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Different Diisocyanates (different + diisocyanate)

Distribution by Scientific Domains

Polymers and Materials Science	100%

Selected Abstracts

Synthesis and characterization of novel Schiff base polyurethanes,

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2009
A. V. Raghu
Abstract Eight different types of novel polyurethanes (PUs) were synthesized through the polyaddition reaction of 4,4,-(ethane-1,2-diylidenedinitrilo)diphenol and 4,4,-(pentane-1,5-diylidenedinitrilo)diphenol with four different diisocyanates: 4,4,-diphenylmethane diisocyanate, toluene 2,4-diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate. The resulting PUs were soluble in polar, aprotic solvents. Structures of the diols and PUs were established with ultraviolet,visible, fluorescence, Fourier transform infrared (FTIR), 1H-NMR, and 13C-NMR spectroscopy data. FTIR and NMR spectral data indicated the disappearance of both hydroxyl and isocyanate groups in the PUs. The thermal properties were investigated with thermogravimetry and differential scanning calorimetry. The weight losses, glass transitions, onset temperatures, and crystalline melting temperatures were measured. All the PUs exhibited semicrystalline and amorphous morphologies, as indicated by X-ray diffraction. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009. [source]

Anionic copolymerization of hexanelactam with functionalized polyisoprene

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 4 2003
R. Mateva
Abstract Block copolymers of the A-B-C-B-A type were synthesized for the first time via the activated anionic polymerization of hexanelactam (HL) with Na-HL as an initiator and macroactivators [or polymeric activators (PACs)] as elastificators for nylon-6. The PACs were prepared by the functionalization of telechelic hydroxyl-terminated poly(ethylene oxide),polyisoprene,poly(ethylene oxide) copolymers with different diisocyanates. Hexamethylene diisocyanate (1,6-diisocyanatohexane) and isophorone diisocyanate (5-isocyanate1-isocyanatomethyl-1,3,3-trimetylcyclohexane) were used as functionalizing agents. This article reports on the effects that the various central elastomeric PAC blocks (type, content, and molecular weight) had on the polymerization kinetics and on the structure and molecular weights of the multiblock copolymers obtained. The copolymers were characterized spectroscopically. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 487,496, 2003 [source]

Synthesis and properties of segmented main-chain liquid-crystalline polyurethanes with a high aspect ratio mesogenic diol as a chain extender

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 10 2002
T. Padmavathy
Abstract Main-chain liquid-crystalline polyurethanes were synthesized based on a high aspect ratio mesogenic diol (4-{[4-(6-hydroxyhexyloxy)-phenylimino]-methyl}-benzoic acid 4-{[4-(6-hydroxyhexyloxy)-phenylimino]-methyl}-phenyl ester) as a chain extender; polycaprolactone (PCL) diol soft segments of different number-average molecular weights (530, 1250, or 2000); and different diisocyanates, including 1,4-hexamethylene diisocyanate (HMDI), 4,4,-methylene bis(cyclohexyl isocyanate) (H12MDI), and 4,4,-methylene bis(phenyl isocyanate) (MDI). The structure of the polymers was confirmed with Fourier transform infrared spectroscopy, and differential scanning calorimetry and polarizing microscopy measurements were carried out to examine the liquid-crystalline and thermal properties of the polyurethanes, respectively. The mesogenic diol was partially replaced with 20,50 mol % PCL. A 20 mol % mesogen content was sufficient to impart a liquid crystalline property to all the polymers. The partial replacement of the mesogenic diol with PCL of various molecular weights, as well as the various diisocyanates, influenced the phase transitions and the occurrence of mesophase textures. Characteristic liquid-crystalline textures were observed when a sufficient content of the mesogenic diol was present. Depending on the flexible spacer length and the mesogenic content, grained and threadlike textures were obtained for the HMDI and H12MDI series polymers, whereas the polyurethanes prepared from MDI showed only grained textures for all the compositions. The polymers formed brittle films and could not be subjected to tensile tests. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1527,1538, 2002 [source]

Syntheses and properties of polyurethanes containing side-chain azobenzene groups

POLYMER INTERNATIONAL, Issue 5 2003
Mi-Ra Kim
Abstract Polymers containing azobenzene groups have the characteristic reaction of photo-induced cis,trans isomerism. The study of new materials for optical information storage has prompted making use of these photo-isomerizations. In this study, we report the syntheses and properties of four different polyurethanes (DR-PUns) containing azobenzene groups in the side-chains. The structurally similar polyurethanes (DR-PUns) were synthesized by the polycondensation reaction of Disperse Red 19 (DR 19) and four different diisocyanates in dimethylformamide. By introducing of DR 19 into the polymer, we obtained polymers containing a photochromic group in the side-chain. The weight-average molecular weights of the DR-PUns were in the range 5500,12,900. The Tgs of the DR-PUns range from 119.5,°C to 157.0,°C, depending on the structure of the diisocyanate. Optical properties and solubilities of the polyurethanes were compared. The diffraction efficiencies of films were measured as a function of the reaction time. Typically, the diffraction efficiencies of the DR-PU1 film prepared from toluene 2,4-diisocyanate were observed up to a level of 0.25%. For the DR-PU1 film, the effect of the intensity of the induced laser beam on the diffraction efficiency is also discussed. © 2003 Society of Chemical Industry [source]