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Sample records for aliphatic isocyanate polyurethanes

  1. Validation of Alternatives to Aliphatic Isocyanate Polyurethanes

    NASA Technical Reports Server (NTRS)

    Curran, Jerome

    2007-01-01

    The National Aeronautics and Space Administration (NASA) Headquarters chartered the Acquisition Pollution Prevention (AP2) Office to coordinate agency activities affecting pollution prevention issues identified during system and component acquisition and sustainment processes. The primary objective of this effort is to demonstrate and validate alternatives to aliphatic isocyanate polyurethane coatings. Successful completion of this project will result in one or more isocyanate-free coating systems qualified for use at Air Force Space Command (AFSPC) and NASA centers participating in this study. The objective of this project is to qualify the candidates under the specifications for the standard system. This project will compare coating performance of the proposed alternatives to existing coating systems or standards.

  2. Cost-Benefit Analysis for Alternatives to Aliphatic Isocyanate Polyurethanes

    NASA Technical Reports Server (NTRS)

    Lewis, Pattie

    2007-01-01

    NASA and Air Force Space Command (AFSPC) have similar missions and therefore similar facilities and structures in similar environments. The standard practice for protecting metallic substrates in atmospheric environments is the application of an applied coating system. The most common topcoats used in coating systems are polyurethanes that contain isocyanates. Isocyanates are classified as potential human carcinogens and are known to cause cancer in animals. The primary objective of this effort was to demonstrate and validate alternatives to aliphatic isocyanate polyurethanes resulting in one or more isocyanate-free coatings qualified for use at AFSPC and NASA installations participating in this project. This Cost-Benefit Analysis (CBA) quantifies the estimated capital and process costs of coating alternatives and cost savings relative to the current coatings. The estimates in this CBA are to be used for assessing the relative merits of the selected alternatives. The actual economic effects at any specific facility will depend on the alternative material or technology implemented, the number of actual applications converted, future workloads, and other factors . The participants initially considered eighteen (18) alternative coatings as described in the Potential Alternatives Report entitled Potential Alternatives Report for Validation of Alternatives to Aliphatic Isocyanate Polyurethanes, prepared by ITB. Of those, 8 alternatives were selected for testing in accordance with the Joint Test Protocol entitled Joint Test Protocol for Validation of Alternatives to Aliphatic Isocyanate Polyurethanes, and the Field Test Plan entitled Field Evaluations Test Plan for Validation of Alternatives 10 Aliphatic Isocyanate Polyurethanes, both of which were prepared by ITB. A joint Test Report entitled Joint Test Report for Validation of Alternatives to Aliphatic Isocyanate Polyurethanes, prepared by ITB, documents the results of the laboratory and field testing, as well as any

  3. Field Evaluations Test Plan for Validation of Alternatives to Aliphatic Isocyanate Polyurethanes

    NASA Technical Reports Server (NTRS)

    Lewis, Pattie

    2005-01-01

    The objective of this project is to qualify candidate alternatives to Aliphatic Isocyanate Polyurethane coatings under the specifications for the standard system. This project will compare coating performance of the proposed alternatives to existing coating systems or standards.

  4. Joint Test Protocol for Validation of Alternatives to Aliphatic Isocyanate Polyurethanes

    NASA Technical Reports Server (NTRS)

    Lewis, Pattie

    2005-01-01

    The primary objective of this effort is to demonstrate and validate alternatives to aliphatic isocyanate polyurethanes. Successful completion of this project will result in one or more isocyanate-free coatings qualified for use at AFSPC and NASA installations participating in this project.

