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Cited by 138Advanced Materials and MechanicsPolymer composites and self-healingHydrogels: synthesis, properties, applications

Review on the Functional Determinants and Durability of Shape Memory Polymers

Open access
Pretsch, Thorsten·2010·Polymers
DOI 10.3390/polym2030120
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Abstract

Shape memory polymers (SMP) belong to the class of stimuli-responsive materials and have generated significant research interest. Their capability to retain an imposed, temporary shape and to recover the initial, permanent shape upon exposure to an external stimulus depends on the “functional determinants”, which in simplistic terms, can be divided into structural/morphological and processing/environmental factors. The primary aim of the first part of this review is to reflect the knowledge about these fundamental relationships. In a next step, recent advances in shape memory polymer composites are summarized. In contrast to earlier reviews, studies on the impairment of shape memory properties through various factors, such as aging, compression and hibernation, lubricants, UV light and thermo-mechanical cycling, are extensively reviewed. Apart from summarizing the state-of-the-art in SMP research, recent progress is commented.

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Written from the paper’s full text.

TL;DR

This review synthesizes functional determinants, composites, triggering methods, durability, cycle life, medical uses, foams, and self-healing of shape memory polymers. It emphasizes that structure/morphology and processing/environment govern SMP behavior, while durability and functional stability remain key challenges.

Key findings

  • SMPs can store maximum strains of several hundred percent versus about 8% for SMAs, but have lower recovery stresses (≤10 MPa vs. up to 900 MPa for NiTi), shorter cycle life (200 cycles vs. up to 10⁶ for NiTi), and longer recovery times (tens of seconds vs. tens of milliseconds).
  • Structure/morphology strongly affect SM properties: in pentaerythritol-cross-linked SMPU, best properties at 25 wt% hard segment and highest cross-linker content gave shape fixity 91% and recovery 94% after the third cycle at εm = 100%; increasing hard segment by 5 wt% dropped fixity to ~50% and recovery to 70%. In PCL/MDI/BDO SMP, short soft segment (Mn 1,600) and 37 wt% hard segment gave recovery ~20%, while soft segment Mn 7,000 and 19 wt% hard segment gave ~100%; below 10 wt% hard segment, domains no longer acted as physical cross-links.
  • Durability/aging: hydrolysis degraded PBA-based SMPU thermo-mechanical properties; a hydrolysis-stabilized PBA-based SMPU delayed onset of mechanical and functional impairment by 44 d and 35–45 d, respectively, and showed a 6.5-fold increase in durability toward embrittlement. Cycle life examples include ~4% loss in shape recoverability after 200 cycles, and PCL-based SMPU/MWCNT ran 420 cycles at 60% strain/30 °C, 150 cycles at 100% strain, and 120 cycles at 60% strain/40 °C.
  • Composites and alternative triggering: 2.9 vol% MWCNTs in Morthane improved shape fixity from 56 to 70% at εm = 250% and recovery stress from 0.6 to 1.4 MPa; 5 wt% functionalized MWCNTs in PCL-based SMPU enabled complete shape recovery within 10 s at 40 V; moisture/solvent uptake can lower Tg and trigger recovery.

Methods

  • Design: narrative review of SMP research, covering fundamentals, functional determinants, composites, solvent-sensitive SMPs, aging, cycle life, medical applications, foams, and impact/self-healing.
  • Data/sample: no primary experimental sample; synthesizes published studies and examples from the literature, including specific SMPUs, composites, foams, and resins.
  • Analysis: qualitative synthesis and discussion of structure-property relationships, processing/environment effects, durability, and testing methods; no systematic search or meta-analysis stated.

Limitations

  • Stated: durability of SMPs is an important facet and deserves more attention; challenges remain in increasing recovery force, stiffness, strength, accelerating recovery time, and convenient triggering.
  • Stated: the variety of possible thermo-mechanical testing settings makes comparison of different scientific data sets difficult unless exactly the same testing method is chosen.
  • Evident from text: as a narrative review, it reports no new experiments and does not use a systematic review protocol; cited results span different materials, composites, and test conditions, limiting direct comparability.

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Integrity signals

Registry

Crossref · 10.3390/polym2030120

Cites

271 of 272 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

0 of 198 cited sources checked · 0 supported · 0 flagged

  • Premisereasoning

    Upon application of an external stimulus like heat, the polymer shows sequential shape recovery responses from twice fixed over once fixed to permanent shape.

    “Upon application of an external stimulus like heat, the polymer shows sequential shape recovery responses, from twice fixed over once fixed to permanent shape.”
    Quote in the paperNot a substantial claim
  • Premisecitation

    SMPs have a shorter cycle life (200 cycles) than NiTi (up to 10^6 cycles).

    “shorter cycle life (200 cycles vs. up to 10 6 cycles reported for NiTi [12])”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [12] Rousseau, 2008, Challenges of shape memory polymers: A review of the progress toward overcoming SMP’s limitations, Polym. Eng. Sci. source

      Not checked in the free run.

  • Premisecitation

    For classical SMPs with one-way shape memory, a programming procedure must be applied every time before the shape memory effect can be triggered.

    “For classical SMPs with so-called “one-way” (non-reversible) SM, a programming procedure has to be applied every time before the SM effect can be triggered [54].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [54] Shirai, Y., and Hayashi, S.-I. (1988). Development of Polymeric Shape Memory Material, Mitsubishi Heavy Industries, Inc.

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  • Premisecitation

    SMPs have much lower recovery stresses (≤10 MPa) than NiTi (up to 900 MPa).

    “Shortcomings of SMPs can be seen in much lower recovery stresses (≤10 MPa [12] vs. up to 900 MPa for NiTi [21])”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [12] Rousseau, 2008, Challenges of shape memory polymers: A review of the progress toward overcoming SMP’s limitations, Polym. Eng. Sci. source

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    • cites [21] 2001, Shape memory alloys: A material and a technology, Adv. Eng. Mater. source

      Not checked in the free run.

  • Premisenone given

    Physical cross-linking is commonly found in block copolymers whose morphologies consist of at least two segregated domains.

    “Physical cross-linking is commonly found in block copolymers, whose morphologies consist of at least two segregated domains.”
    Quote in the paperNot a substantial claim
  • May combine two claims. 82
  • Classified as probably not a substantial claim. 14

  • May combine two claims.

    Premisenone given

    Thermoset SMPs have chemical cross-links, soften but do not melt at elevated temperatures; instead they either start to burn or decompose.

    “Thermoset SMPs have chemical cross-links, which soften, but do not melt at elevated temperatures; instead they either start to burn or decompose.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisenone given

    Shape memory polymers are polymer networks with integrated, stimuli-sensitive switches.

    “Shape memory polymers are polymer networks with integrated, stimuli sensitive switches.”
    Quote in the paperNot a substantial claim

  • Classified as probably not a substantial claim. May combine two claims.

    Premisenone given

    Cross-links can be chemical (covalent bonds) or physical (intermolecular interactions like crystals and chain entanglements); they prevent flow of molecular chains under deformation.

    “The cross-links can be either of chemical nature (covalent bonds) or physical nature (intermolecular interactions like crystals and chain entanglements); they prevent flow of the molecular chains under deformation.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisecitation

    Thermoset SMPs generally have higher stiffness and lower strain capability than thermoplastic SMPs, which are easy to reshape because they have no chemical cross-links.

