Showing papers on "Polyurethane published in 1999"

Damping properties of interpenetrating polymer networks of polyurethane-modified epoxy and polyurethanes

Abstract: Interpenetrating polymer networks (IPNs) were prepared from polyurethane (PU)-modified epoxy with different molecular weight of polyol and polyurethanes based on the mixture of polydiol and polytriol by a one-shot method. Two types of PU-modified epoxy: PU-crosslinked epoxy and PU-dangled epoxy were synthesized, and the effects of the different molecular weights of polyol in the PU-modified epoxy/PU IPNs on the dynamic mechanical properties, morphology, and damping behavior were investigated. The results show that the damping ability is enhanced through the introduction of PU-modified epoxy into the PU matrix to form the IPN structure. As the molecular weight of polyol in PU-modified epoxy increases, the loss area (LA) of the two types of the IPNs increases. PU-dangled epoxy/PU IPNs exhibit much higher damping property than that of the PU-crosslinked epoxy/PU IPNs with 20 wt % of PU-crosslinked epoxy. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 328–335, 1999

Polyurethane and preparation containing polyurethane

Abstract: The invention relates to a polyurethane which can be produced by reacting at least two components A and B, where a) a polyisocyanate or a mixture of two or more polyisocyanates is used as component A and b) a polyol or a mixture of at least two or more polyols is used as component B. The invention is characterized in that component B contains a polyether having a molecular weight (Mn) of at least 4,000 and c) a polydispersity PD (Mw/Mn) of less than 1.5, or d) an OH functionality of between approximately 1.8 and approximately 2.0, or e) a polydispersity PD (Mw/Mn) of less than 1.5 and an OH functionality of between approximately 1.8 and approximately 2.0, or a mixture of two or more such polyethers. The invention also relates to preparations containing such polyurethanes.

Preparation of polyurethane microcapsules with different soft segments and their characteristics

Abstract: Polyurethane microcapsules were synthesized by interfacial polymerization in an aqueous poly(ethylene glycol) dispersion with ethylene diamine as the chain extender of toluene diisocyanate in perfume oil using poly(vinyl alcohol) as the stabilizing agent. The effects of polyol constituent on the average particle size and distributions, morphologies, loading content and release behavior of polyurethane particles were investigated to design microcapsules for a sustained release system. The release rate of microencapsulated disperse dye molecules became increasingly slow with the molecular weight of polyether polyol.

Preparation and properties of segmented thermoplastic polyurethane elastomers with two different soft segments

Abstract: Thermoplastic polyurethane elastomers were prepared from 4,4-diphenylmethane diisocyanate (MDI)/1,4-butanediol (BD)/poly(propylene glycol) (PPG) and MDI/BD/poly(oxytetramethylene glycol) (PTMG). The MDI/BD-based hard-segment content of polyurethane prepared in this study was of 39–65 wt %. These polyurethane elastomers had a constant soft-segment molecular weight (Mn, 2000), but a variable hard-segment block length (n, 3.0–10.1; Mn, 1020–3434). The effects of the hard-segment content on the thermal properties and elastic behavior were investigated. These properties of the PPG-based MPP samples and the PTMG-based MPT samples were compared. The polyurethane prepared in this study had a hard-segment crystalline melting temperature in the range of 185.5–236.5°C. With increasing hard-segment content, the dynamic storage modulus and glass transition temperature increased in both the MPP and MPT samples. The permanent set (%) increased with increasing hard-segment content and successive maximum elongation. The permanent set (%) of the MPP samples was higher than that of MPT samples at the same hard-segment content. The value of K (area of the hydrogen-bonded carbonyl group/area of the free carbonyl group) increased with increasing hard-segment content in both the MPP and MPT samples, and the K value of the MPT samples was higher than that of the MPP samples at the same hard-segment content. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 345–352, 1999

Spectroscopic Investigations of Poly(oxypropylene)glycol-Based Waterborne Polyurethane Doped with Lithium Perchlorate