  5. Potential Alternatives Report for Validation of Alternatives to Aliphatic Isocyanate Polyurethanes

    NASA Technical Reports Server (NTRS)

    Lewis, pattie

    2011-01-01

    Identifying and selecting alternative materials and technologies that have the potential to reduce the identified HazMats and hazardous air pollutants (HAPs), while incorporating sound corrosion prevention and control technologies, is a complicated task due to the fast pace at which new technologies emerge and rules change. The alternatives are identified through literature searches, electronic database and Internet searches, surveys, and/or personal and professional contacts. Available test data was then compiled on the proposed alternatives to determine if the materials meet the test objectives or if further)laboratory or field-testing will be required. After reviewing technical information documented in the PAR, government representatives, technical representatives from the affected facilities, and other stakeholders involved in the process will select the list of viable alternative coatings for consideration and testing under the project's Joint Test Protocol entitled Joint Test Protocol for Validation of Alternatives to Aliphatic Isocyanate Polyurethanes and Field Test Plan entitled Field Evaluations Test Plan for Validation of Alternatives to Aliphatic Isocyanate Polyurethanes, both prepared by ITB. Test results will be reported in a Joint Test Report upon completion oftesting. The selection rationale and conclusions are documented in this PAR. A cost benefit analysis will be prepared to quantify the estimated capital and process costs of coating alternatives and cost savings relative to the current coating processes, however, some initial cost data has been included in this PAR. For this coatings project, isocyanates, as found in aliphatic isocyanate polyurethanes, were identified as the target HazMat to be eliminated. Table 1-1 lists the target HazMats, the related process and application, current specifications, and affected programs.

  6. Joint Test Report For Validation of Alternatives to Aliphatic Isocyanate Polyurethanes

    NASA Technical Reports Server (NTRS)

    Lewis, Pattie

    2007-01-01

    National Aeronautics and Space Administration (NASA) and Air Force Space Command (AFSPC) have similar missions and therefore similar facilities and structures in similar environments. The standard practice for protecting metallic substrates in atmospheric environments is the application of an applied coating system. The most common topcoats used in coating systems are polyurethanes that contain isocyanates. Isocyanates are classified as potential human carcinogens and are known to cause cancer in animals. The primary objective of this effort was to demonstrate and validate alternatives to aliphatic isocyanate polyurethanes resulting in one or more isocyanate-free coatings qualified for use at AFSPC and NASA installations participating in this project. This joint Test Report (JTR) documents the results of the laboratory and field testing as well as any test modifications made during the execution of the testing. The technical stakeholders agreed upon test procedure modifications documented in this document. This JTR is made available as a reference for future pollution prevention endeavors by other NASA centers, the Department of Defense and commercial users to minimize duplication of effort. All coating system candidates were tested using approved NASA and AFSPC standard coating systems as experimental controls. This study looked at eight alternative coating systems and two control coating systems and was divided into Phase I Screening Tests, Phase II Tests, and Field Testing. The Phase I Screening Tests were preliminary tests performed on all the selected candidate coating systems. Candidate coating systems that did not meet the acceptance criteria of the screening tests were eliminated from further testing. Phase I Screening Tests included: Ease of Application, Surface Appearance, Dry-To-Touch (Sanding), Accelerated Storage Stability, Pot Life (Viscosity), Cure Time (Solvent Rubs), Cleanability, Knife Test, Tensile (pull-off) Adhesion, and X-Cut Adhesion by Wet

  7. Transferability of aliphatic isocyanates from recently applied paints to the skin of auto body shop workers.

    PubMed

    De Vries, Thomas T; Bello, Dhimiter; Stowe, Meredith H; Harari, Homero; Slade, Martin D; Redlich, Carrie A

