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Micro-agglomerate corks, made by agglutination of cork granulate through the addition of different adhesives, represent an important slice of the market of cork stoppers. Binder glues which are polyurethane- or butadiene-based have been used since they have strong agglomerating effect. Unfortunately, polyurethane-based glues can have isocyanide end group compounds which can migrate into the wine. 2,4-toluene diisocyanate (2,4-TDI) and 2,6 toluene diisocyanate (2,6-TDI), can be found in adhesive and could migrate into wine. A simple ultrahigh-performance liquid chromatography-mass spectrometry (UHPLC-MS/MS) method for the determination of these active ingredients (a.is.) in wine has been developed. The method has been validated under Eurachem CITAC guidelines (Cooperation on International Traceability in Analytical Chemistry). Instrument limit of detection (LOD) and to a limit of quantification (LOQ) for 2,6 TDI and 2,4 TDI were 0.42 and 0.39 μg/L, and 1.72 and 1.57 μg/L, respectively. Four different solvents applied for recoveries showed quite different rates ranging for 2,6 TDI and 2,4 TDI from 17.96 to 88.53 %, and 40.08 to 99.18 %, respectively. Real sample analysis showed low residue levels, especially of 2,6 TDI, with values always below the LOQ. The data reported on real samples allowed to establish that from a risk management purpose, no toxicology risk can be accomplished.

The relaxation properties of hybrid organomineral composite materials based on sodium liquid glass, 2,4-toluene diisocyanate, and polyisocyanate modified with epoxide resin are studied by spectral methods and concomitant calculations. It is demonstrated that chemical transformations occurring under heating during preparation of monolithic samples follow a complex pattern. Upon modification of the initial blends with the epoxy-diane resin, the composite acquires a homogeneous granular structure and its mechanical properties are improved. The initial relaxation moduli are as high as 1000 and 540 MPa at 20 and 100°С, respectively. For unmodified materials, the initial relaxation moduli are 730 and 520 MPa at 20 and 100°С, respectively. Master relaxation curves making it possible to forecast relaxation behavior under prolonged relaxation are obtained. The material containing the highest amount of polyisocyanate shows an extremely high relaxation modulus.

Polymers prepared from a polyether, 2,4-toluene diisocyanate, and octamethylcyclotetrasiloxane were studied using thermomechanical analysis, mechanical tests, and water vapor adsorption. The adsorption of nitrogen vapor was studied at 77 K, and that of water vapor, at 293 K.

With the use of the method of bulk polymerization, network polyisocyanurate polymer materials based on poly(oxytetramethylene) glycol and 2,4-toluene diisocyanate have been synthesized for the first time. To analyze their performance and relaxation mechanism, the mechanical characteristics of polyisocy-anurates are studied. The above polymers show a quasielastic mechanical behavior, even though their elastic modulus is characteristic of the temperature interval where all traditional polymers experience the transition from the glassy state to the rubbery state, and demonstrate a well-pronounced viscoelastic behavior. The proposed procedure for the construction of master curves shows that, in a certain temperature interval, shift factor remains invariable; in other words, it does not depend on temperature.

The standard sampling methods for toluene diisocyanate (TDI) only collect total TDI without separating the aerosol and gas phases. There are few other samplers, such as the dual filter, triple filter and annular denuder systems (ADS), which are able to sample the aerosol and gas phases simultaneously. This field study was conducted at two workplaces to access the total 2,4-TDI and the gaseous and aerosol TDI concentrations by different samplers simultaneously. In addition to the standard sampling time of 15 min, sampling was done for 30 and 60 min to study the effect of sampling time on the measured 2,4-TDI concentrations. Test results at two workplaces show that gas-phase 2,4-TDI is the predominant species and the aerosol phase concentration is very small. The measurements using various samplers show that the sampling time influences the sampled TDI concentration considerably which may be due to reaction of TDI with water vapor and polyo in the sampling process. It is evident that as sampling time increases the TDI concentration decreases. Laboratory test was also conducted using pure gas-phase 2,4-TDI to confirm the sampling time effect on the measured concentrations found in the field study.

In order to understand the sampling time effect on the 2,4‐TDI (Toluene diisocyanate) concentrations, laboratory and field tests were conducted in this study. An ADS (annular denuder sampler) and two OFFCs (open face filter holders) with different filters were tested for 1 to 120 minutes in the laboratory using 2,4‐TDI gas. In the field study, the standard sampling method, the dual filter the triple filter and annular denuder systems were used at two workplaces to study the change of 2,4‐TDI concentrations with sampling time from 15 to 60 minutes. The test results in both laboratory and field studies show that the sampling time influences the sampled TDI concentration considerably which may be due to reaction of TDI with water vapor and polyo in the sampling process. It is evident that as sampling time increases the TDI concentration decreases very significantly.