    “In general, thermoset SMPs have higher stiffness and lower strain capability than thermoplastic SMPs, which are easy to reshape, since they have no covalent bonds between chains (no chemical cross-links) [20].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [20] Voit, 2010, High-strain shape-memory polymers, Adv. Funct. Mater. source

      Not checked in the free run.

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    Premisecitation

    Depending on the material, SMP stimuli can also be light, electricity, an alternating magnetic field, pH changes, and solvents.

    “Depending on the material used, stimuli can also be light [27] (UV [28], infrared or laser light [29][30][31][32][33]), electricity [30,[34][35][36][37][38][39][40][41][42][43][44], an alternating magnetic field, pH changes [49] and solvents [50][51][52][53].”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites [27] Jiang, 2006, Polymers move in response to light, Adv. Mater. source

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    • cites [28] Lendlein, 2005, Light-induced shape-memory polymers, Nature source

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    • cites [49] Woojin, L. (1996). Polymer Gel Based Actuator: Dynamic Model of Gel for Real Time Control. [Ph.D. Thesis, Massachusetts Institute of Technology].

      Not checked in the free run.

  • May combine two claims.

    Premisereasoning

    Netpoints cross-link chain segments and determine the permanent shape of the polymer.

    “Since the netpoints cross-link the chain segments, they determine the permanent shape of the polymer.”
    Quote in the paperSubstantial claim

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    Premisecitation

    An SMP can be deformed from a permanent into a stress-free temporary shape, which can be fixed and maintained until shape recovery is triggered by an external stimulus, most commonly a temperature increase above the transformation or switching temperature.

    “An SMP can be deformed from a permanent into a stress-free temporary shape, which can be fixed and maintained until shape recovery is triggered through an external stimulus, most common a temperature increase above the SMP's so-called transformation or switching temperature [7,10,11,[24][25][26].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [7,10,11,[24][25][26]

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    Premisenone given

    Suitable polymer network architectures consist of chain segments and netpoints.

    “Suitable polymer network architectures consist of chain segments and netpoints (Scheme I).”
    Quote in the paperNot a substantial claim

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    Premisecitation

    Domains related to the phase with the highest thermal transition temperature (Tperm) are hard domains and act as physical netpoints; they aggregate to form permanent netpoints through polar interactions, hydrogen bonding and crystallization.

    “In such examples, domains related to the phase with the highest thermal transition temperature (T perm ) are called “hard domains” and act as physical netpoints [7], they aggregate to form permanent netpoints through polar interactions, hydrogen bonding and crystallization [61].”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [7] Lendlein, 2002, Shape-memory polymers, Angew. Chem. Int. Ed. source

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    • cites [61] Wei, 1998, Shape-memory materials and hybrid composites for smart systems, J. Mater. Sci. source

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    Premisecitation

    SMPs can store a maximum strain of several hundred percent, whereas SMAs store only about 8%.

    “Beyond this, a maximum strain of several hundred percent can be stored by SMPs [20], in contrast to only about 8% by SMAs [7].”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [20] Voit, 2010, High-strain shape-memory polymers, Adv. Funct. Mater. source

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    • cites [7] Lendlein, 2002, Shape-memory polymers, Angew. Chem. Int. Ed. source

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    Premisecitation

    The rubbery modulus dictates the recovery force of an SMP, is the basis of the shape memory effect in polymers, and scales with the strain capacity of such materials.

    “Accordingly, the rubbery modulus dictates the recovery force of an SMP [63], it is the basis of the SM effect in polymers and scales with the strain capacity of such materials [64].”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [63] Yakacki, 2007, Unconstrained recovery characterization of shape-memory polymer networks for cardiovascular applications, Biomaterials source

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    • cites [64] Safranski, 2008, Effect of chemical structure and crosslinking density on the thermo-mechanical properties and toughness of (meth)acrylate shape memory polymer networks, Polymer source

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    Premisecitation

    As consistent with Flory's theory, the primary driving force for the shape memory effect is the low conformational entropy states created and frozen during shape programming; it is energetically favorable for polymer chains to return to their most disordered conformation.

    “As consistent with Flory's theory [70], the primary driving force for the SM effect is the low conformational entropy states created and frozen during shape programming [71]; it is energetically favorable for the polymer chains to finally return to their most disordered conformation [13].”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites [70] Flory, P.J. (1953). Principles of Polymer Chemistry, Cornell University Press Ithaca.

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    • cites [71] Gall, 2005, Thermomechanics of the shape memory effect in polymers for biomedical applications, J. Biomed. Mater. Res. source

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    • cites [13] Mather, 2009, Shape memory polymer research, Annu. Rev. Mater. Res. source

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    Premisecitation

    D'hollander et al. found a conversion from dispersed, randomly placed hard segment domains into progressively more periodic and interconnected hard segment nanophases with increasing hard segment content from 12 to 35 wt%, and higher cooling rates favored formation of finer phase morphologies.

    “The authors found a conversion from dispersed, randomly placed hard segment domains into progressively more periodic and interconnected hard segment nanophases with increasing hard segment content from 12 to 35 wt% and that higher cooling rates favored the formation of finer phase morphologies.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [154] Gommes, 2010, Modeling the morphology and mechanical behavior of shape memory polyurethanes based on solid-state NMR and synchrotron SAXS/WAXD, J. Mater. Chem. source

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    Premisenone given

    Interactions among hard segments, such as hydrogen bonding, dipole-dipole and induced dipole-dipole interactions, have a significant impact on phase separation of hard and soft segments, as does the ratio of crystalline to amorphous domains and presumably the size distribution of crystallites.

    “As known from thermoplastic block copolymers like SMPUs, such interactions among hard segments, like hydrogen bonding, dipole-dipole and induced dipole-dipole interactions, have a significant impact on the phase separation of hard and soft segments, same as the ratio of crystalline to amorphous domains and presumably the size distribution of crystallites.”
    Quote in the paperSubstantial claim

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    Premisecitation

    The soft segment matrix is the reversible phase and accounts for the material's shape recovery behavior due to the reversibility of phase transition.

    “The latter is the reversible phase and accounts for the material's shape recovery behavior due to the reversibility of phase transition [152].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [152] Cho, 2004, Improved mechanical properties of shape-memory polyurethane block copolymers through the control of the soft-segment arrangement, J. Appl. Polym. Sci. source

      Not checked in the free run.

  • May combine two claims.

    Premisereasoning

    Hard segments constitute the permanent shape of an SMP, but a second phase is required to obtain shape memory functionality.

    “The hard segments constitute the permanent shape of an SMP, but to obtain SM functionality a second phase is required.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisereasoning

    An SMP can be deformed with relative ease at temperatures above the phase transition and fixed by cooling below the phase transition temperature.

    “An SMP can be deformed with relative ease at temperatures above the phase transition and fixed by cooling below the phase transition temperature.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisenone given

    In segregated SMPUs, the sharpness of the glass transition depends on the degree of phase mixing; an increase in phase mixing normally results in broadening of the glass transition.

    “In segregated shape memory polyurethanes (SMPUs), the sharpness of the glass transition is dependent on the degree of phase mixing; an increase in phase mixing normally results in the broadening of a glass transition.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based). May combine two claims.

