Deformation mechanisms of thermoplastic elastomers: Stress-strain behavior and constitutive modeling

Cho, Hansohl; Mayer, Steffen; Pöselt, Elmar; Susoff, Markus; Veld, Pieter J. in ’t; Rutledge, Gregory C.; Boyce, Mary C.

doi:10.1016/j.polymer.2017.08.065

Cited by 77 publications

(75 citation statements)

References 50 publications

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“…The chain extended polyesters showed both of strain softening and strain hardening within the content range of the hard segment polyester in the experiment, which was the microphase separation characteristic of a block copolymer elastomer and was also confirmed by the DSC curves in Figure . For common polyurethanes, there also are strain softening and strain hardening phenomena, but no obvious second yield point is found . The reason for this may be that the hard segment of polyurethanes are composed of carbamate, urethane, and/or biuret.…”

Section: Resultssupporting

confidence: 64%

“…The reason for this may be that the hard segment of polyurethanes are composed of carbamate, urethane, and/or biuret. These links or groups have strong intermolecular and intramolecular interactions caused by their polarity, hydrogen bonding, and sometimes π‐π stacking of the aromatic rings in the case of aromatic isocyanate, in the hard segment domain, relative to the nonpolar and soft segment regions of aliphatic polyesters or polyethers . Since these hard segments of polyurethanes can break without yielding under stress and do not slip easily as the hard segment in the chain‐extended polyester do, as a result that no obvious second yield point can be observed.…”

Section: Resultsmentioning

confidence: 99%

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Preparation of waterborne elastic polyesters by chain extension with isophorone diisocyanate as a chain extender

Zheng

Zhu

Cheng

et al. 2019

J of Applied Polymer Sci

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Isophorone diisocyanate was used as a chain extender to coupling the soft segment water-borne polyester with the hard segment water-borne polyester, to overcome the disadvantages of low molar mass and poor mechanical properties of waterborne sulfonatecontaining polyesters. The molecular structure of the extended polyester was confirmed by FTIR and 1 H NMR, and the increased molar mass of the resultant was characterized by SEC. The extended products could be dispersed in water with the emulsion particle size less than 50 nm in diameter, slightly larger than that of precursors of soft-and hard-segment polyesters. The emulsion viscosity of polyesters after the chain extension was lower when the emulsion concentration was not larger than 25 wt%, which is conducive to the spraying application of the polyester for coating. DSC analysis indicated that the polyester after chain extension had two different glass temperatures, suggesting that the polyester bulk had a microphase separation structure. The mechanical performance of the coupled polyester manifested an obviously improved elongation at break and had a feature of higher elastic recovery rate. The results of this study indicate that the chain extension is an effective method to increase the molar mass and improve mechanical properties of waterborne polyesters.

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Section: Resultssupporting

confidence: 64%

Section: Resultsmentioning

confidence: 99%

Preparation of waterborne elastic polyesters by chain extension with isophorone diisocyanate as a chain extender

Zheng

Zhu

Cheng

et al. 2019

J of Applied Polymer Sci

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“…In the extrusion foaming process, when the die temperature was 180 • C, the die pressure increased from 8.2 MPa for PTFE0 to 14.8 MPa for PTFE5 due to the highly entangled PTFE network. The higher die pressure leads to a higher pressure drop rate, which can dramatically improve the nucleation efficiency and increase the cell density [1]. After the samples are extruded from the die, the cells grow in the air and the temperature of the material decreases.…”

Section: Extrusion Foaming Of Tpee/ptfe Nanocompositesmentioning

confidence: 99%

“…Thermoplastic elastomers (TPEs) are copolymers composed of crystalline rigid segments and amorphous soft segments. They have experienced a market boom during recent decades and the rising trend will continue due to their remarkable thermal, chemical and mechanical properties [1]. TPEs can be easily manufactured by extrusion, injection molding, thermoforming and spinning [2] and can be considered a bridge between thermoplastics and chemically crosslinked elastomers [3].…”

Section: Introductionmentioning

confidence: 99%

Improving the Continuous Microcellular Extrusion Foaming Ability with Supercritical CO2 of Thermoplastic Polyether Ester Elastomer through In-Situ Fibrillation of Polytetrafluoroethylene