    2012-01-01

    Isocyanates, the essential cross-linking chemicals used to make polyurethane, are potent sensitizers and a common cause of occupational asthma. In addition, isocyanate (NCO) skin contact may contribute to the development of isocyanate asthma. Prior work has shown that unbound NCO can persist on recently spray coated auto body parts after appearing dry. The purpose of this study was to assess whether isocyanate skin exposure can result from handling such surfaces. Quantitative surface and skin wipe sampling for total NCO was performed on test panels sprayed with aliphatic isocyanate coatings, and on paired skin samples obtained from participants who had rubbed the recently dried surfaces. Surface and skin samples, obtained from 18 workers in five auto body shops, were prepared following NIOSH method 5525 (modified for skin samples), and isocyanate species derived from hexamethylene diisocyanate and isophorone diisocyanate were analyzed using high-performance liquid chromatography with ultraviolet and fluorescence detectors. Quantifiable unbound NCO species were detected on 84.2% of all sprayed surfaces sampled after initially considered dry. Only 7 out of a total of 104 (6.7%) non-compounded skin samples obtained after contact with the recently dried coatings had detectable quantities of free NCO. The 7 positive samples, all obtained at the initial sampling time (t(0)), had a geometric mean of 0.016 μg NCO cm(-2) (range: 0.002-0.88 μg NCO cm(-2)). Only 1 of 12 (8.3%) of skin samples obtained after compounding contained detectable free NCO. The risk of substantial human isocyanate skin exposure from contact with the dry appearing (yet not fully cured) isocyanate coatings evaluated in this study appears to be low, although other isocyanate coatings and tasks may pose a greater risk of NCO skin exposure.

  8. Exposure to airborne isocyanates and other thermal degradation products at polyurethane-processing workplaces.

    PubMed

    Henriks-Eckerman, Maj-Len; Välimaa, Jarmo; Rosenberg, Christina; Peltonen, Kimmo; Engström, Kerstin

    2002-10-01

    The thermal degradation products of polyurethanes (PURs) and exposure to isocyanates were studied by stationary and personal measurements in five different occupational environments. Isocyanates were collected on glass fibre filters impregnated with 1-(2-methoxyphenyl)piperazine (2MP) and in impingers containing n-dibutylamine (DBA) in toluene. connected to a glass fibre postfilter. The derivatives formed were analysed by liquid chromatography: 2MP derivatives with UV and electrochemical detection and DBA derivatives with mass spectrometric detection. The release of aldehydes and other volatile organic compounds into the air was also studied. In a comparison of the two sampling methods, the 2MP method yielded about 20% lower concentrations for 4,4'-methylenediphenyl diisocyanate (MDI) than did the DBA method. In car repair shops, the median concentration of diisocyanates (given as NCO groups) in the breathing zone was 1.1 microg NCO m(-3) during grinding and 0.3 microg NCO m(-3) during welding, with highest concentrations of 1.7 and 16 pg NCO m(-3), respectively. High concentrations of MDI, up to 25 and 19 microg NCO m(-3), respectively, were also measured in the breathing zone during welding of district heating pipes and turning of a PUR-coated metal cylinder. During installation of PUR-coated floor covering, small amounts of aliphatic diisocyanates were detected in the air. A small-molecular monoisocyanate, methyl isocyanate, and isocyanic acid were detected only during welding and turning operations. The diisocyanate concentrations were in general higher near the emission source than in the workers' breathing zone. A sampling strategy to evaluate the risk of exposure to isocyanates is presented.

  9. Dry sampling of gas-phase isocyanates and isocyanate aerosols from thermal degradation of polyurethane.

    PubMed

    Gylestam, Daniel; Riddar, Jakob B; Karlsson, Daniel; Dahlin, Jakob; Dalene, Marianne; Skarping, Gunnar