    Premisenone given

    Chemical cross-linking is achieved by reaction of functional groups attached to chain segments; the functional groups must be able to reversibly form covalent bonds by reacting with each other.

    “Chemical cross-linking is achieved by the reaction of functional groups, which are attached to chain segments.The functional groups must be able to reversibly form covalent bonds by reacting with each other.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    The shape memory effect in polymers originates from the existence of a thermally reversible phase transition and from distinct phase separation among hard and soft segments due to the incompatible nature of each segment.

    “The SM effect in polymers originates from the existence of a thermally “reversible” phase transition, e.g., from glassy to rubbery state, and from distinct phase separation among hard and soft segments due to the incompatible nature of each segment [151].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [151] Cho, 2007, Structure-property relationship and shape memory effect of polyurethane copolymer cross-linked with pentaerythritol, Fibers Polym. source

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    Premisecitation

    Strain recovery temperature increased by more than 6 °C for systems containing 0.6 wt% ODO and by 4.5 °C for those with 5 wt% LP.

    “It was also found that the strain recovery temperature increased by more than 6 °C for systems containing 0.6 wt% of ODO and by 4.5 °C for those with 5 wt% of LP.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [159] Chen, 2006, Effect of microphase-separation promoters on the shape-memory behavior of polyurethane, J. Appl. Polym. Sci. source

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    Premisecitation

    For (PCL/MDI/BDO/DMPA)-based SMP, phase separation was enforced through introduction of additional intermolecular interactions within hard domains, increasing hard domain cohesions and storage moduli in both glassy and rubbery state.

    “They demonstrated for (PCL/MDI/BDO/dimethylolpropionic acid (DMPA))-based SMP that phase separation was enforced through the introduction of additional intermolecular interactions within hard domains, which had the effect to increase hard domain cohesions and in addition storage moduli, both in the glassy and rubbery state.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [155] Kim, 1998, Polyurethane ionomers having shape memory effects, Polymer source

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    Premisecitation

    Promotion of phase separation through lubricants (ODO and LP) was indicated and shape memory properties could be improved.

    “The unveiled concept turned out to be successful, since the promotion of phase separation through the lubricants was indicated and SM properties could be improved.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [159] Chen, 2006, Effect of microphase-separation promoters on the shape-memory behavior of polyurethane, J. Appl. Polym. Sci. source

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    Premisecitation

    The ionomer gave better shape recoverability compared to the non-ionomer, mainly associated with increase in rubbery state modulus of the ionomer.

    “In conjunction, the ionomer gave better shape recoverability compared to the non-ionomer, as mainly associated with the increase in rubbery state modulus of the ionomer.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [155] Kim, 1998, Polyurethane ionomers having shape memory effects, Polymer source

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    Premisecitation

    Almost complete shape recoverabilities of 96 to 98% and best shape memory properties were witnessed for hard segment contents of 15-35%.

    “Almost complete shape recoverabilities of 96 to 98% and thus the best SM properties could be witnessed for hard segment contents of 15-35%.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [160] Cao, 2006, Structure and mechanical properties of shape memory polyurethane based on hyperbranched polyesters, Polym. Bull. source

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  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisenone given

    Hyperbranched polymers are a special type of dendritic polymers with densely branched structures and a large number of reactive groups.

    “Hyperbranched polymers are a special type of dendritic polymers with densely branched structures and a large number of reactive groups.”
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    Premisecitation

    Associated monomers with mixed reactivities, commonly denoted A2B or A3B, resemble each other in both end-group functionalities and molecular weights and align through polymerization, giving branched structures with exponential growth.

    “The associated monomers with mixed reactivities, commonly denoted A 2 B or A 3 B, resemble each other in both end-group functionalities and molecular weights and align through polymerization, thus giving branched structures with exponential growth [161,162].”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [161] Yates, 2004, Synthesis and applications of hyperbranched polymers, Eur. Polym. J. source

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    • cites [162] Voit, 2009, Hyperbranched and highly branched polymer architectures—Synthetic strategies and major characterization aspects, Chem. Rev. source

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    Premisecitation

    Shape recovery speed could be significantly shortened as substantiated by DMA, which revealed an increase in storage modulus E' for hyperbranched SMPU.

    “However, the shape recovery speed could be significantly shortened as substantiated by dynamic mechanical analysis (DMA), which revealed an increase in the storage modulus E' for hyperbranched SMPU.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [163] Sivakumar, 2009, Poly(ε-caprolactone)-based hyperbranched polyurethanes prepared via A2 + B3 approach and its shape-memory behavior, Eur. Polym. J. source

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    Premisecitation

    Branching density had no effect on crystallizability of the investigated hyperbranched polymers, so shape memory characteristics remained nearly unaffected.

    “It was found that the branching density had no effect on the crystallizability of the investigated hyperbranched polymers, so that the SM characteristics remained nearly unaffected.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [163] Sivakumar, 2009, Poly(ε-caprolactone)-based hyperbranched polyurethanes prepared via A2 + B3 approach and its shape-memory behavior, Eur. Polym. J. source

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    Premisecitation

    Shape fixity ratio decreased from 94 to about 90% with increasing hard segment content, explained by an increase in polymer rigidity.

    “Here, the shape fixity ratio decreased from 94 to about 90% with increasing hard segment content, which was explained by an increase in polymer rigidity.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [160] Cao, 2006, Structure and mechanical properties of shape memory polyurethane based on hyperbranched polyesters, Polym. Bull. source

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    Premisecitation

    SMPs can be formed into an initial, permanent shape by conventional processing methods, e.g., injection molding.

    “In principle, SMPs can be formed into an initial, permanent shape by conventional processing methods, e.g., injection molding [164].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [164] Behl, 2007, Shape-memory polymers, Mater. Today source

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    Premisecitation

    Raising curing temperature from 18 to 80 °C led to an increase in tensile strength from 6 to 16 MPa and in elongation-at-break from 41 to 822%, suggesting a strong increase in cross-linking density.

    “In one case, the raise of curing temperature from 18 to 80 °C led to an increase in tensile strength from 6 to 16 MPa and in elongation-at-break from 41 to 822%, suggesting a strong increase in cross-linking density.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [165] Zeng, 2006, Effects of reaction and cure temperatures on morphology and properties of poly(ester-urethane), J. Appl. Polym. Sci. source

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    Premisecitation

    Wet spinning clearly enhanced recovery stresses; in one example recovery stress increased from approximately 3.3 to 11.0 MPa.

    “In general, a clear enhancement in recovery stresses through wet spinning was observed; in one of their examples even an increase from approximately 3.3 to 11.0 MPa.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [168] Ji, 2006, Smart polymer fibers with shape memory effect, Smart Mater. Struct. source

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    Premisecitation

    Compared to wet-spun fibers, melt-spun fibers had higher tenacity and breaking strains and revealed superior shape fixity and recovery ratios.

    “Compared to wet-spun fibers, the melt-spun fibers had higher tenacity and breaking strains and revealed superior shape fixity and recovery ratios.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [121] Meng, 2007, Morphology, phase separation, thermal and mechanical property differences of shape memory fibres prepared by different spinning methods, Smart Mater. Struct. source

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    Premisecitation

    Films cast at higher temperatures gave rise to high hard segment crystallinity, more apparent phase separation and better water-vapor permeability.

