Polyurethane Dispersions Research Articles

Analysis and Modeling of Viscosity for Aqueous Polyurethane Dispersion as a Function of Shear Rate, Temperature, and Solid Content.

Aqueous polyurethane dispersion (PUD) has attracted increasing attention in a wide range of industrial applications because of their versatile properties as well as ecofriendly nature. In this study, the aqueous PUD used in warp-knitted vamp printing was characterized by Fourier transform infrared spectra, dynamic light scattering, and laser Doppler electrophoresis. The mean diameter and zeta potential are 206.6 nm and −18.3 mV, respectively. The rheological behavior of aqueous PUD as a function of shear rate, temperature, and solid content was investigated experimentally. Besides, a new correlation model was proposed based on the Carreau equation and Arrhenius relation. The resulting model has high accuracy in viscosity estimation under complex conditions according to the prediction interval of 95%. Furthermore, the reasonable ranges of parameters were proposed theoretically for successful printing.

Synthesis and properties of self-crosslinking waterborne polyurethane with side chain for water-based varnish

In this paper, a series of self-crosslinking waterborne polyurethane (WPU) dispersions with side chain, which is (3-(2-Aminoethyl)aminopropyl)trimethoxysilane (AEAPTMS) as the diamine chain extender, were prepared. The characteristics of WPU with different dosages of AEAPTMS were evaluated, including particle size, crystallinity, surface performance, water resistance and thermal stability. It was demonstrated that AEAPTMS was successfully incorporated into the WPU from Fourier-transform infrared spectroscopy (FT-IR). Once the content of AEAPTMS increased to 5 %, the WPU dispersions became gelatinous. That is, the siloxane groups were hydrolyzed into a cross-linked structure during the emulsification process. The particle size enlarged with the increasing dosage of AEAPTMS in transmission electron microscopy (TEM). The X-ray photoelectron spectroscopy showed that the silane in the cross-linked WPU migrated freely towards the WPU film surface. The addition of AEAPTMS enhanced the tensile strength, hydrophobicity, water resistance and thermal stability of WPU film. Meanwhile, the elongation at break and crystallinity of WPU films were declined. Besides, interestingly, the glass transition temperature of WPU films followed the trend of first rising and then falling. By adding wetting agent, antifoaming agent, adhesion promoter and flatting agent into WPU, the water-based varnish was prepared. The pencil hardness, water resistance, adhesion and anti-adhesion of water-based varnish were best in the application on the stainless steel substrate when the WPU sample was Si-WPU-3.

Preparation and characterization of modified castor oil via photo‐click chemistry forUV‐curable waterborne polyurethane with enhanced water resistance and low conductive percolation threshold

AbstractA castor oil (CO) was modified via thiol‐ene click chemistry reaction between CO and 3‐mercaptopropyl trimethoxysilane, with the conversion of CC bonds of CO over 99% based on1HNMR spectra. The obtained modified castor oil (MCO) was used as a biobased polyol to prepare waterborne polyurethane (WPU) dispersions. The modification of CO exhibited a great effect on the properties of WPU dispersions and coatings, and an obvious change is the improvement of the water resistance of WPU coatings. WPU dispersions with MCO had good storage stability. A WPU coating with 7% MCO had high surface hydrophobicity, and its water absorption was as low as 3.2%. Conductive carbon black filled WPU coatings with MCO were cured by efficient UV radiation, and their conductive percolation threshold could decrease to 0.76%, which could be attributed to the well filler dispersion and strong filler‐polymer interaction. The WPU dispersions are ecofriendly, and can be used to produce biobased WPU coatings with a great application potential in antistatic coating fields.

