Preparation and properties of waterborne polyurethane adhesives modified by polystyrene

Waterborne polyurethane (WPU) adhesives modified by polystyrene (PS) were prepared through a prepolymer mixing process from diisocyanates, an anionic polyester, internal emulsifiers, a neutralizer, a chain extender, and PS dispersions. The latter was preformed via the in situ polymerization of styrene in poly(1,4‐butanediol adipate) diol. Transmission electron microscopy, Fourier transform infrared spectroscopy, and ¹H‐NMR techniques were used to characterize the PS dispersions and polyurethane (PU)–PS prepolymer. Experimental results with respect to the performance of the PU–PS adhesives indicate that suitable PS/polyester diol weight ratios improved the mechanical properties, thermal stability, water resistance, and initial adhesive strength of the pristine WPU adhesives. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis and thermal studies of block copolymers from NR and MDI‐based polyurethanes

Five series of block copolymers based on natural rubber and polyurethane were prepared from hydroxyl terminated liquid natural rubber (HTNR) and polyurethane (PU) formed by the reaction of diphenyl methane—4,4′—diisocyanate (MDI) with a chain extender diol, viz., ethylene glycol (EG)/propylene glycol (PG)/1,4‐butane diol (1,4‐BDO)/1,3‐butane diol (1,3‐BDO)/bisphenol A (BPA), by solution polymerization. Structural characterization of the block copolymers was done by infrared (IR) analysis. Thermal studies and kinetic analysis on thermal degradation of the block copolymers were undertaken with the view of characterizing them. Energy of activation and entropy change for the degradation were determined and a probable mechanism for the solid state degradation was suggested which corresponds to a three dimensional diffusion mechanism. DSC analysis has been used for the study of microphase separation in the block copolymers. Thermal transition of the hard segment significantly varies with the extender diol which highlights the effect of extender diol structure on the chain stiffening mechanism. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Hybrid polymer latexes: acrylics-polyurethane from miniemulsion polymerization: properties of hybrid latexes versus blends

Hybrid polymer latexes polyurethane/polyacrylic esters, are prepared through miniemulsion polymerization of polyurethane solutions in acrylic monomers. The polyurethanes are prepared by condensation of isophorone diisocyanate on polypropylene glycol (M_n=1000) and butane diol as chain extender. The NCO chain ends being reacted with water (which act as a further chain extender producing some urea bonds). They are miniemulsified in a mixture of methylmethacrylate and butylacrylate monomers, and the miniemulsion are polymerized using benzoylperoxide as initiator. Films were obtained for different hybrid latexes of various compositions. Their mechanical properties have been compared with those of films from the basic components (polyurethane and acrylic latexes), as well as films from blends of these components. Some specific features of the surface of these films are also discussed from microscope images (TEM and AFM) as well as from contact angle measurements.     

Synthesis and characterization of polyurethane sealants containing rosin intended for sealing defect in annulus for disc regeneration

Thermoplastic polyurethanes containing rosin or mixtures of rosin and 1,4 butane diol in the chain extender were proposed as potential sealants for defects in disc regeneration surgery. The polyurethane sealants were prepared by using the prepolymer method and different mixtures of rosin and 1,4 butane diol were used as chain extenders. The existence of one carboxylic moiety in the rosin structure allowed the reaction with the isocyanate end groups in the prepolymer during polyurethane synthesis, creating additional urethane-amide hard segments. The polyurethanes were characterized by ATR-IR spectroscopy, differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMA), thermal gravimetric analysis (TGA), scanning electron microscopy, X-ray diffraction and laser confocal microscopy. The adhesion of the polyurethane sealants were tested by T-peel test of leather/polyurethane sealant/leather joints and by single lap-shear tests of aluminium/polyurethane sealant/aluminium joints. Depending on the rosin content in the chain extender the structure of the polyurethanes was different, i.e. more urethane and urethane-amide hard segments were created up to 50 eq% rosin in the chain extender and separation of domains was prevailing in the polyurethanes with higher rosin content. Furthermore, the addition of rosin caused an increase in the length of the polymer chains but a decrease in the storage modulus was produced (particularly in the polyurethane containing 50 eq% rosin), likely due to the bulky structure of the rosin as compared to the linear structure of 1,4 butane diol, allowing the separation of the linear polyurethane chains. On the other hand, the melting of the soft segments in the polyurethanes started at 40–57 °C and the addition of more than 50 eq% rosin in the chain extender decreased the melting enthalpy. Moreover, the crystallinity of the polyurethanes containing up to 50 eq% rosin showed lower number and smaller spherulites. Finally, the peel strength increased in the joints made with the polyurethane sealants containing rosin whereas the adhesive shear strength decreased when the polyurethane sealant contained 50 eq% rosin or less.     