    “The films casted at higher temperatures gave rise to high hard segment crystallinity, more apparent phase separation and better water-vapor permeability.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [167] Hu, 2003, Influence of processing conditions on the microstructure and properties of shape memory polyurethane membranes, Text. Res. J. source

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    Premisecitation

    Wet-spun SMPU fibers showed less pronounced shape fixities but better shape recoverabilities than films.

    “It was found that the fibers showed less pronounced shape fixities, but better shape recoverabilities than the films.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [168] Ji, 2006, Smart polymer fibers with shape memory effect, Smart Mater. Struct. source

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    Premisecitation

    Temperature dependency of water-vapor permeability is an important criterion for effective utilization of polymers in water-proof textiles.

    “Apart from that, it is worth mentioning that the temperature dependency of water-vapor permeability (WVP) is an important criterion, which has to be taken into account for the effective utilization of polymers in water-proof textiles [171,172].”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [171] Mondal, 2006, Structural characterization and mass transfer properties of nonporous-segmented polyurethane membrane: Influence of the hydrophilic segment content and soft segment melting temperature, J. Membr. Sci. source

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    • cites [172] Mondal, 2007, A Novel Approach to excellent uv protecting cotton fabric with functionalized MWNT Containing water vapor permeable PU coating, J. Appl. Polym. Sci. source

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  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Premisenone given

    To date, literature focuses on the functional study of SMPs in a laboratory environment (thermochamber, water bath, etc.).

    “To date, literature focuses on the functional study of SMPs in a laboratory environment (thermochamber, water bath, etc.).”
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    Premisecitation

    Ultrafine fibers provide unexpectedly high surface area to volume ratios and are of interest for many applications, ranging from textile to composite reinforcement, sensors, biomaterials and membrane technology.

    “Ultrafine fibers provide unexpected high surface area to volume ratios and are of interest for many applications, ranging from textile to composite reinforcement, sensors, biomaterials and membrane technology [170].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [170] Han, 2009, Synthesis and characterization of biodegradable polyurethane based on poly(ε-caprolactone) and L-lysine ethyl ester diisocyanate, Front. Mater. Sci. China source

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    Premisecitation

    For electrospun PCL-based SMPU nanofibers, shape recoverabilities of 98% and shape fixities of 80% were detected.

    “In detail, shape recoverabilities of 98% and shape fixities of 80% could be detected.”
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    • cites [169] Zhuo, 2008, Electrospun polyurethane nanofibres having shape memory effect, Mater. Lett. source

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    Premisecitation

    The observed increase in water-vapor permeability was attributed to an improvement of chain mobility when passing the phase transition.

    “The observed increase in WVP was attributed to an improvement of chain mobility when passing the phase transition.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [173] Jeong, 2000, Water vapor permeability of shape memory polyurethane with amorphous reversible phase, J. Polym. Sci. Part B Polym. Phys. source

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    Premisecitation

    Recovery behavior is strongly influenced by the amount of stress applied to the polymer and by its thermal expansion behavior.

    “The recovery behavior is strongly influenced by the amount of stress applied to the polymer and by its thermal expansion behavior [101,186,187].”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites [101] Liu, 2006, Thermomechanics of shape memory polymers: Uniaxial experiments and constitutive modeling, Int. J. Plast. source

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    • cites [186] Gunes, 2008, Effect of thermal expansion on shape memory behavior of polyurethane and its nanocomposites, J. Polym. Sci. B Polym. Phys. source

      Not checked in the free run.

    • cites [187] Yakacki, 2008, Deformation Limits in shape-memory polymers, Adv. Eng. Mater. source

      Not checked in the free run.

  • May combine two claims.

    Premisereasoning

    Applications for SMPs are diverse and involve deformations like bending, compression and drawing; accordingly there are different testing methods to quantify the shape memory behavior of a polymer.

    “Applications for SMPs are diverse and involve deformations like bending, compression and drawing, accordingly there are different testing methods to quantify the SM behavior of a polymer, such as bending tests [174-176], fold-deploy tests [135], uniaxial experiments”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    For acrylate-based SMP (Ttrans = Tg), lower deformation temperatures (Td < Tg) decrease the temperature required for free strain recovery and favor much higher recovery stresses.

    “The same group [71] also observed for acrylate-based SMP (T trans = T g ) that lower deformation temperatures (T d < T g ) decrease the temperature required for free strain recovery and favor much higher recovery stresses.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [71] Gall, 2005, Thermomechanics of the shape memory effect in polymers for biomedical applications, J. Biomed. Mater. Res. source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    Increasing fraction of reinforcement leads to an increase in modulus and in recoverable force, whereas ductility and shape recoverability decrease.

    “They also reported that an increasing fraction of reinforcement leads to an increase in modulus and in recoverable force, whereas ductility and shape recoverability decrease.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [191] Ohki, 2004, Mechanical and shape memory behavior of composites with shape memory polymer, Compos. A source

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  • May combine two claims.

    Interpretationreasoning

    Polymer chains can relax when deformed at temperatures well above Tg, but not below.

    “This phenomenon is explicable with the fact that polymer chains can relax when deformed at temperatures well above T g , but not below.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisecitation

    Woven fiberglass SMPU composites displayed increased ultimate strength (by 50%) and improved Young's modulus (by almost 400%) compared to non-reinforced analogs.

    “Woven fiberglass SMPU composites, for instance, displayed increased ultimate strength (by 50%) and improved Young's modulus (by almost 400%) towards their non-reinforced analogs [190].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [190] Liang, 1997, Investigation of shape memory polymers and their hybrid composites, J. Intell. Mater. Sys. Struct. source

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  • May combine two claims.

    Premisecitation

    Incorporation of 40 wt% AlN slightly increased shape fixity ratio from about 43 to 45% but lowered shape recovery ratio by more than 20%.

    “The incorporation of 40 wt% AlN slightly increased the weak shape fixity ratio from about 43 to 45%, but lowered the shape recovery ratio by more than 20%.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [199] Razzaq, 2007, Thermomechanical studies of aluminum nitride filled shape memory polymer composites, Polym. Compos. source

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  • May combine two claims.

    Premisecitation

    Porous fibers remaining after thermal degradation of PVA/SWCNT composites comprised entangled CNTs held by van der Waals interactions and had better mechanical properties than random assemblies of nanotubes in bucky paper.

    “The remaining porous fibers were comprised of entangled CNTs, held together by van der Waals interactions, and had much better mechanical properties than random assemblies of nanotubes in bucky paper.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [192] Viry, 2010, Nanotube fibers for electromechanical and shape memory actuators, J. Mater. Chem. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    In PU-silica chemical hybrid formulations, the most functionally reliable material contained 1 wt% silica and had shape fixities and recoverabilities of 99% up to the fourth thermo-mechanical cycle.

    “The most functionally reliable material, among the investigated PU-silica chemical hybrid formulations, contained 1 wt% of silica and revealed excellent shape fixities and recoverabilities of 99% up to the fourth thermo-mechanical cycle.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [194] Jung, 2010, Organic-inorganic chemical hybrids having shape memory effect, J. Mater. Chem. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Fillers can negatively affect shape recoverability of an SMP due to their size and higher stiffness compared to matrix polymer, and at high loading levels may disturb polymer networks responsible for SM functionality.

