Toluene diisocyanate, sampling

Two final examples of the sensitivity and general applicability of the FTIR gas analysis technique are illustrated in Fig. 8. Trace (A) shows the spectrum obtained from an ultra-air filled 70 liter sampling bag into which had been injected, 18 hours previously, 4.8 microliters of TDI, toluene diisocyanate. On the basis of the single feature at 2273 cm l, it is estimated that 50 ppb TDI could be detected. The lower Trace (B), shows the spectrum of nickel carbonyl. This highly toxic but unstable gas was found to decay rapidly at ppm concentrations in ultra air (50% lifetime 15 minutes). Calibration of its spectrum was established by recording successive spectra at ten minute intervals and by attributing the increase in carbon monoxide concentration (calibration known) to an equivalent but four times slower decrease in nickel carbonyl concentration. The spectrum shown represents 0.6 ppm of the material. Note the extraordinary absorption strength. The detection limit is thus less than 10 ppb. 

Adducts to hemoglobin are perhaps the most useful means of biological monitoring by adduct formation. Hemoglobin is, of course, present in blood, which is the most accurate type of sample for biological monitoring. Adducts to blood plasma albumin are also useful monitors and have been applied to the determination of exposure to toluene diisocyanate, benzo(a)pyrene, styrene, styrene oxide, and aflatoxin Bj. The DNA adduct of styrene oxide has been measured to indicate exposure to carcinogenic styrene oxide.12... 

Ten days after a spill of 13 tons of toluene diisocyanate onto wet forest soil, the area was covered with sand. The soil concentration of toluene diisocyanate and toluenediamine declined from parts per thousand to parts per million from 10 days to 12 weeks after the spill. Six years later, only polyureas were found. Under controlled conditions, 5 kg of toluene diisocyanate was covered with 50 kg of sand and 5 kg of water and samples taken from the top and bottom of the sand. After 24 h, <6% toluene diisocyanate remained. Toluene diisocyanate is rapidly hydrolyzed... 

Nordqvist, Y., Melin, J., Nilsson, U., Johansson, R., and Colmsjo, A., Comparison of denuder and impinger sampling for determination of gaseous toluene diisocyanate (TDI), Eresenius J. Anal. Chem., 371, 39-43, 2001. 

Lind, P., Skarping, G., and Dalene, M., Biomarkers of toluene diisocyanate and thermal degradation products of polyurethane, with special reference to the sample preparation. Anal. Chim. Acta, 333, 277-283, 1996. 

Levine, S. P. 2002. Critical review of methods for sampling, analysis, and monitoring of vapor-phase toluene diisocyanate. Appl. Occup. Environ. Hyg. 17(12) 878-90. 

Prepolymers of polybutadiene diol (M. 2500), polytetramethylene oxide diol (M. 1400 and M. 2100), and prepolymer of polypropylene oxide diol (M. 1400) were used to obtain segmented elastomers SPU-1 to SPU-5. Prepolymers were prepared by reaction of appropriate diol with 2,4-toluene diisocyanate (2 moles per one mole of diol). Prepolymers of polytetramethylene oxide diol (elastomers SPU-1 and SPU-4) were cured by methylene-bis-o-chloroaniline, MOCA, or by mixture of MOCA and polytetramethylene oxide diol (SPU-2 and SPU-3). SPU-5 samples, prepared from prepolymer of polypropylene oxide diol, were cured by MOCA, and prepolymer of polybutadiene diol was cured by a mixture of MOCA and polytetramethylene oxide diol (SPU-6). Various concentrations of hard segments, Cj, in SPU were set by a ratio of mixture components and molecular weight of prepolymer (Table 10.14). Excess of NCO-groups was in the range 1.03-1.06 for SPU-1 to SPU-5 and 0.99 for SPU-6. All samples were cured at 80°C for 4 days. The... 