UV‐shielding by a polyurethane/f‐Oil fly ash‐CeO2 protective coating

AbstractA waste material called oil fly ash (OFA) was acid‐functionalized, yielding f‐OFA‐COOH, which was then reacted with cerium oxide (CeO2) to make CeO2‐functionalized OFA, or f‐OFA‐CeO2. Pristine OFA and f‐OFA‐CeO2 were used to make waterborne polyurethane (WBPU) dispersions, referred to as WBPU/OFA and WBPU/f‐OFA‐CeO2, respectively, with defined OFA and f‐OFA‐CeO2 content. All the dispersions were applied to mild steel as organic coatings to evaluate their protective properties, such as their hydrophobicity, adhesive strength and UV‐shielding resistance. These protective properties varied based on the OFA and f‐OFA‐CeO2 content. The highest water contact angle, minimum water swelling and maximum adhesive strength were found using WBPU/f‐OFA‐CeO2‐20 coating (using 2.00 wt% f‐OFA‐CeO2), which also showed the maximum ultraviolet (UV) absorption via UV–vis spectroscopy analysis. This UV shielding result also matched field test results, as that coating was found to exhibit the lowest UV degradation near a marine atmosphere, as shown by X‐ray photoelectron spectroscopy (XPS) analysis. The least affected hydrophobicity was also recorded for the sample with the WBPU/f‐OFA‐CeO2‐20 coating.

Fabrication of electrospun fibers from a waterborne soy‐based polyurethane employing polyethylene oxide as a coformer

AbstractThe fabrication of electrospun fibers made from aqueous dispersions of polyurethane obtained from renewable sources is an eco‐friendly method to produce porous membranes for different applications. Polyethylene oxide (PEO) has been already employed in formulations for allowing fiber formation, but its role was not yet completely understood. In this work the fabrication of electrospun fibers made from biobased polyurethane aqueous dispersion with PEO in order to obtain regular fibers is performed. The role of PEO was studied by thermal analysis, infrared and Raman spectroscopy, rheology, and fiber morphology. Polyurethane fibers were obtained only when PEO was added, otherwise the dispersion is electrosprayed and particles are formed. It was observed that PEO modifies the rheology of dispersion and assists coalescence of polyurethane particles. On the other hand, polyurethane fibers conserved their diameter and their homogeneous structure after removal of PEO by immersion in water, which indicates that the distribution of both polymers was even within the fibers. This work provides both an insight on the role of PEO and a route for the fabrication of eco‐friendly biobased polyurethane microfibers from aqueous dispersions.

Eco-Friendly Castor Oil-Based Delivery System with Sustained Pesticide Release and Enhanced Retention

The deposition of pesticides and their retention on plant surfaces are critical challenges for modern precision agriculture, which directly affect phytosanitary treatment, bioavailability, efficacy, and the loss of pesticides. Herein, a novel and eco-friendly waterborne polyurethane delivery system was developed to enhance the spray deposition and pesticide retention on plant surfaces. More specifically, biobased cationic and anionic waterborne polyurethane dispersions were synthesized from castor oil. Both cationic and anionic polyurethane dispersions exhibited remarkable microstructural, amphiphilic, and nanoparticle morphologies with a core-shell structure that served to encapsulate a biopesticide (azadirachtin) in their hydrophobic cores (WPU-ACT). The results indicated that the cationic WPU-ACT carriers exhibited a better sustained release behavior and a better protective effect from light and heat for azadirachtin. In addition, the simultaneous spray of anionic and cationic WPU-ACT significantly enhanced the spray deposition and prolonged the retention of pesticides due to the reduced surface tension and surface precipitation induced by the electrostatic interaction when two droplets with opposite charges come into contact with each other. A field efficacy assessment also indicated that the simultaneous spray of anionic and cationic WPU-ACT could control the infestation of brown planthopper in rice crops. Castor oil-based waterborne polyurethanes in this study work as an efficient pesticide delivery system by exhibiting enhanced deposition, rainfastness, retention ability, protection, and sustained release behavior, holding great promise for spraying pesticide formulations in modern and environmentally friendly agricultural applications.

