Methylenedi Phenyl Isocyanate Research Articles

Ignifugation de polyuréthanes: I. Utilisation d’un polyol insaturé modifié par le 1-thioéthyl diéthylphosphonate

A new phosphonate was used for fireproofing of polyurethane. This product, 1-thioethyl phosphonate, was synthesized in two steps. The first one was an Arbuzov reaction between 1,2-dibromoethane and triethyl phosphite. The second step was a nucleophilic substitution of bromine by the –SH function of thiourea, followed by in-situ saponification and neutralization. Radical addition of this thiophosphonate onto hydroxy telechelic polybutadiene led to a polyol with various ratios of phosphorus. Different polyurethanes were prepared from this polyol and methylene diphenyl isocyanate (MDI) (wt% of P = 1 and 2%). Besides an increase of glass transition temperature, one can notice, by using thermogravimetric analysis, that the amount of residue beyond 600°C notably increases — up to 8% — with the percentage of phosphorus.

Poly(amide-imide)s Containing Polybutadiene Blocks

Poly(amide-imide)s containing polybutadiene blocks were prepared by reaction of 4,4'-methylenedi(phenyl isocyanate) with trimellitic anhydride and α,ω-diisocyanatopolybutadiene. The polymers were characterized by spectroscopic methods and X-ray diffraction. Incorporation of 5 wt.% of polybutadiene structures into polyimide decreases the temperature of 10% weight loss in nitrogen by 90 °C. Glass transition temperature of the polymer also decreases with the increasing content of soft polybutadiene segments, but the decrease is moderate for the contents higher than 20 wt.%. Broad amorphous halo dominates wide-angle X-ray diffractograms of all the samples, but sharper peaks of a more ordered structure were observed in definite concentration range of polybutadiene blocks. The copolymers are soluble in N-methylpyrrolidone.

Molecular order and dynamic mechanical behavior of polyurethanes based on liquid crystalline diol

Synthesis of the liquid crystalline (LC) diol 6,6′-[ethylenebis(l,4-phenylene-oxy)]-dihexanol (I) is described. The structure of polyurethanes prepared from diol I and 4,4′-methylenedi(phenyl isocyanate) (MDI), 4,4′-methylenedi(cyclohexyl isocyanate) (HMDI), or 2(4)-methyl-l,3-phenylene diisocyanate (TDI) at 1:1 molar ratios of isocyanate and hydroxy groups is studied by dynamic mechanical spectroscopy, differential scanning calorimetry (DSC), polarizing microscopy, and x-ray scattering. The polymer prepared from HMDI and the diol (I/HMDI) shows, on cooling, thermal behavior typical of amorphous polymers. A frequency-temperature superposition could be applied to the mechanical data, and the horizontal shift factor satisfied the Williams-Landel-Ferry (WLF) equation. A more-complex thermal behavior was found for I/HMDI polymer during subsequent heating; above 70°C, the formation of an ordered structure takes place, and this structure melts at about 120°C. Complex thermal behavior is exhibited by I/TDI polymer. On cooling its melt, the polymer forms a nematic phase at about 80°C, which freezes into the LC glassy state. On heating, the mesophase melts, and. subsequently, a better-ordered smectic phase is formed at 95°C, which melts at 120°C. This structure buildup is accompanied by a rapid increase in storage modulus G′, and the sample shows thermorheologically complex mechanical behavior. The polymer formed from the diol and MDI (I/MDI) exhibits a most-complex thermal behavior. On cooling and heating, four transitions can be detected in its thermal mechanical behavior, and the structure of the polymer is strongly dependent on its thermal history.

Liquid chromatography and mass spectrometry determination of aromatic amines in hydrolysed urine from workers exposed to thermal degradation products of polyurethane

An LC-MS method is described for the determination of 4,4′-MDA (4,4′-methylene dianiline) in hydrolysed urine as a biomarker for exposure to 4,4′-MDI (4,4′-methylene diphenylisocyanate). Dideuterated 4,4′-MDA (MDDA) was used as the internal standard. Urine was hydrolysed using sulphuric acid. and 4,4′-MDA was then derivatised with pentafluoro propionic anhydride (PFPA). Thermospray (TSP) and plasmaspray (discharge assisted thermospray, PSP) mass spectrometry monitoring both positive and negative ions were investigated. LC combined with negative ion PSP-MS gave a highly selective and sensitive method of analysis. Quantification was performed monitoring the (M-20)− ions of 4,4′-MDA-PFPA and the MDDA-PFPA. The instrumental detection limit was 0.1 pg/μl of 4,4′-MDA-PFPA. A linear calibration curve was obtained with a The overall precision for human urine spiked to a concentration of 0.5 μg/L was 10% (n=5). The detection limit was about 0.2 μg/l of urine. In technical grade MDA, the precursor of technical grade MDI, several isomers and oligomers with 2–5 aromatic rings were found. In pooled urine samples from ten workers exposed to thermal degradation products of a MDI based polyurethane (PUR) the concentration of 4,4′-MDA was 4 μg/litre. Several MDA isomers and oligomers were observed in the samples.

