PU Dispersions Research Articles

Structure-property relationship of thermoplastic polyurethane cationomers carrying quaternary ammonium groups

This study reports the synthesis and characterization of thermoplastic polyurethane cationomers and its dispersion in water. The cationomeric polyurethanes were synthesized by reacting polyol, isocyanate, NMDEA and dihydrazide followed by ionization of the tertiary nitrogen atoms of NMDEA moieties with alkyl bromides. Variations were done with respect to chain length of cationizing agent, isocyanate type and chain extender and all the compositions were compression molded into sheets. The ionization of the tertiary nitrogen atom in the PU backbone was confirmed by NMR and GPC results showed that the compositions with increasing alkyl chain length showed increasing molecular weight. The cationomers showed a Tg corresponding to the soft segments around −60°C and hard segment in the 5–15°C range. PU cationomers exhibited enhanced tensile strength and elongation but lower storage modulus compared to the unionized samples. Water contact angle measurements indicated that the contact angle increased with increase in the length of the pendant alkyl groups and the composition carrying sebacic dihydrazide as chain extender in the place of adipic dihydrazide exhibited the highest contact angle (112°). The polymers had antifouling properties since there was no growth of microorganisms over the films and solution of polymer in DMSO (2 mg/ml) exhibited antimicrobial properties against E. coli and S. aureus with a growth inhibition of 10 to 29% and 9 to28% respectively. Among all the cationomers, the one carrying C8 alkyl chain as pendant group with the right balance of hydrophilicity-hydrophobicity could be dispersed in water yielding cationomeric waterborne PU dispersion. This dispersion was very stable and suitable for coating hydrophobic surfaces like polypropylene.

Effects of polyolefin polyol contents on the properties of waterborne olefin polyurethane adhesives for thermoplastic polyolefins

In this study, water-based polyurethane adhesives (WOPU) with excellent adhesion to thermoplastic polyolefines (TPOs) were synthesized. Polyester polyol and polyolefin polyol, 4,4'-dicyclohexylmethane diisocyanate, and isophorone diamine were used. The properties of the PU dispersion were evaluated by Fourier transfer infrared spectroscopy, differential scanning calorimetry, thermogravimetry and a universal testing machine. The effects of polyolefin polyol on the properties of the PU dispersion adhesives were systematically investigated. The PU dispersion showed highest tensile strength of 278 kgf/cm2 when the ratio of polyester polyols to polyolefin polyols was 9:1. The adhesion strength and water resistance showed the same trend.

Metal–organic framework (UiO‐66)‐dispersed polyurethane composite films for the decontamination of methyl paraoxon

AbstractPolyurethane (PU) composite films containing UiO‐66 were prepared for the decontamination of methyl paraoxon (MPO), an organophosphate‐type nerve agent simulant. Waterborne PU dispersions were synthesized by changing the type of polyol to improve the miscibility with UiO‐66. Depending on the size of the polyol, the PU films had different surface free energy, flexibility and compatibility with UiO‐66. UiO‐66 was well dispersed in PU films when the flexibility of the films increased. The tensile strength of the UiO‐66/PU composite films gradually increased from 7.5 to 11.3 MPa with increasing UiO‐66 content, but the elongation decreased from 781 to 120%. The decomposition of MPO by the UiO‐66/PU composite films increased with an increase of the UiO‐66 content and hydrolysis time. In the case of the 21.2 wt% UiO‐66/PU composite film, 48% of MPO was decomposed within 3 h. This was similar to the decomposition when using a UiO‐66 slurry (52%) under the same decomposition conditions. Unlike the UiO‐66 slurry, the 21.2 wt% UiO‐66/PU composite film maintained a similar MPO decomposition performance after 10 repeated experiments. © 2019 Society of Chemical Industry

Distinctive distributions and migrations of 239+240Pu and 241Am in Chinese forest, grassland and desert soils