Полиуретаны, наполненные модифицированным базальтовым волокном

The use of basalt fiber as a reinforcing filler is mainly used instead of glass fibers due to its unique properties. Basalt fiber in comparison with glass has a 10-22% greater modulus, higher absolute strength after exposure to 400 °C, superior to glass in alkali and especially acid resistance, approximately identical in water resistance, i.e. close in properties to high-modulus glass fibers. However, it is most often used as a filler for concrete and other building structures. There is much less information about its use as a polymer reinforcing filler. The polymer matrix for creating polymer composite materials is most often epoxy resins, less often polyester. At the same time, there is practically no data on polyurethanes that have a unique combination of high strength indicators with elasticity and hardness, resistance to solvents and aggressive media, abrasion resistance, etc. The use of basalt fiber as a filler that increases the strength characteristics of polyurethanes and gives them specific properties can significantly expand the scope of their application. In this regard, this study attempts to use crushed basalt fiber as a reinforcing filler for polyurethanes. In order to increase the adhesion of the polymer matrix – filler system, an adhesive based on water-based polyurethane dispersion is used. Samples were obtained based on a polyurethane binder filled with basalt fiber in amounts up to 10.0 % by weight, treated with water-polyurethane dispersion with a concentration of 10 to 20 % by weight. The best complex of strength properties is provided by polyurethanes filled with basalt fiber in the amount of 1.0% by weight, treated with 15 % by weight water-based polyurethane dispersion. At the same time, the tensile strength increased by 15% compared to the same filling without processing and by 50% compared to the unfilled analog and amounted to 33.7 MPa. These changes are explained by a more uniform distribution of crushed basalt fiber in the polymer matrix and an increase in the adhesion interaction of fiber-adhesive-polymer matrix due to the biphilicity of the adhesive, as well as the same (polyurethane) nature of the adhesive and the matrix. The developed polymer composite materials have high hydrolytic resistance, as well as resistance to acetone and hexane. At the same time, the greatest degree of swelling did not exceed 0.9 % of the mass.

Synthesis and properties of waterborne polyurethane dispersions for surface coatings on poly(vinyl chloride)

Recently, conventional solvent-typed polyurethanes are subject to many regulations due to emission of organic volatile compounds(VOCs) and researches have been focused on eco-friendly waterborne polyurethane dispersions(WPUDs) as an alternative of conventional solvent-typed ones causing poor working environment. PVC is widely used because of low price and good heat and fire resistance. To develop eco-friendly coatings on poly(vinyl chloride) (PVC), various WPUDs were synthesized by combination of polyol such as polyester, polycaprolactone, polyether or polycarbonate, hydrophilic compounds (dimethylol butanoic acid, DMBA), and reactive silicone. The structure and properties of synthesized WPUDs were characterized by FT-IR, particle size, contact angle, surface energy, tensile strength, elongation, and adhesion strength. Also, their particle sizes decreased while tensile strengths increased with increasing DMBA content. Surface energy and contact angle of WPUDs were strongly affected by the content of hydrophobic reactive silicone. The optimum properties of WPUDs were obtained by controlling their compositions, polyol, hydrophilic compound, and reactive silicone.

Engineering foam skeletons with multilayered graphene oxide coatings for enhanced energy dissipation

This work shows how to improve the energy dissipation of open-cell polyurethane (PU) foams by creating multilayered graphene oxide (GO) nano-architectures onto the struts via a modified dip-coating process. Pristine PU foams are alternately dip-coated with GO coatings and water-based polyurethane dispersions (PUD) for a given number of times. The GO coating morphologies are carefully adjusted and the inner energy dissipation mechanisms reach the optimized interfacial frictions of GO-PU and GO-GO. Along with the synergistic effect of the multiple interpenetrating structure of GO/PU coating phases, these engineered composite foams with extremely low GO content (~0.12 wt%) afford a significant increase of quasi-static energy dissipation (52%) and dynamic damping (76%) when compared with counterpart foams coated with the same number of pure PUD layers. The specific Young’s modulus and strength of the designed foams also show remarkable enhancements of 310% and 490% respectively compared with those of pristine PU foams.

Fundamental insight into anionic aqueous polyurethane dispersions

Abstract Aqueous Polyurethane Dispersions (APUD) have been at the epicenter of the coating industry & research, devising greener solutions to modern coating problems. The formulation of APUDs involves many components namely, polyols, isocyanates, chain extenders, and ionic centers which enable the Polyurethane to be dispersed in water. This reduces the dependence on solvent-based coatings, providing a better and eco-friendly replacement for existing systems. Advantages like ambient temperature curing and excellent adhesion further reinforce the case for APUD. This review encompasses the synergistic effect of said components while painting a vivid picture of how they would affect the final properties of the coating.

