Curing reaction of amino‐terminated aqueous‐based polyurethane dispersions with triglycidyl‐containing compound

Amino‐terminated anionic aqueous‐based polyurethane (PU) dispersion was obtained from NCO‐terminated PU prepolymer, which was neutralized with an excess triethylamine (TEA) and chain extended by ethylenediamine (EDA) during water dispersion process. That PU prepolymer was obtained from a polyaddition reaction of isophorone diisocyanate (IPDI), polypropylene glycol‐2000 (PPG‐2000), and 2,2′‐dimethylol propanoic acid (DMPA). This aqueous‐based PU dispersion was treated with trimethylolpropane triglycidyl ether (TMPTGE) as a latent curing agent and resulted in a self‐cured PU resin on drying. A model ring‐opening curing reaction between oxirane group of TMPTGE with terminal amino group of PU was demonstrated by glycidol with n‐butyl amine. The physical and mechanical properties as well as thermogravimetric analyses of these self‐cured PU resins were evaluated in this article. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis of bio‐based polyurethanes from epoxidized soybean oil and isopropanolamine

Epoxidized soybean oil (ESO) and isopropanolamine were used to synthesize a new polyol mixture for preparation of bio‐based polyurethanes. The chemical synthetic route for reaction of ESO with isopropanolamine was analyzed by ¹H‐NMR. The results suggested that both ester groups and epoxy groups in ESO had reacted with amino group of isopropanolamine through simultaneous ring‐opening and amidation reactions. Epoxy groups in various situations exhibited different reactivity, and the unreacted epoxy groups were further opened by hydrochloric acid. The synthesized polyol mixture had high hydroxyl number of 317.0 mg KOH/g. A series of polyurethanes were prepared by curing the synthesized polyol mixture with 1,6‐diisocyanatohexance along with different amount of 1,3‐propanediol (PDO) as chain extender. Tensile tests showed that yield strengths of the polyurethanes ranged from 2.74 to 27.76 MPa depending on the content of PDO. Differential scanning calorimetry analysis displayed one glass transition temperature in the range of 24.4–28.7°C for all of the polyurethane samples, and one melt peak at high content of PDO. Thermogravimetric analysis showed that thermal degradations of the polyurethanes started at 240–255°C. In consideration of simple preparation process and renewable property of ESO, the bio‐based polyurethane would have wide range of applications. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Low-pressure plasma surface modification of polyurethane films with chitosan and collagen biomolecules

Polyurethane (PU) was synthesized using castor oil and a trade grade of hexamethylene diisocyanate, and then PU films were prepared for wound dressing applications. The PU films were then plasma treated with the low-pressure nitrogen plasma to functionalize with peroxide and hydroperoxide groups in order to attach with acrylic acid monomers. Therefore, the polyacrylic acid polymer branches were formed on the film surfaces. Carboxylic acid groups were activated by N-(3-dimethylaminopropyl)-N′-ethyl carbodiimide hydrochloride/N-hydroxysuccinimide and bonded with chitosan and collagen biomolecules. Untreated, nitrogen plasma treated, polyacrylic acid grafted, and finally chitosan and collagen-immobilized PU films were characterized by several tests. The tests included the attenuated total reflectance Fourier transform infrared spectroscopy, static contact angle, atomic force microscopy, scanning electron microscopy, fibroblast L929 cell culture, and antibacterial activity assay to evaluate their in vitro cytocompatibility. The results confirmed that chitosan and collagen were immobilized successfully on the PU surfaces. The chitosan-immobilized PU and collagen-immobilized PU improved the adhesion and proliferation of fibroblast cells compared to untreated PU films. The chitosan-modified PU films exhibit the best antibacterial properties. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47567.     

