Microphase separation and rheology of a semicrystalline poly(ether-ester) multiblock copolymer

Veenstra, Harm; Hoogvliet, Rene M.; Norder, Ben; Boer, A. Posthuma De

doi:10.1002/(sici)1099-0488(199808)36:11<1795::aid-polb1>3.0.co;2-q

Cited by 43 publications

(40 citation statements)

References 11 publications

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“…The melt rheology of copoly(ether ester)s consisting of PBT hard segments and PTMO soft segments is significantly different. Veenstra et al 7 showed that for these materials crystallization occurs from a homogeneous melt. Temperature-dependent dynamic shear experiments revealed that upon cooling from the homogeneous melt a sharp rise in G′ is observed, resulting from crystallization of the hard segment.…”

Section: Resultsmentioning

confidence: 99%

Morphology, Surface Structure, and Elastic Properties of PBT-Based Copolyesters with PEO-b-PEB-b-PEO Triblock Copolymer Soft Segments

et al. 2002

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The elasticity of commonly known poly(butylene terephthalate)-poly(tetramethylene oxide) (PBT-PTMO)-based copoly(ether ester)s is increased by replacement of PTMO soft segments with poly-(ethylene oxide)-block-poly(ethylene-stat-butylene)-block-poly(ethylene oxide) (PEO-b-PEB-b-PEO) triblock copolymer soft segments containing a nonpolar middle block based on hydrogenated polybutadiene (PEB). The incorporation of this strongly incompatible PEB block resulted in the aimed increased phase separation between the PBT hard blocks and the soft segment phase, leading to a disperse PBT phase and hence to an increased elasticity. Dynamic shear experiments in combination with small-angle X-ray scattering revealed that crystallization of the PBT hard segments occurs from a microphase-separated melt. The resulting dispersed PBT hard phase in these materials is shown using transmission electron microscopy (TEM) and scanning force microscopy (SFM), whereas the increased elasticity is demonstrated using mechanical characterization. Hysteresis measurements reveal that the plastic deformation after recovery from 100% strain is only 1-6% (depending on composition) for the new PEB-containing copolyesters compared to 33% for a PBT-PTMO-based copoly(ether ester). The combination of results obtained with differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) points toward a complex morphology for the PEB-containing copolyesters. Five different phases exist: a crystalline pure PBT phase, pure amorphous PEB, and PBT phases and a PEO-rich phase besides an amorphous mixed PEO/PBT phase.

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Section: Resultsmentioning

confidence: 99%

Morphology, Surface Structure, and Elastic Properties of PBT-Based Copolyesters with PEO-b-PEB-b-PEO Triblock Copolymer Soft Segments

et al. 2002

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“…It is worthwhile to note that for a typical block copolymer, there exists microphase separation temperature (MST) or order–disorder temperature (ODT), at its molten states 15–17. Considering the fact that the MST for the copolymer (namely, Pebax 7233 resin)18, 19 is ca.…”

Section: Materials Charcaterization Techniquementioning

confidence: 99%

“…It is worthwhile to note that for a typical block copolymer, there exists microphase separation temperature (MST) or order-disorder temperature (ODT), at its molten states. [15][16][17] Considering the fact that the MST for the copolymer (namely, Pebax 7233 resin) 18,19 is ca. 1808C, the dynamic rheometry was selectively conducted at melt temperature of 2008C, at which the molten states of the copolymer resin and filled compounds would be surely isotropic and lack of any microphase-separated structure.…”

Section: Dynamic Rheometrymentioning

confidence: 99%

Radiopaque, barium sulfate‐filled biomedical compounds of a poly(ether‐block‐amide) copolymer

Guo

2008

J of Applied Polymer Sci

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Various radiopaque compounds of a poly (ether‐block‐amide) copolymer resin filled with fine barium sulfate particles were prepared by melt mixing. Material properties of the filled compounds were investigated using various material characterization techniques, including thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), dynamic rheometry, uniaxial tensile test, and dynamic mechanical thermal analysis (DMTA). The effects of the filler and its concentration on the measured material properties are evaluated. It has been found that in addition to its well‐known X‐ray radiopacity, the filler is quite effective in reinforcing some mechanical properties of the copolymer, including modulus of elasticity and yield strength. More interestingly, it has been observed that at low loading concentrations near 10 wt %, the filler may also act as a rigid, inorganic toughener for the copolymer by improving the postyield material extensibility of strain hardening against ultimate material fracture. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

