Effects of the reagent molar ratio on the phase separation and properties of waterborne polyurethane for application in a water‐based ink binder

In this work, segmented waterborne polyurethane‐urea (WBPUU) dispersions containing hydrophobic polycaprolactone (PCL) and hydrophilic poly(ethylene glycol) (PEG) in different molar ratios are synthesized and used for the subsequent preparation of films by casting. The molar ratio of PEG is gradually increased up to 0.20 in order to analyze the effect of low hydrophilic PEG content (from 1.7 to 7.1 wt %) on the properties of resulting dispersions and films. Regarding the dispersions, the addition of PEG results in an increase of the particle size, from 86 ± 1 in the case of pure PCL‐based system to 112 ± 15 for systems containing 7.1 wt % of PEG, as well as in the formation of a core–shell structure in the particles. Films show different behaviors depending on their PEG content. WBPUUs containing just PCL or very low content of PEG in the soft segment present higher stiffness. However, the addition of PEG in a content of 3.4 wt % or higher hinder the ability of the short‐range ordering of the hard segment, increasing the elongation at break from 842 ± 102 MPa for PCL‐based WBPUU to 1312 ± 84 MPa for the system with the highest PEG content. Systems with higher PEG content form nanoparticles with more segregated core–shell structures inducing to the film a higher hydrophilicity. Hence, the addition of PEG to a PCL‐based WBPUU allows to tune the properties of the resulting film increasing the range of application of these materials. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48847.

Section: Resultsmentioning

confidence: 93%

Influence of the addition of PEG into PCL‐based waterborne polyurethane‐urea dispersions and films properties

Vadillo

Larraza²,

Arbelaiz³

et al. 2019

“…All WPU dispersions in this study were synthesized with an NCO/OH molar ratio of 1.70, 5 wt% DMPA 3 and 100% neutralization. 11,20 The theoretical solid content and hard segment content are 40 wt%…”

Section: Preparation Of Wpu Emulsion By Two-step Methodsmentioning

confidence: 99%

“…The stronger the hydrogen bond forms, the more the wave number decreases. Generally, the peak at 3500 cm −1 corresponds to free NH stretching vibration, the hydrogen bonded N H stretching band is present at 3300-3200 cm −1 , 11,21 and the free C O stretching band is at 1730 cm −1 . In this study, the N H and C O stretching peak of WPU shifts to 3325 and 1720 cm −1 , indicating that the hydrogen bonds are formed between N H group and carbonyl…”

Section: Ftir Spectra Of Wpumentioning

confidence: 99%

“…This method provided theoretical guidance for the preparation of WPU with low viscosity and high solid content. Zhihui, Yang et al 11 prepared successfully WPU dispersions with a high solid content and low viscosity by a two-step polymerization with isophorone diisocyanate, poly(propylene glycol), and dimethylol propionic acid as the main raw materials. Suzana M. Caki c et al 12 synthesized a series of nontoxic biodegradable WPU elastomers by twostep polymerization, using isophorone diisocyanate (IPDI), different macrodiols, 1,4-butandiol (BDO), and l-lysine as a chain extender.…”

mentioning

confidence: 99%

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Influence of preparation method on adhesion and drying performances of polyurethane dispersion

Wang

Xin

Liu

et al. 2021

Waterborne polyurethane (WPU) dispersions with a high solid content were prepared by one-step and two-step methods with polyester and polyether type macromolecular diols as the main raw materials. The effects of two synthesis methods on the properties of WPU of polyester and polyether were studied. Fourier transform infrared spectroscopy, particle size and distribution, and Thermogravimetric analysis (TGA) measurements were utilized to characterize the structure. The dryness test results showed that the WPU synthesized with polyester diol as the soft segment by the two-step method had the best drying. In addition, the microstructure of WPU was characterized by transmission electron microscopy, which confirmed that WPU was mainly spherical structure. TGA and scanning electron microscopy results showed that the microphase separation between the soft and hard segments of WPU prepared by the two-step method was weaker, the hydrogen bonding was stronger, the adhesion, and thermal stability of WPU was improved.

Effects of the molecular structure on the vibration reduction and properties of hyperbranched waterborne polyurethane–acrylate for damping coatings

Zhang

Deng

et al. 2019

A series of hyperbranched waterborne polyurethane-acrylate (HWPUA) hybrid emulsions were prepared with isocyanate-terminated PU prepolymers, hyperbranched polyol (HP), and acrylate monomers. The HP as crosslinker was synthesized with isophorone diisocyanate, dimethylol propionic acid, and diethanol amine. The influence of the HP content on the chemical structure, particle size, morphology, damping properties, and thermal stability of the HWPUA hybrid emulsions and films were investigated by Fourier transform infrared spectroscopy, dynamic light scattering, transmission electron microscopy, dynamic mechanical analysis (DMA), and thermogravimetric analysis, respectively. The results show that the addition of HP obviously improved the damping and thermal properties of the HWPUA films. However, the addition of excessive HP had a detrimental impact on the performance of films. The DMA curves indicated that when the HP content was 1%, tan δ was 0.3 or greater and spanned the broadest temperature range, with a maximum value of 0.65. The HWPUA hybrid emulsions could be used as damping coatings.