    “However, in some cases fillers are prone to have negative effects on the shape recoverability of an SMP due to their size and substantially higher stiffness compared to the matrix polymer.At high loading levels, they may even disturb the polymer networks responsible for SM functionality [198].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [198] Gunes, 2008, Evaluation of nanoparticulate fillers for development of shape memory polyurethane nanocomposites, Polymer source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Mesua ferrea L. seed oil-based epoxy-modified hyperbranched PU composites with MWCNTs and 5, 10, 20 wt% epoxy resin had shape retentions 74-87%, shape recoverabilities 90-98%, and improved tensile strengths vs pristine hyperbranched PU.

    “The composites with 5, 10 and 20 wt% of epoxy resin revealed shape retentions between 74 and 87%, shape recoverabilities of 90 to 98% and significantly improved tensile strengths towards pristine hyperbranched PU.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [197] Deka, 2010, Biocompatible hyperbranched polyurethane/multi-walled carbon nanotube composites as shape memory materials, Carbon source

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  • May combine two claims.

    Premisecitation

    Morthane/MWCNT composites containing 2.9 vol% (5 wt%) MWCNTs exhibited improved shape fixity ratios from 56 to 70% for εm = 250% and increased recovery stresses from 0.6 to 1.4 MPa across the soft segment melting transition.

    “polymer carbon nanotube composites containing 2.9 vol% (5 wt%) MWCNTs exhibited improved shape fixity ratios (from 56 to 70% for ε m = 250%) and increased recovery stresses from 0.6 MPa to 1.4 MPa, when passing the soft segmental melting transition.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [196] Koerner, 2004, Remotely actuated polymer nanocomposites—Stress-recovery of carbon-nanotube-filled thermoplastic elastomers, Nat. Mater. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Shape fixity ratio and shape recovery ratio improved with increasing celite content; both ratios of the first thermo-mechanical cycle were close to 100% for specimens containing 0.8 wt% celite.

    “the shape fixity ratio and shape recovery ratio improved with increasing celite content, both ratios of the first thermo-mechanical cycle were close to 100% for specimens containing 0.8 wt% celite.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [80] Park, 2008, Shape memory effects of polyurethane block copolymers cross-linked by celite, Fiber. Polym. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    α-cyclodextrin-PEG inclusion crystallites served as fixing phase and PEG crystallites as reversible phase in PEG inclusion complexes.

    “The α-cyclodextrin-PEG inclusion crystallites served as fixing phase and the PEG crystallites as reversible phase.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [200] Zhang, 2008, A novel supramolecular shape memory material based on partial α-CD-PEG inclusion complex, Polymer source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    SMPU containing up to 30 wt% chopped strand glass fibers of 3 mm length had improved creep properties (rupture strain and time) and enhanced resistance to cyclic loading.

    “Ohki et al. [202] found an improvement in creep properties (rupture strain and time) and enhancement in resistance to cyclic loading for SMPU from Diaplex Co., Ltd., containing up to 30 wt% of chopped strand glass fibers of 3 mm length.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [202] Ohki, 2004, Creep and cyclic mechanical properties of composites based on shape memory polymer, Sci. Eng. Compos. Mater. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Presence of clay particles hindered soft segment crystallization and promoted phase mixing between hard and soft segments.

    “However, the presence of clay particles hindered soft segment crystallization and promoted phase mixing between hard and soft segments.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [203] Cao, 2007, Nanoclay-tethered shape memory polyurethane nanocomposites, Polymer source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    For material with 6.7 wt% filler at thickness 3 mm, EMI SE exceeded 30 dB for all three frequency bands; maximum value reached 65 dB.

    “For a material with 6.7 wt% filler at a thickness of 3 mm, the value of EMI SE exceeded over 30 dB for all three frequency bands; its maximum value even reached 65 dB.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [204] Zhang, 2007, Electromagnetic interference shielding effect of nanocomposites with carbon nanotube and shape memory polymer, Compos. Sci. Technol. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    In carbon nanofiber/nanopaper epoxy SMP composites, shortest detected shape recoveries took 186 s and shape recoverabilities were reduced with increasing carbon nanofiber contents.

    “Nevertheless, the shortest detected shape recoveries took quite long (186 s) and shape recoverabilities were reduced with increasing carbon nanofiber contents”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [210] Lu, H., Liu, Y., Gou, J., Leng, J., and Du, S. (2010). Synergistic effect of carbon nanofiber and carbon nanopaper on shape memory polymer composite. Appl. Phys. Lett. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Major challenges for magnetically induced actuation are increase in inductive heating efficiency, applied frequencies should not exceed clinically usable window 50-100 kHz, and tailoring transition temperatures near body temperature for multi-shape polymers.

    “major challenges are still the increase in inductive heating efficiency [13,45] (the applied frequencies should not exceed the restrictive window of clinically usable frequencies (50-100 kHz) [216]), and in case of polymers with multi-shape capabilities the tailoring of transition temperatures in a region close to body temperature.”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites [13] Mather, 2009, Shape memory polymer research, Annu. Rev. Mater. Res. source

      Not checked in the free run.

    • cites [45] Buckley, 2006, Inductively heated shape memory polymer for the magnetic actuation of medical devices, IEEE Trans. Biomed. Eng. source

      Not checked in the free run.

    • cites [216] Jordan, 1999, Magnetic fluid hyperthermia (MFH): Cancer treatment with AC magnetic field induced excitation of biocompatible superparamagnetic nanoparticles, J. Magn. Magn. Mater. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Mixing 0.5 vol% Ni particles and 4-10 vol% carbon black with SMPU and applying low magnetic field during DMF volatilization formed conductive Ni powder chains and improved electrical conductivity.

    “The authors obtained electrically conductive composites by mixing 0.5 vol% Ni particles and 4-10 vol% carbon black with an SMPU (T trans = T g ), which was dissolved in DMF.During volatilization of DMF, a low magnetic field was applied to the polymer/filler solution.As a result, conductive Ni powder chains formed and the electrical conductivity improved (Figure 2).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [48] Leng, J.S., Huang, W.M., Lan, X., Liu, Y.J., and Du, S.Y. (2008). Significantly reducing electrical resistivity by forming conductive Ni chains in a polyurethane shape-memory polymer/carbon-black composite. Appl. Phys. Lett. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Shirai and Hayashi reported thermoplastic SMPU had excellent heat resistance at 70 °C for 500 h and good weatherability after 300 h sunshine exposure, proven by insignificant changes in elastic modulus.

    “Excellent heat resistance at 70 °C for 500 h and good weatherability even after 300 h of sunshine exposure, were proven by insignificant changes in the elastic modulus of the specimens.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [54] Shirai, Y., and Hayashi, S.-I. (1988). Development of Polymeric Shape Memory Material, Mitsubishi Heavy Industries, Inc.

      Not checked in the free run.

  • May combine two claims.

    Interpretationcitation

    Absorption of moisture strongly lowered the material's transition temperature, and since Tg fell below room temperature, shape recovery was initiated.

    “The reason behind was the absorption of moisture, which strongly lowered the material's transition temperature (Figure 3).Since T g fell below room temperature, shape recovery was initiated.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [217] Yang, 2004, On the effects of moisture in a polyurethane shape memory polymer, Smart Mater. Struct. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    For SMPU composites containing carbon nanopowder, higher resistances towards humidity were verified; higher filler contents lowered moisture sensitivity.