    2014-01-01

    The performance of a dry sampler, with an impregnated denuder in series with a glass fibre filter, using di-n-butylamine (DBA) for airborne isocyanates (200ml min(-1)) is investigated and compared with an impinger flask with a glass fibre filter in series (1 l min(-1)). An exposure chamber containing 1,6-hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), and 2,4- and 2,6-toluene diisocyanate (TDI) in the concentration range of 5-205 μg m(-3) [0.7-33 p.p.b.; relative humidity (RH) 50%], generated by gas- and liquid-phase permeation, was used for the investigation. The precision for the dry sampling for five series with eight samplers were in the range of 2.0-6.1% with an average of 3.8%. During 120-min sampling (n = 4), no breakthrough was observed when analysing samplers in series. Sixty-four exposed samplers were analysed after storage for 0, 7, 14, and 21 days. No breakdown of isocyanate derivatives was observed. Twenty-eight samplers in groups of eight were collecting isocyanates during 0.5-32h. Virtually linear relationships were obtained with regard to sampling time and collected isocyanates with correlation coefficients in the range of 0.998-0.999 with the intercept close to the origin. Pre- or post-exposure to ambient air did not affect the result. Dry sampling (n = 48) with impinger-filter sampling (n = 48) of thermal decomposition product of polyurethane polymers, at RH 20, 40, 60, and 90%, was compared for 11 isocyanate compounds. The ratio between the different isocyanates collected with dry samplers and impinger-filter samplers was in the range of 0.80-1.14 for RH = 20%, 0.8-1.25 for RH = 40%, 0.76-1.4 for RH = 60%, and 0.72-3.7 for RH = 90%. Taking into account experimental errors, it seems clear that isocyanic acid DBA derivatives are found at higher levels in the dry samples compared with impinger-filter samplers at elevated humidity. The dry sampling using DBA as the reagent enables easy and robust sampling without the need of field

  10. Isocyanates.

    PubMed

    Wenk, Kurt S; Ehrlich, Alison

    2012-01-01

    Owing to the widespread use of isocyanate-derived products across multiple industries, it is important for physicians to be aware of their sensitizing potential. We first provide a general overview of isocyanates and the industries that may be associated with exposure to these compounds. This is followed by a description of the most commonly used isocyanate products in commercial patch test preparations. Finally, we discuss appropriate isocyanate patch testing methodology and optimal isocyanate patch test concentrations.

  11. Determination of isocyanates, aminoisocyanates and amines in air formed during the thermal degradation of polyurethane.

    PubMed

    Karlsson, Daniel; Dahlin, Jakob; Skarping, Gunnar; Dalene, Marianne

    2002-04-01

    An air sampling method for the determination of isocyanates, aminoisocyanates and amines formed during the thermal degradation of polyurethane (PUR) is presented. The method is based on the collection of air samples using impinger flasks containing di-n-butylamine (DBA) in toluene with a glass fibre filter in series. Isocyanates are derivatized with DBA to urea derivatives, and amines are derivatized in a subsequent work-up procedure with ethyl chloroformate (ET) to carbamate esters. Amine, aminoisocyanate and isocyanate derivatives were characterized using liquid chromatography-time of flight mass spectrometry (LC-TOFMS) and liquid chromatography-chemiluminescent nitrogen detection (LC-CLND). Quantification was performed by LC-MS, monitoring molecular ions [MH]+ in the electrospray mode. The instrumental detection limits for amines, aminoisocyanates and isocyanates were in the ranges 30-40, 2-3 and 3-70 fmol, respectively. Thermal degradation products of PUR were observed in high concentrations during welding in district heating pipes and PUR-coated metal sheets. Eleven isocyanates, three amines and five aminoisocyanates were identified. The concentrations of isocyanates, aminoisocyanates and amines in samples collected in the smoke close to the welding spot were in the ranges 150-650, 4-290 and 1-70 ppb, respectively. In samples collected in the breathing zone, isocyanates and aminoisocyanates were observed in the ranges 9-120 and 4-19 ppb, respectively. The compounds were present in both gas and particle phases. Volatile compounds dominated in the gas phase, whereas less volatile compounds dominated in the particle phase. The method presented makes it possible to sample and determine amines and aminoisocyanates, in addition to isocyanates. The need to monitor these compounds is clearly illustrated by the high concentrations found during the thermal degradation of PUR.

  12. Renewable non-isocyanate based thermoplastic polyurethanes via polycondensation of dimethyl carbamate monomers with diols.

    PubMed

    Unverferth, Maike; Kreye, Oliver; Prohammer, Alexander; Meier, Michael A R

    2013-10-01

    1,5,7-Triazabicyclo[4.4.0]dec-5-ene (TBD)-catalyzed polycondensation reactions of fatty acid derived dimethyl dicarbamates and diols are introduced as a versatile, non-isocyanate route to renewable polyurethanes. The key step for the synthesis of dimethyl carbamate monomers from plant-oil-derived dicarboxylic acids is based on a sustainable base-catalyzed Lossen rearrangement. The formed polyurethanes with molecular weights up to 25 kDa are characterized by SEC, DSC, and NMR analysis.

