Semicrystalline polyurethane

McKeiman RL, Heintz AM, Hsu SL, Atkins EDT, Penelle J, Gido SP. Influence of hydrogen bonding on the crystallization behavior of semicrystalline polyurethanes. Macromolecules 2002 35 6970-6974. 

Semicrystalline polyurethane/(styrene-acrylic acid) copolymer-... 

Boiteux G, Cuve L and Pascault J-P (1994) Synthesis and properties of polyurethanes based on polyolefin. 3. Monitoring of phase separation by dielectric relaxation spectroscopy of segmented semicrystalline polyurethane prepared in bulk by the use... 

Currently, important TPE s include blends of semicrystalline thermoplastic polyolefins such as propylene copolymers, with ethylene-propylene terepolymer elastomer. Block copolymers of styrene with other monomers such as butadiene, isoprene, and ethylene or ethylene/propy-lene are the most widely used TPE s. Styrene-butadiene-styrene (SBS) accounted for 70% of global styrene block copolymers (SBC). Currently, global capacity of SBC is approximately 1.1 million tons. Polyurethane thermoplastic elastomers are relatively more expensive then other TPE s. However, they are noted for their flexibility, strength, toughness, and abrasion and chemical resistance. Blends of polyvinyl chloride with elastomers such as butyl are widely used in Japan. ... 

Mechanical properties. See also Dynamic mechanical analysis (DMA) of polyamides, 138 of polyester LCPs, 52 of polyurethanes, 242-244 of semicrystalline aromatic-aliphatic polyesters, 45 Mechanical recycling, 208 Medical applications, for polyurethanes, 207... 

Several poly(urea urethane) oligomers 28 (Figure 12) were prepared by one-component polycondensation of iV-(hydroxyalkyl)-2 -oxo-1,3-diazepane-l-carboxamides, which act as intramolecular blocked isocyanates <2005PLM 1459>. These oligomers are semicrystalline materials and their melting points show the odd/even effect observed earlier for [ ]-polyamides, [ ]-polyurethanes, poly(ester amide)s, and poly (amide urethane)s. Further analysis showed that the polymers are stable up to ca. 205-230 °C, the polymers with the lower number of methylene groups in the amino alcohol decomposing at the lowest temperature. 

Block copolymers were developed rapidly in the 1960s when living anionic polymerization was first utilized to synthesize triblock thermoplastic elastomers or elastoplastics. At the same time, step or condensation polymerization to produce thermoplastic polyurethanes, urea-urethane spandex fibers, and later more specialized materials, such as the semicrystalline polyester-polyether copolymers were developed [10]. Imide block or segmented copolymers utilizing... 

As for ASAXS, we are currently using this technique to separate the crystallite and ionic "peak" scattering in the semicrystalline ionomers Nafion and Surlyn. Since these two scattering sources overlap in q-space, it has in the past proved difficult to separate and model these scattering sources, but with ASAXS this task becomes possible. Also, we are investigating the hlgh-q shoulder we have observed in the SAXS patterns of sulfonated polyurethane ionomers[45], which may be evidence of structural order within the ionic aggregates. 

As outlined before, the question of interest now is first, how the photochrome would react when incorporated in the backbone of amorphous and semicrystalline polymers such as segmented polyurethanes and if the isomerization behaviour of the photochrome would allow conclusions on the structure, morphology, and segmental mobility of this matrix. 

OlWan Wang, H.-H., Chen, J.-C. Toughening of epoxy resin by functional-terminated polyurethanes and/or semicrystalline polymer powders. J. Appl. Polym. Sci. 82 (2001) 2903-2912. 

Figure 5.6. Modulus-temperature curves for several polyurethanes in comparison with various classes of polymer (A) Schematic curve for a linear amorphous polymer (B) schematic curve for a crosslinked polymer (C) schematic curve for a semicrystalline polymer (D) poly(ester urethane),Estane 5740-100 (E) poly(ester urethane),Estane 5740-070. Note that the polyurethanes exhibit two distinct glass transitions. (Cooper and Tobolsky, 1966u.)...

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