Fluorescence method using labeled chromophores to study the curing kinetics of a polyurethane system

A fluorescence method using labeled chromophores to study the curing kinetics of a polyurethane (PU) system was developed. A PU system based on fluorescent‐labeled hexamethylene diisocyanate and a polyol (polyether/polyester) was cured at different temperatures (25, 40, 50, and 65°C). The fluorescent response from the 5‐dimethylaminonaphtalene‐1‐(N‐2‐aminoethyl)sulfonamide and 4‐methacryloylamino‐4′‐nitrostilbene moieties chemically bonded to the PU system was monitored as a function of the curing time. With the fluorescence data, it was possible to model the kinetics of the curing process. Methods based on the fluorescence intensity ratio and the first moment of the fluorescent band emission were applied to determine the degree of curing of the PU system. In addition, it was possible to calculate an apparent activation energy for the curing process, and a value of 17 kJ/mol was obtained. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2992–3000, 2002     

Synthesis of CNT‐polyurethane nanocomposites using ester‐based polyols with different molecular structure: Mechanical,thermal, and electrical properties

Polyurethanes (PUs) were prepared by in situ polymerization of three diisocyanate with three synthesized low cost ester‐based polyols. The effect of diisocyanate type, diol structure, and molar ratio of diisocyanate to polyol on the mechanical properties was examined and the optimum chemical structure was introduced regarding the superior mechanical properties. Also, in presence of well dispersed hydroxylated multiwalled carbon nanotubes (CNT), PU/CNT nanocomposites were synthesized and fully characterized. The results showed that PU synthesized based on 1,4‐butane diol (BDO) has the best mechanical properties and thermal stability. Also, the PU samples synthesized from 1,6‐hexamethylene diisocyanate (HDI) were more profitable than aromatic diisocyanate structures due to higher crystallinity and microstructure packing. The nanocomposite sample containing 1.5% CNT was the optimum composition for the maximum tensile strength and electrical conductivity. This result was related to the uniform dispersion and bonding of CNTs to PU chains at this composition, while aggregates were formed at higher concentration of CNTs which increased the defects and reduced the uniformity of the structure. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44567.     

Effect of ionic content,solid content,degree of neutralization,and chain extension on aqueous polyurethane dispersions prepared by prepolymer method

There are many variables in the preparation of aqueous polyurethane (PU) dispersions. Carboxylic acid content, solid content, degree of pre/postneutralization of the carboxylic acids, and chain extension all impact dispersion particle size, viscosity, pH, molecular weights, and glass transition temperature. This study evaluated the impact of these variables on a given PU dispersion formulation prepared from isophorone diisocyanate, an aliphatic polyester polyol, dimethylol propionic acid, and hexamethylene diamine with triethyl amine as the neutralizing base and N‐methyl pyrrolidone as the cosolvent. Changes in carboxylic acid content, degree of preneutralization, and chain extension were found to have the expected impacts on dispersions properties. Increased ionic content in the dispersion step led to lower particle size and higher viscosity, increased chain extension with its concurrent increase in molecular improved subsequent film properties. Surprising results were obtained by varying the amount of postneutralization and from increased solids content at the time of dispersion. Unexpectedly, both of these variations led to much higher dispersion viscosities and particle size in solution. To have these changes take place, it is theorized that there is a major change in solution morphology caused by these modifications. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 2514–2520, 2005     

Noncatalytic polymerization of ethylene glycol and epoxy molecules for rigid polyurethane foam applications

The study investigated an approach to incorporate modified epoxidized soy‐based vegetable oil polyol as a replacement for petroleum‐based polyether polyol and to substantially reduce the isocyanate loading in the rigid foam formulation. Noncatalytic polymerization of epoxidized bodied soybean oil and ethylene glycol (EG) was carried out in a closed batch reaction. Cleavage of the oxirane rings and hydroxyl group attachment at optimum conditions provided the desired polyol products. The polyols were characterized based on its hydroxyl numbers, acidity, viscosity, iodine number, and Gardner color index for quality purposes. Reactions of oxirane ring and EG were verified by spectroscopic FTIR. Crosslinking performance was evaluated by extractability analysis on the polyurethane (PU) elastomer wafers. Rigid foaming performed at 50 and 75% petroleum‐based polyether polyol replacements have shown excellent thermoinsulating and mechanical properties compared with epoxidized soybean oil (ESBO) alone or petroleum‐based polyether polyol alone. A reduction of up to 8% of the polymeric diphenylmethane diisocyanate was achieved using the synthesized ESBO‐EG‐based polyols. A higher average functionality polyol is key component to the reduction of isocyanate in PU synthesis. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Biobased chain extended polyurethane and its composites with silk fiber