Abstract: Polyaddition of isophorone diisocyanate to poly(oxypropylene)glycol (PPG)-Based waterborne polyurethane (WPU) synthesized by a modified acetone process was performed Fourier transform infrared spe

Synthesis and properties of polyurethane modified with aminoethylaminopropyl poly(dimethyl siloxane)

Abstract: A series of polyurethanes with different siloxane contents were synthesized, which were based on 4,4′-methylene diphenyl diisocyanate (MDI), poly(tetramethylene oxide) (PTMO), aminoethylaminopropyl poly(dimethyl siloxane) (AEAPS), and butanediol (BD). The chemical compositions, structures, and bulk and surface properties were investigated using an infrared surface quantitative analysis technique (FTIR-ATR), surface contact angle, electron spectroscopy for chemical analysis (ESCA), stress–strain analysis, and dynamic mechanical thermal analysis (DMTA). It was shown that siloxane concentration on the surface region of the elastormers was higher than that in the bulk for a resulting surface enrichment of the siloxane, and the tensile properties of these elastomers were not changed significantly with the AEAPS modification. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 2552–2558, 1999

Molded and slab polyurethane foam prepared from double metal cyanide complex-catalyzed polyoxyalkylene polyols and polyols suitable for the preparation thereof

Abstract: Copolymer DMC-catalyzed polyoxypropylene polyols which exhibit processing latitude similar to base-catalyzed copolymer analogs and base-catalyzed homopolyoxypropylene analogs may be prepared by oxyalkylation with a mixture of propylene oxide and ethylene oxide such that a finite ethylene oxide content is maintained in the oxyalkylation reactor for the most substantial part of the oxyalkylation, the polyoxypropylene polyol having randomly distributed oxyethylene moieties which constitute 15 weight percent or more of the polyol product

The influence of the degree of neutralization, the ionic moiety, and the counterion on water‐dispersible polyurethanes

Abstract: A number of polyurethane anionomers based on isophorone diisocyanate, polytetrahydrofuran, and cyclohexane dimethanol were prepared as aqueous dispersions. The dispersions were stabilized by the use of an internal emulsifier. The principal ionic moiety used was dimethylol propanoic acid, but dimethylol butanoic acid and an experimental suphonate diol sodium salt were also used. The consequence of the neutralization step, the degree of neutralization, the type of ionic component, and the type of counterion were investigated for their effect on the mechanical and colloidal properties of the polyurethanes. Dynamic mechanical thermal analysis, tensiometry, solvent spot testing, and swelling studies were used for the characterization of the materials. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 556–566, 1999

Polyurethane prepolymer compositions, foams made therefrom and methods of making each thereof

Abstract: A polyisocyanate prepolymer composition is comprised of the reaction product of (a) a polyisocyanate having an average functionality of at least 2 and containing at least 20 percent by weight of a diisocyanate monomer, (b) a monohydric alcohol and (c) a polyol having an average hydroxyl functionality of at least 1.8 to at most 3.2, wherein the prepolymer composition has (i) an amount of isocyanate groups by weight sufficient to react with water in the absence of a supplemental blowing agent to make a foam, (ii) at most 10.0 percent by weight of the diisocyanate monomer and (iii) an amount of the polyisocyanate that is capped by the monohydric alcohol sufficient to prevent gelling of the prepolymer composition. The prepolymer composition may be formed by contacting (i) an organic polyisocyanate having an average isocyanate functionality of at least 2.0 and an amount of diisocyanate monomer of at least 20 percent by weight, (ii) a monohydric alcohol and (iii) a polyol having an average hydroxyl functionality of at least 1.8 to at most 3.2 for a time and temperature sufficient to form the prepolymer composition, wherein the organic polyisocyanate, monohydric alcohol and polyol are contacted at a ratio of NCO to hydroxyl of at least 2, to at most 5, and the monohydric alcohol and polyol are provided in a ratio of monohydric alcohol to polyol of at least 0.1, to at most 2, based upon the hydroxyl equivalence of the monohydric alcohol and polyol. The prepolymer composition may be reacted with water to form a polyurethane foam.