Modification of aqueous polyurethane dispersions via tetraphenylethane iniferters

Aqueous polyurethane (PU) dispersions containing tetraphenylethane iniferter groups were prepared from 4,4′‐diphenylmethane diisocyanate, poly(propylene oxide)glycols, dimethylol propionic acid, and 1,1,2,2‐tetraphenylethane‐1,2‐diol. To improve the water resistance of the dispersions, methyl methacrylate monomers were added into these dispersions and block‐copolymerized onto the main PU chain. The viscosity and particle size of the dispersions were determined. Dispersion‐cast films were characterized in terms of the contact angle, the swell in water, and the mechanical properties. Contact‐angle and water‐swell measurements showed that the hydrophilicity of the films was decreased significantly when methyl methacrylate was polymerized in the presence of tetraphenylethane containing aqueous PU dispersions. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 2993–3000, 1999     

Thermal and dynamic mechanical characterization of polyurethane–urea–imide coatings

A series of NCO terminated polyurethane (PU)–imide copolymers were synthesized by a systematic three‐step process and were chain extended with different diol/diamine chain extenders. In the first step, isocyanate terminated PU prepolymers were prepared by reacting soft segments such as polyester (PE) polyols and polyether polyols such as polypropylene glycol (PPG‐1000) with hard segments like 2,4‐tolylene‐diisocyanate (TDI) or isophorone‐diisocyanate (IPDI) with NCO/OH ratio 2:1. In the second step, thermally stable heterocyclic imide ring was incorporated using isocyanate terminated PU prepolymers by reacting with pyromellitic dianhydride (PMDA) in a excess‐NCO:anhydride ratio of 1:0.5. The surplus NCO content after imidization was both moisture cured or partially reacted with chain extender and moisture cured. The films were characterized by thermogravimetric (TG), differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA) instruments. The adhesion strength of these coatings on mild steel (MS), copper (Cu), and aluminum (Al) is dependent on the nature of the substrate. The TGA analysis show good thermal stability. The DMTA results show the microphase separation between the different hard and soft segments. Finally, a structure to property correlation was drawn based on the structure of the soft, hard, and chain extender and the observed properties are useful for understanding and design of intelligent coatings. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3158–3167, 2006     

Thermal and mechanical properties of multiple‐component aliphatic degradable polyurethanes

Macroscopic thermal and mechanical properties of complex aliphatic polycarbonate‐based polyurethane (PU) films containing degradable ester units in PU backbone were studied by a combination of several experimental techniques. Differential scanning calorimetry (DSC) revealed that the synthesized oligomeric diol (DL‐L) contributes (in addition to polycarbonate diol) to the formation of soft‐segment domains, while the hard‐segment domains are formed from 1,6‐diisocyanatohexane (HDI) and butane‐1,4‐diol (BD). Three main phase transitions were detected by DSC and by dynamic mechanical thermal analysis. Thermogravimetric analysis (TGA) of two‐component PUs showed that the PU made from DL‐L and HDI is the least thermostable product, while the PU made from polycarbonate diol and HDI is the most stable one. The differences in the thermal stability of different four‐component PUs are not important. Tensile properties very sensitively reflect the changes in composition and in microstructure of PU samples; the best tensile properties exhibits the degradable sample containing the equimolar ratio of hydroxyl groups of macrodiol, oligomeric diol DL‐L and butane‐1,4‐diol. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41872.     