    “For composites containing carbon nanopowder as filler, much higher resistances towards humidity could be verified; higher contents of fillers even lowered moisture sensitivity.”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [36] Yang, 2005, Qualitative separation of the effects of carbon nano-powder and moisture on the glass transition temperature of polyurethane shape memory polymer, Scr. Mater. source

      Not checked in the free run.

    • cites [218] Yang, 2005, Effects of moisture on the glass transition temperature of polyurethane shape memory polymer filled with nano-carbon powder, Eur. Polym. J. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Uptake of moisture lowered Tg and activated shape recovery on programmed specimens of SMPU containing pyridine moieties.

    “the authors noted that the uptake of moisture lowered T g and activated shape recovery on programmed specimens.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [53] Chen, 2009, Novel moisture-sensitive shape memory polyurethanes containing pyridine moieties, Polymer source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Shape recovery of styrene-based SM thermosetting resin can be triggered through uptake of DMF; Tg dropped from 70 to 56 °C within 120 min of DMF immersion.

    “Lv et al. [52] have proven for commercially available styrene-based SM thermosetting resin that shape recovery can also be triggered through the uptake of DMF.The investigated material displayed a drop in T g from 70 to 56 °C within 120 min of DMF immersion.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [52] Lv, 2008, Shape-memory polymer in resonse to solution, Adv. Eng. Mater. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Among bound water and free water, bound water strongly lowered Tg, whereas influence of free water on Tg seemed negligible.

    “Among the two types of water species investigated, namely bound water (directly attached to the polymer backbone) and free water (clustered water), bound water was observed to strongly lower T g , whereas the influence of free water on T g seemed to be negligible.”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [36] Yang, 2005, Qualitative separation of the effects of carbon nano-powder and moisture on the glass transition temperature of polyurethane shape memory polymer, Scr. Mater. source

      Not checked in the free run.

    • cites [218] Yang, 2005, Effects of moisture on the glass transition temperature of polyurethane shape memory polymer filled with nano-carbon powder, Eur. Polym. J. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Thermoplastic SMPU had good endurance to repeated loading, demonstrated by constant glass transition temperatures after cycling temperature between 5 and 40 °C with regular stress-loading and unloading.

    “Good endurance to repeated loading was demonstrated by constant glass transition temperatures after cycling temperature between 5 and 40 °C, accompanied by regular stress-loading and unloading steps.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [54] Shirai, Y., and Hayashi, S.-I. (1988). Development of Polymeric Shape Memory Material, Mitsubishi Heavy Industries, Inc.

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    After SMPU soaked 24 h at 35 °C in aqueous solution, elongation capability virtually remained same, tensile strength decreased by 27%, and Tg reduced from 55 to 40 °C.

    “The experiments revealed that the material's elongation capability virtually remained the same after the SMPU had been soaked for 24 h at 35 °C in an aqueous solution.At the same time, the tensile strength decreased by 27% and the glass transition temperature was reduced from 55 to 40 °C.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [224] Hayashi, S. (1990). Technical Report on Shape Memory Polymers, Nagoya Research and Development Center, Mitsubishi Heavy Industries, Inc.

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Styrene-based SMP specimens displayed distinct sensitivity to lube oil as shown by development of microcracks on their surface, whereas no microcracking was observed for epoxy-based SMP.

    “Styrene-based specimens displayed distinct sensitivity to lube oil as shown by the development of microcracks on their surface.In contrast, no microcracking was observed for epoxy-based SMP.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [230] Tandon, 2009, Durability assessment of styrene- and epoxy-based shape-memory polymer resins, J. Intell. Mater. Sys. Struct. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Styrene-based and epoxy-based SMP resins after exposure to water, lube oil, and UV conditioning had reasonable stress recovery and excellent shape recoverabilities: styrene close to 100% (including 75 UV cycles, no lube oil data); epoxy 96-100% (N=1) and 94-100% (N=2, including 125 UV cycles and lube oil data).

    “The good specimen resistance towards the different exposure scenarios was demonstrated by reasonable stress recovery data and excellent shape recoverabilities for styrene-based SMP (N = 1 and 2: close to 100%, including data for 75 UV cycles, but no lube oil data) and for epoxy-based SMP (N = 1:96-100%; N = 2:94-100%, including the data for 125 UV cycles and lube oil data).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [230] Tandon, 2009, Durability assessment of styrene- and epoxy-based shape-memory polymer resins, J. Intell. Mater. Sys. Struct. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    In dual-shape testing of hydrolyzed PBA-based SMPU, residual strain and transition temperature gradually increased, and shape and total shape recoverabilities worsened, accompanied by growth in soft segment crystallinity and changes in phase separation.

    “The testing results gave gradual increases in residual strain ε p , associated with the amount of unrecoverable strain, and in transition temperature.The shape and total shape recoverabilities of the polymer worsened as a consequence of degradation (Figure 4), which was accompanied by growth in soft segment crystallinity, as indicated by differential scanning calorimetry (DSC), and changes in”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites [225] Pretsch, 2010, Hydrolytic aging of crystallizable shape memory poly(ester urethane): Effects on the thermo-mechanical properties and visco-elastic modeling, Eur. Polym. J. source

      Not checked in the free run.

    • cites [226] Pretsch, T. (2008). Degradation, Functional Stability and Protection of a Shape Memory Polymer, WMRIF Workshop for young scientists. Available online: http://www.bam.de/de/kompetenzen/fachabteilungen/abteilung_4/fg43/fg43_medien/div43_ag2_article_pretsch_japan_2008.pdf.

      Not checked in the free run.

    • cites [227] Pretsch, 2009, Hydrolytic degradation and functional stability of a segmented shape memory poly(ester urethane), Polym. Degradation Stability source

      Not checked in the free run.

    • Rests on an assumption: SM properties show aging in functionality and each SMP displays an individual aging behavior.

  • May combine two claims.

    Premisecitation

    Both styrene-based and epoxy-based SMPs developed a slight yellow tint during UV exposure.

    “Both types of SMPs developed a slight yellow tint in the course of UV exposure.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [230] Tandon, 2009, Durability assessment of styrene- and epoxy-based shape-memory polymer resins, J. Intell. Mater. Sys. Struct. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Hydrolysis-stabilized PBA-based SMPU from Bayer had improved long-term stability and SM functionality, with delay of mechanical and functional impairment through hydrolysis (80 °C) by 44 d and 35 to 45 d, respectively, and 6.5-fold increase in durability towards embrittlement.

    “The concept turned out to be successful; the SMPU's long-term stability and thus long-term SM functionality improved as evidenced by a retard of the beginning of mechanical and functional impairment through hydrolysis (80 °C) by 44 d and 35 to 45 d, respectively.Hence, the SMPU revealed a 6.5-fold increase in durability towards embrittlement.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [228] Pretsch, 2010, Shape memory poly(ester urethane) with improved hydrolytic stability, Polym. Degrad. Stab. source

      Not checked in the free run.

    • Rests on an assumption: SM properties show aging in functionality and each SMP displays an individual aging behavior.

  • May combine two claims.

    Premisecitation

    Shape recovery ratio of samples containing 15 wt% Fe3O4 decreased from 75% before degradation to 20% in 12th week; dropped by about 35% for 5 wt% Fe3O4 and by about 25% for pristine material.