The vertical distributions and downward migrations of the global fallout derived 239+240Pu and 241Am in diverse types of Chinese soils (forest, grassland and desert) were studied. The mean 239+240Pu and 241Am activity concentrations in the investigated soil cores were 0.28–0.69 mBq/g and 0.13–0.37 mBq/g, respectively, while the accumulative inventories were 61.53–138.99 Bq/m2 for 239+240Pu and 28.29–61.05 Bq/m2 for 241Am. The convection-dispersion equation (CDE) was used to calculate the migration parameters of 239+240Pu and higher apparent dispersion coefficients (D) were observed for the acidic forest soils compared with the alkaline grassland and desert soils; meanwhile a compartment model was employed to compare the migration of 239+240Pu and 241Am in successive soil layers which showed that the migration behaviors of 239+240Pu and 241Am were rather similar; both velocities were less than 0.3 cm/y in diverse types of soils and these findings were compatible with those of short-term laboratory simulation experiments in China.

Study of ionic/nonionic polyurethane dispersions with high solid content and low viscosity using a complex hydrophilic chain-extending agent

An ionic/nonionic polyurethane dispersion with high solid content and low viscosity with a complex hydrophilic chain-extending agent was prepared using isophorone diisocyanate as a hard segment and propylene oxide glycol as a soft segment. The complex hydrophilic chain-extending agent consisted of DPSA and BDSA. The effects of the molar ratio of DPSA/BDSA on the properties of the resultant polyurethane dispersions were studied. The morphologies and properties of the ionic/nonionic PU dispersions were examined using particle-size, TEM, and viscosity analyses. It was found that the ionic/nonionic dispersions possessed wide particle-size distributions due to the addition of the complex hydrophilic chain-extending agent. The ionic/nonionic PU dispersions possessed higher solid content than conventional WPU dispersions because the number and volume percentage of the large particles and small particles of the ionic/nonionic dispersions met the requirements for high solid content. It was observed that the solid content of the ionic/nonionic dispersion increased and then decreased with an increasing molar ratio of DPSA/BDSA. When the ratio ranged from 4:10 to 5:10, the solid content of the ionic/nonionic PU dispersion reached up to 55%. It was also noticed that the apparent viscosity of the ionic/nonionic polyurethane dispersion decreased with an increasing molar ratio of DPSA/BDSA. The complex hydrophilic chain-extending agent consisting of DPSA and BDSA enhanced the solid content and decreased the viscosity of the ionic/nonionic dispersions, which are very important for improving the properties and expanding the applications of PU dispersions. In addition, the ionic/nonionic polyurethane dispersion had good electrolyte-resistance properties, stability at both high and low temperatures, and storage stability.

Self-Cross-Linkable Anionic Waterborne Polyurethane–Silanol Dispersions from Cottonseed-Oil-Based Phosphorylated Polyol as Ionic Soft Segment

Phosphorylated polyols (phospols) derived from cottonseed oil (CSO) were employed to synthesize novel, DMPA- (dimethylol propanoic acid-) free, catalyst-free, waterborne polyurethane dispersions (PUDs). Three different phospols bearing both hydroxyl and ionizable phosphoryl groups were synthesized through the ring-opening hydrolysis of epoxidized cottonseed oil (ECSO) in the presence of ortho-phosphoric acid. The phospols were characterized by 1H NMR spectroscopy, FTIR spectroscopy, and gel permeation chromatography. Three phospols (phospol-P5, -P10, and -P15) having hydroxyl numbers of 130, 160, and 180 mg of KOH/g, respectively, were used as internal emulsifiers in waterborne PUDs with isophorone diisocyanate and 3-aminopropyltriethoxysilane (APTES). All three PU dispersions showed excellent storage stabilities (>6 months), and the average particle sizes of the PUDs ranged from 30 to 68 nm. The cured films were characterized by FTIR (ATR) and solid-state 29Si NMR analyses. The hydrophobicities of the fi...

