Remotely actuated polymer nanocomposites—stress-recovery of carbon-nanotube-filled thermoplastic elastomers

Koerner, Hilmar; Price, Gary E.; Pearce, Nathan A.; Alexander, M.; Vaia, Richard A.

doi:10.1038/nmat1059

Cited by 976 publications

(704 citation statements)

References 23 publications

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“…In the PU films, we observed a single peak at ~25 o C. A number of researchers have associated this peak with melting of soft segment crystallites. [32][33][34][35][36][37][38] For both solvents, we see the reduction in intensity of this peak as graphene content is increased until by 30wt% no SS crystallites are observable. This strongly suggests that the presence of graphene somehow impedes the formation of soft segment crystallites.…”

Section: Graphene Dispersion and Composite Morphologymentioning

confidence: 99%

Development of stiff, strong, yet tough composites by the addition of solvent exfoliated graphene to polyurethane

Khan

May

O’Neill

et al. 2010

Carbon

280

200

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Please cite this article as: Khan, U., May, P., O'Neill, A., Coleman, J.N., Development of stiff, strong, yet tough composites by the addition of solvent exfoliated graphene to polyurethane, Carbon (2010), doi: 10.1016/j.carbon. 2010.07.008 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.Development of stiff, strong, yet tough composites by the addition of solvent We have prepared graphene dispersions, stabilised by polyurethane in tetrahydrofuran and dimethylformamide. These dispersions can be drop-cast to produce free-standing composite films. The graphene mass fraction is determined by the concentration of dispersed graphene and can be controllably varied from 0% to 90%. Raman spectroscopy and Helium ion microscopy show the graphene to well-dispersed and well-exfoliated in the composites, even at mass fractions of 55%. On addition of graphene, the Young's modulus and stress at 3% strain increase by ×100, saturating at 1 GPa and 25 MPa respectively for mass fractions above 50wt%. While the ultimate tensile strength does not vary significantly with graphene content, the strain at break and toughness degrade heavily on graphene addition. Both these properties fall by ×1000 as the graphene content is increased to 90wt%. However, the rate of increase of Young's modulus and stress at 3% strain with mass fraction is greater than the rate of decrease of ductility and toughness.This makes it possible to prepare composites with high modulus, stress at low strain and ultimate tensile strength as well as relatively high toughness and ductility. This could lead to new materials that are stiff, strong and tough. With this in mind, we propose a different approach. Rather than reinforcing thermoplastics, we suggest that graphene might make an impact reinforcing elastomers.Reinforcement mechanisms in elastomeric composites are more complex than in thermoplastic based composites, a fact that may circumvent the poor stress transfer described above. Hard thermoplastics are characterised by relatively high stiffness and strength but low ductility and toughness (work done to fracture). Conversely, elastomers are characterised by low stiffness and low stress at low strain but high ductility and toughness. We propose that addition of graphene to elastomers could result in a material with positive elements of both hard thermoplastics and elastomers: high stiffness and strength yet relatively large ductility and toughness. Such materials would be useful in a range of applications.For such composites to have the properties outlined, a delicate balance must be maintained. While addition of nano-fillers such as nanotubes, nano...

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Section: Graphene Dispersion and Composite Morphologymentioning

confidence: 99%

Development of stiff, strong, yet tough composites by the addition of solvent exfoliated graphene to polyurethane

Khan

May

O’Neill

et al. 2010

Carbon

280

200

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“…19 Additionally, using weakly interacting rod-like nanoparticles in an elastomeric or thermosetting matrix leads to the possibility of forming interpenetrating polymeric network with highly disparate mechanical properties that are hitherto unanticipated based on traditional polymeric interpenetrating networks. 25 While significant challenges still remain in predicting the dispersion of nanoparticles in single component polymeric matrices, 26 the ability to disperse nanoparticles in multicomponent polymeric matrices, especially to direct them to specific phases or to the interface between phaseseparated structures, promises even greater opportunities. Experimental and theoretical efforts are only just beginning.…”

Section: Introductionmentioning

confidence: 99%

Polymer nanocomposites

Krishnamoorti

Vaia

2007

J Polym Sci B Polym Phys

Self Cite

243

166

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Polymer nanocomposites are distinguished by the convergence of length scales corresponding to the radius of gyration of the polymer chains, a dimension of the nanoparticle and the mean distance between the nanoparticles. The consequences of this convergence on the physics of the polymer chains are considered, and some of the outstanding issues and their potential consequences on structure-property relations for polymer nanocomposites are highlighted.