    “the shape recovery ratio of samples containing 15 wt% Fe 3 O 4 decreased from 75% before degradation to 20% in the 12th week.At the same time, the shape recovery ratio dropped by about 35% for samples loaded with 5 wt% Fe 3 O 4 and by about 25% for pristine material.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [233] Yu, 2009, Influence of in vitro degradation of a biodegradable nanocomposite on its shape memory effect, J. Phys. Chem. C source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Higher thermal stabilities (e.g., higher activation energies at 10% degradation) were achieved for SMPUs with attached MWCNTs, which seemed to enable better dispersion of fillers in polymer matrix.

    “Higher thermal stabilities, e.g., higher activation energies at 10% degradation, were achieved for SMPUs with attached MWCNTs, which seemed to enable a better dispersion of the fillers in the polymer matrix.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [238] Jana, 2008, Thermal stability and molecular interaction of polyurethane nanocomposites prepared by in situ polymerization with functionalized multiwalled carbon nanotubes, J. Appl. Polym. Sci. source

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  • May combine two claims.

    Premisecitation

    In POSS hybrid copolymers containing 50 wt% POSS in polynorbornene matrix, Tg increased from 57 to 66 °C for cyclopentyl corner groups and to 73 °C for cyclohexyl corner groups.

    “Due to the presence of the fillers, T g increased from 57 to 66 °C, when cyclopentyl (Cp) corner groups were chosen, and to 73 °C in case of cyclohexyl (Cy) corner groups.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [88] Jeon, 2000, Shape memory and nanostructure in poly(norbornyl-POSS) copolymers, Polym. Int. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    At 1×10^4 Gy Co-60 gamma irradiation of styrene-based SMP, gel content decreased from 35 to 30%, tensile strength reduced by 17%, and tan δ peak associated with Tg decreased from 87 to 82 °C.

    “At a dose of 1 × 10 4 Gy, they witnessed a decrease in gel content from 35 to 30%, a reduction in tensile strength by -17% and a decrease in the DMA's tan δ peak associated with T g from 87 to 82 °C.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [234] Zhang, D., Liu, Y., and Leng, J. (2009). Influence of radiation dose on shape memory effect of styrene copolymer. Proc. SPIE. source

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  • May combine two claims.

    Premisecitation

    Above and at 85 °C, recovery speed of styrene-based SMP was decelerated by irradiation, whereas at 75 and 80 °C it was the opposite; at 75 °C irradiated SMP took 60 s and pristine 90 s.

    “In particular above and at 85 °C, the SMP's recovery speed was decelerated through irradiation, whereas at 75 and 80 °C it was the other way around.At 75 °C, for instance, irradiated SMP took 60 s to recover and pristine SMP 90 s.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [234] Zhang, D., Liu, Y., and Leng, J. (2009). Influence of radiation dose on shape memory effect of styrene copolymer. Proc. SPIE. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Results of 50-cycle thermo-mechanical measurements on Tecoflex depended on highest testing temperature; higher maximum strains (100, 200, 400, 600%) favored lower shape recoverabilities at 90 °C, whereas at 80 °C a virtually opposite trend was indicated.

    “The results of 50-cycle thermo-mechanical measurements were dependent on the choice of the highest testing temperature.Higher maximum strains in the order 100, 200, 400 and 600% favored throughout lower shape recoverabilities at 90 °C; whereas at 80 °C a virtually opposite trend was indicated.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [240] Schmidt, 2009, Functional fatigue of shape-memory polymers, Mater. Res. Soc. Symp. Proc. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    In glass fiber reinforced SMPU composites, loss in stress keeping ratio was strongest for bulk specimens and improved with increasing filler contents from 10 to 30 wt%.

    “In the course of cycling, the loss in stress keeping ratio was strongest for bulk specimens and improved with increasing filler contents from 10 to 30 wt%.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [191] Ohki, 2004, Mechanical and shape memory behavior of composites with shape memory polymer, Compos. A source

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  • May combine two claims.

    Premisecitation

    After N = 19 thermo-mechanical cycles (εm = 100%), commercial SMP Veriflex displayed steady decrease in shape recoverability and changed surface from flat to wavy.

    “After applying a series of N = 19 thermo-mechanical cycles (ε m = 100%), the material displayed a steady decrease in shape recoverability and changed its surface from flat to wavy.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [239] Schmidt, 2008, Functional fatigue of shape memory polymers, Adv. Eng. Mater. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    For glass fiber reinforced SMPU composites, stress keeping ratio depends both on weight fraction of reinforcement and on number of tested cycles.

    “The measurement data for up to 60 consecutive cycles, generated from static tensile tests, revealed that the “stress keeping ratio” depends both on the weight fraction of the reinforcement and on the number of tested cycles.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [191] Ohki, 2004, Mechanical and shape memory behavior of composites with shape memory polymer, Compos. A source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    For commercial amorphous cycloaliphatic poly(ether urethane) Tecoflex, Tg of mixed phase used as switching phase was 74 °C and softening temperature of hard domains was 120 °C as evidenced by DMA.

    “The T g of a mixed phase, which was used as switching phase, was 74 °C and the softening temperature of the hard domains was 120 °C as evidenced by DMA measurements.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [240] Schmidt, 2009, Functional fatigue of shape-memory polymers, Mater. Res. Soc. Symp. Proc. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Repeated cycling in air (N > 50) had no significant impact on shape fixing abilities and shape recoverabilities of Si-O-Si cross-linked organic/inorganic hybrid polyurethanes, but cycling in water lowered shape fixing abilities.

    “They found that repeated cycling in air (N > 50) had no significant impact on the material's shape fixing abilities and shape recoverabilities, but cycling in water lowered the shape fixing abilities, which presumably is due to the plasticizer effect of water.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [79] Xu, 2006, Synthesis and shape memory effects of Si–O–Si cross-linked hybrid polyurethanes, Polymer source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Presence of POSS molecules and aggregates decreased shape recoverabilities from 92% for PN homopolymer to 84% for CpPN and 70% for CyPN, while providing superior thermal stability.

    “Although the presence of POSS molecules and their aggregates influenced the relaxation of polynorbornene chains, counteracting the recovery process and thus decreasing shape recoverabilities (from 92% for PN homopolymer to 84% for CpPN and 70% for CyPN, respectively), the advantage of such systems lies in their superior thermal stability.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [88] Jeon, 2000, Shape memory and nanostructure in poly(norbornyl-POSS) copolymers, Polym. Int. source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    The majority of SMP patents lie in the medical sector.

    “As noted about three years ago by Dietsch and Tong [9], the majority of SMP patents lie in the medical sector.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [9] Dietsch, 2007, A review—features and benefits of shape memory polymers (SMPs), J. Adv. Mater.

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    An SMP is able to recover several times from its temporary, compression-programmed shape into its permanent shape, thus repairing internal damages.

    “The reason behind is that an SMP is able to recover several times from its temporary, compression-programmed [181] into its permanent shape, thus repairing internal damages.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [181] Li, 2010, Thermomechanical characterization of a shape memory polymer based self-repairing syntactic foam, Polymer source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Microcracks in the studied SMP-based syntactic foam could be reduced in length and microcrack openings were narrowed as a result of healing.