Synthesis and Properties of Cationic Polyurethane Dispersions

A series of water dispersible polyurethanes containing quaternary ammonium group as the hydrophilic group with different content of trimethylolpropane (TMP) as inner crosslinker were prepared. IR spectroscopy was adopted to demonstrate the polymerization reaction and structure of polymer. The effects of TMP content on PU properties were investigated. Particle size distribution (PSD) analysis and morphology of PU observed by TEM showed that particle size of PU dispersions initially decreased and then increased with increasing TMP content. The viscosity of the PU dispersions with TMP addition was bigger than the PU dispersions without TMP. TG analysis indicated thermal stability and microphase separation degree of PU was enhanced with increasing TMP content. Contact angle and gel content of PU also increased as increasing TMP content. Meanwhile, tensile strength increased and then decreased with the increment of TMP content.

Synthesis, characterization and efficiency evaluation of chitosan-polyurethane based textile finishes

A series of polyurethane dispersions were synthesized through two step polymerization technique. A PU prepolymer with NCO termini was prepared using isophorone diisocyanate (IPDI), poly caprolactone diols (CAPA of mol. wt. 1000) and DMPA (3:1:1), and PU prepolymer chain was extended with different mole ratios of low molecular weight chitosan and finally aqueous emulsion was prepared by adding suitable volume of water. The proposed structure of chitosan based PU dispersions was confirmed through FTIR spectroscopy. The prepared aqueous CS(LMW)-CPUIs emulsions were applied onto the different quality plain weave poly-cotton dyed and printed fabric pieces using pad-dry-cure procedures. The physical properties such as air permeability, stiffness and crease recovery angle (CRA), pilling resistance, tear and tensile strength of the treated and untreated fabric samples were also evaluated. The results revealed that the incorporation of chitosan has pronounced effect on the properties of treated fabrics. This research could be extended in future for performance evaluation of pure cotton and woolen fabrics.

Glycolysis of high resilience flexible polyurethane foams containing polyurethane dispersion polyol

In the last years, high resilience polyurethane foams (HR foams) production has experienced an intensive growth as a consequence of their wide application field, causing an important increment of the generated waste. HR foams containing PU dispersions polyols are the last tendency in the HR foam industry, due to the improvement of the flame retardant properties and the emissions reduction of volatile compounds in comparison to the traditional graft polymeric HR polyols. In this work the extension of the glycolysis process to the recycling of this kind of foams has been carried out. Diethylene glycol (DEG), glycerol 99% PS and crude glycerol, coming from the biodiesel production, have been assayed as glycolysis agents. All of these glycolysis agents provided a split phase product with an upper phase mainly constituted by a traditional HR polyol and a bottom phase consisting of the excess of glycolysis agent and several reaction byproducts. However, the polyol content in the final product has been greater with the employment of glycerol. Moreover, flexible and rigid foams have been synthesized by using the recycled polyols or the glycolysis bottom phase, respectively. This way, it is achieved a global and sustainable recycling process for the valorization of two waste substances: the HR PU foam and the crude glycerol.

Bio-based poly(urethane urea) dispersions with low internal stabilizing agent contents and tunable thermal properties

Poly(urethane urea)s dispersed in water were prepared from biobased monomers, including a fatty acid-derived diisocyanate (DDI), the lysine-derived ethyl ester l-lysine diisocyanate (EELDI) and 1,4:3,6-dianhydro-d-glucitol (isosorbide, IS). Ionic stabilization of the polymer particles in water was achieved by incorporating dimethylolpropionic acid (DMPA) in the polyurethane backbone. The synthesis of isocyanate-functional prepolymers with number-average molecular weights (Mn) of approximately 6000 g/mol was followed by their dispersion in water and chain extension using ethylene diamine. The chain extension procedure was optimized, resulting in final Mn values of approximately 17,000 g/mol. The replacement of DDI by EELDI and the incorporation of IS into the polymer composition effectively reduced the required amount of DMPA from 6.0 to 2.0 wt% to render stable dispersions and significantly enhanced the Tg values of dispersion-cast films to 60 °C (1st Tg) and to above 70 °C (2nd Tg), however, at the expense of slightly reduced thermal stability. The asymmetric structure of EELDI and its pendant ester group potentially facilitated the dispersion stability, the latter through possible (partial) hydrolysis. Accordingly, aqueous PU dispersions with a renewable content up to 97 wt% and sufficiently high, tunable film Tg values have been obtained.

