The Role of Hard Segment Content on the Molecular Dynamics of Poly(tetramethylene oxide)-Based Polyurethane Copolymers

Castagna, Alicia; Fragiadakis, D.; Lee, HyungKi; Choi, Taeyi; Runt, James

doi:10.1021/ma2017138

Cited by 92 publications

(82 citation statements)

References 37 publications

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“…So it was expected that hydrogen bonding could enhance phase separation whenever significant amounts of hydrogen-bonded -NH and C_O groups were observed synchronously. It was also assumed that phase separation could generally be enhanced by increasing hard segment content (Castagna et al, 2011). The increase of HSC up to 40% led (Fig.…”

Section: Atr-ir Spectroscopymentioning

confidence: 99%

Microstructure–property relationships of organo-montmorillonite/polyurethane nanocomposites: Influence of hard segment content

Taheri

Sadeghi

2015

Applied Clay Science

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Section: Atr-ir Spectroscopymentioning

confidence: 99%

Microstructure–property relationships of organo-montmorillonite/polyurethane nanocomposites: Influence of hard segment content

Taheri

Sadeghi

2015

Applied Clay Science

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“…The apparent increase in the loss at low frequencies is due to a combination of dc conductivity, interfacial polarization (i.e., mobile ions trapped at the interfaces between hard and soft domains), and possibly other relaxation modes such as local motion of the hard segments. 44 In the unstretched, dry polyurea, a very broad double peak is observed. On the basis of the behavior when changing stoichiometry, temperature, or pressure, we previously attributed the lower-frequency component (α′ process) to segmental relaxation of the soft phase in the interfacial regions between the soft and hard domains, while the primary, higher-frequency component was ascribed to segmental relaxation in the soft phase distant from interfaces.…”

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confidence: 98%

Microstructure and Segmental Dynamics of Polyurea under Uniaxial Deformation

et al. 2012

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Polyureas, formed by the rapid reaction between isocyanates and diamines, are attractive for various applications due to their outstanding mechanical properties, which can be tuned by varying component chemistry, molecular weight, and stoichiometry. Polyureas synthesized from a modified methylene diphenyl diisocyanate (Isonate 143 L) and polytetramethylene oxide-di-p-aminobenzoate (Versalink P1000) are widely utilized and investigated for energy absorbing applications such as impact mitigation and ballistic protection. In order to develop a more complete understanding of their mechanical response, we explore the effect of uniaxial strain on the phase separated microstructure and molecular dynamics. We utilize wide-and small-angle X-ray scattering to investigate amorphous segment and hard domain orientation, and broadband dielectric spectroscopy for interrogation of the dynamics. Uniaxial deformation was found to significantly perturb the phase-separated microstructure and chain orientation and result in a considerable slowing down and broadening of the polyurea soft phase segmental relaxation.

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“…The T g of the nanocomposite films was found to be increase with the increase of BT ratio, this may be attributed to the aggregation of BT nanoparticles in the free volume between the chains of PVC matrix. Generally, the mobility of chain segments in polymers is reflected in its T g [32,33] i.e a lower mobility resulted from a higher T g . This could be ascribed to the interaction between the PVC chain segments and the BT [32][33][34].…”

Section: -3 the Fourier Transform Infrared Spectroscopymentioning

confidence: 99%

X-Ray Diffraction and Differential Scanning Calorimetry of BaTiO3/ Polyvinyl Chloride Nanocomposites

Zayat

Shobak

Abdel‐Baset

et al. 2015

Int J of Adv in Sci Res

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Aiming to improve the inferior properties of polyvinyl chloride polymer, (BaTiO 3 ) x (PVC) 100-x composite samples were prepared and investigated. The structural changes of the composite (BaTiO 3 ) x (PVC) 100-x were studied as a function of BT content using FTIR, XRD and DSC measurements. Attention is paid to the tetragonality changes during composition changes.It was found that the hindrance to the PVC crystallization becomes less and less serious with the increase of BT ratio in the composite. This behavior could be attributed to the interaction between Ba +2 ions and Chlorine in the polymer. The FTIR spectra indicate a clear interaction between PVC and BaTiO 3 particles as is concluded from XRD results.The Scherrer formula was used to estimate the grain size for the included BT in the (BT) x (PVC) 100-x composite samples. The composite samples show abnormally small tetragonality for its BT content less than unity (с/a < 1). It seems that in (BaTiO 3 ) x (PVC) 100-x composite samples, the stress that stabilized the tetragonal phase of the core regions of BT decreased, leading to lower tetragonality (c/a ratio). It seems that T g of the composite samples increases with the increase of its BT content. Also DSC results reveal the increase of crystallization with the increase of BT content in the composite.

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The Role of Hard Segment Content on the Molecular Dynamics of Poly(tetramethylene oxide)-Based Polyurethane Copolymers

Cited by 92 publications

References 37 publications

Microstructure–property relationships of organo-montmorillonite/polyurethane nanocomposites: Influence of hard segment content

Microstructure–property relationships of organo-montmorillonite/polyurethane nanocomposites: Influence of hard segment content

Microstructure and Segmental Dynamics of Polyurea under Uniaxial Deformation

X-Ray Diffraction and Differential Scanning Calorimetry of BaTiO3/ Polyvinyl Chloride Nanocomposites

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