Rigid and semi rigid polyurethane resins: A structural investigation using DMA, SAXS and Le Bail method

Trovati, Graziella; Sanches, Edgar Aparecido; Souza, Sérgio Michielon de; Santos, Amilton dos; Neto, Salvador Claro; Mascarenhas, Yvonne P.; Chierice, Gilberto Orivaldo

doi:10.1016/j.molstruc.2014.07.024

Cited by 23 publications

(16 citation statements)

References 30 publications

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“…Further, from Figure (b), a broad peak is found at 30° in the original, programmed, and recovered states, but the intensity of programmed SMPU is much higher than those of original and recovered samples. This is because the molecular chains in soft segments are stretched from the curled state in the horizontal direction during the programming . All these further validate the presence of molecular orientation in the programmed SMPU as shown in Figure (b).…”

Section: Resultssupporting

confidence: 71%

Microstructural and mechanical property evolutions of shape memory polyurethane during a thermodynamic cycle

Shi

Shen

2017

J of Applied Polymer Sci

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To better understand the shape memory behaviors of synthesized shape memory polyurethane (SMPU) sealant with a tailored transition temperature (Tt) for concrete pavement joints, the thermal and dynamic mechanical properties of SMPU were first characterized to determine the shape memory switching temperature of SMPU. Then the microstructural and mechanical property evolutions of SMPU in the original, programmed, and recovered states during a five‐step thermodynamic cycle were discussed, respectively. The results indicate that the tailored Tt of prepared SMPU can be used as the shape memory switching temperature to match its working temperature. Further, the programming causes the phase separation in SMPU, leading to an obvious anisotropy. The SMPU has satisfactory shape memory performance. The orientation of molecular chains in soft segments is confirmed along the stretching direction. The oriented molecular chains can restore to the naturally curled state during the free recovery. Finally, the programming improves the mechanical properties of SMPU. The recovered SMPU shows a slight decrease in mechanical properties because of the partially impaired crystal structures and broken molecular segments during the programming and recovery. It is concluded that the synthesized SMPU with the specially tailored Tt is suitable to use as a sealant of concrete pavement joints. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45703.

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Section: Resultssupporting

confidence: 71%

Microstructural and mechanical property evolutions of shape memory polyurethane during a thermodynamic cycle

Shi

Shen

2017

J of Applied Polymer Sci

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“…Larger values of R g show larger size of phase domain. Rigid polyurethanes evidence larger R g values than semi rigid polyurethanes [28]. The highest R g value is shown by polyurethane P3 due to its more crystalline PEO segment and highest molecular weight which can be correlated with its highest value of storage modulus, E 0 [15].…”

Section: Saxs Analysismentioning

confidence: 93%

Molecular dynamics, conductivity and morphology of sodium deoxycholate-based poly(ester ether)urethane ionomer biomaterials

et al. 2016

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Broad-band dielectric spectroscopy technique was used to investigate the molecular dynamics of new sodium deoxycholate-based poly(ester ether)urethane ionomers of particular interest in biomedical devices. These polyurethane ionomers have identical hard segment containing bile salt moiety but with different soft segment chemistries. Poly(ethylene oxide)-rich soft segment promotes stronger ionic interactions and solvation capacity of ions and higher ionic conductivity in these polyurethane ionomers. The universal power law was employed to study the evolution of alternating conductivity (AC) with frequency and temperature. The calculated values of fractional exponent ranged between 0 and 1 which indicate AC conduction through hopping mechanism. Direct current conductivity evidences Arrhenius behaviour in the function of temperature and the estimated values of activation energy for poly(ethylene oxide)-rich soft segment polyurethane ionomers are found higher. The increase in the conductivity with temperature can be interpreted as a hopping mechanism assisted by chain relaxation. AFM and SAXS investigations evidence lamellar arrangement at the sub-micron scale and the nanophase-separated morphology for these polyurethane ionomers. The tensile tests evidenced that the polyurethane with highest molecular weight exhibits the highest values of mechanical properties and ductile behaviour.

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“…PUs having different soft segment chemistries commonly exhibit rather incomplete hard/soft demixing when polymerized in bulk or cast from solution, and the extent of segment segregation (and resulting hard domain morphology) is particularly important in determining mechanical and other physical properties [2]. Thus, hard segments having short sequence lengths (as well as so-called "lone" isocyanates [3], more prevalent at lower hard segment contents), show higher solubility in the soft phase than longer sequences for entropic reasons. In addition, similarity in cohesive energy density and/or the possibility of hydrogen bonding between hard and soft repeating units also encourages mixing processes [2].…”

mentioning

confidence: 99%

“…Thermoplastic polyurethanes have been extensively investigated with XRD (X-ray diffraction) and SAXS (small-angle X-ray scattering) for detailed structural information [2][3][4][5][6][7].…”

mentioning

confidence: 99%

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Investigation of Temperature Dependency of Morphological Properties of Thermoplastic Polyurethane using WAXS and SAXS Monitoring

Witzleben¹,

Walbrueck²,

Klein³

et al. 2015

JCCE

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Abstract:Polyether and polyether/ester based TPU (thermoplastic polyurethanes) were investigated with wide-angle XRD (X-ray diffraction) and SAXS (small angle X-ray scattering). Furthermore, SAXS measurements were performed in the temperature range of 30 °C to 130 °C . Polyether based polymers exhibit only one broad diffraction signal in a region of 2 θ 15° to 25°. In case of polyurethanes with ether/ester modification, the broad diffraction signal arises with small sharp diffraction signals. SAXS measurements of polymers reveal the size and shape of the crystalline zones of the polymer. Between 30 °C and 130 °C the size of the crystalline zone changes significantly. The size decreases in most of investigated TPU. In the case of Desmopan 9365D an increase of the particle size was observed.

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Rigid and semi rigid polyurethane resins: A structural investigation using DMA, SAXS and Le Bail method

Cited by 23 publications

References 30 publications

Microstructural and mechanical property evolutions of shape memory polyurethane during a thermodynamic cycle

Microstructural and mechanical property evolutions of shape memory polyurethane during a thermodynamic cycle

Molecular dynamics, conductivity and morphology of sodium deoxycholate-based poly(ester ether)urethane ionomer biomaterials

Investigation of Temperature Dependency of Morphological Properties of Thermoplastic Polyurethane using WAXS and SAXS Monitoring

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