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“…This must be borne in mind when interpreting viscoelastic data of block copolymers that are unlikely to have long-range order. For example, from the liquidlike terminal behavior of polyetherester multiblock copolymer melts, Veenstra et al 23 concluded that these melts were singlephase; this cannot be regarded as conclusive in the absence of scattering data.…”

Section: Dynamics Of Disordered Microphase-separated Block Copolymersmentioning

confidence: 99%

Microphase Separation and Rheological Properties of Polyurethane Melts. 3. Effect of Block Incompatibility on the Viscoelastic Properties

Velankar

Cooper

2000

Macromolecules

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The accompanying paper described the structural characterization of polyurethane multiblock copolymers that varied block incompatibility at fixed block length and composition. Their linear viscoelastic properties are presented in this paper. Dynamic mechanical experiments in temperature sweep mode confirmed that the materials ranged from almost homogeneous to highly microphaseseparated. Dynamic mechanical frequency sweep experiments showed a Rouse-like frequency response in all materials at high temperatures, including those polyurethanes that were highly microphaseseparated. This is in stark contrast to the numerous reports on microphase-separated block copolymers that show nonliquidlike terminal behavior at low frequencies. We attribute this homopolymer-like response of microphase-separated polyurethanes to a lack of long-range order in their microphase-separated structure and regard it to be a crucial feature of most commercial multiblock copolymers. The apparent activation energy for terminal flow was found to be insensitive to the extent of microphase separation, indicating that the thermodynamic penalty N expected for chain motion in block copolymers plays an insignificant role in the dynamics of the present materials. We demonstrate that bare effects (primarily proximity to the T g) and dynamic asymmetry (friction in one block much larger than in the other) play a major role in the dynamics of polyurethanes. The latter is expected to be especially important in the dynamics of elastomeric block copolymers whose blocks usually have widely separated Tg's. IntroductionPolyurethanes are (AB) n type multiblock copolymers composed of "hard" and "soft" segments that microphaseseparate due to thermodynamic incompatibility. The resulting microstructure of low-T g soft-segment-rich domains reinforced by rigid hard-segment-rich domains has excellent elastomeric properties, making polyurethanes useful as thermoplastic elastomers, coatings, textiles, etc. 1 The most important parameters that influence the properties of multiblock copolymers are block length N, block incompatibility , and composition. The first paper in this series investigated the effect of block length on the structure and the viscoelastic properties at constant incompatibility and composition. 2 In that work, we studied the "E-series" of materials with polycaprolactone soft segments and isophorone diisocyanate/1,4-butanediol hard segments as a function of block length. There were three primary conclusions regarding the viscoelastic properties of polyurethanes in that paper. First, block length had a very large effect on the terminal properties of polyurethane melts with terminal viscosity varying as approximately (block length) 4.5 . Second, at sufficiently high temperature the polyurethanes had a relaxation spectrum similar to that of a homopolymer of low molecular weight, indicating that either the polyurethanes were homogeneous at high temperatures or microphase separation did not affect the relaxation spectrum. Finally, the shift factors at suffic...

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Microphase separation and rheology of a semicrystalline poly(ether-ester) multiblock copolymer

Cited by 43 publications

References 11 publications

Morphology, Surface Structure, and Elastic Properties of PBT-Based Copolyesters with PEO-b-PEB-b-PEO Triblock Copolymer Soft Segments

Morphology, Surface Structure, and Elastic Properties of PBT-Based Copolyesters with PEO-b-PEB-b-PEO Triblock Copolymer Soft Segments

Radiopaque, barium sulfate‐filled biomedical compounds of a poly(ether‐block‐amide) copolymer

Microphase Separation and Rheological Properties of Polyurethane Melts. 3. Effect of Block Incompatibility on the Viscoelastic Properties

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