Reactivity of common functional groups with urethanes: Models for reactive compatibilization of thermoplastic polyurethane blends

Abstract

Two model urethane compounds, dibutyl 4,4′‐methylenebis(phenyl carbamate) (BMB) and dioctyl 4,4′‐methylenebis(phenyl carbamate) (OMO) were prepared by capping 4,4′‐methylenebis(phenyl isocyanate) with n‐butanol and n‐octanol, respectively. The reactions of the two model urethane compounds with several small monofunctional compounds as well as two model poly(ethylene glycols) were carried out with neat mixtures at elevated temperatures. The ranking of reactivity of the functional groups with the urethanes was determined as follows—primary amine > secondary amine ≫ hydroxyl ∼ acid ∼ anhydride ≫ epoxide. Nuclear magnetic resonance spectroscopy (NMR) was used for the quantitative analysis. Fourier transform infrared spectroscopy was used to complement the NMR analysis. Conversions of carbamate in each reaction were monitored over time at constant temperature (200 °C). The reactions between OMO and primary amine were conducted at 170, 180, 190, and 200 °C and best described with a second‐order bimolecular reaction model. The rate constant was estimated to be 1.8 × 10−3 L · mol−1 · s−1 and activation energy 115 kJ · mol−1. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2310–2328, 2002

Flow accelerates adhesion between functional polyethylene and polyurethane

“…This ranking of functional groups agrees with reaction rates measured on model urethanes. 12 We also found increased adhesion strength with annealing time and concentration of incorporated functional PEs, as these effects resulted in increased interfacial copolymer coverage. Based on the calculation of interfacial copolymer coverage, reaction rates for two processes, lamination and coextrusion, were compared.…”

Interfacial reaction and its influence on phase morphology and impact properties of modified‐polyacetal/thermoplastic polyurethane blends

“…On the other hand, the mol % of the hydroxyl end-group in POM-2 did not decrease, when the blending time reached 10 min, as shown in Figure 4 for reference. These results indicate that the hydroxyl end-group in POM also partially reacted with the isocyanate end-group contained in TPU [Scheme 2(2)], 28 and that, in the case of the POM-2/TPU blend, both carboxyl and hydroxyl end-groups in POM-2 reacted with TPU during the melt blending.…”

“…The experimental results indicate that the carboxyl end-group in POM-2 [Scheme 1(A)] partially reacted with the isocyanate end-group contained in TPU during the melt blending [Scheme 2(1)]. 28 In Figure 3, the constant value after 10 min was attributed to the ester unit, which was less reactive with TPU, in POM-2 [Scheme 1(C)].…”

How to explain low molar masses in PolyHydroxyUrethanes (PHUs)

“…Another possibility concerns the transreaction between a formed urethane and an amine. Macosko et al [2,31] demonstrated the formation of urea compounds by the fast reaction of amines with urethanes, but as it was meant to prepare modified polymers under melt-blending conditions, it has only been studied at a quite high temperature (180°C, Scheme 2).…”