Development of high shrinkage polyethylene terephthalate (PET) shape memory polymer tendons for concrete crack closure

Teall, Oliver; Pilegis, Martins; Sweeney, J.; Gough, Tim; Thompson, Glen; Jefferson, Tony; Lark, Robert John; Gardner, Diane Ruth

doi:10.1088/1361-665x/aa5d66

Cited by 14 publications

(4 citation statements)

References 24 publications

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“…Results when heated at 5 °C/min to a hold temperature of 92 °C are shown in Figure 3 . The hold temperature is greater than the glass transition temperature measured previously [ 38 ] in the range of 70–78 °C, and that of 78 °C according to the manufacturer. The choice of a hold temperature of 90 °C has been shown to be highly effective for this material in terms of obtaining a high shrinkage force [ 38 ] and this is consistent with the value used here.…”

Section: Manufacturing Methods For Shape Memory Polymerscontrasting

confidence: 55%

Applications and Life Cycle Assessment of Shape Memory Polyethylene Terephthalate in Concrete for Crack Closure

et al. 2022

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Shape memory polymer (SMP) products have been developed for application as crack closure devices in concrete. They have been made from PET in the form of both fibres and hollow tubes. Here, manufacturing methods using die-drawing and mandrel-drawing to induce shape memory are reported. The fibre-based devices are incorporated into concrete and, upon triggering, exert shrinkage restraint forces that close cracks in the concrete. The evolution of shrinkage restraint force in the fibres as manufactured was measured as a function of temperature, showing stresses in excess of 35 MPa. Tendons consisting of fibre bundles are incorporated into concreate beams subjected to controlled cracking. When activated, the tendons reduce the crack widths by 80%. The same fibres are used to produce another class of device known as knotted fibres, which have knotted ends that act as anchor points when they incorporated directly into concrete. Upon activation within the cracked concrete, these devices are shown to completely close cracks. The tubes are used to enclose and restrain prestressed Kevlar fibres. When the tubes are triggered, they shrink and release the prestress force in the Kevlar, which is transferred to the surrounding concrete in the form of a compressive force, thereby closing cracks. The Kevlar fibres also provide substantial reinforcement after activation. The devices are shown to be able to partially and fully close cracks that have been opened to 0.3 mm and achieve post-activation flexural strengths comparable to those of conventional reinforced and prestressed structural elements. Finally, a preliminary life cycle assessment study was used to assess the carbon footprint a nominal unit of concrete made with SMPs fibres compared to conventional concrete.

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Section: Manufacturing Methods For Shape Memory Polymerscontrasting

confidence: 55%

Applications and Life Cycle Assessment of Shape Memory Polyethylene Terephthalate in Concrete for Crack Closure

et al. 2022

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“…The heated PET tube can also be converted between liquid and solid states of the substance by adjusting the temperature. However, since the present device is considered for medical and clinical applications, its adjustable temperature range is small [33]. In contrast, the state change achieved based on granular jamming theory is not affected by temperature and can be achieved by simply adjusting the air pressure.…”

Section: Introductionmentioning

confidence: 99%

Stiffness Modelling and Performance Evaluation of a Soft Cardiac Fixator Flexible Arm with Granular Jamming

Gao

Zhu

et al. 2021

Machines

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To meet the practical application requirements of cardiac fixation during off-pump coronary artery bypass surgery, a soft cardiac fixator with a flexible arm was previously designed. To enable the soft cardiac fixator to adapt to uncertain external forces, this study evaluates the variable-stiffness performance of the flexible arm. First, the flexible arm was simplified as a soft silicone manipulator measuring 60 mm × 90 mm × 120 mm, which can actuate, soften, or stiffen independently along the length of the arm by combining granular jamming with input pressure. Then, the soft manipulator was modelled as a cantilever beam to analyse its variable-stiffness performance with granular jamming. Next, based on theoretical analysis and calculations, many experiments were conducted to evaluate the variable-stiffness performance of the soft manipulator. The experimental results demonstrated that the variable-stiffness performance is influenced by the flexible arm length, the size of the granules, and the input pressure.

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“…In particular, the latter affects the amount of crystallized domains and their orientation, as well as the degree of orientation of amorphous regions. [1,2] Several fiber processing techniques of amorphous and semicrystalline polymers such as extrusion, [3,4] spinning, [5][6][7] drawing of multimaterial fibers. Multimaterial thermal drawing starts with the design of macroscopic thermoplastic preforms containing materials with a wide range of optical, electronic, and mechanical properties arranged in complex structures.…”

Section: Introductionmentioning

confidence: 99%

“…In particular, the latter affects the amount of crystallized domains and their orientation, as well as the degree of orientation of amorphous regions. [ 1,2 ] Several fiber processing techniques of amorphous and semicrystalline polymers such as extrusion, [ 3,4 ] spinning, [ 5–7 ] and drawing [ 8–10 ] have revealed the presence of polymer chain alignment induced by the significant amount of flow and fast cooling. This orientation induces anisotropic properties and has a significant impact on the mechanical properties and failure mechanisms [ 11 ] that must be anticipated.…”

Section: Introductionmentioning

confidence: 99%

Unraveling the Influence of Thermal Drawing Parameters on the Microstructure and Thermo–Mechanical Properties of Multimaterial Fibers

Richard

Maurya

Shadman

et al. 2021

Small

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Multimaterial thermally drawn fibers are becoming important building blocks in several foreseen applications in surgical probes, protective gears, or medical textiles. Here, the influence of the thermal drawing parameters on the degree of polymer chain orientation, the related thermal shrinkage behavior, and the mechanical properties of the final fibers is investigated via thermo–mechanical testing and small‐ and wide‐angle X‐ray scattering (SAXS and WAXS) analyses. This study on polyetherimide fibers reveals that the drawing stress, which depends on the drawing speed and temperature, controls the thermal shrinkage behavior and mechanical properties. Furthermore, SAXS and WAXS analyses show that the degree of chain orientation increases with drawing stresses below 8 MPa and then saturates, which correlates with the amount of observed shrinkage. The use of this process‐dependent polymer chain alignment to tune the mechanical and shrinkage properties of the fibers is highlighted and controlled bending multimaterial fibers made of two polymethyl methacrylates having different molecular weights are developed. Finally, a heat treatment procedure is proposed to relax the chain alignment and increase the dimensional stability of devices such as temperature sensors. This deeper understanding can serve as a guide for the processing of complex fibers requiring specific mechanical properties or enhanced thermal stability.

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Development of high shrinkage polyethylene terephthalate (PET) shape memory polymer tendons for concrete crack closure

Cited by 14 publications

References 24 publications

Applications and Life Cycle Assessment of Shape Memory Polyethylene Terephthalate in Concrete for Crack Closure

Applications and Life Cycle Assessment of Shape Memory Polyethylene Terephthalate in Concrete for Crack Closure

Stiffness Modelling and Performance Evaluation of a Soft Cardiac Fixator Flexible Arm with Granular Jamming

Unraveling the Influence of Thermal Drawing Parameters on the Microstructure and Thermo–Mechanical Properties of Multimaterial Fibers

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