High‐molecular‐weight polyurethanes prepared by one‐step miniemulsion polymerization

Through one‐step miniemulsion polymerization, hydrophobic polyurethane (PU) dispersions were prepared, with hexadecane (HD) as costabilizer in the oil phase and sodium dodecyl sulfate (SDS) as surfactant in the water phase. The oil phase, including isophorone diisocyanate, poly(oxytetramethylene) glycol, a costabilizer HD, a chain extender 1,4‐butanediol, a crosslinking agent trimethylol propane, and a catalyst dibutyltin dilaurate (SnDBL), was dispersed in the water phase containing SDS. The influences of experimental parameters, such as SnDBL, NCO/OH equivalents, and concentrations of surfactant, were discussed. The particle size and the molecular weight of PU polymer were measured by light scattering and gel permeation chromatography, respectively. With the addition of SnDBL and higher NCO/OH ratio, PU films with higher molecular weights were produced. The chemical structure of the PU polymer was identified by Fourier transform infrared spectrometer, and the adsorption of urethane group was observed. Thermal gravimetric analysis was used to characterize the thermal stability of PU. Furthermore, mechanical property was also investigated and characterized by tensile strength and elongation at break. With a higher NCO/OH ratio and the existence of SnDBL, the tensile strength of PU films was significantly increased. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

新型紫外线固化环氧树脂/丙烯酸酯改性水性聚氨酯的合成与性能

合成了一种新型的具有高交联密度和优异涂膜性能的环氧树脂和丙烯酸酯同时改性的紫外线（UV）固化水性聚氨酯（UV-EP-AC-WPUD）。通过环氧基团与以异氰酸酯基团（-N=C=O）封端的聚氨酯预聚体之间的反应引入质量分数为4%的环氧树脂E-20。同时,通过聚氨酯链的-N=C=O与二元丙烯酸酯（PEDA）以及季戊四醇三丙烯酸酯（PETA）的羟基之间的反应引入碳碳双键（C=C）,C=C的含量达到4.65 meq·g-1。 质量分数为3%的光引发剂Irgacure 2959被用于引发涂膜中C=C的聚合,涂膜的凝胶含量在12 s UV辐射之后达到91%,意味着C=C的聚合和交联速度快,同时所得到的涂膜的交联度非常高,不溶于溶剂丙酮,测试表明环氧树脂和两种丙烯酸酯单体已经成功嵌入聚氨酯链中,涂膜具有优异的力学性能和化学性能。     

IPDI-based polyurethane ionomer dispersions: Effects of ionic,nonionic hydrophilic segments,and extender on particle size and physical properties of emulsion cast film

Isophoron diisocyanate (IPDI) -based polyester polyurethane (PU) dispersion in water was prepared in a prepolymer mixing process. Dimethylol propionic acid (DMPA), triethylamine (TEA), and triethyl tetramine (TETA) were used, respectively, as potential anionic center, neutralizing agent, and chain extender in aqueous phase. The effects of DMPA, butanediol (BD), and nonionic hydrophilic segment, viz. monofunctional ethylene–propylene oxide ether polyol, on the particle size of dispersion and the mechanical and viscoelastic properties of the emulsion cast films were systematically analyzed.     

酮亚胺对水性聚氨酯性能的改进

用丙酮分别和乙二胺、己二胺反应制备酮亚胺,并以其作为潜伏性扩链剂改善水性聚氨酯(PU)的性能。研究了酮亚胺以不同方式、加量对水性PU漆膜的厚度、硬度、耐水性、耐酸性、热稳定性和机械性能的影响。结果表明,采用丙酮缩乙二胺扩链的水性PU乳液的漆膜的耐水性优于用丙酮缩己二胺和用水扩链的PU乳液的漆膜,且加入过量的酮亚胺扩链效果较好,但其热稳定性并没有得到明显提高。     

