Journal ArticleDOI
A dielectric study of the glass transition region in segmented polyether-urethane copolymers
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In this paper, ten polyether-urethane thermoplastic elastomers of varying chemical structure have been characterized by dielectric spectroscopy and scanning calorimetry.Abstract:
Ten polyether-urethane thermoplastic elastomers of varying chemical structure have been characterized by dielectric spectroscopy and scanning calorimetry. In the temperature range corresponding to the glass-rubber transition of the predominantly polyether phase, modification of the primary dielectric transition and the occurrence of a second transition at somewhat higher temperature have been observed. Through comparison with calorimetric data, these events have been related to supercooling of crystallizable polyether segments. Supercooling suppresses dielectric loss processes in some regimes and enhances losses in others. By systematic variation of chemical structure these phenomena have been classified.read more
Citations
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Journal ArticleDOI
Microphase separation and rheological properties of polyurethane melts. 1. Effect of block length
Sachin Velankar,Stuart L. Cooper +1 more
TL;DR: In this article, a series of polyesterurethanes with differing block length and constant composition have been synthesized for rheological studies, and temperature-resolved SAXS experiments demonstrated gradual microphase mixing of the microphase-separated materials as the temperature increased.
Journal ArticleDOI
Synthesis and properties of polyurethanes based on polyolefine: 1. Rigid polyurethanes and amorphous segmented polyurethanes prepared in polar solvents under homogeneous conditions
TL;DR: In this article, the phase separation of pure hard-block polyurethanes and amorphous segmented hydrogenated polybutadiene (H.PBD) was analyzed using dielectric measurements.
Journal ArticleDOI
Molecular mobility and crystallinity in polytetramethylene ether glycol in the bulk and as soft component in polyurethanes
Konstantinos N. Raftopoulos,Bartlomiej Janowski,L. Apekis,Krzysztof Pielichowski,Polycarpos Pissis +4 more
TL;DR: In this paper, a series of polyurethanes prepared with polytetramethylene ether glycol (PTMEG) with varying molecular weights as soft component, methylene diisocyanate (MDI) as diiscyanate component and butanediol as chain extender were studied.
Journal ArticleDOI
Influence of Dangling Chains on Molecular Dynamics of Polyurethanes
TL;DR: In this article, the effect of dangling chains on phase-separated microstructure and molecular dynamics for polyurethanes (PUs) with different dangling chain lengths and polar groups was investigated.
Journal ArticleDOI
Direct and indirect effects of POSS on the molecular mobility of polyurethanes with varying segment Mw
Konstantinos N. Raftopoulos,Bartlomiej Janowski,L. Apekis,Polycarpos Pissis,Krzysztof Pielichowski +4 more
TL;DR: In this paper, it was shown that tethering of polyhedral Oligomeric Silsesquioxanne particles by urethane or urea linkages leads to increase of glass transition temperature by a few degrees due to two mechanisms: the direct POSS-chain interactions and the indirect slowing of dynamics by disruption of microphase separation.
References
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Book
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TL;DR: In this article, the authors describe the nature of Viscoelastic behavior of polymeric systems and approximate relations among the linear Viscoels and approximate interrelations among the Viscelastic Functions.
Book
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Journal ArticleDOI
Ideal copolymers and the second-order transitions of synthetic rubbers. i. non-crystalline copolymers
Manfred Gordon,James S. Taylor +1 more
TL;DR: In this article, the second-order transition temperature of binary copolymers is derived from the two secondorder transition temperatures of the pure polymers and their coefficients of expansion in the glassy and rubbery states.
Journal ArticleDOI
Thermodynamics of Crystallization in High Polymers. IV. A Theory of Crystalline States and Fusion in Polymers, Copolymers, and Their Mixtures with Diluents
TL;DR: In this paper, the configurational entropy of a mixture of solvent and polymer molecules composed of segments connected by flexible bonds is derived for the case in which the lattice they occupy contains limited regions of perfect order (i.e., the crystallites), which are reserved for occupancy by polymer segments exclusively.
Journal ArticleDOI
Effect of segment size and polydispersity on the properties of polyurethane block polymers
TL;DR: In this paper, the dynamic-mechanical and thermal scanning behavior of a series of specially synthesized linear segmented polyurethanes is presented, and the results are explained in terms of hard segment domain perfection.
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