Morphology and properties of segmented polyether polyurethaneureas

Abstract

Two series of polyether polyurethaneureas (PEUU) based on 4,4'-methylenebis(phenylene isocyanate), ethylenediamine, and either 1000 or 2000 molecular weight poly(tetramethylene oxide) were synthesized. The effect of the urea linkage, hard segment content, and block length on the extent of phase separation, domain structure, and physical properties was studied by utilizing differential scanning calorimetry, dynamic mechanical, stress-strain, stress hysteresis, and infrared dichroism experiments. The mechanical properties of these polyurethanes depend primarily on the sample's hard segment content, although a higher concentration of urea groups in the PEUU-2000 series results in properties superior to those of the PEUU-1000 series at similar hard segment weight fractions. The presence of three-dimensional hydrogen bonding within hard domains leads to the unusually strong hard domain cohesion. Upon decrease of the hard segment content, a change of morphology from interconnecting to more isolated hard domains took place. Orientation behavior of chain segments within either domain and in the interfacial region is described and related to sample morphology.

Mechanical Properties, Thermal Stability, and Glass Transition Behaviors of a Waterborne Polyurethane/Graphene Oxide Nanocomposite

“…Figure 5 shows the FTIR spectra for pristine WPUs and their composites with graphene oxide. It is known that the N-H stretching vibration of polyurethane in the range of 3300-3600 cm −1 is sensitive to hydrogen bond distribution 30) . Addition of GO into aWPU does not change the spectrum of aWPU signi cantly.…”

Structure Evolution in a Polyurea Segmented Block Copolymer Because of Mechanical Deformation

“…49 Of course, the soft segments in ordered segmented block copolymers can see both environments rich in themselves (in the matrix) and environments consisting of hard segments (at the interface between soft and hard segments). 20 In systems with coupled ODT and crystallization, these two scattering peaks are expected. Since the mesophase is much larger than the crystal (lamellar) size, the peak from the hardsegment enriched domains falls at lower q than the peak due to the semicrystalline hard segments.…”

Nanocompósitos derivados de dispersões aquosas de poliuretano e argila: influência da argila na morfologia e propriedades mecânicas

“…Diversos autores [15][16][17] definiram essa razão para os grupos carbonila do uretano como "R". Desse modo, quanto maior a proporção de carbonilas ligadas ou quanto menor a proporção de carbonilas livres, maior será o valor de R indicando um grau de separação de microfases maior.…”