  13. Assessing isocyanate exposures in polyurethane industry sectors using biological and air monitoring methods.

    PubMed

    Creely, K S; Hughson, G W; Cocker, J; Jones, K

    2006-08-01

    Isocyanates, as a chemical group, are considered to be the biggest cause of occupational asthma in the UK. Monitoring of airborne exposures to total isocyanate is costly, requiring considerable expertise, both in terms of sample collection and chemical analysis and cannot be used to assess the effectiveness of protection from wearing respiratory protective equipment (RPE). Biological monitoring by analysis of metabolites in urine can be a relatively simple and inexpensive way to assess exposure to isocyanates. It may also be a useful way to evaluate the effectiveness of control measures in place. In this study biological and inhalation monitoring were undertaken to assess exposure in a variety of workplaces in the non-motor vehicle repair sector. Companies selected to participate in the survey included only those judged to be using good working practices when using isocyanate formulations. This included companies that used isocyanates to produce moulded polyurethane products, insulation material and those involved in industrial painting. Air samples were collected by personal monitoring and were analysed for total isocyanate content. Urine samples were collected soon after exposure and analysed for the metabolites of different isocyanate species, allowing calculation of the total metabolite concentration. Details of the control measures used and observed contamination of exposed skin were also recorded. A total of 21 companies agreed to participate in the study, with exposure measurements being collected from 22 sites. The airborne isocyanate concentrations were generally very low (range 0.0005-0.066 mg m(-3)). A total of 50 of the 70 samples were <0.001 mg m(-3), the limit of quantification (LOQ), therefore samples below the LOQ were assigned a value of 1/2 LOQ (0.0005 mg m(-3)). Of the 70 samples, 67 were below the current workplace exposure limit of 0.02 mg m(-3). The highest inhalation exposures occurred during spray painting activities in a truck manufacturing

  14. Validation of a solvent-free sampler for the determination of low molecular weight aliphatic isocyanates under thermal degradation conditions.

    PubMed

    Boutin, M; Lesage, J; Ostiguy, C; Pauluhn, J

    2005-09-01

    During the thermal degradation of 1,6-hexamethylenediiso- cyanate-based (HDI) car paint, the eight most abundant isocyanates generated are isocyanic acid, methyl isocyanate, ethyl isocyanate, propyl isocyanate, butyl isocyanate, pentyl isocyanate, hexyl isocyanate, and 1,6-hexamethylenediisocyanate. For the first time, a method using solvent-free samplers is proposed and validated for the simultaneous sampling of all these isocyanates. The sampling efficiency during thermal degradation of car paint can be affected by the formation of dust and aerosols and by the emission of many chemicals, such as isocyanic acid, anhydrides, amines, and alcohols that consume the reagent or interfere in the derivatization procedure. Sampling was performed using cassettes containing two 1-(2-methoxyphenyl)piperazine (MOPIP)-coated glass fiber filters (MFs) (approximately 4.9 mg per filter) and compared with bubblers containing 15 mL of MOPIP solution in toluene (1.0 mg/mL(-1)) and with bubblers backed with MFs. A DIN 53436 laboratory scale furnace was used to generate the isocyanates under thermal degradation conditions. For an aliphatic isocyanate concentration of approximately 42 microg(NCO) m(-3), no significant difference in sampling efficiency was observed between the three techniques studied, thus confirming the sampling efficiency of the MFs. The samples were analyzed using high-performance liquid chromatography coupled with electrospray/tandem mass spectrometry. Quantification was performed in daughter mode monitoring (MOPIP+H)(+) fragments. For concentrations between 0.013 microg(NCO) mL(-1) and 0.52 microg(NCO) mL(-1) for the monoisocyanates, and between 0.026 microg(NCO) mL(-1) and 1.04 microg(NCO) mL(-1) for the HDI, the correlation coefficients were in the 0.9974-0.9996 range (n = 18). Analytical reproducibility and precision were better than 95.4% and 94.9%, respectively, for all the isocyanates. The instrumental detection limits, defined as three times the standard

  15. Validation of a solvent-free sampler for the determination of low molecular weight aliphatic isocyanates under thermal degradation conditions.

