Fine Structure of the Glass Transition in Amorphous Polymers:  Slight Shoulder in the Shear <i>H</i> Spectrum at the <i>L</i> Peak

Reissig, S.; Beiner, Mario; Vieweg, S.; Schröter, Klaus; Donth, E.

doi:10.1021/ma951346a

Cited by 20 publications

(30 citation statements)

References 20 publications

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“…These results indicate that polyricinoleate has a good low temperature flexibility compared to natural rubber, with a T g in the range of À62 to À67 8C. [22,23] Also, crosslinked polyricinoleate had no T c or T m , but showed a T g of À64.7 8C (data not shown). The T g increased slightly with crosslinking, probably due to restriction of the polymer chain.…”

Section: Thermal Propertiesmentioning

confidence: 88%

Lipase‐Catalyzed Synthesis and Curing of High‐Molecular‐Weight Polyricinoleate

Ebata

Toshima

Matsumura

2007

Macromolecular Bioscience

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High-molecular-weight polyricinoleate, with an M(w) of 100,600, was enzymatically prepared by the polycondensation of methylricinoleate using immobilized lipase from Pseudomonas cepacia (IM-PC) in bulk in the presence of 4 A molecular sieves at 80 degrees C for 7 d. Polyricinoleate was a viscous liquid at room temperature with a glass transition temperature (T(g)) of -74.8 degrees C, showed no crystallinity and was biodegraded by activated sludge. Polyricinoleate was readily cured using a dicumyl peroxide at 170 degrees C for 30 min to produce a chloroform insoluble crosslinked polyricinoleate with a hardness of 50A using durometer A.

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Section: Thermal Propertiesmentioning

confidence: 88%

Lipase‐Catalyzed Synthesis and Curing of High‐Molecular‐Weight Polyricinoleate

Ebata

Toshima

Matsumura

2007

Macromolecular Bioscience

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“…These data of L (τ/ a T ) from refs. 52 and 53 exhibit a shoulder at L (τ/ a T ) ≈ −9.25 Pa −1 , which suggests the contribution from the segmental α‐relaxation is given by the smallest peak (open triangles) in the figure.…”

Section: Molecular Motions In the Softening Dispersion Of Bulk Polymersmentioning

confidence: 99%

“…Two experimental facts have helped to isolate the segmental α‐relaxation and to determine its contribution to the compliance. One is from the appearance of a shoulder in the shear retardation spectrum, L (λ), of a high‐molecular‐weight PS 52–54 . L (λ) is related to the creep compliance J ( t ) by where λ is the retardation time.…”

Section: Molecular Motions In the Softening Dispersion Of Bulk Polymersmentioning

confidence: 99%

“…With the assistance of dielectric and enthalpy relaxation measurements, Donth and coworkers52–54 have identified the shoulder originating from the termination of the contribution to L (λ) from the segmental α‐relaxation, which is responsible for glass transition at T g . The shoulder also was found by Plazek in L (λ) of PS, PVAc,56 and atactic polypropylene,57 by Grassia et al in the relaxation spectra of PS Dylene 858(a) and PC58(b‐c), and by Guo et al in L (λ) of star‐PS 58(d).…”

Section: Molecular Motions In the Softening Dispersion Of Bulk Polymersmentioning

confidence: 99%

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Viscoelasticity of nanobubble‐inflated ultrathin polymer films: Justification by the coupling model

Ngai

Prevosto

Grassia

2012

J Polym Sci B Polym Phys

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The nanobubble inflation method is the only experimental technique that can measure the viscoelastic creep compliance of unsupported ultrathin films of polymers over the glass-rubber transition zone as well as the dependence of the glass transition temperature (T g ) on film thickness. Sizeable reduction of T g was observed in polystyrene (PS) and bisphenol A polycarbonate by the shift of the creep compliance to shorter times. The dependence of T g on film thickness is consistent with the published data of free-standing PS ultrathin films. However, accompanying the shift of the compliance to shorter times, a decrease in the rubbery plateau compliance is observed. The decrease becomes more dramatic in thinner films and at lower temperatures. This anomalous viscoelastic behavior was also observed in poly(vinyl acetate) and poly (n-butyl methacrylate), but with large variation in the change of either the T g or the plateau compliance. By now, well established in bulk polymers is the presence of three different viscoelastic mechanisms in the glass-rubber transition zone, namely, the Rouse modes, the sub-Rouse modes, and the segmental a-relaxation. Based on the thermorheological complexity of the three mechanisms, the viscoelastic anomaly observed in ultrathin polymer films and its dependence on chemical structure are explained in the framework of the Coupling Model.Next, the softening dispersion of PBMA had been obtained by the measurements of the complex shear compliance (J* ¼ J 0 À J 00 ) in the frequency range from 24 to 2400 cycles by Child and Ferry. 79 Both J 0 and J 00 show very broad width of

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“…On the other hand, the cured carbon black-filled polyricinoleate compounds showed no T c and T m , but showed a T g of -68.5 ~ -70.8 as measured by DSC. Polyricinoleate showed a T g of -74.8 , and exhibited a good low temperature flexibility compared to natural rubber having a T g of -62 ~ -67 22,23) .…”

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confidence: 99%

Poly (Ricinoleic Acid) Based Novel Thermosetting Elastomer

et al. 2008

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A novel bio-based thermosetting elastomer was prepared by the lipase-catalyzed polymerization of methyl ricinoleate with subsequent vulcanization. Some mechanical properties of the cured carbon black-filled polyricinoleate compounds were evaluated as a thermosetting elastomer. It was found that the carbon black-filled polyricinoleate compounds were readily cured by sulfur curatives to produce a thermosetting elastomer that formed a rubber-like sheet with a smooth and non-sticky surface. The curing behaviors and mechanical properties were dependent on both the molecular weight of the polyricinoleate and the amount of the sulfur curatives. Cured compounds consisting of polyricinoleate with a molecular weight of 100,800 showed good mechanical properties, such as a hardness of 48 A based on the durometer A measurements, a tensile strength at break of 6.91 MPa and an elongation at break of 350%.

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Fine Structure of the Glass Transition in Amorphous Polymers: Slight Shoulder in the Shear H Spectrum at the L Peak

Cited by 20 publications

References 20 publications

Lipase‐Catalyzed Synthesis and Curing of High‐Molecular‐Weight Polyricinoleate

Lipase‐Catalyzed Synthesis and Curing of High‐Molecular‐Weight Polyricinoleate

Viscoelasticity of nanobubble‐inflated ultrathin polymer films: Justification by the coupling model

Poly (Ricinoleic Acid) Based Novel Thermosetting Elastomer

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