Relationship between nanoscale deformation processes and elastic behavior of polyurethane elastomers

Christenson, Elizabeth M.; Anderson, James M.; Hiltner, A.; Baer, E.

doi:10.1016/j.polymer.2005.08.083

Cited by 140 publications

(137 citation statements)

References 25 publications

(31 reference statements)

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“…In this work, uniaxial tensile and cyclic deformation tests ( figure 9 and table 3) showed that bi-layered PU scaffolds possessed an elastomeric-like mechanical behaviour. After five deformation cycles (at 0-10% strain), a rsfs.royalsocietypublishing.org Interface Focus 4: 20130045 permanent deformation of around 3.1% was recorded, owing to chain orientation along the stress direction occurring mostly during the first deformation cycle (2.5% permanent strain) [19]. Human-derived CPCs were found to firmly adhere to the scaffolds, keeping viability and showing a proliferative behaviour and a spreading morphology after 3 days of culture time ( figure 10).…”

Section: Discussionmentioning

confidence: 99%

“…Cyclic tensile tests (five cycles; 0-10% deformation; table 3) evidenced a permanent strain of around 2.5% after the first cycle, probably owing to chain orientation along the stress direction [19]. During the following deformation cycles, permanent strain only weakly increased up to 3.1%, suggesting an elastomeric-like behaviour of PU scaffolds.…”

Section: Polyurethane Scaffoldsmentioning

confidence: 96%

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Polyurethane-based scaffolds for myocardial tissue engineering

et al. 2014

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Bi-layered scaffolds with a 0°/90° lay-down pattern were prepared by melt-extrusion additive manufacturing (AM) using a poly(ester urethane) (PU) synthesized from poly(ε-caprolactone) diol, 1,4-butandiisocyanate and l -lysine ethyl ester dihydrochloride chain extender. Rheological analysis and differential scanning calorimetry of the starting material showed that compression moulded PU films were in the molten state at a higher temperature than 155°C. The AM processing temperature was set at 155°C after verifying the absence of PU thermal degradation phenomena by isothermal thermogravimetry analysis and rheological characterization performed at 165°C. Scaffolds highly reproduced computer-aided design geometry and showed an elastomeric-like behaviour which is promising for applications in myocardial regeneration. PU scaffolds supported the adhesion and spreading of human cardiac progenitor cells (CPCs), whereas they did not stimulate CPC proliferation after 1–14 days culture time. In the future, scaffold surface functionalization with bioactive peptides/proteins will be performed to specifically guide CPC behaviour.

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Section: Discussionmentioning

confidence: 99%

Section: Polyurethane Scaffoldsmentioning

confidence: 96%

Polyurethane-based scaffolds for myocardial tissue engineering

et al. 2014

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“…This tensile behavior can be explained by the unique polymer chain composition of PU comprising soft and hard segments whereby the soft segments provide high elongation while hard segments provide stiffness. [35][36][37][38][39] Therefore, the initial stiff response stems solely from the rigid hard segment domains. The compliant behavior observed at mid-range strains is attributed to the combination of soft segment extension, fi brillar hard segment orientation in the direction of the strain, and lamellar hard segment domain rotation perpendicular to the strain direction.…”

Section: Shown Inmentioning

confidence: 99%

“…The compliant behavior observed at mid-range strains is attributed to the combination of soft segment extension, fi brillar hard segment orientation in the direction of the strain, and lamellar hard segment domain rotation perpendicular to the strain direction. [ 36,38,40 ] The strain-hardening observed at high elongation is due mainly to strain-induced crystallization in soft segments. [ 36,38 ] For our composite fi bers, we believe that the addition of PEDOT:PSS to PU increases the rigid component content thereby increasing the stiffness and yield stress.…”

Section: Shown Inmentioning

confidence: 99%

Strain‐Responsive Polyurethane/PEDOT:PSS Elastomeric Composite Fibers with High Electrical Conductivity