The biobased chain extended polyurethane (PU) was synthesized by reacting castor oil based polyol with different diisocyanates [toluene‐2,4‐diisocyanate (TDI) and hexamethylene diisocyanate (HMDI)] and chain extender such as glutaric acid. Biocomposites have been fabricated by incorporating the silk fiber into both TDI‐ and HMDI‐based PUs. The effect of incorporation of silk fiber into TDI‐ and HMDI‐based neat PU on the physicomechanical properties such as density, surface hardness, tensile strength, and percentage elongation have been investigated. The dynamic mechanical properties and the thermal stability of neat PUs and the silk fiber incorporated PU composites have been evaluated. The TDI‐based neat PU has showed higher mechanical properties compared to HMDI‐based PU. The incorporation of 10% silk fiber into TDI‐ and HMDI‐based PU resulted in an enhancement of tensile strength by 1.8 and 2.2 folds, respectively. The incorporation of silk fiber into biobased chain extended PU increased the glass transition temperature (T_g) of the resultant biocomposites. The morphology of tensile fractured neat PUs and their biocomposites with silk fiber was studied using scanning electron microscope (SEM). POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers     

Polyurethanes derived from coal extract

Subbituminous coal from the powder river basin was extracted with N,N-dimethylformamide at atmospheric pressure to yield a solid extract that provided phenolic and carboxylic acid groups. The coal extract was employed as polyol in polyurethane (PU) synthesis. A solvent-free synthesis using 2,4-toluene diisocyanate (TDI) resulted in a porous PU solid. Reaction with TDI in solution resulted in a soluble PU that could be applied as adhesive or coating. Coatings were also prepared from coal extract solutions and commercial, polymeric isocyanates, providing excellent adhesion to aluminum. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48776.     

聚氨酯型阳离子交换膜的制备及其还原草酸中的应用

用六亚甲基二异氰酸酯(HDI)、聚酯多元醇、2,2-二羟甲基丙酸(DMPA)和乙二胺为原料,采用阴离子自乳化法,制备了带有羧基活性官能团的聚氨酯(PU)乳液.将聚氨酯乳液流延在平置的玻璃上,室温下干燥,即可制得聚氨酯型阳离子交换膜.用聚氨酯型阳离子交换膜作为电解草酸还原为乙醇酸的电解槽隔膜.以电流密度、反应时间和温度做...     

Synthesis and characterization of aqueous cationomeric polyurethanes and their use as adhesives

Aqueous cationomeric polyurethanes (ACPU) were synthesized by a multistep reaction process. The alipathic diisocyanate, e.g., hexamethylene diisocyanate (HDI), was reacted with polyol, e.g., polypropylene glycol (PPG400) to form a prepolymer and it was chain-extended by reacting it with N-methyldietanolamine (N-MEDA). Quarternization was then carried out by using dimethyl sulfate (DMS), acetic acid (HAc), or hydrochloric acid (HCI). The resultant cationomers were self-emulsified with deionized water. The effect of different percentages of N-MEDA in the polymer backbone on the structure and properties of ACPU were studied. Viscosity, thermal properties, electrolytic stability, and pH stability of the cationomeric polyurethanes were also studied along with the adhesion strengths between flexible and rigid surfaces. © 1996 John Wiley & Sons, Inc.     

Oxirane Cleavage Kinetics of Epoxidized Soybean Oil by Water and UV‐Polymerized Resin Adhesion Properties