Terminal Hydrophilicity-Induced Dispersion of Cationic Waterborne Polyurethane from CO2-Based Polyol

Cationic waterborne polyurethane (CWPU) was initially developed as a specific adhesive for anionic surface but now is ubiquitous in innovative material systems such as poly(ionic liquid)s, polyelec...

Synthesis and molecular interaction of tung oil‐based anionic waterborne polyurethane dispersion

AbstractIn the present work, four types of anionic waterborne polyurethane dispersions (APUD) based on polytetramethylene ether glycol (PTMG) and two aliphatic diisocyanates, dicyclohexylmethane diisocyanate (HMDI) or isophorone diisocyanate (IPDI), were prepared by polymerization methods which for the first time controlled the location (soft or hard segment) of hydroxylated tung oil (HTO) incorporation into the final APUD. The resulting HTO‐containing APUD polymers (HTO‐APUDs) with postpolymerization crosslinking capability were characterized using FTIR, DMA, AFM and water imbibition methods, and compared to model compounds synthesized to have the same parts of chemical structural linkages for band assignment. A common PUD sample, as well as polypropylene oxide (PPG) with molecular weight similar to HTO (Mn = 400), was used to replace it for preparing control samples to highlight the role of long branched chains and conjugated double bonds in HTO. Based on the analysis of multiple H‐bond interactions, the relationship of HTO location in the APUD polymer structure to the soft/hard segment compatibility and the diisocyanate structure was further studied. This work is expected to provide basic data for properties regulation in practical applications by adjusting the chain and phase structure, as well as the intermolecular interactions, in these APUDs.

Bio-derived water dispersible polyurethane/rGO@α-MnO2/rGO@δ-MnO2 nanocomposite as a heterogeneous catalyst and anticorrosive material

Herein, we report the fabrication of rGO@α-MnO2/rGO@δ-MnO2 nanohybrid containing bio-derived water dispersed polyurethane (PU) nanocomposite (PUNH). Three nanocomposites of PU were fabricated with 0.5, 1.0 and 1.5 wt percentages of rGO@α-MnO2/rGO@δ-MnO2 and characterized by using various techniques including FTIR, XRD, BET, CV, FESEM, and TEM. Thermo-mechanical properties of PUNHs increase with the increase of nanohybrid content in the pristine PU. Chemical resistance and UV-aging capabilities of PUNHs increase, whereas biodegradation of them decreases with the increase of nanohybrid concentration in the pristine PU. The catalytic activities as well as anticorrosive performance of the nanocomposite were found to be excellent. PUNH1.5 showed proficient catalytic efficiency for the synthesis of N-(4-nitrobenzylidene)aniline with high yield (∼ 83 %). The used nanocomposite was recycled for five times without significant loss of activity. Furthermore, PUNH1.5 showed favorable corrosion current density (9.64 × 10−9A/cm2), corrosion potential (-0.318 V) and corrosion rate of 5.98 × 10-4 mm/yr after 8 days of exposure in 3.5 wt percentage NaCl aqueous solution.

Improving water resistance of waterborne polyurethane coating with high transparency and good mechanical properties

Polyester based waterborne polyurethane (WPU) dispersions modified with hydroxypropyl-terminated polydimethylsiloxane (HPDMS) and sulfonate polyester diol were synthesized. The water resistance of WPU coating improved significantly when 5% HPDMS was used for modification, but it also leads to the decreasing of dispersion stability and damages in the mechanical properties and transparency of WPU coating. It was found that incorporating ionic groups in soft segments (sulfonate polyester diol) of WPU can obtain a coating with good water resistance where only 0.5% HPDMS is needed. In this case, the water swelling of WPU coating decreased to 7.0% while the pure WPU was 15.2%. Meanwhile, the mechanical and optical properties of modified coating change slightly. Its tensile strength was 62.6 MPa, and its light transmittance at 532 nm was 83.8%. Zeta potential test indicated the introduction of sulfonate polyester diol could improve the stability of WPU dispersions. The water resistance improvement of the WPU coating could be ascribe to the decrease of surface free energy and the change of phase separation degree. The water swelling, X-ray photoelectron spectroscopy, and contact angle test results demonstrated the migration of HPDMS and sulfonate polyester diol segments on the coating surface. The phase separation of WPU coatings was measured by dynamic thermomechanical analysis. The modified WPU with excellent water resistance is promising in the application of transparent coatings.

