A New Molecular Theory of Non-Linear Viscoelasticity for Vitrifiable (or Crystallizable) Thermoplastic Polyurethane Elastomers

Song, Mingshi; Chen, Han; Jiang, Chaodong; Zhao, Bin; Li, Xiaoyü

doi:10.1002/1521-3919(20021101)11:8<845::aid-mats845>3.0.co;2-b

Cited by 5 publications

(3 citation statements)

References 11 publications

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“…Song et al [2] recently proposed a model based on the network of chain segments that may be expected in different environments within vitrifiable or semicrystalline TPUs. For uniaxial strain, their model gave:…”

Section: P R Laity Et Al 262mentioning

confidence: 99%

“…In the models of rubber-like elasticity proposed by Klüppel and Schramm, [31] Song et al, [2] and others, [15,27 -29] chain entanglements are assumed to undergo limited free movement between covalent cross-links. In the models of rubber-like elasticity proposed by Klüppel and Schramm, [31] Song et al, [2] and others, [15,27 -29] chain entanglements are assumed to undergo limited free movement between covalent cross-links.…”

Section: Polyurethane Composition and Processing History 281mentioning

confidence: 99%

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The Effect of Polyurethane Composition and Processing History on Mechanical Properties

Laity

Taylor

Wong

et al. 2005

Journal of Macromolecular Science, Part B

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Uniaxial stress-strain behavior of a wide range of polyurethane elastomers was compared with current models of rubber-like elasticity. Although the data could be described well by a semi-empirical model, a systematic discrepancy was observed with more theoretically based models. This took the form of an additional energy term during deformation, which depended on the polyurethane composition. Microdomain fragmentation may provide a possible explanation. Alternatively, it may be due to the effects of segmental interactions on the relaxation of polymer chain entanglements during deformation.This combination of useful mechanical properties and ease of processing has led to the use of TPUs in many diverse applications, such as conveyer belts, rollers, solid tires, upholstery, elastomeric textile fibers, and shoe soles. [8 -11] Moreover, many TPUs exhibit good biocompatibility, making them promising candidates for medical and surgical applications such as gloves, catheters, arterial stents, and replacement heart valves. [12,13] Uniaxial tensile stress-strain curves of TPUs generally exhibit sigmoidal shapes characteristic of rubber-like elastomers. A relatively steep increase in stress (s) at low strain (1) is followed by a gradual decrease in slope (i.e., strain-softening), a less steep section of curve at intermediate strain and a second region of increased slope (i.e., strain-hardening) at higher strain. [1 -7,9] Young's modulus (E) generally increases with HS content, which has been attributed to HS microdomains acting as reinforcing filler, [1 -9] while the pronounced strain-softening behavior, mechanical hysteresis, and "tensile set" (i.e., the relaxed sample is elongated, compared with its original unstrained length) observed with some formulations may be caused by microdomain fragmentation. Strain hardening has been attributed to strain-induced crystallization; [2,3,7 -9] however, observations of similar behavior with cross-linked rubbers and other elastomers [14] suggest that alternative mechanisms may be possible in some cases.The work presented here investgated the mechanical properties of thermoplastic poly(ether-urethane) (PEU) and poly(carbonate-urethane) (PCU) copolymers at moderate strain. In particular, the effects of composition, processing history, and morphology on Young's modulus and the stress-strain behavior were studied. This forms part of an ongoing project to develop polyurethanes with improved characteristics and performance for medical applications. Rubber-like ElasticityRubber-like elasticity was discussed extensively by Heinrich et al., [15] Treloar, [16] and Dušek and Prins. [17] Recent developments in theory were reviewed by Mark. [14] and Beda and Chevallier. [18] Therefore, only a few key points need be discussed here.The stress-strain relationship of a rubber-like elastomer in uniaxial extension at low strain (i.e., before strain hardening is observed) can generally be described by the semiempirical equation derived by Mooney [19] and Rivlin: [20]

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Section: P R Laity Et Al 262mentioning

confidence: 99%

Section: Polyurethane Composition and Processing History 281mentioning

confidence: 99%

The Effect of Polyurethane Composition and Processing History on Mechanical Properties

Laity

Taylor

Wong

et al. 2005

Journal of Macromolecular Science, Part B

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“…Polyurethane (PU) was selected as the substrate to simulate skin mechanical properties because a range of viscoelasticity could be adjusted by controlling the compositions of hard and soft segments in its chemical structure (12). Polyurethane plates (5 cm x 5 cm) were purchased from Beaulax Co., Ltd.…”

Section: Viscoelastic Substrate To Mimic Skin Mechanical Propertiesmentioning

confidence: 99%

Mechanical Characterization of Cosmetic and Viscoelastic Effects of Firming Polymers

Chiang

Huang

Ghatlia

2013

ACS Symposium Series

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In personal care products, polymers may be used as emulsifiers, stabilizers, rheology modifiers (e.g. thickening agent), or film formers. When deposited on the skin, polymer usually doesn't penetrate the skin due to its high molecular weight and size. It remains on the skin surface to form a film, which may potentially provide conditioning benefits. One of the conditioning effects is to enhance the tactile stimulus by altering the overall mechanical properties of skin. This mechanical alteration is highly associated with the viscoelastic properties of the polymeric film forming on the skin surface. In order to select a suitable polymer from numerous choices of polymers when designing a product, it is important to have a method to screen polymers and benchmark the performances. In this report, a screening method, a mechanical measurement and its modeling methods to evaluate the mechanical effects of polymers will be presented. A variety of synthetic and natural polymers were tested, and the result suggested that synthetic polymers might provide broader ranges of designs for altering skin mechanical properties. Although most polymers seem to have similar modes of actions in enhancing skin firmness and elasticity, further investigations will be required to completely reveal the design principles and to expand the ranges of mechanical alterations that are delivered by the applications of firming polymers.

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Constitutive equations for the nonlinear viscoelastic and viscoplastic behavior of thermoplastic elastomers

Drozdov

Christiansen

2006

International Journal of Engineering Science

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A New Molecular Theory of Non-Linear Viscoelasticity for Vitrifiable (or Crystallizable) Thermoplastic Polyurethane Elastomers

Cited by 5 publications

References 11 publications

The Effect of Polyurethane Composition and Processing History on Mechanical Properties

The Effect of Polyurethane Composition and Processing History on Mechanical Properties

Mechanical Characterization of Cosmetic and Viscoelastic Effects of Firming Polymers

Constitutive equations for the nonlinear viscoelastic and viscoplastic behavior of thermoplastic elastomers

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