Di‐hydroxylated soybean oil (DSO), a biobased polyol synthesized from epoxidized soybean oil (ESO) could be used to formulate resins for adhesives; however, current DSO synthesis requires harsh reaction conditions that significantly increase both cost and waste generation. In this paper, we investigate the kinetics of oxirane cleavage in ESO to DSO by water and elucidate the role of different process parameters in the reaction rate and optimization of reaction conditions. Our kinetic study showed that ESO oxirane cleavage was a first‐order reaction and that the ESO oxirane cleavage rate was greatly influenced by tetrahydrofuran (THF)/ESO ratio, H₂O/ESO ratio, catalyst content, and temperature. Optimized reaction parameters were THF/ESO of 0.5, H₂O/ESO of 0.25, catalyst content of 1.5 %, and reaction time of 3 h at 25 °C. DSO with hydroxyl value of 242 mg KOH/g was obtained under these conditions. We also characterized the structure, thermal properties, adhesion performance, and viscoelasticity of UV‐polymerized resins based on this DSO. The resin tape exhibited peel adhesion strength of 3.6 N/in., which is comparable to some commercial tapes measured under similar conditions.     

Development of a novel composite film based on polyurethane and defatted Chlorella biomass: Physical and functional characterization

Novel composite films made of polyurethane (PU) and defatted Chlorella biomass (DCB) at different mass proportions (10–70 wt%) were prepared using polyethylene glycol (PEG) as a model polyol and hexamethylene diisocyanate (HMDI) as a coupling agent. Increasing DCB content led to a respective increase in tensile strength and elongation at break of the composites in the range of 33.9–116% and 69.6–248%, compared to the neat PU-PEG film. As confirmed by Fourier transform infrared and scanning electron microscopy analysis, such improvement in mechanical properties can be attributed to the establishment of hydrogen bonds and other molecular interactions between isocyanate groups of PEG-HMDI prepolymer and hydroxyl groups of DCB biofiller along with the uniform distribution of the incorporated DCB into the PU-PEG based matrix. DCB incorporation at the highest content of 70% increased both antioxidant activity and bulk hydrophilicity of the composites by more than 69.3 and 85.0%, respectively, compared to the neat PU-PEG.     

Re-Mendable Polyurethanes

Novel re-mendable polyurethanes were prepared by the Diels-Alder cycloaddition reaction of urethane bismaleimides to bisfuryl monomers. The urethane bismaleimides were synthesized by an addition reaction of 4-maleimidophenylisocyanate to macrodiols, such as polycaprolactone diol (M_n ? 1250 and 2000), PEA-2000 and PBA-2000. The bisfuryl monomers were obtained by the reaction of 2-furfuryl alcohol with hexamethylene diisocyanate or by open-ring reaction of the oxirane ring from diglycidyl bisphenol A with furfuryl amine.     

Rapeseed oil‐based polyurethane foams modified with glycerol and cellulose micro/nanocrystals

A rapeseed oil‐based polyol (ROPO) was synthesized using chemical modification of the rapeseed oil (RO) by epoxidation reaction followed by oxirane ring‐opening with diethylene glycol. The ROPO was used in the formulation of low‐density green polyurethane (PU) foams. The use of glycerol as hydroxyl component, water as a reactive blowing agent and micro/nanocellulose (MNC) as a reinforcement increases the content of natural components in the formulations with important effects on the final foam properties. The ROPO and their intermediate products are characterized by analytical techniques and FTIR spectroscopy, while the final PU foams are characterized by morphological and mechanical analysis. The results show that the addition of glycerol increases the modulus and yield stress. The incorporation of MNC in small amounts is enough to increase the modulus at low temperatures. Both modifiers cause an increase in water absorption and the fragility of the cell walls, reflected in the micrographs of the foams. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41602.     

Synthesis and Characterization of New Diisocyanate-Based Polyurethane Cationomers

New diisocyanates, which contain tertiary nitrogen, have been prepared and used in the preparation of polyurethane cationomers. The ionomers were synthesized from commercial diisocyanates (toluene diisocyanate or hexamethylene diisocyanate) as well as from new diisocyanates [N,N′-bis(m- or p-isocyanato-phenyl)pyromellitic diimide] with polypropylene glycol, chain extended with 1,4-butanediol and/or N-methyldiethanolamine and then quaternized with 1,4-bis(chloromethyl)benzene. The cationomers thus formed were characterized by thermogravimetric analysis and differential scanning calorimetric measurements.     