Effect of different carboxylic acid group contents on microstructure and properties of waterborne polyurethane dispersions

The waterborne polyurethane (WPU) with different carboxylic acid group contents were prepared by a prepolymer method, adopting polycarbonate diol (PCDL) as soft segments and isophorone diisocyanate (IPDI) as hard segments. The different amounts of 2,2-dimethylolbutyric acid (DMPA) as hydrophilic chain extender were introduced into polyurethane molecular for studying the effect on microstructure and properties. The solid content, pH value and viscosity measurement were used to characterize the performance of WPU emulsion. The fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermogravimetric (TG), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), water contact angle tester and mechanical testing machine were utilized to measure the structure, crystallization performance, thermal stability, low temperature flexibility, wetting performance and mechanical properties of WPU films, respectively. The test value of impact, adhesive, flexibility and pencil hardness on tinplate of WPU coatings were obtained for observing film properties. The results indicated that the emulsification effect increase with the increased DMPA contents. The decomposition temperature of WPU films perform a slight decrease and the WPU films have excellence low temperature flexibility with the increased DMPA contents. The hydrophilic property of WPU films mainly are about 80°and the tensile strength value of 7 wt% WPU reaches 45 MPa and elongation at break at 420%.

Higher thermal conductivity and mechanical enhancements in hybrid 2D polymer nanocomposites

Nanocomposites based on graphene oxide (GO), hexagonal boron nitride (h-BN), and their hybrid GO/h-BN as nanofillers in polyurethane (PU) were prepared, and their structures and morphologies were studied. The efficient production of a few layers of nanofillers was completed using the direct liquid-phase exfoliation process. Mechanical and thermal tests were carried out to study the effect of the addition of GO, h-BN, and GO/h-BN at different wt% in the PU system. The tensile strength and Young's modulus showed an increase of up to 85% and 140%, respectively, for the composite containing 0.5 wt% of the hybrid GO/h-BN mixture. An impressive improvement of up to ~1450% in thermal conductivity was observed for the same sample when compared to neat polymer. In order to gain further insights regarding the mechanism behind the nanofiller dispersion and adhesion processes in PU, fully atomistic classical molecular dynamics simulations were carried out. Based on these simulations, it was possible to build structural models that help to explain the thermal and mechanical improvements in the hybrid GO/h-BN composites, with a focus on its stabilization energy.

Effect of DMPA Content on Colloidal Stability of Jatropha Oil-based waterborne Polyurethane Dispersion

Driven by the increase of oil price in the market as well as environmental concerns by the society, a renewable raw material such as vegetable oil becomes the alternative to produce bio-based polyol to replace non-renewable polyols in polyurethane production. The recent development of aqueous polyurethane dispersion proves that environmentally waterborne PUD offers an efficient alternative to the solvent-borne PUD for the application in ink, adhesives, and coatings. In this study, the jatropha oil has been successfully functionalized to polyol (JOL) by epoxidation and oxirane ring opening steps. Jatropha oil-based waterborne polyurethane (JPU) dispersions were produced by polymerizing the JOL with isophorone diisocyanate (IPDI) and dimethylolpropionic acid (DMPA). The colloidal stability of JPU dispersions was studied in terms of particle size and zeta potential. Varying DMPA content from 5.0-7.0 wt.% resulted in small average particle size of dispersion from 39.40 nm to 133.2 nm. High zeta potential obtained in a range of -52 mV to -65 mV indicates the particles in the dispersion are sufficiently separated and therefore stable. Eventually, the study provides an overview of vegetable oil-based waterborne polyurethane dispersion with good stability for surface coating application.

