Diisocyanate polymeric methylene

PMDA, 20 266. See also Polymeric methylenedianiline (PMDA) PMDA-ODA, gel casting of, 20 271-272 PMDA-ODA structures, 10 214 PMDI polymeric isocyanate, 25 456, 457, 462. See also Polymeric methylene diisocyanate resins (PMDI) rigid polyurethanes from, 25 471-472 PMF/PMUF resins, 15 779 PMF resins, hardening of, 15 781 PMMA ionomer, 4DA and, 14 479 PM optimization (PMO), 15 466 PM process, 21 50 Pneumatic classification, 22 288 health and safety factors related to,... 

Carr, R.H. Jackson, A.T. PreUminary MALDI-TOF and Field Desorption Mass Spectrometric Analyses of Polymeric Methylene Diphenylene Diisocyanate, Its Amine Precursor and a Model Polyedier Prepolymer. Rapid Commun. Mass Spectrom. 1998, 72,2047-2050. 

Reuzel PGJ, Arts JHE, Lomax LG, et al Chronic inhalation toxicity and carcinogenicity studies of respirable polymeric methylene diphenyl diisocyanate (polymeric MDI) aerosol in rats. Fundam Appl Toxicol 22 195-210, 1994... 

Reuzel, P.G.J., Arts, J.H.E., Lomax, L.G, Kuijpers, M.H.K., Kuper. C.F., Gembardt, C., Feron, V.J. Loser, E. (1994) Chronic inhalation toxicity and carcinogenicity study of respirable polymeric methylene diphenyl diisocyanate (polymeric MDI) aerosol in rats. Fundam. appl. Toxicol., 22, 195-210... 

MC MDI MEKP MF MMA MPEG MPF NBR NDI NR OPET OPP OSA PA PAEK PAI PAN PB PBAN PBI PBN PBS PBT PC PCD PCT PCTFE PE PEC PEG PEI PEK PEN PES PET PF PFA PI PIBI PMDI PMMA PMP PO PP PPA PPC PPO PPS PPSU Methyl cellulose Methylene diphenylene diisocyanate Methyl ethyl ketone peroxide Melamine formaldehyde Methyl methacrylate Polyethylene glycol monomethyl ether Melamine-phenol-formaldehyde Nitrile butyl rubber Naphthalene diisocyanate Natural rubber Oriented polyethylene terephthalate Oriented polypropylene Olefin-modified styrene-acrylonitrile Polyamide Poly(aryl ether-ketone) Poly(amide-imide) Polyacrylonitrile Polybutylene Poly(butadiene-acrylonitrile) Polybenzimidazole Polybutylene naphthalate Poly(butadiene-styrene) Poly(butylene terephthalate) Polycarbonate Polycarbodiimide Poly(cyclohexylene-dimethylene terephthalate) Polychlorotrifluoroethylene Polyethylene Chlorinated polyethylene Poly(ethylene glycol) Poly(ether-imide) Poly(ether-ketone) Polyethylene naphthalate Polyether sulfone Polyethylene terephthalate Phenol-formaldehyde copolymer Perfluoroalkoxy resin Polyimide Poly(isobutylene), Butyl rubber Polymeric methylene diphenylene diisocyanate Poly(methyl methacrylate) Poly(methylpentene) Polyolefins Polypropylene Polyphthalamide Chlorinated polypropylene Poly(phenylene oxide) Poly(phenylene sulfide) Poly(phenylene sulfone)... 

Nonemulsifiable and emulsifiable polymeric methylene diisocyanates (Desmodur VP PU 1520 A 31 and 1520 E, Messrs. Bayer, West Germany) were combined with maize starch and solutions of tannin extract or protein. 

Pauluhn, J. and Lewalter, J., Analysis of markers of exposure to polymeric methylene-diphenyl diisocyanate (pMDI) in rats a comparison of dermal and inhalation routes of exposure, Exp. Toxicol. Pathol, 54, 135-146, 2002. 

In certain niche applications, aliphatic isocyanates, such as isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), methylene 4,4 -biscyclo-hexylisocyanate (H12MDI), and polymeric versions of these diisocyanates, are used, e.g., in instances where light stability or reduced reactivity is needed. These isocyanates usually cost more than the aromatic diisocyanates. Thus, they are used in adhesive areas that can justify the higher costs. 

Among these, the most common diisocyanates used on a large scale are toluene diisocyanate (TDI) and MDI.TDI was the first commercially available isocyanate and is available as a mixture of 80% 2,4- and 20% 2,6-toluene diisocyanate isomers (Table 6.2), although they are also available as pure single isomers. Similarly, MDI has three isomers, namely 4,4 -, 2,4 -and 2,2 -diphenylmethane diisocyanate. However, only the 4,4 -isomer is used for commercial purposes although all the isomers are present in polymeric methylene diphenyl diisocyanate (PMDI) which is also used in the preparation of polyurethane. 

Fig. 4. Typical structure of polymeric methylene-diphenyl-diisocyanate (PMDI).

Specific interaction of polymeric methylene diphenyl diisocyanate (PMDI) with aluminum. Negative ToF-SIMS spectra at nominal mass m/z 102 u from aluminum treated with PMDI of varying solution concentration, (a) 5 v/v%, (b) 0.5 v/v%, (c) 0.35 v/v%, (d) 0.1 v/v%, (e) 0.05 v/v%, (f) no PMDI (Reproduced from Shimizu et al. (2010), with permission)... 