    “The excellent polymer performance was proven in seven impact-healing cycles through the ability to repeatedly heal the impact damages; microcracks could be reduced in length and microcrack openings were narrowed as a result of healing.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [282] Li, 2008, A self-healing smart syntactic foam under multiple impacts, Compos. Sci. Technol. source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S2 (checkable), S3 (load-bearing).

    Interpretationcitation

    The SMP technology is on the verge of entering applications where self-healing plays a dominant role.

    “The given findings show that impact testing is a powerful tool to characterize the self-healing efficiency of SMP foams and indicate that the SMP technology is on the verge of entering applications, where self-healing plays a dominant role.”
    Quote in the paperNot a substantial claim
    • Rests on an assumption: SMP foams are able to repeatedly heal matrix crackings created by environmental effects.
    • Rests on an assumption: Polymers are susceptible to damage in the form of cracks, which lead to mechanical degradation.
90 of 90

  • The paper relies on this without support.

    There is no linear relationship between the hard-to-soft segment ratio, cross-linker content, and the shape memory properties of a polymer.

    “The difficulty is mostly due to the fact, that there is no linear relationship between the mentioned parameters.”

  • The paper relies on this without support.

    Significant changes in processing go along with substantial modification of shape memory properties.

    “Although not reported, it is most likely that significant changes in processing go along with the substantial modification of SM properties.”

  • The paper relies on this without support.

    The environment used to evaluate shape memory properties is equalized with the utilized thermo-mechanical characterization method.

    “In this way, the environment, which is used to evaluate SM properties, is equalized with the utilized thermo-mechanical characterization method.”

  • The paper relies on this without support.

    The prerequisite for magneto-sensitivity in SMP composites is uniform dispersion of suitable fillers inside the SMP matrix.

    “The prerequisite for magneto-sensitivity in SMP composites is the uniform dispersion of suitable fillers inside the SMP matrix.”

  • The paper relies on this without support.

    SM properties show aging in functionality and each SMP displays an individual aging behavior.

    “In line with aging processes in other materials, SM properties show aging in functionality and each SMP displays an individual aging behavior.”

  • The paper relies on this without support.

    Altering the relative foam density allows for an optimized trade-off between weight and mechanical properties.

    “The altering of the relative foam density allows for an optimized trade-off between weight and mechanical properties.”

  • The paper relies on this without support.

    The main advantage of SMP foams is that structures, when compressed and stored below a transition temperature, are a small fraction of their original size.

    “The main advantage of this technology is that structures, when compressed and stored below a transition temperature, are a small fraction of their original size.”

  • The paper relies on this without support.

    SMP foams are able to repeatedly heal matrix crackings created by environmental effects.

    “SMP foams have been identified as useful alternative to the described single-use systems, since they are able to repeatedly heal matrix crackings, created e.g., by environmental effects.”

  • The paper relies on this without support.

    Reversible actuation is a vital factor in terms of the acceptance of SMPs in actuator applications.

    “For instance, reversible actuation is a vital factor in terms of the acceptance of SMPs in actuator applications, illustrating strong need for further research in this field.”

  • The paper relies on this without support.

    Polymers are susceptible to damage in the form of cracks, which lead to mechanical degradation.

    “Polymers are susceptible to damage in the form of cracks, which lead to mechanical degradation.”
10 of 10

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

  • The frequency of the magnetic field should be in the clinically safety range (50-100 kHz).

    “First of all, the frequency of the magnetic field should be in the clinically safety range (50e100 kHz) [397].”

    From A review of stimuli-responsive shape memory polymer composites (2013) · cites this paper as [397]

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • Reported hard-segment content exceeds the stated study range

    Minor

    The stated hard-segment-content range ends at 27%, but the next sentence describes a specimen from the same study with 37 wt% hard segments.

1 of 1

Cites

Flagged first, then by citations

3 of the 275 references couldn’t be matched to a known paper.

Research works printed but not linked: 9

  1. Nakayama, 1991, Properties and applications of shape-memory polymers, Int. Polym. Sci. Tech., 18, T43
  2. Safranski, 2008, Effect of chemical structure and crosslinking density on the thermo-mechanical properties and toughness of (meth)acrylate shape memory polymer networks, Polymer, 49, 4446, 10.1016/j.polymer.2008.07.060 · DOI
  3. Radusch, 2009, Shape-memory behavior of peroxidic cross-linked polyethylene based blends, Chem. Listy, 103, S33
  4. Russel, 1999, Potential uses of shape memory film in clothing, Tech. Text. Int., 8, 17
  5. Everhart, 2005, High strain fiber reinforced reusable shape memory polymer mandrels, Int. SAMPE Symp. Exhib., 50, 955
  6. Lin, 1998, Study on shape-memory behavior of polyether-based polyurethanes. II. Influence of soft-segment molecular weight, J. Appl. Polym. Sci., 69, 1575, 10.1002/(sici)1097-4628(19980822)69:8<1575::aid-app12>3.0.co;2-u · DOI
  7. Koerner, 2004, Remotely actuated polymer nanocomposites—Stress-recovery of carbon-nanotube-filled thermoplastic elastomers, Nat. Mater., 3, 115, 10.1038/nmat1059 · DOI · Paper page
  8. Pretsch, T. (2008). Degradation, Functional Stability and Protection of a Shape Memory Polymer, WMRIF Workshop for young scientists. Available online: http://www.bam.de/de/kompetenzen/fachabteilungen/abteilung_4/fg43/fg43_medien/div43_ag2_article_pretsch_japan_2008.pdf.
  9. Meents, E.P., Barnell, T.J., Cable, K.M., Margraf, T.W., and Havens, E. (2009, January 18–21). Self-healing reflexive composite structures for marine environments. Proceedings of SAMPE 2009, Baltimore, MD, USA.

Cited by

Sorted by citations

Related

Authors
Pretsch, T.
Affiliations
Federal Institute For Materials Research and Testing (DE)
Corresponding author
Pretsch, Thorsten
ORCID
Pretsch, Thorsten
Venue
Polymers
Publisher
MDPI AG
Published
2010-07-28
Volume
2
Issue
3
Pages
120-158
ISSN
2073-4360 (ISSN-L)
DOI
10.3390/polym2030120
OpenAlex
W1987057728
Semantic Scholar
7e01ff7994d000cbfeac468d05c5ccbae523f3dd
Cited by
138
References
275
Citations by year
2026: 9 · 2025: 10 · 2024: 3 · 2023: 8 · 2022: 6 · 2021: 10 · 2020: 7 · 2019: 10 · 2018: 5 · 2017: 9 · 2016: 9 · 2015: 16 · 2014: 7 · 2013: 15 · 2012: 7
FWCI
17.62
Type
journal article
Language
en
Open access
Licence
Locations
  • Polymers (publishedVersion, cc-by)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion)
Topics
  • Physical Sciences › Engineering › Mechanical Engineering › Advanced Materials and Mechanics
  • Physical Sciences › Materials Science › Polymers and Plastics › Polymer composites and self-healing
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Medicine › Hydrogels: synthesis, properties, applications
Keywords
shape memory polymers, stimuli-responsive materials, shape recovery, shape preservation, functional determinants, polymer composites, aging materials, compression, hibernation, lubricants, ultraviolet radiation, thermomechanical cycling

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Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Claims read by deepseek-v4.1-flash under definition version 3 (extract-v3) on 2026-10-09.

Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-10-09.

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