Thermal stability enhancement of polyurethanes by surface treatment

Both oxidation and methoxymethylation of the surfaces of a series of MDI (methylene diphenyl isocyanate) and TDI (toluene diisocyanate) polyether and polyester soft segment 1–4 butanediol polyurethanes result in increased thermal stability as measured by TG. Explosive loss of mass above the hard segment melting temperature suggests that the diffusion of the dissociated diisocyanate moiety is hindered at lower temperatures. Thus suppression of the depolycondensation reaction by chemical blockage of the surface may result in a material with an increased service life at use temperatures as thermal stability of a polyurethane may depend upon the low diffusivity of its diisocyanate comonomer. The effect of vacuum, oxygen and water vapor on the kinetics of mass-loss of several of the polyurethanes is presented.

Preparation of Hydrophobic Silica with Isocyanates

Hydrophobic silicas were prepared as follows: 0.5g of silica powder was dried at 200°C in an electric furnace and then the powder was treated in n-hexane solution containing 1.0g of 2, 4-tolylenediisocyanate (2, 4-TDI) at room temperature for 4h. The other isocyanates, hexamethylene diisocyanate (HMDI), isophorone diisocyanate (IPDI), methylene diphenylisocyanate (MDI) and phenyl isocyanate (PI) were used. Surface modification by IPDI and MDI gave hydrophobic silica. The conditions for preparing hydrophobic silica, such as drying temperature and reaction time were investigated. Also the dispersibility of the products to some organic solvents was discussed.

Thermodegradable polyurethanes having azo groups in the main chains. 1. Synthesis and thermal properties

Thermodegradable polyurethanes were synthesized from α,ω-dihydroxypolycaprolactone (PCL), 4,4'-methylenediphenylisocyanate (MDI), and 2,2'-azobis(2-cyanopropanol) (ACP) in a two-step polyaddition reaction. The thermodegradations of ACP and the polyurethanes were investigated by TGA and FTIR. The molecular degradation processes of the polyurethanes were followed by GPC. Degradation kinetics were discussed based on the disproportionation termination of radicals generated by the scission of an azo group. The experimental results showed a more complex mechanism

Oxygen diffusion behaviour in poly(ether urethane) cationomers based on 4,4′-methylenediphenyl isocyanate

Dynamic oxygen permeation measurements are carried out on films cast from solutions and emulsions of polyurethane (PU) cationomers. For the former, ionization leads to the permeation coefficients P at 20–40°C (below the glass transition temperature of the hard domains, T gh) being higher than those at 50–70°C (above T gh) by a factor of about 10 2. This is opposite to the results observed for normal homopolymers and un-ionized PU. For the latter, dispersion leads to a drop in P at 20–40°C and an increase in P at 50–70°C. These variations in P correlate quite well with the variation in morphology resulting from ionization and dispersion.

Synthesis and permeation behavior of membranes from segmented multiblock copolymers containing poly(ethylene oxide) and poly(β‐benzyl L‐aspartate) blocks

AbstractNovel segmented multiblock copolymers (7) were synthesized by linking poly(ethylene oxide) (PEO) blocks with poly(β‐benzyl L‐aspartate)(PBLA) blocks via urethane and urea bonds, which were formed by the reaction of 4,4′‐methylenediphenyl isocyanate (5) with the terminal hydroxyl groups of α‐hydro‐ω‐hydroxypoly(oxyethylene) (4) and the terminal amino groups of poly(β‐benzyl L‐aspartate)‐block‐iminohexamethyleneimino‐block‐poly(β‐benzyl L‐aspartate) (3) [prepared from 1,6‐hexanediamine (1) and β‐benzyl L‐aspartate N‐carboxy anhydride (2)], respectively. Membranes with various water contents were obtained from these copolymers by changing the lengths of the PEO and PBLA segments. The study of the permeation of 1‐phenyl‐1,2‐ethanediol, vitamin B12 and myoglobin through the membranes showed a high dependency of the permeability on the molecular weight of the solutes.