Preparation and characterization of polyurethane/POSS hybrid aqueous dispersions from mono-amino substituted POSS

A series of linear polyurethane (PU) aqueous dispersions modified by polyhedral oligomeric silsesquioxane (POSS) was synthesized by incorporating various amounts (ca. 2–10 wt%) of a secondary amino-terminated monofunctional POSS in hexamethylene diisocyanate trimer (HDI-T), hexamethylene diisocyanate, poly(tetramethylene-oxide) and 2,2-bis(hydroxymethyl)propionic acid. Results from the gel permeation chromatography, Fourier-transform infrared spectroscopy, transmission electron microscopy, and X-ray diffraction showed that the POSS monomers could be effectively introduced into the PU matrices based on HDI-T to obtain stable aqueous and homogenous PU/POSS hybrid dispersions. The thermal properties of the hybrids do not significantly affect the degradation mechanism of the PU. The physical properties of the PU/POSS hybrid films changed, with a notable increase in tensile strength and surface hydrophobicity.     

Preparation and characterization of aqueous polyurethane dispersions with well‐defined soft segments

Novel aqueous polyurethane (PU) hybrid dispersions were successfully prepared with 5–15 mol % functionalized hexamethylene diisocynate trimer modified by N‐(n‐butyl)‐3‐aminopropyltriethoxysilane and dihydroxylpropyl‐terminated siloxane oligomers (TS). The results of the differential scanning calorimetry and X‐ray diffraction tests show that the degree of segment order was reduced by the introduction of TS. The hybrid polymer films with TS introduced into the PU backbone displayed excellent water and xylene resistance. Atomic force microscopy showed that the films had a smooth surface. It was noticeable that the tensile strength (σ_b) and Young's modulus of the films increased simultaneously when TS was incorporated into PU; σ_b of the PU15 film with 15 mol % TS was much higher than that of the neat PU0 film, and the breaking elongation of the film with 10 mol % TS was clearly higher than that of the other films. The results indicate that an appropriate content of TS significantly improved the properties of the aqueous PU hybrids. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Engineering plastics from lignin. XV. Polyurethane films from chain-extended hydroxypropyl lignin

A series of polyurethane (PU) films was prepared from chain-extended hydroxypropyl lignins (CEHPL). In appearance, these films ranged from brittle and dark brown to rubbery and bronze. The thermal, mechanical, and network properties of these PUs were investigated by DMTA and DSC analysis. All films exhibited single T_g's which varied between ?53° and 101°C, depending on lignin content. From swelling experiments, molecular weight between crosslinks (M _c) was determined and found to vary over 2.5 orders of magnitude. The M _c's were related to the change in T_g that accompanied network formation. Stress–strain experiments showed a variation in Young's modulus between 7 and 1300 MPa. Most of the variation in material properties was related to lignin content and to a lesser extent to diisocyanate type, hexamethylene diisocyanate, or toluene diisocyanate. The source of the CEHPL had no effect on the observed properties. From these results it was concluded that the properties of PUs can be controlled and engineered for a wide variety of practical uses.     

Characteristics and performance of electroactive paper actuator made with cellulose/polyurethane semi‐interpenetrating polymer networks

This article introduces a cellulose/polyurethane (PU) semi‐IPN‐based electroactive paper (EAPap) actuator. The fabrication process, bending actuation test, and its characteristics are explained. For the fabrication of cellulose/PU semi‐IPN EAPap actuator, cotton cellulose was dissolved into N,N‐dimethylacetamide (DMAc) and lithium chloride (LiCl) solvent system. PU prepolymer prepared by poly[di(ethylene glycol) adipate] and hexamethylene diisocyanate (HDI) was mixed with DMAc cellulose solution by stirring. The mixed solution was spin‐coated on a wafer and cured to form cellulose/PU semi‐IPN films using 1,1,1‐tris(hudroxymethyl)propane as the crosslinker. The characteristics of the cellulose/PU semi‐IPN film were investigated by FTIR, scanning electron microscopy (SEM), X‐ray diffraction pattern (XRD), and tensile test. The bending actuation performance of the actuator was evaluated in terms of free bending displacement with respect to the actuation frequencies, voltages, and humidity levels. It shows a good bending actuation at room humidity condition. The actuation principle of the actuator is also discussed. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008