Jiang

Liu

et al. 2019

Polymers

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In-situ fibrillated polytetrafluoroethylene (PTFE) enhanced nanocomposites were successfully prepared by mixing thermoplastic polyether ester elastomer (TPEE) and PTFE using a twin-screw extruder. Well-dispersed, long aspect ratio PTFE nanofibrils with a diameter of less than 200 nm were generated and interwoven into networks. Differential scanning calorimetry and in-situ polarized optical microscopy showed that the PTFE nanofibrils can greatly accelerate and promote crystallization of the TPEE matrix and the crystallization temperature can be increased by 6 • C. Both shearing and elongational rheometry results confirmed that the introduction of PTFE nanofibrils can significantly improve the rheological properties. The remarkable changes in the strain-hardening effect and the melt viscoelastic response, as well as the promoted crystallization, led to substantially improved foaming behavior in the continuous extrusion process using supercritical CO 2 as the blowing agent. The existing PTFE nanofibrils dramatically decreased the cell diameter and increased cell density, together with a higher expansion ratio and more uniform cell structure. The sample with 5% PTFE fibrils showed the best foaming ability, with an average diameter of 10.4-14.7 µm, an expansion ratio of 9.5-12.3 and a cell density of 6.6 × 10 7 -8.6 × 10 7 cells/cm 3 .2 of 16 has many excellent properties including thermal stability, good elasticity, chemical and oil resistance and, especially, rebound resilience at low-temperatures [3,5]. Also, TPEE has higher tear and impact strengths over a broad range of service temperatures when compared with other traditional TPEs [8]. Because of the extraordinary performance of TPEE, it has attracted increasing interest from many fields such as the sports, automotive and military industries.Although TPEE is an attractive engineering material, its application has to overcome the exorbitant price. To overcome this shortcoming, many attempts have been made to further improve the mechanical properties or to lower the weight (i.e., material consumption). Blending the matrix with micro-sized particles is an efficient method to improve the thermal or mechanical properties of TPEE [9][10][11][12][13]. Paszkiewicz et al. [12] added carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs) to poly(trimethylene terephthalate) (PTT)-based TPEE to improve the electrical conductivity. They found that CNTs had greater potential to improve electrical conductivity when compared to GNPs due to the higher purity and higher aspect ratio. Qiu et al. [13] controlled the structure of mixed filler particles in TPEE to enhance the mechanical properties. The results showed that a closely packed particle structure can significantly improve the yield strength by about 40% with a decrease of about 20% in the Young's modulus, which is preferred in TPEE used as an elastomer.Foaming is a very effective way to lower the weight and expand the application of polymers. In recent decades, foamed materials have exhibited a balance between price and...

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“…Subsequent to and, to some extent, in parallel with Boyce and coworkers, Anand and coworkers [9][10][11][12][13][14][15][16] have also made notable contributions to the development of the mechanical modeling of polymers. In an early paper [9], benefits of using the Hencky strain for large deformations are presented.…”

Section: Introductionmentioning

confidence: 99%

Explicit, fully implicit and forward gradient numerical integration of a hyperelasto-viscoplastic constitutive model for amorphous polymers undergoing finite deformation

Bonnaud

Faleskog

2019

Comput Mech

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Following the growing use of amorphous polymers in an expanding range of applications, interest for numerical modeling of polymer behavior has greatly increased. Together with reliable constitutive models, stable, accurate and rapid integration algorithms valid for large deformations need to be developed. Here, in the framework of hyperelasto-viscoplasticity and multiplicative split formulation, three integration algorithms (explicit, fully implicit and forward gradient) are generated for a constitutive polymer model and respective stability is investigated. The algorithms are furthermore implemented in a commercial Finite Element code and simulation of a full field tensile test is shown to capture the actual deformation behavior of polymers. Keywords Amorphous polymers • Viscoplasticity • Finite element method • Stress update algorithm • Finite strain Mobile Communications AB, whose support is greatly acknowledged.

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Deformation mechanisms of thermoplastic elastomers: Stress-strain behavior and constitutive modeling

Cited by 77 publications

References 50 publications

Preparation of waterborne elastic polyesters by chain extension with isophorone diisocyanate as a chain extender

Preparation of waterborne elastic polyesters by chain extension with isophorone diisocyanate as a chain extender

Improving the Continuous Microcellular Extrusion Foaming Ability with Supercritical CO2 of Thermoplastic Polyether Ester Elastomer through In-Situ Fibrillation of Polytetrafluoroethylene

Explicit, fully implicit and forward gradient numerical integration of a hyperelasto-viscoplastic constitutive model for amorphous polymers undergoing finite deformation

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