Liquid‐crystalline polyurethanes, 6. Amphiphilic polyurethanes containing long alkyl chains in the side chains and amino or quaternary ammonium groups in the main chains

AbstractAmphiphilic polyurethanes 5a–c, 6a–c, 10a–c and 11a–c containing hydrophilic amino or quaternary ammonium groups in the main chain, and hydrophobic ocatadecyl or docosyl groups in the side chain, were synthesized by polycondensation of 2,2′‐octadecyliminodiethanol (3a), 2,2′‐docosyliminodiethanol (3b), bis(2‐hydroxyethyl)methyloctadecylammonium bromide (8) and bis(2‐hydroxyethyl)docosylmethylammonium bromide (9) with a diisocyanate such a hexamethylene diisocyanate (4a), 2,4‐toluylene diisocyanate (4b) and 4,4′‐methylenediphenyl isocyanate (4c). Some of them show a thermotropic liquid‐crystalline state, as determined by DSC and polarizing microscopy.

Phase separation during fast (RIM) poly‐urethane polymerization

AbstractPhase separation dynamics during a reaction injection molding process of an elastomeric polyurethane was studied via FT‐IR and rheology. 4, 4′ methylenediphenyl isocyanate and 1, 4 butanediol were mixed with 50 wt% of a 2000 molecular weight poly(proplyene oxide)polyol catalyzed by dibutyltin dilaurate. A small reaction injection molding machine was used to impingement mix the chemicals and inject these directly into a Fourier transform infrared spectrometer or into a rheometer. The reaction conversion was followed by the isocyanate absorbance and the development of inter‐urethane hydrogen bonding was related to phase separation dynamics. Isothermal dynamic mechanical modulus build‐up during reaction was monitored by a thin gap parallel plate geometry subjected to small amplitude oscillation. An optimum reaction temperature was found, below which phase separation prematurely cuts off high molecular weight build up. Above this temperature phase separation is too slow and incomplete; modulus values are lower. Increasing catalyst reduces this optimum temperature.

Determination of Isocyanate and Aromatic Amine Emissions from Thermally Degraded Polyurethanes in Foundries

Thermal degradation of polyurethanes can cause emissions of isocyanates and aromatic amines into work atmospheres. Results from laboratory studies on the use of 4,4′-methylenediphenyl isocyanate (MDI)-based polyurethane bound foundry core materials showed that anilines and phenyl isocyanates are major degradation products, but the possibility for emissions of MDI and its corresponding diamine, 4,4′-methylenedianiline, also was demonstrated. Results from field investigations in two different foundries showed that of these degradation products, mainly anilines and phenyl isocyanates are found in foundry work atmospheres, whereas MDI and methylenedianiline concentrations were negligible. The selection of air sampling and analytical procedures for, as well as interpretation of results from, simultaneous determination of isocyanates and their corresponding amines are discussed.

Determination of Isocyanate and Aromatic Amine Emissions from Thermally Degraded Polyurethanes in Foundries

Thermal degradation of polyurethanes can cause emissions of isocyanates and aromatic amines into work atmospheres. Results from laboratory studies on the use of 4,4′-methylenediphenyl isocyanate (MDI)-based polyurethane bound foundry core materials showed that anilines and phenyl isocyanates are major degradation products, but the possibility for emissions of MDI and its corresponding diamine, 4,4′-methylenedianiline, also was demonstrated. Results from field investigations in two different foundries showed that of these degradation products, mainly anilines and phenyl isocyanates are found in foundry work atmospheres, whereas MDI and methylenedianiline concentrations were negligible. The selection of air sampling and analytical procedures for, as well as interpretation of results from, simultaneous determination of isocyanates and their corresponding amines are discussed.

Liquid crystalline polyurethanes, 1. Polyurethanes based on 4,4′‐[1,4‐phenylenebis(methylidynenitrilo)]diphenylethanol

AbstractPolyurethanes were synthesized from 4,4′‐[1,4‐phenylenebis(methylidynenitrilo)]diphenylethanol (3) with diisocyanates such as hexamethylene diisocyanate (4a), 4,4′‐methylenedicyclohexyl isocyanate (4b), 1,3‐cyclohexylenedimethyl isocyanate (4c), 2,4‐toluylene diisocyanate (4d) and 4,4′‐methylenediphenyl isocyanate (4e), and their thermal properties were investigated. The resulting polymers show a liquid crystalline state at 206–230, 160–216, 186–226 and 144–204°C, respectively, and the polymer obtained from 4e has a melting point at 272°C, determined by DSC and polarizing microscopy.

Systèmes réactifs polyuréthannes bloqués, 3. Etude du blocage des fonctions isocyanate par le butanone‐2 oxime et de leur déblocage par 1H NMR à 350 MHz

AbstractThe structures of the adducts of 2‐butanone oxime (1) to different diisocyanates were determined by 1H NMR spectroscopy. The reaction of diisocyanate blocking is quantitative. The different adducts of 1 to 4,4′‐methylenediphenyl isocyanate (2), 2‐methyl‐1,4‐phenylene and 2‐methyl‐1,3‐phenylene diisocyanates (8 and 10) and to the isocyanate resulting from α‐hydro‐ω‐hydroxypoly(oxytetramethylene) and an excess of 2, dissociate upon heating to reform the starting materials. The residual water in the NMR solvent reacts partially with the regenerated diisocyanates to give primary amines and then ureas.