Hybridization of aqueous-based polyurethane with glycidyl methacrylate copolymer

Abstract: The carboxyl group containing aqueous-based polyurethane (PU) dispersions were prepared from isophorone diisocyanate, poly(propylene glycol)-1000, and 2,2-dimethylol propanic acid via a PU prepolymer process. The amino content of this amino-terminated aqueous-based PU system was determined by a styrene oxide titration method. Glycidyl methacrylate (GMA) copolymer emulsions were prepared by an emulsion polymerization of GMA and other alkyl acrylates. The curing behavior of the GMA copolymer was demonstrated by a model reaction of the GMA copolymer with ethylenediamine. In the same token, the reaction took place between the PU amino groups and the GMA copolymer epoxides at ambient temperature and resulted in the formation of a hybridized homogeneous copolymer. This hybridized copolymer also consisted of carboxylic acid on the PU fraction after drying. Carboxylic acids of the copolymer were exchanged with calcium ion and this ionic coordination resulted in a calcium ion-crosslinked copolymer. The physical and mechanical properties and the thermal behaviors of the hybridized copolymers were evaluated. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 903–913, 1999

Multi-layer sheet comprising a protective polyurethane layer

Abstract: The present invention provides a multilayer sheet comprising a polymeric film having on a first major side a cross-linked polyurethane layer, the major part of said cross-linked polyurethane layer comprising a polycarbonate based polyurethane containing acid groups and cross-linked with a cross-linker, the polycarbonate-based polyurethane comprising the reaction product of a polycarbonate polyol or a polycarbonate polyamine and an aliphatic polyisocyanate and the uncross-linked polycarbonate-based polyurethane having a Koenig hardness of at least 150 seconds.

Manufacturing process for leather-like sheet

Abstract: In a process for making a leather-like sheet by impregnating a fibrous substrate with a polyurethane emulsion, heat gellable polyurethane emulsion having a specific modulus of elasticity is employed as the polyurethane emulsion, and either of following methods (1) and (2) is also employed. (1) before impregnation of the polyurethane emulsion, the fibrous substrates are pretreated with a surfactant having a function of inhibiting adhesion between fibers and polyurethane (2) in addition to the above modulus of elasticity, the polyurethane emulsion has a specific α dispersion temperature, the fibrous substrates are composed of microfine fiber-forming fibers, and after coagulation of polyurethane emulsion, the fibers are converted to microfine fibers. The leather-like sheets obtained according to this invention exhibits natural leather-like softness and hand touchness as well as excellent physical properties such as bending fatigue resistance.

Near-Edge X-ray Absorption Fine Structure Spectroscopy of MDI and TDI Polyurethane Polymers

Abstract: The sensitivity of near-edge X-ray absorption fine structure (NEXAFS) to differences in key chemical components of polyurethane polymers is presented. Carbon 1s NEXAFS spectra of polyurethane polymers made from 4,4‘-methylene di-p-phenylene isocyanate (MDI) and toluene diisocyanate (TDI) isocyanate monomers illustrate that there is an unambiguous spectroscopic fingerprint for distinguishing between MDI-based and TDI-based polyurethane polymers. NEXAFS spectra of MDI and TDI polyurea and polyurethane models show that the urea and carbamate (urethane) linkages in these polymers can be distinguished. The NEXAFS spectroscopy of the polyether component of these polymers is discussed, and the differences between the spectra of MDI and TDI polyurethanes synthesized with polyether polyols of different molecular composition and different molecular weight are presented. These polymer spectra reported herein provide appropriate model spectra to represent the pure components for quantitative microanalysis.

