Influence of diethanolamine on hard segment ordering in flexible polyurethane foams

Shape memory polyurethane‐urea foams with improved toughness

“…In the 0% HDI series, incorporation of DEA resulted in more isotropic pores, or pores that have similar diameters in the axial and transverse directions; this trend can be viewed in Figure (b) qualitatively in images and quantitatively in the axial to transverse ratio calculations below images. This observation correlates with previous studies that utilized DEA, which qualitatively show a similar result using SEM images . This result can be attributed to the increased reactivity of the amine groups in DEA with isocyanates (relative uncatalyzed reaction rates with isocyanates of secondary aliphatic amine: 20,000–50,000 and of primary hydroxyl: 100), thus causing faster/more efficient crosslinking and restricting foam rise .…”

“…This observation correlates with previous studies that utilized DEA, which qualitatively show a similar result using SEM images . This result can be attributed to the increased reactivity of the amine groups in DEA with isocyanates (relative uncatalyzed reaction rates with isocyanates of secondary aliphatic amine: 20,000–50,000 and of primary hydroxyl: 100), thus causing faster/more efficient crosslinking and restricting foam rise . In the 20% DEA ratio series, the introduction of HDI led to more anisotropic pores, or pores that have different diameters in the axial and transverse directions, Figure (c).…”

“…This observation correlates with previous studies that utilized DEA, which qualitatively show a similar result using SEM images. 16 This result can be attributed to the increased reactivity of the amine groups in DEA with isocyanates (relative uncatalyzed reaction rates with isocyanates of secondary aliphatic amine: 20,000-50,000 and of primary hydroxyl: 100), 17 Figure 2. Attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectra of DEA-containing SMP foams, demonstrating relative increases in the urea peak at 1647 cm −1 with increasing amounts of DEA.…”

Biodegradable shape memory polymer foams with appropriate thermal properties for hemostatic applications

“…The densities for the ester‐containing foams (0.030–0.076 g/cm 3 ) were higher than their controls (0.022–0.049 g/cm 3 ) due to shorter rising heights of the ester‐containing foams than those of the control foams. Shorter rising height was attributed to faster reactions between amines on ester‐containing monomers and isocyanates, and it correlates with previous results of polyurethane–urea foam synthesis (Easley et al, ; Dounis & Wilkes, ). Additionally, the NCO premixes of ester‐containing foams had to be more viscous than the controls to prevent collapse during foaming, which further restricted foam rise.…”

A New Molecular Theory of Non-Linear Viscoelasticity for Vitrifiable (or Crystallizable) Thermoplastic Polyurethane Elastomers

“…[4] Now, the idea is extended to establish the molecular theory of viscoelasticity for VTPUE with real chains by combining statistical thermodynamics with kinetics. It is evident, that the segment polyurethanes [5] differ from the diene type of block copolymers (SBS or SIS) in superstructure and morphology. [6] The generally agreed morphology suggested by Abouzahr and Wilkes [7] for some of spherulitic segment polyurethanes is shown in Figure 1a, whereas those which tend to form lamellar with chain folding are shown in Figure 1b, the latter had been proposed by Lilaonitkul et al [8] According to the above morphologies, a structure model for VTPUE networks consisting of trapped entanglement networks, chemical and physical hard-domain and soft-domain networks by strain induced vitrification (or crystallization) is proposed.…”