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Hexamethylene Diisocyanate (hexamethylene + diisocyanate)
Selected AbstractsAnionic copolymerization of hexanelactam with functionalized polyisopreneJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 4 2003R. 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] Chemical modification of polypropylene with diisocyanates for improved gas barrier and mechanical propertiesADVANCES IN POLYMER TECHNOLOGY, Issue 4 2009R. S. Jagadish Abstract In this investigation, modification of polypropylene (PP) with an objective to obtain packaging film with improved gas barrier properties has been studied. The chemical reaction of PP resin with hexamethylene diisocyanate and toluene diisocyanate was monitored by Fourier transform infrared spectroscopy, wherein the appearance of new peaks at 3333 cm,1 for NH stretching, 1620,1641 cm,1 for (CO)NH stretching and 1552,1578 cm,1 corresponding to NH bending in an amide moiety was observed for both the modified PP films. Films of excellent clarity and uniform thickness were obtained by the extrusion of cross-linked polypropylene. The barrier, mechanical, optical, and thermal properties of the modified PP films were studied. The results clearly indicated significant changes in gas barrier and mechanical properties. Food compatibility of the films was evaluated by overall migration in to different food simulants. © 2010 Wiley Periodicals, Inc. Adv Polym Techn 28:233,245, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20168 [source] Synthesis and characterization of novel Schiff base polyurethanes,JOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2009A. 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] Synthesis and characterization of novel polyurethanes based on N1,N4 -bis[(4-hydroxyphenyl)methylene]succinohydrazide hard segment,JOURNAL OF APPLIED POLYMER SCIENCE, Issue 4 2008A. V. Raghu Abstract This article deals with the synthesis and characterization of novel polyurethanes (PUs) by the reaction between two aromatic diisocyanates (4,4,-diphenylmethane diisocyanate and tolylene 2,4-diisocyanate) and two aliphatic diisocyanates (isophorone diisocyanate and hexamethylene diisocyanate) with N1,N4 -bis[(4-hydroxyphenyl)methylene]succinohydrazide, which acted as hard segment. UV,vis, FTIR, 1H NMR, 13C NMR, and DSC/TGA analytical technique has been used to determine the structural characterization and thermal properties of the hard segmented PUs. X-ray diffraction revealed that PUs contained semicrystalline and amorphous regions that varied depending upon the nature of the backbone structures. PUs were soluble in polar aprotic solvents. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Synthesis of cyclodextrin-based polymers and their use as debittering agentsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 4 2008Arianna Binello Abstract Cyclodextrins (CDs) and their derivatives are used to suppress unpleasant tastes and odors or to achieve a controlled release of certain food constituents. This article describes the synthesis by nonconventional methods of (1) crosslinked, insoluble CD polymers and (2) water-soluble, CD-grafted carboxymethylchitosan and carboxymethylcellulose. The CD polymers were obtained by the reaction of ,-CD with one of the following crosslinking agents: epichlorohydrin, diphenyl carbonate, or hexamethylene diisocyanate. Their preparations were usually carried out under high-intensity ultrasound, which resulted in much shorter reaction times and narrower distributions of particle size (as determined by scanning electron microscopy measurements). A novel, insoluble CD polymer was obtained by reticulation under microwaves of propargyl-,-CD with 1,3-bis(azidomethyl)benzene through Huisgen 1,3-dipolar cycloaddition. Short columns packed with the insoluble polymers were found to efficiently sequester naringin from aqueous solutions; successively, they could be easily regenerated by a counter-current ethanol wash that also achieved an excellent recovery of the flavonoid. Differential scanning calorimetry thermograms showed that the crosslinked CD polymers formed inclusion complexes with naringin. The soluble polymers also interacted with bitter flavonoids of citrus fruits (naringin and limonin), as shown by the results of sensorial panel tests, in which they behaved as bitter-masking agents. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Synthesis, characterization, and acoustic properties of new soluble polyurethanes based on 2,2,-[1,4-phenylenebis(nitrilomethylylidene)diphenol and 2,2,-[4,4,-methylene-di-2-methylphenylene-1,1,-bis(nitrilomethylylidene)]diphenol,JOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2007A. V. Raghu Abstract Eight novel polyurethanes based on 2,2,-[1,4-phenylenebis(nitrilomethylylidene)]diphenol and 2,2,-[4,4,-methylene-di-2-methylphenylene-1,1,-bis(nitrilomethylylidene)]diphenol acting as hard segments with two aromatic and two aliphatic diisocyanates (4,4,-diphenylmethane diisocyanate, toluene 2,4-diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate) were prepared and characterized with Fourier transform infrared, UV spectrophotometry, fluorescence spectroscopy, 1H-NMR and 13C-NMR spectroscopy, thermogravimetric analysis, and differential thermal analysis. All the polyurethanes contained domains of semicrystalline and amorphous structures, as indicated by X-ray diffraction. The acoustic properties and solubility parameters were calculated with the group contribution method. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 [source] Electrospinning and crosslinking of zein nanofiber matsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2007Chen Yao Abstract Electrospinning processing can be applied to fabricate fibrous polymer mats composed of fibers whose diameters range from several microns down to 100 nm or less. In this article, we describe how electrospinning was used to produce zein nanofiber mats and combined with crosslinking to improve the mechanical properties of the as-spun mats. Aqueous ethanol solutions of zein were electrospun, and nanoparticles, nanofiber mats, or ribbonlike nanofiber mats were obtained. The effects of the electrospinning solvent and zein concentration on the morphology of the as-spun nanofiber mats were investigated by scanning electron microscopy. The results showed that the morphologies of the electrospun products exhibited a zein-dependent concentration. Optimizing conditions for zein produced nanofibers with a diameter of about 500 nm with fewer beads or ribbonlike nanofibers with a diameter of approximately 1,6 ,m. Zein nanofiber mats were crosslinked by hexamethylene diisocyanate (HDI). The tensile strength of the crosslinked electrospun zein nanofiber mats was increased significantly. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103:380,385, 2007 [source] Methods for the identi,cation of chemical respiratory allergens in rodents: comparisons of cytokine pro,ling with induced changes in serum IgEJOURNAL OF APPLIED TOXICOLOGY, Issue 4 2003R. J. Dearman Abstract No validated or widely recognized test methods are currently available for the prospective identi,cation of chemicals with the potential to cause respiratory allergy. The cellular and molecular mechanisms that result in the induction of chemical sensitization of the respiratory tract are unclear, although there is evidence for the selective development of T helper 2 (Th2)-type responses and, in some cases, the production of IgE antibody. We have therefore examined the utility of cytokine pro,ling using BALB/c mice, together with the measurement of induced increases in the total serum concentration of IgE in the Brown Norway (BN) rat, as markers for the prospective identi,cation of chemical respiratory allergens. Responses provoked by the reference respiratory allergen trimellitic anhydride (TMA) have been compared with those stimulated by the respiratory sensitizing diisocyanates toluene diisocyanate (TDI) and hexamethylene diisocyanate (HDI) and by the acid anhydride hexahydrophthalic anhydride (HHPA). Topical exposure of BN rats to TMA, TDI and HHPA each provoked marked immune activation (increases in lymph node cellularity and proliferation). However, only treatment with TMA stimulated vigorous increases in the total serum concentration of IgE. In contrast, exposure to HHPA, TDI or HDI failed to provoke signi,cant changes in serum IgE concentration or induced only transient and relatively weak increases in serum IgE levels. In parallel experiments using BALB/c strain mice, however, topical application of all four chemical respiratory allergens provoked a marked Th2-type cytokine secretion pro,le in draining lymph node cells. These data suggest that the measurement of induced changes in serum IgE is not suf,ciently sensitive for the robust identi,cation of chemical respiratory allergens. Furthermore, irrespective of the reasons for variations in TMA-induced IgE production among BN rats, doubts remain regarding the utility of these animals for the characterization of immune responses to chemical allergens. Cytokine pro,ling using the BALB/c strain mouse apparently provides a more robust method for the hazard assessment of chemical respiratory allergens. Copyright © 2003 John Wiley & Sons, Ltd. [source] Linear polyurethanes made from naturally occurring tartaric acidJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 9 2009Romina Marín Abstract Naturally occurring tartaric acid was used as raw material for the synthesis of novel linear polyurethanes (PURs) bearing two carboxylate side-groups in the repeating unit. Aliphatic and aromatic PURs were obtained by reaction in solution of alkyl and benzyl tartrates with hexamethylene diisocyanate and 4,4,-methylene-bis(phenyl isocyanate), respectively. All the novel PURs were thermally stable and optically active. The aliphatic carboxylate-containing PURs had Mw in the 40,70 kDa range, with PD between 2.1 and 2.5; all were semicrystalline polymers with melting temperatures between 100 and 150 °C and Tg in the 50,80 °C range. The aromatic PURs were amorphous materials with molecular weights between 18 kDa and 25 kDa and Tg above 130 °C. Hydrogenolysis of the PUR made from hexamethylene diisocyanate and benzyl tartrate yielded PURs containing up to 40% of free carboxylic side-groups. The tartrate-derived PURs displayed enhanced sensitivity to hydrolysis compared with their unsubstituted 2,6-PUR homologs. The PURs bearing free carboxylic groups were unique in being degraded by water upon incubation under physiological conditions. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2391,2407, 2009 [source] Synthesis, characterization, and molecular modeling studies of novel polyurethanes based on 2,2,-[ethane-1,2-diylbis(nitrilomethylylidene)]diphenol and 2,2,-[hexane-1,6-diylbis(nitrilomethylylidene)] diphenol hard segments,JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 20 2006A. V. Raghu Abstract Novel polyurethanes (PUs) based on 2,2,-[ethane-1,2-diylbis(nitrilomethylylidene)]diphenol and 2,2,-[hexane-1,6-diylbis(nitrilomethylylidene)]diphenol as hard segments containing four aromatic diisocyanates (4,4,-diphenylmethane diisocyanate, toluene 2,4-diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate) have been prepared. Fourier transform infrared, UV spectrophotometry, fluorescence spectroscopy, 1H NMR and 13C NMR spectroscopy, thermogravimetric analysis, and differential thermal analysis have been used to determine the structural characterization and thermal properties of the segmented PUs. All the PUs contain domains of both semicrystalline and amorphous structures, as indicated by X-ray diffraction. The acoustic properties have been calculated with the group contribution method. Molecular dynamics simulations have been performed on all the PUs to estimate the cohesive energy density and solubility parameter values, which compare well with the values calculated with the group contribution method. Furthermore, the simulation protocols have been applied to the PUs to produce X-ray diffraction plots to determine the phase morphology of the PUs. The surface properties of the PUs have been estimated from the simulation protocols. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6032,6046, 2006 [source] Polyurethanes Based on Castor Oil: Kinetics, Chemical, Mechanical and Thermal PropertiesMACROMOLECULAR MATERIALS & ENGINEERING, Issue 11 2008Elodie Hablot Abstract Polyurethanes based on vegetable oil were synthesized with castor oil and toluene diisocyanate, isophorone diisocyanate or hexamethylene diisocyanate, using dibutyltin dilaurate as a catalyst. The effects of the nature of the diisocyanate on the evolution of the kinetics, as well as the physical and mechanical properties and the thermal stability, of the different synthesized polyurethanes were investigated, and these complement data from the literature on equivalent systems. The polymerization kinetics, degree of swelling and mechanical properties were greatly affected by the diisocyanate nature, whereas the rheological properties and thermal stability were found to be similar for all polyurethanes. [source] Preparation and characterization of novel hybrid thermoplastic poly(ether urethane)/poly(vinylidene fluoride) elastomers, and their application as solid polymer electrolytesPOLYMER INTERNATIONAL, Issue 5 2007Ye Lin Abstract A comb-like polyether, poly(3-2-[2-(2-methoxyethoxy)ethoxy]ethoxymethyl-3,-methyloxetane) (PMEOX), was reacted with hexamethylene diisocyanate and extended with butanediol in a one-pot procedure to give novel thermoplastic elastomeric poly(ether urethane)s (TPEUs). The corresponding hybrid solid polymer electrolytes were fabricated through doping a mixture of TPEU and poly(vinylidene fluoride) with three kinds of lithium salts, LiClO4, LiBF4 and lithium trifluoromethanesulfonimide (LiTFSI), and were characterized using differential scanning calorimetry, thermogravimetric analysis and Fourier transform infrared spectroscopy. The ionic conductivity of the resulting polymer electrolytes was then assessed by means of AC impedance measurements, which reached 2.1 × 10,4 S cm,1 at 30 °C and 1.7 × 10,3 S cm,1 at 80 °C when LiTFSI was added at a ratio of O:Li = 20. These values can be further increased to 3.5 × 10,4 S cm,1 at 30 °C and 2.2 × 10,3 S cm,1 at 80 °C by introducing nanosized SiO2 particles into the polymer electrolytes. Copyright © 2006 Society of Chemical Industry [source] Synthesis and characterization of urethane vinyl ether crystalline monomersPOLYMER INTERNATIONAL, Issue 3 2006Zhaohua Zeng Abstract UV powder coatings combine the advantages of both conventional thermoset powder coatings and liquid UV-curing coatings. In this paper, a series of crystalline monomers based on urethane vinyl ether have been synthesized by reaction of hexamethylene diisocyanate (HDI) with hydroxybutyl vinyl ether (HBVE) or together with a saturated alcohol such as 1-octanol, 2-butoxy ethanol and 2-ethoxy ethanol. The crystallinity of the monomers was characterized by DSC, WAXD and polarizing microscopy. It was found that the melting point of the monomer can be expediently adjusted to an adequately low level by changing the type and/or the amount of the saturated alcohol added during the synthesis procedure. Thus, when 20,40 mol% of HBVE was replaced by a saturated alcohol, the melting point decreased to around 75,90 °C, which is suitable for UV-curing powder coating formulations. Copyright © 2006 Society of Chemical Industry [source] | |||||||||||||