    PubMed

    Boutin, M; Lesage, J; Ostiguy, C; Pauluhn, J

    2005-09-01

    During the thermal degradation of 1,6-hexamethylenediiso- cyanate-based (HDI) car paint, the eight most abundant isocyanates generated are isocyanic acid, methyl isocyanate, ethyl isocyanate, propyl isocyanate, butyl isocyanate, pentyl isocyanate, hexyl isocyanate, and 1,6-hexamethylenediisocyanate. For the first time, a method using solvent-free samplers is proposed and validated for the simultaneous sampling of all these isocyanates. The sampling efficiency during thermal degradation of car paint can be affected by the formation of dust and aerosols and by the emission of many chemicals, such as isocyanic acid, anhydrides, amines, and alcohols that consume the reagent or interfere in the derivatization procedure. Sampling was performed using cassettes containing two 1-(2-methoxyphenyl)piperazine (MOPIP)-coated glass fiber filters (MFs) (approximately 4.9 mg per filter) and compared with bubblers containing 15 mL of MOPIP solution in toluene (1.0 mg/mL(-1)) and with bubblers backed with MFs. A DIN 53436 laboratory scale furnace was used to generate the isocyanates under thermal degradation conditions. For an aliphatic isocyanate concentration of approximately 42 microg(NCO) m(-3), no significant difference in sampling efficiency was observed between the three techniques studied, thus confirming the sampling efficiency of the MFs. The samples were analyzed using high-performance liquid chromatography coupled with electrospray/tandem mass spectrometry. Quantification was performed in daughter mode monitoring (MOPIP+H)(+) fragments. For concentrations between 0.013 microg(NCO) mL(-1) and 0.52 microg(NCO) mL(-1) for the monoisocyanates, and between 0.026 microg(NCO) mL(-1) and 1.04 microg(NCO) mL(-1) for the HDI, the correlation coefficients were in the 0.9974-0.9996 range (n = 18). Analytical reproducibility and precision were better than 95.4% and 94.9%, respectively, for all the isocyanates. The instrumental detection limits, defined as three times the standard

  16. Synthesis and characterization of free-isocyanate polyurethane as renewable coating materials

    NASA Astrophysics Data System (ADS)

    Saputra, O. A.; Apriany, K.; Putri, F. R.; Firdaus, M.

    2016-02-01

    Green synthesis of diethyl ethane-1,2-diyldicarbamate (M1) as starting dimer of free-isocyanate polyurethane from an excess of diethyl carbonate and ethylene diamine catalyzed by TBD (1,5,7-triazabicyclo-[4,4,0]dec-5-ene) at 80 °C for 4 hours has been carried out. The product has high yield and purity up to 92% and 99,18%, respectively. The product was obtained in the form of rod-shaped white crystals and characterized with 1H-NMR, 13C-NMR and FTIR spectroscopy. Polyurethane (P1) has successfully synthesized via polycondensation methods by reacting of M1 with cis-2-butene-1,4-diol. This reaction also catalyzed by TBD organo catalyst. P1 chemical structure has been confirmed using 1H-NMR and FTIR techniques.