人造麂皮用聚氨酯涂层剂的合成

以聚酯二醇、二苯基甲烷二异氰酸酯、扩链剂已二醇等为原料合成了人造麂皮用聚氨酯涂层剂,讨论了NCO与OH基团的摩尔比（即R值）对聚氨酯溶液粘度及其膜的物理性能的影响。结果表明,R愈近于1,溶液的粘度愈大,所合成的聚氨酯的分子量愈高,膜的物理性能愈高。     

Effect of nano ZnO on the phase mixing of polyurethane hybrid dispersions

In the present study series of aqueous polyurethane (PU)/ZnO hybrid dispersions were prepared using dimethylolpropionic acid (bis-MPA) as an ionic center. For this, NCO terminated PU prepolymers with pendent acid groups were prepared first, then different concentrations of nano ZnO powder was incorporated into the PU matrix. The hybrid dispersions were prepared by adding required amount of triethylamine (TEA), water and chain extender. The prepared PU/ZnO hybrid dispersions were casted in a Teflon petri dish and the dried films were used for TGA, DMTA, SEM, gel content and contact angle measurements. The phase mixing behavior was studied from FT-IR peak deconvolution technique and DMTA analysis and the result suggests that phase mixing increases with ZnO content. The DMTA data suggest that the phase mixing and soft segment glass transition increases but storage modulus decreases with increasing with ZnO content. The FT-IR deconvolution result supports to the DMTA analysis. The coating properties like adhesive strength, water absorption, contact angle, gel content and corrosion resistance of the hybrid coatings were also evaluated.     

有机硅改性聚氨酯乳液的研制

将甲苯二异氰酸酯加到聚醚二元醇和端羟基有机硅单体的混合物中进行反应,生成端基为异氰酸酯基的聚氨酯预聚体,用1,4-丁二醇进行扩链反应,之后用二羟甲基丙酸进行亲水扩链,然后用三乙胺中和,最后加水乳化,合成了一种有机硅改性聚氨酯乳液。通过傅立叶红外光谱,DSC,TGA,电子拉力试验机,吸水率测试对其进行了研究。结果表明,有机硅改性的聚氨酯材料其耐水性、耐热性和耐低温性有所提高,本体的力学性能也有所提高。     

Preparation,mechanical properties of waterborne polyurethane and crosslinked polyurethane‐acrylate composite

The waterborne polyurethane (PU) prepolymer was first prepared based on isophorone diisocyanate, polyether polyol (NJ‐210), dimethylol propionic acid (DMPA), and hydroxyethyl methyl acrylate via in situ method. The crosslinked waterborne polyurethane‐acrylate (PUA) dispersions were prepared with the different functional crosslinkers. The chemical structures, optical transparency, and thermal properties of PU and PUA were confirmed by Fourier transform infrared spectrometry, ultraviolet–visible spectrophotometry, and differential scanning calorimetry. Some physical properties of the aqueous dispersions such as viscosity, particle size, and surface tension were measured. Some mechanical performances and solvent resistance of PUA films were systemically investigated. The experimental results showed that the particle sizes of the crosslinked PUA aqueous dispersions were larger than the PU and increased from 57.3 to 254.4 nm. When the ratios of BA/St, BA/TPGDA, and BA/TMPTA were 70/30, PUA films exhibited excellent comprehensive mechanical properties. The tensile strength and elongation at break of the film were 2.17 MPa and 197.19%. When the ratio of BA/St was 30/70, the film had excellent water resistance and was only 6.47%. The obtained PUA composites have great potential application such as coatings, leather finishing, adhesives, sealants, plastic coatings, and wood finishes. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

New Polyurethane Elastomers with Enhanced Thermal Stability

A series of polyurethane elastomers with enhanced thermal stability was prepared and their physical and thermal properties were studied. For this purpose in the first step, an excess amount of methylene diphenyl diisocyanate was reacted with poly(tetramethylene ether) glycol to produce isocyanate-terminated polyurethane pre-polymer. In the second step, a new imide-based diol chain extender was synthesized via reaction of benzophenonetetracarboxylic dianhydride with 5-amino-1-naphthol. Finally, reaction of the pre-polymer with chain extender resulted in preparation of polyurethane elastomers. Presence of imide unit in the polymer backbone improved their properties and enhanced thermal stability of polyurethane.     