Anionic copolymerization of 2,4-toluene diisocyanate with γ-butyrolactone in the presence of triethylamine was performed. The chemical structure of the copolymer obtained was determined by IR and 1H NMR spectroscopy, and some kinetic features of the process were revealed.

Background: Isocyanates with the general formula R-(N=C=O) are theoretically contact sensitizers. However, allergic contact dermatitis (ACD) from isocyanates is seldom reported. In previous reports, patients reacted to their isocyanate-based work materials but not to commercial patch-test preparations of isocyanates. Therefore, we suspected that the low frequency of reported ACD from isocyanates was partly due to inadequate commercial preparations. A past study also showed the concentrations of diphenylmethane-4,4'-diisocyanate (4,4'-MDI) in petrolatum preparations to be much lower than declared. Objective: In this study, 2,4-toluene diisocyanate (2,4-TDI), 1,6-hexamethylene diisocyanate (1,6-HDI), and isophorone diisocyanate (IPDI) were investigated in a similar fashion. Methods: In preparations from 12 dermatology departments and two suppliers of patch-test allergens, we determined the isocyanate content as the isocyanate-dibutylamine derivative, using liquid chromatography and mass spectrometry. The preparations were considered stable if the ratio between the stated and found concentrations was within the range of 0.8 to 1.2. Results: Although 28 of 36 investigated preparations had ratios outside of the stable range, they were in its vicinity, which indicates that preparations of 2,4-TDI, 1,6-HDI, and IPDI are more stable than are preparations of 4,4'-MDI where previously reported results showed ratios far outside of stable range. Conclusion: As opposed to preparations of 4,4'-MDI, preparations of 2,4-TDI, 1,6-HDI, and IPDI can be considered to be stable. (Less)

Various numbers of LB monolayers of a metal-free phthalocyanine derivative, A410H2Pc, have been deposited onto ultrasonically cleaned quartz substrates with platinum interdigitated electrodes. Similar devices i.e. those with the same number of LB layers, show the same response characteristics in the presence of 35 ppb (0.035 ppm) toluene diisocyanate (TDI)—a toxic substance used in the production of plastics and found in certain types of paint. The response times of the LB devices studied so far have been calculated to be about 40s. The electrical properties of evaporated films of a metal-free phthalocyanine derivative, α-H2Pc, and those of the A410H2Pc LB films have been found to be similar. The response time for the evaporated films has been found to be much less that that for the LB films. Although a direct comparison cannot be made between the LB and evaporated films, in this case, results suggest that devices fabricated from evaporated films will be much faster at detecting the presence of TDI than devices fabricated from LB films.

Skin reactivity in guinea pigs sensitized with 2,4-toluene diisocyanate (TDI) has been examined. For sensitization, guinea pigs were treated daily with a 10% TDI solution in ethyl acetate by intranasal application for 5 consecutive days. Local application of TDI onto the flank skin of these TDI-sensitized animals resulted in an immediate development of the flare-and-wheal reaction at the site of application. The extent of the skin response was dependent on the concentration of TDI used for provocation. It was also demonstrated that the skin reactivity was successfully transferred to untreated animals by injecting sera obtained from actively sensitized animals. However, heat treatment of sensitized sera resulted in a slight, but not significant decrease in its ability to sensitize recipient animals. Histological examination revealed degranulation of mast cells and infiltration of basophils and eosinophils in the superficial dermis as the characteristics of the skin reaction in the immediate and late phase, respectively. Pretreatment of TDI-sensitized animals with dexamethasone, a steroidal agent, mepyramine, an antagonist of the histamine H1 receptor, or several antiallergic agents including ketotifen, azelastine and oxatomide resulted in a significant inhibition of the skin reactivity. However, some antiallergic agents such as tranilast, ibuzilast and DSCG were not effective in inhibiting this skin reactivity.

2, 4-toluene diisocyanate (TDI) in air was detected and determined by a piezoelectric quartz crystal sensor coated with tetrakis(hydroxyethyl)ethylenediamine (THEED)/dithizone(diphenylthiocarbazone) solution (l:3v/v in acetone). The response curve is linear over the concentration range 3–24 ppb of TDI. The sensor can be used for more than 2 months without loss in sensitivity and presented good reversibility and reproducibility. Of the different possible interferents tested, only SO2 caused a frequency change.