  17. Structure-property-glass transition relationships in non-isocyanate polyurethanes investigated by dynamic nanoindentation

    NASA Astrophysics Data System (ADS)

    Weyand, Stephan; Blattmann, Hannes; Schimpf, Vitalij; Mülhaupt, Rolf; Schwaiger, Ruth

    2016-07-01

    Newly developed green-chemistry approaches towards the synthesis of non-isocyanate polyurethane (NIPU) systems represent a promising alternative to polyurethanes (PU) eliminating the need for harmful ingredients. A series of NIPU systems were studied using different nanoindentation techniques in order to understand the influence of molecular parameters on the mechanical behavior. Nanoindentation revealed a unique characteristic feature of those materials, i.e. stiffening with increasing deformation. It is argued that the origin of this observed stiffening is a consequence of the thermodynamic state of the polymer network, the molecular characteristics of the chemical building blocks and resulting anisotropic elastic response of the network structure. Flat-punch nanoindentation was applied in order to characterize the constitutive viscoelastic nature of the materials. The complex modulus shows distinct changes as a function of the NIPU network topology illustrating the influence of the chemical building blocks. The reproducibility of the data indicates that the materials are homogeneous over the volumes sampled by nanoindentation. Our study demonstrates that nanoindentation is very well-suited to investigate the molecular characteristics of NIPU materials that cannot be quantified in conventional experiments. Moreover, the technique provides insight into the functional significance of complex molecular architectures thereby supporting the development of NIPU materials with tailored properties.

  18. Isocyanate Exposure Below Analytical Detection When a Paint Brush and Roller Are Used to Apply Moisture-Cure Polyurethane Paint.

    PubMed

    Reeb-Whitaker, Carolyn K; Schoonover, Todd M

    2016-05-01

    Isocyanate exposure is known to be hazardous when polyurethane paints are applied with a spray gun, but less is known of exposure when paint is applied with a paint brush and roller. Concentrations of 1,6-hexamethylene diisocyanate (HDI) monomer and three HDI polymers were assessed when two moisture-cure polyurethane paints containing 31-35% isocyanates were applied with a paint roller and brush. Short-term 15-min samples were taken during paint application in an indoor test environment with no ventilation (n= 12); in an outdoor test environment (n= 11); and in an outdoor in-situ assessment (n= 22). The outdoor in-situ assessment involved the painting of a bus shelter and light poles at a public transit station over two night shifts. All isocyanate samples were below analytical detection. The analytical limits of detection for HDI monomer, HDI biuret, HDI isocyanurate, and HDI uretdione were 0.005, 0.84, 0.87, and 0.88 µg, respectively. The finding that isocyanate concentrations were below detection is attributed to the use of paint roller and brush which minimize paint aerosolization and the paint formulation itself which contained <1% of volatile HDI monomer.

  19. Isocyanate Exposure Below Analytical Detection When a Paint Brush and Roller Are Used to Apply Moisture-Cure Polyurethane Paint.

    PubMed

    Reeb-Whitaker, Carolyn K; Schoonover, Todd M

    2016-05-01

    Isocyanate exposure is known to be hazardous when polyurethane paints are applied with a spray gun, but less is known of exposure when paint is applied with a paint brush and roller. Concentrations of 1,6-hexamethylene diisocyanate (HDI) monomer and three HDI polymers were assessed when two moisture-cure polyurethane paints containing 31-35% isocyanates were applied with a paint roller and brush. Short-term 15-min samples were taken during paint application in an indoor test environment with no ventilation (n= 12); in an outdoor test environment (n= 11); and in an outdoor in-situ assessment (n= 22). The outdoor in-situ assessment involved the painting of a bus shelter and light poles at a public transit station over two night shifts. All isocyanate samples were below analytical detection. The analytical limits of detection for HDI monomer, HDI biuret, HDI isocyanurate, and HDI uretdione were 0.005, 0.84, 0.87, and 0.88 µg, respectively. The finding that isocyanate concentrations were below detection is attributed to the use of paint roller and brush which minimize paint aerosolization and the paint formulation itself which contained <1% of volatile HDI monomer. PMID:26833099

  20. Studies on the effect of virtual crosslinking on the hydrolytic stability of novel aliphatic polyurethane ureas for blood contact applications.

