Effect of Chain Extender on Phase Mixing and Coating Properties of Polyurethane Ureas

Abstract

Structural effects of chain extender on phase mixing and coating properties of polyether-based moisture-cured polyurethane ureas (MCPUs) were determined with a polytetramethylene glycol (PTMG-1000), trimethylol propane (TMP), and isophorone diisocyanate (IPDI)-based system. The reaction of PTMG/TMP/IPDI was carried out using a NCO/OH ratio of 1.6:1. The excess isocyanate of the prepolymer was chain extended in the ratio of 2:1 (NCO/OH) with different aliphatic diols and 4:1 with different aromatic diamines just before the coating application. The viscoelastic properties of the cross-linked films were evaluated with a dynamic mechanical and thermal analyzer (DMTA). The mechanical film properties such as tensile strength, adhesion strength, and hardness were measured and related to chemical composition and cohesion of the hard segment. Surface properties were evaluated through angle resolved X-ray photoelectron spectroscopy (AR-XPS). The degree of phase mixing was found to be dependent on the chain extender structure. The results indicate that the combined analysis of the hard segment cohesion helps in correlating the structure-to-property relationship.

Enhancement of the gas separation properties of polyurethane membranes by alumina nanoparticles

“…It seems that the MPD chain extender perturbs the formation of hard segment aggregate morphology, whereas the straight chain 1, 4-butanediol provides more phase-separated morphology. Chattopadhyay et al observed the same result in the synthesis of polyurethanes with different chain extenders [30]. In addition, we have deconvoluted the -CQO stretching zone of the PU/Al 2 O 3 samples to understand the effect of Al 2 O 3 nanoparticles on the phase mixing behavior of the samples.…”

Phase behavior, interaction and properties of acetic acid lignin-containing polyurethane films coupled with aminopropyltriethoxy silane

“…As the APTS content increases, the C-O/ (C-C/C-H) ratio decreases from 0.919 to 0.510. It is reported that low surface energy soft segment resides towards the top surface and high surface [44][45]. Therefore, it can be concluded that the addition of APTS promotes the phase mixing of polyurethane.…”

“…XPS has been extensively utilized to study the surface functionalization and phase mixing for polyurethane materials [43][44]. The elemental compositions from the XPS survey spectra (Figure 8) and the peak area ratio from the de-convoluted spectra are presented in Table 3.…”

The phase mixing studies on moisture cured polyurethane-ureas during cure

“…Cure of MCPU advances with progress of time and produces crosslink networks by the diffusion of moisture, nucleophilic attack and generation of primary amine that further react to produce urea bonds [2,3]. As the chemical reaction proceeds, urea chain length increases and the interaction parameters between the polyether soft and polyurea hard segment also changes.…”