A New Approach for Synthesizing the Hybrid Silica Aerogels

Uniform Polyurethane/silica hybrid aerogels were achieved at ambient pressure via an approach in which an aqueous polyurethane dispersion was used and the hybridization step carried out before gelation step. The FT-IR spectra confirmed the incorporation of polymer chains into the silica network and hybrid network formation.As the H2O/TEOS molar ratio increased after hybridization in this method, the effect of H2O/TEOS molar ratio changes and PU content on the density of hybrid aerogels was investigated separately. The density of native silica aerogels decreases commonly with increasing the water content while increasing the aqueous PU dispersion content increases the density of hybrid aerogels. The density difference between the hybrid aerogel sample with a certain aqueous PU dispersion and the similar native silica aerogel with the same H2O/TEOS molar ratio demonstrated the intensive polyurethane chain effect on the aerogel density. The results showed that the simultaneous increase of H2O/TEOS molar ratio and PU content could be led to the uniform structure of hybrid aerogels. However, the effect of polyurethane on the aerogel density was more sensitive than H2O/TEOS molar ratio effect especially in high polyurethane content (≥10wt.%) that increased the density of hybrid aerogels.

Effect of 2‐ethylhexyl acrylate and N‐acryloylmorpholine on the properties of polyurethane/acrylic hybrid materials

ABSTRACTA hybrid synthesis technology was used to prepare waterborne polyurethane/acrylic hybrid emulsions by polymerization of methyl methacrylate, butyl acrylate, 2‐ethylhexyl acrylate(EHA), and N‐acryloylmorpholine (AMCO) in presence of acrylic‐terminated PU dispersion. Various characterization methods were used to investigate the effect of EHA and ACMO content on the properties of the hybrid emulsions and their resultant films. The research results show that the introduction of EHA can enhance the elasticity of their films, meanwhile, ACMO endows the film with high gloss, adhesion on substrate, toughness, and hardness. Mixing the two monomers leads to yield the hybrid materials with moderate properties. While increasing the weight ratio of ACMO/EHA, the average particle size of the hybrid emulsions increases and their viscosity decreases. For the resultant films, their surface water contact angle, adhesion on substrates, tensile strength, and hardness increase, but the water resistance and elasticity decrease. It has been found that EHA and ACMO have a synergistic effect on gloss of the hybrid films and the hydrogen bond interaction increases with an increase in the ACMO content. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41463.

Effect of cardanol diol on the synthesis, characterization, and film properties of aqueous polyurethane dispersions

This article reports on the effect of a diol prepared from a renewable resource, cardanol, on the synthesis, film formation and film properties of aqueous polyurethane dispersions. The PU dispersions were prepared by the acetone process from poly(tetramethylene ether)glycol (PTMEG) and isophorone diisocyanate (IPDI) prepolymer at constant NCO/OH ratio of 1:1.1. Dispersions with two different concentrations of cardanol diol (OH value 140 mg KOH/g) were prepared through chain extension and characterized for solid content, particle size, and particle-size distribution (PSD). Free films were prepared by casting and were studied for their thermal, mechanical, viscoelastic, and hydrophobic properties. Due to the broad PSD, the dispersions containing cardanol diol exhibit better film formation property in comparison to the butane diol chain-extended PU. Soft and flexible films were obtained using cardanol diol as chain extender, whereas brittle film was obtained with butane diol chain extender. Morphological characterization using atomic force microscopy (AFM) and scanning electron microscopy (SEM) suggests a heterogeneous and amorphous nature of the polyurethanes-containing cardanol diol. The thermomechanical and viscoelastic properties show that incorporation of cardanol diol decreases the glass transition temperature and modulus of the films but enhances the properties like thermal stability, hydrophobicity, elongation, etc., of the polyurethane films.

