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Polyurethane Prepolymer (polyurethane + prepolymer)

Distribution by Scientific Domains

Polymers and Materials Science	100%

Selected Abstracts

Structural investigations of polypropylene glycol (PPG) and isophorone diisocyanate (IPDI)-based polyurethane prepolymer by 1D and 2D NMR spectroscopy

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 6 2005
A. Prabhakar
Abstract Polyurethane prepolymers are widely used in reactive hot melt adhesives and moisture cured coatings. NCO-terminated polyurethane of polypropylene glycol (PPG)-1000 and isophoron diisocyanate (IPDI) with an NCO/OH ratio of 1.2:1 were prepared without any catalyst or solvent. 1D and 2D NMR spectroscopy was used for the structural investigation of the synthesized prepolymer. 1H NMR spectra and dibutylamine back-titration were used to monitor the reaction of isocyanate groups with the hydroxyl function of PPG and to allow a good description of the evaluation of the urethane groups. The data on percentage conversion were crosschecked with 13C NMR spectroscopy in the urethane zone for the methanol endcapped prepolymer. The observations show a higher reactivity of the secondary NCO group than of the primary group. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1196,1209, 2005 [source]

Effects of soft segments on the surface properties of polydimethylsiloxane waterborne polyurethane prepolymer blends and treated nylon fabrics

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2010
Meng-Shung Yen
Abstract This study of waterborne polyurethane prepolymer blends was done to investigate the effects of different types of soft segments on the dispersion properties and other properties of treated nylon fabrics. The particle size of the dispersion increased, the surface tension of the dispersion decreased, and the contact angle of the nylon fabric with the dispersion decreased when the blending amount of the polydimethylsiloxane polyurethane prepolymer increased. The add-on of ether-type polyurethane increased rapidly when the ether-type polyurethane was blended with a small amount of the polydimethylsiloxane polyurethane prepolymer, whereas the add-on of the ether-type polyurethane reached a maximum at a blending content of 10%. The add-on of the ester-type polyurethane prepolymer constantly decreased with increasing blending amount of the polydimethylsiloxane polyurethane prepolymer. The vertical wicking height of the treated nylon fabrics decreased slightly when the treating agent contained a small amount of the polydimethylsiloxane polyurethane prepolymer. For the treated nylon fabrics with blended prepolymers, the drying time was faster than for the untreated fabric, and the moisture ratio reached about 10% in 15 min © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source]

Synthesis of a novel cyclic 5-membered dithiocarbonate (DTC) having hydroxy group and its application to terminal functionalization of polyurethane

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 16 2005
Suguru Motokucho
A novel 5-membered cyclic dithiocarbonate (DTC) having a hydroxy group, 5-hydroxymethyl-1,3-oxathiolane-2-thione (DTC-OH), was synthesized from glycidol. On the basis of the highly efficient reaction of its hydroxyl group with isocyanate, a polyurethane having isocyanate terminals was modified with DTC-OH into a new type of polyurethane prepolymer having DTC-terminals, which was highly reactive with amines but tolerant to moisture. [source]

Structural investigations of polypropylene glycol (PPG) and isophorone diisocyanate (IPDI)-based polyurethane prepolymer by 1D and 2D NMR spectroscopy

Synthesis and characterization of novel thermoplastic poly(oligophosphazene-urethane)s

POLYMER INTERNATIONAL, Issue 6 2009
Yubo Zhou
Abstract BACKGROUND: Polyurethanes are some of the most popular polymers used in a variety of products, such as coatings, adhesives, flexible and rigid foams, elastomers, etc. Despite the possibility of tailoring their properties, polyurethanes suffer a serious disadvantage of poor thermal stability. Many attempts have been made in order to improve the thermal stability of polyurethanes. RESULTS: A new hydroxyl-terminated oligomer containing sulfone groups, 2,2-bis(4-hydroxy-4,4-sulfonyldiphoneloxy)tetraphenoxyoligocyclotriphosphazene (HSPPZ), was synthesized. HSPPZ was characterized using Fourier transform infrared (FTIR), NMR and gel permeation chromatography analyses. A series of novel thermoplastic poly(oligophosphazene-urethane)s were then synthesized via the reaction of NCO-terminated polyurethane prepolymer with HSPPZ containing chain-extender diols. Their structure and properties were investigated using FTIR spectroscopy, thermogravimetric analysis, differential scanning calorimetry, X-ray diffraction, water contact angle measurement and tensile measurements. CONCLUSION: Compared to conventional thermoplastic polyurethanes, poly(oligophosphazene-urethane)s exhibit better thermal stability, low-temperature resistance and hydrophobicity, but their mechanical properties are slightly poorer. Copyright © 2009 Society of Chemical Industry [source]

Synthesis and dissociation of amine-blocked diisocyanates and polyurethane prepolymers

POLYMER INTERNATIONAL, Issue 3 2002
T Philip Gnanarajan
Abstract Substituted N -methylanilines are shown to act as blocking agents for toluenediisocyanate. N -methylaniline-, N -methyl- p -anisidine- and N -methyl- p -nitroaniline-blocked toluene diisocyanates have been prepared and characterized by FTIR, 1H NMR and 13C NMR spectroscopies, and nitrogen content analysis. A new method for determining the minimum deblocking temperature of the blocked isocyanate is described. The method has advantages in that it can be used to find the minimum deblocking temperature of even non-volatile blocking agents. The minimum deblocking temperature of the adducts is found to be in the following order: N -methyl- p -anisidine,TDI adduct,<,N -methyaniline,TDI adduct,<,N -methyl- p -nitroaniline,TDI adduct. The anilines exhibit the same trend when they block a polyurethane prepolymer prepared using polypropylene glycol of molecular weight 2000,g,mol,1 and tolylene-2,6-diisocyanate. The deblocking temperatures are lower in the case of blocked prepolymers than in the blocked adducts. The blocked adducts and prepolymers are reacted with pyromellitic dianhydride (PMDA) in dimethylpropylene urea (DMPU) and the evolution of carbon dioxide is monitored to study the completion of imidization. The reaction time is in accordance with the deblocking ability of the adducts. The regeneration of the blocking agent is confirmed by gas chromatography. © 2002 Society of Chemical Industry [source]

Synthesis and characterization of polyurethane,urea nanoparticles containing methylenedi- p -phenyl diisocyanate and isophorone diisocyanate

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 17 2004
In Woo Cheong
Abstract Water-based polyurethane,urea (WPUU) nanoparticles containing 4,4,-methylenedi- p -phenyl diisocyanate (MDI) and isophorone diisocyanate (IPDI) were synthesized by a stepwise prepolymer mixing process, that is, the consecutive formation of hydroxyl-terminated and isocyanate-terminated polyurethane prepolymers. The reaction behavior, chemical structure, and consequent morphology of the polyurethane prepolymers and WPUU were investigated with Fourier transform infrared (FTIR), gel permeation chromatography, and NMR techniques with MDI concentrations ranging from 0 (pure IPDI) to 50% with respect to the total moles of isocyanate. Wide-angle X-ray diffraction and differential scanning calorimetry patterns showed that the crystallinity of WPUU, which mostly originated from crystallizable poly(tetramethylene adipate) polyol, was significantly affected by the MDI content. Both the crystallinity and melting temperature of WPUU decreased as the MDI content increased. Deconvoluted relative peak areas of the carbonyl region in the FTIR spectrum revealed that the effect of hydrogen bonding among the hard segments became favorable as the MDI content increased, whereas the hydrogen bonding of the soft segments significantly decreased. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4353,4369, 2004 [source]