Hybrid nonisocyanate polyurethane network polymers and composites formed therefrom

Abstract: This invention relates to a hybrid nonisocyanate polyurethane network polymer formed by cross-linking at least one cyclocarbonate oligomer and at least one amine oligomer The cyclocarbonate oligomer contains a plurality of terminal cyclocarbonate groups At least one cyclocarbonate oligomer further comprises from about 4 % to about 12 % by weight of terminal epoxy groups Because at least one cyclocarbonate oligomer contains both cyclocarbonate and epoxy reactive groups, the network formed therefrom is referred to as a hybrid nonisocyanate polyurethane network The cyclocarbonate oligomer or oligomers have an average functionality towards primary amines of from about 20 to about 544 The amine oligomer comprises at least one primary amine-terminated oligomer terminated with primary amine groups and has an average functionality towards cyclocarbonate groups of from about 30 to about 38 The amine oligomer is present in an amount from about 093 to about 099 of the amount of the amine oligomer that would be required to achieve a stoichiometric ratio between the primary amine groups of the amine oligomer and the cyclocarbonate groups of the cyclocarbonate oligomer The hybrid nonisocyanate polyurethane network polymer formed has a gel fraction of not less than about 096 by weight This invention also relates to methods of making hybrid nonisocyanate polyurethane networks and their use as a composite matrix material

Biodegradability of regenerated cellulose films coated with polyurethane/natural polymers interpenetrating polymer networks

Abstract: Interpenetrating polymer network (IPN) coatings synthesized from castor- oil-based polyurethane (PU) with chitosan, nitrocellulose, or elaeostearin were coated on regenerated cellulose (RC) film fo ...

Water blown free rise polyurethane foams

Abstract: A model is developed in this work for predicting the bubble size distribution in polyurethane foams generated by using water as a chemical blowing agent. The model combines equations of energy balance, kinetics of the reactions of isocyanate with water and polyol, and nucleation and growth of $CO_2$ bubbles. It is found that as the water content of the reaction mixture is increased, the mean bubble size decreases and the bubble size distribution become narrower. Exactly the opposite occurs in polyurethanes foamed with a physical blowing agent, e.g., DuPont Freons. This suggests that a combination of physical and chemical blowing agents can be employed to control bubble size distribution.

Thermal and Phase Behavior of Polyurethane Based on Chain Extender, 2, 2-Bis-[4-(2-hydroxyethoxy) phenyl] propane

Abstract: A series of polyurethanes based on Poly(oxytetramethylene)glycol (PTMG), 4,4′-diphenylmethane diisocyanate (MDI) and 2,2-bis-[4-(2-hydroxyethoxy)phenyl]propane (BHPP) was synthesized by two-step solution polymerization varying PTMG soft segment length and hard segment content. Thermal and dynamic mechanical properties were studied by DSC and DMA. Solubility and interactions were calculated and quantitative assessment based on the shift of glass transition temperature and heat capacity change at glass transition was used to predict the extent of phase separation. DSC and DMA results showed that Tg shifted to higher temperature with increasing hard segment content and decreasing soft segment molecular weight, indicating partial phase mixing between hard and soft segment.

Rigid polyurethane foam

Abstract: PROBLEM TO BE SOLVED: To obtain a rigid polyurethane foam completely foamed with water without using a fluorocarbon-based foaming agent such as dichloromonofluoroethane and hydrofluorocarbon as a foaming agent, not only excellent in application, operability and dimensional stability, but also having a density same as or lower than that obtained by using the fluorocarbon-based foaming agent. SOLUTION: This rigid polyurethane foam is obtained by an airless spray foaming comprising mixing a formulated liquid obtained by mixing a polyisocyanate component, a polyol component, water, a catalyst and an adjuvant thereof by a mixing head, and foaming the resultant polyurethane by the carbon dioxide generated by the reaction of the polyisocyanate component and the water. The foaming-starting time when reacting the polyisocyanate with the formulated liquid each at 10°C liquid temperature by stirring and mixing is within 7 sec after the start of the stirring. The proportion of closed cells in the cells of the foam obtained when the mixture is sprayed and laminated so as to have 30-40 mm total thickness by a foaming machine is regulated so as to be 40-70%. COPYRIGHT: (C)2001,JPO