Thermo‐Mechanical and Antibacterial Properties of Soybean Oil‐Based Cationic Polyurethane Coatings: Effects of Amine Ratio and Degree of Crosslinking

AbstractSoybean‐oil‐based cationic polyurethane coatings with antibacterial properties have been prepared with a range of different molar ratios of hydroxyl groups from an amine diol. A second series of polyurethane coatings were prepared from soy polyols with different hydroxyl numbers. All of the cationic PU dispersions and films exhibit inhibitory activity against three foodborne pathogens: Salmonella enterica ssp. enterica ser. Typhimurium, Listeria monocytogenes, and Staphylococcus aureus. It is generally observed that increases in the ratio of ammonium cations improve the antibacterial performance. Reduction of the crosslink density by decreasing the hydroxyl number of the soy polyol also results in slightly improved antibacterial properties. Higher glass transition temperatures and improved mechanical properties are observed with corresponding increases in the molar ratios of the amine diol and the diisocyanate. These results show that the mechanical properties of these coatings can be tuned, while maintaining good antibacterial activity.

Synthesis and properties of aqueous polyurethane dispersions: Influence of molecular weight of polyethylene glycol

Aqueous polyurethane dispersions (PUDs) have recently emerged as important alternatives to their solvent-based counterparts for various applications due to increasing health and environmental awareness. A series of aqueous polyurethane dispersions containing carboxylate anion as hydrophilic pendant groups were synthesized through step growth polymerization reaction using hexamethylene diisocyanate (HDI), 1,4-butanediol (1,4-BDO), dimethylol propionic acid (DMPA) and polyethylene glycol (PEG) of different molecular weight. Effect of PEG molecular weight was investigated on molecular structure, contact angle measurement, and physical and adhesive properties of PU emulsions. Fourier transform infrared spectroscopy (FT-IR) was used to check the completion of polymerization reaction. Contact angle measurement indicated that the hydrophilicity of polymer increases by increasing molecular weight of PEG with a corresponding decrease in contact angle. Results of T-peel test showed a decrease in peel strength by increasing molecular weight of PEG. Moreover, solid contents%, drying time and storage stability suggested fast drying properties and greater stability of aqueous PU dispersions.

Trench ‘Bathtubbing’ and Surface Plutonium Contamination at a Legacy Radioactive Waste Site

Radioactive waste containing a few grams of plutonium (Pu) was disposed between 1960 and 1968 in trenches at the Little Forest Burial Ground (LFBG), near Sydney, Australia. A water sampling point installed in a former trench has enabled the radionuclide content of trench water and the response of the water level to rainfall to be studied. The trench water contains readily measurable Pu activity (∼12 Bq/L of 239+240Pu in 0.45 μm-filtered water), and there is an associated contamination of Pu in surface soils. The highest 239+240Pu soil activity was 829 Bq/kg in a shallow sample (0–1 cm depth) near the trench sampling point. Away from the trenches, the elevated concentrations of Pu in surface soils extend for tens of meters down-slope. The broader contamination may be partly attributable to dispersion events in the first decade after disposal, after which a layer of soil was added above the trenched area. Since this time, further Pu contamination has occurred near the trench-sampler within this added layer. The water level in the trench-sampler responds quickly to rainfall and intermittently reaches the surface, hence the Pu dispersion is attributed to saturation and overflow of the trenches during extreme rainfall events, referred to as the ‘bathtub’ effect.