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“…Another example for shape-memory polymers with T trans being a T m are block copolymers from poly(ethylene terephthalate) and poly(ethylene oxide) (5). Compounds from shape-memory polymers and inorganic particles, including SiC particles (6, 7), carbon black (8,9), and nanotubes (10,11), were prepared. The incorporation of particles leads to enhanced mechanical properties (6,8) or electric conductivity (7,9).…”

mentioning

confidence: 99%

Initiation of shape-memory effect by inductive heating of magnetic nanoparticles in thermoplastic polymers

Mohr

Kratz

Weigel

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

754

586

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In shape-memory polymers, changes in shape are mostly induced by heating, and exceeding a specific switching temperature, T switch. If polymers cannot be warmed up by heat transfer using a hot liquid or gaseous medium, noncontact triggering will be required. In this article, the magnetically induced shape-memory effect of composites from magnetic nanoparticles and thermoplastic shapememory polymers is introduced. A polyetherurethane (TFX) and a biodegradable multiblock copolymer (PDC) with poly(p-dioxanone) as hard segment and poly( -caprolactone) as soft segment were investigated as matrix component. Nanoparticles consisting of an iron(III)oxide core in a silica matrix could be processed into both polymers. A homogeneous particle distribution in TFX could be shown. Compounds have suitable elastic and thermal properties for the shape-memory functionalization. Temporary shapes of TFX compounds were obtained by elongating at increased temperature and subsequent cooling under constant stress. Cold-drawing of PDC compounds at 25°C resulted in temporary fixation of the mechanical deformation by 50 -60%. The shape-memory effect of both composite systems could be induced by inductive heating in an alternating magnetic field (f ‫؍‬ 258 kHz; H ‫؍‬ 30 kA⅐m ؊1 ). The maximum temperatures achievable by inductive heating in a specific magnetic field depend on sample geometry and nanoparticle content. Shape recovery rates of composites resulting from magnetic triggering are comparable to those obtained by increasing the environmental temperature.nanocomposite ͉ shape-memory polymer ͉ stimuli-sensitive polymer S hape-memory polymers are able to recover their predefined original shape when exposed to an external stimulus. A prerequisite for the shape-memory effect is a preceding functionalization of the material to temporarily fix a mechanical deformation. Most shape-memory polymers are thermosensitive materials. The shape is actuated by exceeding a specific switching temperature, T switch (1). Thermoplastic shape-memory polymers have at least two separated phases, where the domains with the highest thermal transition (T perm ) stabilize the permanent shape by acting as physical netpoints. A second phase having another thermal transition T trans serves as switch. At temperatures above T trans the chain segments forming this phase are flexible and the material is highly elastic, whereas the flexibility of the chains below T trans is limited and enables the fixation of the temporary shape. T trans can either be a glass transition (T g ) or a melting temperature (T m ). Whereas T trans is the thermal transition of the switching segment phase, typically determined by differential scanning calorimetry (DSC), T switch is result of a thermomechanical test used to quantify the shape-memory effect.An important class of thermoplastic shape-memory polymers are polyurethanes. They often contain a hard segment from methylene bis(4-phenylisocyanate) (MDI) and 1,4-butanediol. Depending on the switching segment, T trans can be either a melting...

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Remotely actuated polymer nanocomposites—stress-recovery of carbon-nanotube-filled thermoplastic elastomers

Cited by 976 publications

References 23 publications

Development of stiff, strong, yet tough composites by the addition of solvent exfoliated graphene to polyurethane

Development of stiff, strong, yet tough composites by the addition of solvent exfoliated graphene to polyurethane

Polymer nanocomposites

Initiation of shape-memory effect by inductive heating of magnetic nanoparticles in thermoplastic polymers

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