Silicon oxycarbide foams from a silicone preceramic polymer and polyurethane

Abstract: Ceramic open-cell foams were obtained from a preceramic polymer (a silicone resin) and blown polyurethanes, by pyrolysis at 1200°C in nitrogen Silicon carbide submicron powders were also added to the silicone resin to give SiOC + SiC composite foams The morphology of the foams was dependent on the architecture of the blown polyurethanes The crushing strength as well as the elastic modulus increased with increasing relative density, reaching values as high as 14 and 450 MPa, respectively Some of the foams displayed an excellent thermal stability (resistance to oxidation in air and decomposition in inert atmosphere) up to elevated temperatures

Process for preparing polyurethane foam

Abstract: A process for preparing a polyurethane foam is provided which comprises reacting a polyisocyanate and an active hydrogen-containing component, including water and an organic polyol, in the presence of a catalytically effective amount of a delayed action amine catalyst system, and optionally an organotin catalyst. The delayed action catalyst is composed of the reaction product of (a) one or more carboxylic acids having hydroxy and/or halo functionality; (b) one or more tertiary amine ureas; and, optionally, (c) a reactant selected from the group consisting of specific reactive tertiary amine(s), specific tertiary amine carbamate(s) and mixture thereof.

UV-curable Poly(ethylene glycol)-based polyurethane acrylate hydrogel

Abstract: Poly(ethylene glycol) (PEG) with molecular weight (Mn) of 1000, 2000, 3000, and 4000 g/mol, four types of diisocyanate [hexamethylene diisocyanate (HDI), 4,4′-dicyclohexylmethane diisocyanate (H12MDI), isophorone diisocyanate (IPDI), and toluene diisocyanate (TDI)], two types of comonomers [acrylamide (AAm) and acrylic acid (AAc)] that comprised up to 60% of the total solid were used to prepare UV-curable PEG–based polyurethane (PU) acrylate hydrogel. The gels were evaluated in terms of mechanical properties, water content as a function of immersion time and pH, and X-ray diffraction profiles of dry and swollen films. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2703–2709, 1999

Polyurethanes with carboxylate functionality for hair fixative applications

Abstract: A polyurethane, soluble or dispersible in water, prepared from organic diisocyanate diols or other isocyanate reactive materials and a 2,2-hydroxymethyl-substituted carboxylic acid diol neutralized with a cosmetically acceptable organic or inorganic base and formulated into a hair fixative composition containing low amounts of volatile organic solvent. The present invention is also directed to a process for the preparation of polyurethanes comprising dispersing the polyurethane after at least 70% of the theoretical isocyanate reaction has taken place, but before completion of the reaction.

Study of Correlations between Microstructure and Conductivity in a Thermoplastic Polyurethane Electrolyte

Abstract: Micro-Raman and positron annihilation lifetime spectroscopy (PALS) have been used to investigate the structure of a thermoplastic polyurethane/LiClO4 solid flexible polymer electrolyte at room temperature. Correlation between the free volume and carrier concentration with ionic conductivity was observed. The polyurethane soft phase consisted of a poly(tetramethylene glycol-co-ethylene glycol) copolymer reinforced by condensation with hexamethyldiisocianate. The range of salt concentration between 5 and 35 wt %, which attained the beginning of phase segregation, was also studied by differential scanning calorimetry (DSC), which showed the presence of three thermal events; the soft-phase Tg, a change in heat capacity suggested as the hard-phase Tg, and a hard-phase ordering endotherm. The total ionic conductivity was found to be approximately 4 × 10-6 S cm-1 at 23 °C up to 27 wt % salt, whereas there were pronounced changes observed by the spectroscopic techniques. The PALS measurements indicated a decrease...