The determination of residual monomer is frequently required in the quality control of polymers, and may easily be achieved by SEC. Toluene diisocyanate (TDI) in a polyurethane was determined by Spagnolo [43] by derivatization of the sample with ethanol, followed by SEC. 

Magnetic biofoams can be prepared using different contents of water and toluene diisocyanate. In our experiments, we used the compositions shown in Table 1. The optical micrographs of the produced biofoams are shown in Figure 4. It can be noticed that the sample PU-1 has large pores coimected, which presents a most open aspect. Moreover, it is possible to infer that the sample PU-2 also has large pores, but one can see that these pores are smaller and posses thicker walls. The increase of the pore walls becomes more visible as more water is used, as observed in the sample PU-3. 

Toluene Diisocyanate 100 7 7 Appearance practically unchanged <1 >90 Foraflon Atochem Specimen Samples according to ASTM D 3222-73, tensile strength at yield (ASTM 1708)... 

The object of the study was a micro-heteropneous polyurethane urea (PUU) based on the prepolymer SKU-PFL-100 (M 1.4 x 10 ), synthesized by the interaction of oli-gotetramethylene oxide diol (M 1 x 10 ) with a double excess of 2,4-toluene diisocyanate. MOCA (aromatic diamine 3,3 -dichloro-4,4 -diaminodiphenyl methane) was used to cme SKU-PFL-100. The NCO/NH2 ratio was 1.2 for this reaction. Piepolymer was degassed at 50 + 10 °C before the reaction. Reaction mixture was stirred for 3 minutes at 50 + 1 °C and a residnal pressure of 1-2 kPa after injection of melted aromatic diamine. Cnring period was 3 days at 80 2 °C. Cured samples were further stored at the room temperature for at least 30 days. 

Recently Chelmecki et aL reported the ionic conductivity results of HPC-PEO networks containing LiN(CF3S02)2- These networks were obtained by thermal crosslinking of HPC with tri(ethylene glycol) and toluene diisocyanate through the urethane bonds, as shown in Fig. 3.1. The ionic conductivities of these samples were in the range of 10 S/cm. The... 

Two visco-elastic foam samples were selected for this investigation and were designated as VE foam 1 and 2. VE foam 1 is a toluene diisocyanate (TDI) based and VE foam 2 is a methylene diphenyl diisocyanate (MDI) based viscoelastic foam. Some basic material characterizations were run to characterize these two foams such as density, air flow, compression set (90%) according to the ASTM 395 B standard, resiUency (ball rebound), and resiliency (BASF recovery). 

Isoouanates. Various isocyanates are employed in the polymer industry. These compounds are powerful irritants and they are highly toxic. Of particular interest are methylene-di-paraphenylene isocyanate (MDI) and toluene-2,4-diisocyanate (TDI). Various alkyl isocyanates (e.g., methyl, ethyl, propyl, butyl, and cyclohexyl) derivatives may also be of current interest with respect to potential occupational health hazards. Simultaneous analysis of MDI and TDI by HPLC has been accomplished by a modification of the method of Dunlap et al. (28). Air samples are collected in impingers containing p-nitrobenzyl-n-... 

The polymer is prepared by crosslinking p-CyD in DMSO with toluene 2,4-diisocyanate (TDI) in the presence of cholesterol as the template. In order to obtain homogeneous samples, the amount of TDI is kept small. Matrix-assisted laser desorption/ionization time-of-flight mass spectra (MALDI-TOFMS) are presented in Fig. 5.5. In the presence of the template (a), both the dimers of P-CyD (mass number (M) = 2000-3500) and its trimers (M = 4000-4500) are efficiently formed. In its absence (b), however, virtually all the products are monomeric P-CyDs (M = 1000-2000). The template enormously accelerates the bridging between two P-CyD molecules. Each of the signals in the spectra corresponds to different amount of substitution by TDI. These analyses clearly show that dimeric P-CyDs (the binding sites for choles-... 

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