Polybutadiène hydroxytéléchélique, 7. Cinétique de polycondensation en solution et en masse du polybutadiène hydroxytéléchélique avec le méthylène‐4,4′ di(isocyanate de phényle) en l'absence de catalyseur. Etude par 1H NMR et 13C NMR

AbstractQuantitative determinations by 13C NMR performed with insoluble polyurethanes allow to study the kinetics of the polymerization in bulk between hydroxytelechelic polybutadiene G 1000 and 4,4′‐methylene diphenylisocyanate (MDI). Comparisons have been made with (G 1000 + MDI) polymerization and (monoalcohol or G 1000 + phenyl isocyanate) model reactions in toluene. With [NCO]/[OH] = 1 and T ⩽ 60°C, in solution as well as in bulk, conversions are not complete. Because of the presence of gels, part of the reactive functions have been found to be trapped. For kinetic tests, only the first stage of the polymerization (conversion < 70%) may be taken into account. In bulk, the two alcohol functions are equally reactive, whereas in toluene, the hydroxylated 1,4 ends of the polybutadiene chains are more reactive. As evidenced for model reactions in the foregoing paper of this series, the kinetics fit better with the 3rd order than with the 2nd order equation. Nevertheless, at higher temperatures, the 2nd order may be used. The autocatalysis phenomenon found effective for model reactions is negligible in polymerization. All kinetic constants and activation parameters calculated must be considered to be apparent ones only.

ChemInform Abstract: CRYSTAL STRUCTURE AND SOLID‐STATE REACTIVITY OF 4,4′‐METHYLENEDIPHENYL ISOCYANATE (MDI)

Chemischer InformationsdienstVolume 14, Issue 39 Physical Organic Chemistry ChemInform Abstract: CRYSTAL STRUCTURE AND SOLID-STATE REACTIVITY OF 4,4′-METHYLENEDIPHENYL ISOCYANATE (MDI) R. B. WILSON, R. B. WILSONSearch for more papers by this authorY.-S. CHEN, Y.-S. CHENSearch for more papers by this authorI. C. PAUL, I. C. PAULSearch for more papers by this authorD. Y. CURTIN, D. Y. CURTINSearch for more papers by this author R. B. WILSON, R. B. WILSONSearch for more papers by this authorY.-S. CHEN, Y.-S. CHENSearch for more papers by this authorI. C. PAUL, I. C. PAULSearch for more papers by this authorD. Y. CURTIN, D. Y. CURTINSearch for more papers by this author First published: September 27, 1983 https://doi.org/10.1002/chin.198339084Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume14, Issue39September 27, 1983 RelatedInformation

Crystal structure and solid-state reactivity of 4,4'-methylenediphenyl isocyanate (MDI)

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCrystal structure and solid-state reactivity of 4,4'-methylenediphenyl isocyanate (MDI)Roxy B. Wilson, Yue Shen Chen, Iain C. Paul, and David Y. CurtinCite this: J. Am. Chem. Soc. 1983, 105, 6, 1672–1674Publication Date (Print):March 1, 1983Publication History Published online1 May 2002Published inissue 1 March 1983https://doi.org/10.1021/ja00344a054RIGHTS & PERMISSIONSArticle Views415Altmetric-Citations23LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (373 KB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts

Mutagenic action of isocyanates used in the production of polyurethanes.

Isocyanates used in the production of polyurethanes were investigated for mutagenic action in Salmonella typhimurium. These investigations showed that the most commonly used isocyanates, toluene diisocyanate (TDI) and 4,4'-methylene-diphenylisocyanate (MDI), are mutagenic. This effect can be ascribed to the amine analogues formed during the hydrolysis of isocyanates: TDI is mutagenic in TA 1538 and TA 98 after metabolic activation. This finding agrees with the results obtained with the amine analogue 2,4-toluenediamine. MDI, like the amine analogue 4,4'-methylenedianiline, is mutagenic in TA 100 after metabolic activation by rat liver enzymes (S-9 mix). A prepolymerized polyisocyanate of the MDI type is also mutagenic in assays using TA 100 and S-9 mix. It is concluded that isocyanates are potentially mutagenic and carcinogenic to man. In view of their widespread use in the work environment and in light of the high production figures for polyurethanes in industrialized countries, isocyanates must be considered to represent a serious health hazard.