect)—have been investigated, but their efficiency and scalability remain a concern. Materials with a large barocaloric response—temperature/entropy change induced by hydrostatic pressure—hold a significant promise for solid-state cooling but remain comparatively less explored. These materials need to be inexpensive, compressible, and show a large barocaloric response around the temperature of interest. Soft materials have the potential to meet these requirements and enable the development of low-cost high-efficiency solid-state heat pumps. Here, we investigate the barocaloric performance of commercially available block copolymer thermoplastic elastomers. We characterized the mechanical, thermal, and barocaloric properties of these materials and evaluated their potential for solid-state refrigeration. We utilized rheometric measurements to evaluate the isothermal compressibility and normalized refrigerant capacity of the thermoplastic elastomers. In addition, we directly measured the pressure-induced temperature change of the test materials and compared them with their normalized refrigeration capacity. The measured isothermal compressibility was in the 0.1–0.4 GPa−1 range, while the normalized refrigeration capacity varied between 13.2 and 41.9 kJ K−1 GPa−1 for a 100 MPa applied pressure and 65°C temperature span. The corresponding pressure-induced temperature change for an applied pressure of 434.1 MPa varied between 2.2 and 28°C. These results demonstrated the superior barocaloric properties of thermoplastic elastomers and their promise for next generation barocaloric solid-state refrigeration devices.

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Section: Barocaloric Propertiessupporting

confidence: 86%

Section: Introductionmentioning

confidence: 84%

Barocaloric Properties of Thermoplastic Elastomers

et al. 2022

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“…Refrigeration materials that undergo cooling because of any type of mechanical deformation are called mechanocaloric, and those that cool because of changes in uniaxial stress (5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15) or hydrostatic pressure (5,(15)(16)(17) are more specifically called elastocaloric and barocaloric, respectively (6). We here demonstrate cooling by a change in yarn or fiber twist, which we call twistocaloric cooling.…”

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confidence: 73%

Torsional refrigeration by twisted, coiled, and supercoiled fibers

Wang

Fang

Xiao

et al. 2019

Science

158

101

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Higher efficiency, lower cost refrigeration is needed for both large and small scale cooling. Refrigerators using entropy changes during cycles of stretching or hydrostatically compression of a solid are possible alternatives to the vapor-compression fridges found in homes. We show that high cooling results from twist changes for twisted, coiled, or supercoiled fibers, including those of natural rubber, NiTi, and polyethylene fishing line. By using opposite chiralities of twist and coiling, supercoiled natural rubber fibers and coiled fishing line fibers result that cool when stretched. A demonstrated twistbased device for cooling flowing water provides a high cooling energy and device efficiency. Theory describes the axial and spring index dependencies of twist-enhanced cooling and its origin in a phase transformation for polyethylene fibers.Summary: Twist-exploiting mechanocaloric cooling is demonstrated for rubber fibers, fishing line fibers, and NiTi shape-memory wires.3

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“…The colossal barocaloric effects in plastic crystals open up new possibilities with high entropy changes and an adiabatic temperature change T ∆ of 50 K 13,14 , but the required pressure variations are hundreds of MPa, and a practical application is still far away. For elastocaloric devices, NiTi-based alloys are the most prominent active material.…”

Section: Introductionmentioning

confidence: 99%

Elastocaloric heat pump with specific cooling power of 20.9 W g–1 exploiting snap-through instability and strain-induced crystallization

et al. 2021

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Conventional refrigeration relies on hazardous agents, contributing to global warming. Soft, cheap, biodegradable solid-state elastocaloric cooling based on natural rubber offers an environmental friendly alternative. However, no such practical cooler has been developed, as conventional soft elastocaloric designs are not fast enough to ensure adiabaticity.In this work, we combine snap-through instability with strain-induced crystallization and achieve a sub-100 ms quasi-adiabatic cycling which is 30 times faster than previous design.Negligible heat exchange in expansion/contraction stages combined with the latent heat of phase transitions result in a giant elastocaloric crystallization effect. The rubber-based all-soft heat pump enables a specific cooling power of 20.9 W/g, a heat-flux of 256 mW/cm 2 , a coefficient of performance of 4.7 and a single-stage temperature span between hot and cold reservoirs of 7.9 K (full adiabatic temperature change of rubber membrane exceeding 23 K).The pump permits a compact all-soft voltage-actuated setup, opening up the opportunity of a viable plug-in-ready cooling device.

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Giant room-temperature barocaloric effects in PDMS rubber at low pressures

Cited by 50 publications

References 48 publications

Barocaloric Properties of Thermoplastic Elastomers

Barocaloric Properties of Thermoplastic Elastomers

Torsional refrigeration by twisted, coiled, and supercoiled fibers

Elastocaloric heat pump with specific cooling power of 20.9 W g–1 exploiting snap-through instability and strain-induced crystallization

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