离子基团对聚氨酯水分散液性能的影响

以含有磺酸盐基团的聚酯二元醇和异佛二酮二异氰酸酯(IPDI)为主要原料,用二羟甲基丙酸(DMPA)为亲水单体制备了一组不同组成的聚氨酯分散液,经测定粒径和力学性能,研究了磺酸盐基团含量对分散液及其胶膜性能的影响.结果表明:软段中磺酸盐基团含量对分散液胶膜的热力学性能和胶粘剂的初粘强度都有较大的影响.     

Morphology and particle size of nanograde polyurethane/polyacrylate hybrid emulsions

Poly(urethane acrylate) (PUA) composite particles were prepared by seeded surfactant‐free emulsion polymerization. The aqueous polyurethane (PU) dispersions were used as seed particles. The diameters of the seed particles of the aqueous PU dispersions and PUA composite latexes were measured by dynamic light scattering. The microstructures of the PUA composite emulsion particles were observed by transmission electron microscopy. The influences of the amount of the hydrophilic chain extender, the types of initiators, and the PU/polyacrylate (PA) weight ratios on the diameters of the aqueous PU and composite emulsions were also studied. The results showed that the PUA composite emulsions formed a core–shell structure with PU as the shell and with PA as the core. The diameter of the PU seed particles and the particle size of the PUA composite emulsions greatly depended on the amounts of the hydrophilic chain extender used in the preparation of the PU seed; when the hydrophilic chain extender concentration was 7.4%, the average diameter of the PUA composite emulsion particles showed the minimum value. The types of initiators and PU/PA weight ratios did not have a significant influence on the diameter of the PUA composite latex particles. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

新型非离子水性聚氨酯的制备及性能研究

采用聚四氢呋喃醚二醇(PTMEG,Mn=2000)、异佛尔酮二异氰酸酯(IPDI)和1,4-丁二醇(1,4-BD)为主要原料合成了非离子水性聚氨酯乳液。采用三羟甲基丙烷聚乙二醇单甲醚(TMPEG,Mn=1200)作为非离子型亲水扩链剂,将重复的(—CH2CH2O—)引入聚氨酯大分子中,作为侧链。采用傅里叶变换红外表征了非离子聚氨酯的结构。使用电子拉力试验机研究了氰羟比R值[n(—NCO)/n(—OH)]、交联剂三羟甲基丙烷(TMP)和后扩链剂乙二胺(EDA)的用量对非离子型水性聚氨酯力学性能和吸水溶胀比的影响。透射电镜(TEM)图片和乳液粒径测试证实了非离子聚氨酯能够很好地分散在水中,并且粒径随TMPEG用量增大而减小。研究结果表明,R值的增大和TMP、EDA用量的提高都使得胶膜拉伸强度增大,而断裂伸长率和吸水溶胀比下降。     

Waterborne polyurethane dispersions obtained by the acetone process: A study of colloidal features

Waterborne polyurethane (PU) dispersions were prepared from isophorone diisocyanate (IPDI), 2‐bis(hydroxymethyl) propionic acid (DMPA), 1,4‐butane diol (BD), poly(propylene glycol) (PPG), and triethylamine (TEA) by means of phase inversion through the acetone process. Changes in DMPA content, initial PU content in acetone, phase‐inversion temperature, evaporation conditions, and solvent nature were found to have a great impact on dispersion properties. Using a DMPA concentration of 0.30 mmol/g_pol, stable PU dispersions could only be obtained when the initial PU content in acetone was at least 60 wt %, and phase‐inversion temperature was lower than 30°C. However, when increasing the PU content to 75 wt %, stable dispersions were obtained using DMPA concentrations three times lower. Finally, viscosity curves during the water addition step as well as a phase diagram were determined to understand the particle formation mechanism. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011