Commonly used isocyanates are toluene diisocyanate, methylene diphenyl isocyanate, and polymeric isocyanates. Polyols used are macroglycols based on either polyester or polyether. The former [polyethylene phthalate) or polyethylene 1,6-hexanedioate)] have hydroxyl groups that are free to react with the isocyanate. Most flexible foam is made from 80/20 toluene diisocyanate (which refers to the ratio of 2,4-toluene diisocyanate to 2,6-toluene diisocyanate). High-resilience foam contains about 80% 80/20 toluene diisocyanate and 20% poly(methylene diphenyl isocyanate), while semi-flexible foam is almost always 100% poly(methylene diphenyl isocyanate). Much of the latter reacts by trimerization to form isocyanurate rings. 

The uses of aniline obtained from nitrobenzene are given in Table 11.5. Aniline s use in the rubber industry is in the manufacture of various vulcanization accelerators and age resistors. By far the most important and growing use for aniline is in the manufacture of jP,jP-methylene diphenyl diisocyanate (MDI), which is polymerized with a diol to give a polyurethane. 

The aerosol technique can also be used to produce polymer colloids by addition polymerization. Thus, when droplets of toluene-2,4-diisocyanate (TD1) or 1,6-hexa-methylene diisocyanate (HDI) were brought into contact with ethylenediamine (EDA) vapor (in the apparatus shown in Fig. 1.5.3) spherical polyurea particles with modal diameters of 1-3 p,m were formed. The entire process, i.e., the formation of droplets and the polymerization, was carried out at moderate temperatures (<80°C)... 

In the polyurethane industry, the polymeric glycols are prepared by anionic polymerization of epoxides such as ethylene oxide and propylene oxide. Poly(tetra-methylene glycol), which was prepared by polymerization of tetrahydrofuran, was subjected to chain extension by reaction with diisocyanate (polyurethane formation) and with dimethyl terephthalate (polyester by alcoholysis). 

C(N02)3 Jr mw (548.74)n, N 23.82%, OB to CO2 -39.36%, amorph solid, mp 75—85°, Sol in acet. The initial polymer is prepd by dropwise addition of the diisocyanate in abs dioxane to a dioxane sob of an equiv amt of the did plus 5x10" mole of ferric acetylacetonate catalyst, over a period of 30 nuns while mamtammg the temp at 40-50°. Polymerization at 50° requires 43 hrs to complete. After acet soln and w pptn, the yield is vacuum dried. Post polymerization nitration is accomplished by sob of the polymer m 100% nitric acid at 0° m the ratio of 1 g polymer to 10ml acid. The nitration is completed upon sob of the polymer in acid. The excess nitric acid is removed at RT by vacuum distn, the polymer is dissolved b acet and pptd m methylene chloride... 

NO2 NO2 0 NO2 -C.N.(CH2)2.N.(CH2)2.N.C.0.CH2.C.CH20-N02 CH2 mw (425.32)n, N 23.06%, OB to CO2 -58.31%, amorph solid, mp 70—80°. Sol m acet. The imtial polymer is prepd by dropwise addition of a sob of the diisocyanate in dimethylforma-mide to a dimethylformamide sob of an equiv wt of diol plus 1x10" mole ferric acetylacetonate catalyst over a period of 15 mbs. Polymerization is completed b 136 hrs at 50°. After dilution with dimethylformamide, the polymer is pptd b w and vacuum dried. Post polymerization nitration is accomphshed by soln of the polymer b 100% nitric acid at 0° b the ratio of 1 g polymer to 15ml acid. Nitration is completed on sob of the polymer. The excess acid is vacuum distd at RT, the polymer is dissolved b acet and pptd in methylene chloride... 

Synthesis and Modification. A series of polyurethanes and polyurethane-ureas of varying degress of hydrophilicity and hydrophobicity and mechanical property were synthesized. The polymers were prepared by a solution polymerization method and consisted of three components a polyether, a diisocyanate, and a chain extender. In our studies, polyurethanes (Table I) were based on a carbowax (polyoxyethylene glycol), MDI (methylene bis-4-phenyl isocyanate) and 1,5-pentanediol. Polyurethane-ureas (Table II) were obtained by substituting the chain extender from a diol to a diamine. The polyurethane-ureas (Table II) were obtained by changing the chain extender from a diol to a more reactive diamine. The polyurea-urethanes (Table III) were obtained by using a diamine terminated polyether instead of the carbowax. 

The pbosgenation of methylene diphenylamine yields methylene diisocyanate, while that of the polyamines leads to polymeric MDI ... 

This is an addition reaction that proceeds via a mechanism of step growth (stagewise) polymerization. The most common isocyanates are toluene diisocyanate (TDI) and methylene bis 4-phenylisocyanate (MDI). TDI is cheaper and is mostly used for flexible foams, but MDI competes because of its lower vapor pressure and reduced sensitivity in handling. Polyfunctional isocyanates are added for cross-linking. The interesting reaction between isocyanate... 

Precaution Combustible moderate fire risk incompat. with strong oxidizers, halogen gases, halogenated compds., 2,4,6-trichloro-1,3,5-triazine vigorous reactions possible polymerizes violently on contact with methylene bisphenyl diisocyanate Hazardous Decomp. Prods. On decomp., emits toxic fumes of NOx... 

---