Synthesis and swelling behavior of pH‐responsive polyurethane/poly[2‐(diethylamino)ethyl methacrylate] hybrid materials

ABSTRACTPolyurethane (PU)/poly[2‐(diethylamino)ethyl methacrylate] hybrids, having a chemical bond between the PU and acrylic moieties and with different compositions, were prepared by the dispersion polymerization of 2‐(diethylamino)ethyl methacrylate (DEA) in the presence of preformed PU chains with polymerizable terminal vinyl groups. The PU dispersion was synthesized according to a prepolymer mixing process by the polyaddition of isophorone diisocyanate, poly(propylene glycol), 2‐hydroxyethyl methacrylate, and dimethylol propionic acid (DMPA). Then, it was dispersed in water by the prior neutralization of the carboxylic acid groups of DMPA with triethylamine, chain‐extended with ethylenediamine. The effect of the DEA content on the swelling properties (water uptake and dynamic swelling degree) at different pHs and at 37°C was determined. The samples were also characterized by Fourier transform infrared spectroscopy and modulated differential scanning calorimetry. The experimental results indicate a higher water uptake when the DEA content was increased on the hybrid materials and a significant change in the kinetics of swelling at pH 4 compared to those at pH 7. The water content of the hydrogels depended on the DEA content, and it was inversely proportional to the pH value. The pure PU film did not show important changes over the pH range examined in this study. The synthesized hybrids were useful as drug‐delivery, pH‐sensitive matrices. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39799.

Degradable Polyurethane/Soy Protein Shape-Memory Polymer Blends Prepared Via Environmentally-Friendly Aqueous Dispersions

The authors would like to add a mentioning of previous work that was missing in the originally published Acknowledgements. The completed version should read as follows: Acknowledgements The authors thank M. Schossig (HZG, Teltow) for performing the SEM and STEM investigations, Prof. Otaigbe's group (University of Southern Mississippi) for providing PU dispersions, and Dr. K. Schmälzlin for administrative support. A part of this work has been presented at the ANTEC 2010 meeting. We apologize for any inconvenience caused.

Study on high‐solid content Si/PU polyurethane dispersion with PES/PPG composite soft segment

AbstractA polyol consists of silicone chains and epoxy acrylate structures, referred to as silicon polyether (PES), was used to prepare crosslinked Si/PU dispersions. Both PES and propylene oxide glycol (PPG) were mixed as soft segments. The effects weight ratios of PES to PPG on properties of the resultant polyurethane dispersions were studied. Morphology and properties of the Si/PU dispersions were characterized by particle size, transmission electron microscopy (TEM), and viscometer. It is shown that the Si/PU dispersions possessed wider particle size distribution and higher average particles diameter because of the use of PES, which contains crosslinked silicone side chains. The Si/PU dispersions have higher solid content as compared to the conventional water‐based polyurethane, because of the volume fraction ratio of bigger particle to small particle from the Si/PU dispersions. As increasing weight ratio of PES to PPG, the solid content of the Si/PU dispersions increased firstly, and then decreased. When the ratio ranges from 4 : 10 to 5 : 10, solid content of the Si/PU dispersions is up to 55%. It was also noticed that apparent viscosity of the Si/PU dispersions decreased with increasing PES to PPG ratio. In the Si/PU dispersions, solid content was increased and viscosity was decreased by the use of PES. Therefore, PES is a potential compound for the application of PU dispersions. In addition, stability of the crosslinked Si/PU dispersions decreases slightly at high‐ and low‐temperature; however, which can meet the basical requirements. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Castor‐Oil‐Based Waterborne Polyurethane Dispersions Cured with an Aziridine‐Based Crosslinker

AbstractCastor‐oil‐based anionic PU dispersions are post‐cured using a multiaziridine‐based crosslinker CX‐100. Thermal and mechanical properties of the resulting films are studied by DMA, DSC, TGA, and tensile tests. Mechanical properties are dramatically improved by the crosslinker. For example, the Young's modulus and tensile strength increase from 14.5 to 125 MPa and 13.1 to 18.1 MPa, respectively, when the aziridine fraction increases from 0 to 100%. The onset decomposition temperature of the films, T5, increases from 162 to 209 °C, indicating a significant increase in the thermal stability as the amount of aziridine is increased. This work provides an effective way of curing biorenewable anionic PU dispersions to prepare high performance, environmentally friendly coatings. magnified image