Seyedin

Razal

Innis

et al. 2014

Adv Funct Materials

251

235

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2957www.MaterialsViews.com wileyonlinelibrary.com response to be measurable in a wide range of applied strain. In practical situations, the applied strains can be as small as less than a few percent or as large as tens to hundreds of percent. Some applications where small strains are important are damage detection, structural characterisation, and fatigue studies in materials, [24][25][26] while applications such as body movement measurement, [ 16,20 ] medical monitoring, [ 18,19,27 ] and sports rehabilitation and injury prevention [ 21,28 ] require large strains sensing. This work reports for the fi rst time, the production of elastomeric composite fi bers with high electrical conductivity that are capable of monitoring wide range of applied strains (up to 260%) and can therefore be useful in applications such as strain gauge sensors in wearable bionics and stretchable electronics. The fi ber wet-spinning approach that we have developed effi ciently exploits the high stretchability of a medical grade elastomeric polyurethane (PU) and the high conductivity of PEDOT:PSS.This work contributes to the relatively unexplored production of conductive and elastomeric composite fi bers. The lack of progress in this fi eld can be attributed to the limited development of elastomeric composite formulations that contain welldispersed conducting fi llers, which are also processable by fi ber wet-spinning methods. In the limited cases where conductive fi llers such as polyaniline, [ 29 ] polythiophene [ 30 ] and carbon nanotubes [ 31 ] were utilized in the wet-spinning of conducting fi ber composites, the observed change in the electrical properties have only been marginal at large deformations. These reports also show that signifi cant amount of fi ller loading is necessary to achieve percolation of conducting networks, which was found to be detrimental to the overall mechanical properties of the composite. The most common alternative approach to produce fi bers with both elastic and conductive properties is by coating the elastomeric fi ber (some reports use yarn or textile) with a thin layer of the conducting material. This approach has been used for conductor/elastomer combinations such as polypyrrole on Tactel/Lycra [ 32 ] and nylon/Lycra [ 21 ] fabrics and PEDOT:PSS on Spandex fabric [ 23 ] to name a few, employing methods such as oxidative chemical polymerization, in situ chemical polymerization, chemical vapor deposition, and dip-coating. However, the conductive coatings produced often have poor adhesion and are less stretchy than the parent elastomer fi ber resulting in poor overall electrical and mechanical performance. [ 21,23,32 ] The surface and mechanical property mismatch between the conductive Strain-Responsive Polyurethane/PEDOT:PSS Elastomeric Composite Fibers with High Electrical ConductivityMohammad Ziabari Seyedin , Joselito M. Razal , * Peter C. Innis , and Gordon G. Wallace * It is a challenge to retain the high stretchability of an elastomer when used in polymer composites. Likewise, the high conductivit...

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“…This is not only due to crystallinity as long as this parameter is the largest for the material SPU 4 , but not in the case of polymer SPU 2 . Taking into account the morphology model of the hard segment phase dispersed into the soft segment phase, 14 our assumption is that the domains of the soft segment crystals (if present) joined by hard segment matrices are small and dense in the SPUs obtained by the one-step prepolymer route, whereas they are bulky and rare in the SPUs obtained by the two-step prepolymer techniques. Such morphology is supported by the topographic three-dimensional and two-dimensional images in Figure 9 if, for example, the images of the samples SPU 2 and SPU 5 are compared with those of the samples SPU 2 and SPU 3 , respectively.…”

Section: Segmented Polyurethanes With Mixtures Of Diisocyanates C Primentioning

confidence: 99%

Morphological features and thermal and mechanical response in segmented polyurethane elastomers based on mixtures of isocyanates

Prisăcariu

Scortanu

Stoica

et al. 2011

Polym J

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A family of segmented polyurethane elastomers (SPUs) was synthesized. Hard segments were chosen to be generated from two isocyanates: the rigid 4,4-diphenylmethane diisocyanate (MDI) and the flexible 4,4-dibenzyl diisocyanate (DBDI), alone or as mixtures. A polyester soft segment polyethylene adipate of molar mass 2000 g mol À1 and a small molecule chain-extender diol, ethylene glycol, were used. Hard segment fraction was maintained at B40%. The structure-property relationship of SPUs was investigated using several characterization techniques. Morphological features such as interdomains of the soft and hard segments were identified by means of atomic force microscopy. The thermal and mechanical behavior was evaluated by using dynamic mechanical analysis, differential scanning calorimetry and uniaxial tensile tests. Structural changes induced by varying the type and the number of isocyanates and the order of their introduction were also followed by using wide-angle X-ray. Materials with hard segments based on the single diisocyanate DBDI were observed to crystallize. Crystallinity was strongly reduced when DBDI was mixed with MDI. Improvement in elastomeric properties was obtained when both diisocyanates were included and reacted together in a random manner.

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Relationship between nanoscale deformation processes and elastic behavior of polyurethane elastomers

Cited by 140 publications

References 25 publications

Polyurethane-based scaffolds for myocardial tissue engineering

Polyurethane-based scaffolds for myocardial tissue engineering

Strain‐Responsive Polyurethane/PEDOT:PSS Elastomeric Composite Fibers with High Electrical Conductivity

Morphological features and thermal and mechanical response in segmented polyurethane elastomers based on mixtures of isocyanates

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