Preparation of Cationic Polyurethane Dispersion and Its Effectiveness as Denim Dye Fixing Agent

The issue encountered by the textile industry is that the colours are fading off, particularly in denim fabric, by constant washing, so fixing agent is needed to enhance the colour fastness of the denim fabric. Polyurethane is one of the promising types of nonformaldehyde dye fixing agents. It has good film covering properties and allows air permeability. In this study, cationic polyurethane dispersions (CPU) were syntheses and applied as fixing agent for sulphur dye denim fabric. Different formulation of CPU were synthesized using isophorone diisocyanate, different molecular weight of polyols, and tertiary amine. Formulated CPU were then analysed using FTIR, zeta potential analyser and viscometer. Zeta potential obtained was in the range of +8.1 mV to +41.7 mV indicates that some of the CPU particles tend to agglomerate and some are stable. After fixing treatment, colour fastness to crocking of the treated fabric has improved. Surface morphology changes were determined by SEM and it shows that smooth finishing fibre surface was obtained in treated black denim fabric.

Waterborne polyurethanes from castor oil-based polyols for next generation of environmentally-friendly hair-styling agents

Commercial hair-styling spray is often formulated with multiple components that contribute to toxicity and environmental pollution. In this work, a series of bio-based waterborne polyurethanes (CWPU) as hair styling agent were prepared from castor oil-based polyols. The resulting polyurethane dispersions exhibit excellent storage stability for at least 24 months. The effects of the castor oil functionality and chain extender structure on the particle size of the polyurethane dispersions were systematically investigated. Hair-styling performance and skin irritation tests on animals were also carefully performed to assess styling performance and safety of these CWPUs. A series of CWPU films was successfully prepared to study the relationship between the structure and performance of the bio-based polymer films. The resulting films show low moisture uptake rate, high transmittance, hydrophilicity and good mechanical properties. When CWPU films exhibit Young’s modulus >50 MPa, elongation at break in the 15–300 % range, and moisture uptake <4 %, these samples exhibit good hair-styling performance, and even better than commercial hair spray product. The skin irritation test is also proved that there is no evidence of skin irritation for these CWPUs which hold great promise for hair styling applications.

New Waterborne Polyurethane-Urea Synthesized with Ether-Carbonate Copolymer and Amino-Alcohol Chain Extenders with Tailored Pressure-Sensitive Adhesion Properties.

New waterborne polyurethane-urea dispersions with adequate adhesion and cohesion properties have been synthesized by reacting isophorone diisocyanate, copolymer of ether and carbonate diol polyol and three amino-alcohols with different number of OH groups chain extenders using the prepolymer method. The waterborne polyurethane-urea dispersions were characterized by pH, particle-size distribution, and viscosity, and the polyurethane-urea films were characterized by attenuated total reflectance infrared (ATR-IR) spectroscopy, differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), and plate-plate rheology (temperature and frequency sweeps). Polyurethane-urea pressure-sensitive adhesives (PUU PSAs) were prepared by placing the waterborne polyurethane dispersions on polyethylene terephthalate (PET) films and they were characterized at 25 °C by creep test, tack and 180° peel test. The waterborne polyurethane-urea dispersions showed mean particle sizes between 51 and 78 nm and viscosities in the range of 58–133 mPa·s. The polyurethane-urea films showed glass transition temperatures (Tgs) lower than −64 °C, and they showed a cross of the storage and loss moduli between −8 and 68 °C depending on the number of OH groups in the amino-alcohol chain extender. Different types of PUU PSAs (removable, high shear) were obtained by changing the number of OH groups in the amino-alcohol chain extender. The tack at 25 °C of the PUU PSAs varied between 488 and 1807 kPa and the 180° peel strength values ranged between 0.4 and 6.4 N/cm, and their holding times were between 2 min and 5 days. The new PUU PSAs made with amino-alcohol chain extender seemed very promising for designing environmentally friendly waterborne PSAs with high tack and improved cohesion and adhesion property.