    PubMed

    Thomas, V; Jayabalan, M

    2001-07-01

    The effect of virtual crosslinking on the hydrolytic stability of completely aliphatic novel poly(urethane ureas), HFL9-PU1 (hard-segment content 57.5%) and HFL13-PU2 (hard-segment content 67.9%) based on 4,4'-methylene bis(cyclohexyl isocyanate) (H(12)MDI)-hydroxy-terminated polybutadiene-1,6-hexamethylene diamine, was studied. Fourier transform infrared-attenuated total reflectance and wide-angle X-ray diffraction studies revealed hydrogen-bonding interaction and microphase separation and formation of crystallites by short- and long-range ordering in hard-segment domains. Three-dimensional networks from hydrogen bonding in the present polymers lead to virtually crosslinking and insolubility. These polymers were noncytotoxic to L929 fibroblast cells. The hemolytic potential is below the accepted limit. The studies on in vitro biostability in Ringer's solution, phosphate buffered saline, and papain enzyme revealed no weight loss. The infrared spectral studies revealed changes in the surface, especially on HFL9-PU1 aged in Ringer's solution and phosphate buffered saline, and no changes when aged in papain. The marginal changes noticed in tensile properties were attributed to the changes in degree of hydrogen bonding and associated rearrangement of molecular structure in the bulk. The results revealed that the lesser the crosslinking in virgin polymer, the higher the crosslinking in aged polymer and vice versa. Increased crosslinking during aging provided increased tensile properties in the aged polymer over the virgin polymer and vice versa. For comparison, an aliphatic polyetherurethane urea (HFL16-PU3) was also synthesized using poly(oxy tetra methylene glycol) in addition to the above reactants. Though both HFL9-PU1 and HFL16-PU3 contained the same hard-segment content, the aged sample of the latter showed decreased tensile properties with increased crosslinking during aging in contrast to the former. This was attributed to less microphase separation in the

  1. Nanostructure to microstructure self-assembly of aliphatic polyurethanes: the effect on mechanical properties.

    PubMed

    Mishra, Abhinay; Aswal, Vinod K; Maiti, Pralay

    2010-04-29

    We report the step by step self-assembly from nanostructure to microstructure (bottom-up approach through X-ray diffraction (1.6 nm), small angle neutron scattering (SANS) (11.6 nm), atomic force microscopy (70 nm smaller crystallite from enlarged image and 450 nm greater crystallites), and polarizing optical microscope (2 microm)) of aliphatic polyurethanes (PU) in contrast to aromatic polyurethanes depending on hard segment content (HSC). Polyurethanes of 10 to 80% HSC have been synthesized by using appropriate amount of polyol and chain extender. The effect of self-assembled patterns on mechanical properties both in solid and liquid state has been established exhibiting structure-property relationship of supramolecular polyurethanes. The crystallinity enhances but the degradation temperature decreases with increasing HSC. The characteristic length (measure of gap between lamellar crystallites), as revealed from SANS, gradually decreases with increasing HSC suggesting compactness of the crystallites through extensive hydrogen bonding. The Young's modulus increases with increasing HSC with a percolation threshold of hard segment (50%) while the toughness improves up to 30% HSC followed by gradual decrease in presence of bigger crystallites which promote brittle fracture. The origin of self-assembly in aliphatic PUs has been demonstrated through electronic structure calculations to form a loop structure with minimum intermolecular distance (2.2 A) while that distance is quite large in aromatic polyurethanes (4.6 A) that cannot form hydrogen bonds. The unique splintering of domain structure and its subsequent reformation under dynamic shear experiment has been established. PMID:20361786

  2. Synthesis and characterization of an isocyanate functionalized polyhedral oligosilsesquioxane and the subsequent formation of an organic-inorganic hybrid polyurethane.

    PubMed

    Neumann, Daniel; Fisher, Mark; Tran, Linh; Matisons, Janis G

    2002-11-27

    Organic-inorganic hybrids are an important class of new materials that offer improved thermal and mechanical properties over normal polymers. They may be produced by either the sol-gel route or through the use of inorganic compounds possessing reactive functional groups. Polyhedral oligosilsesquioxanes (POSS) are completely defined molecules of nanoscale dimensions that may be functionalized with reactive groups suitable for the synthesis of new organic-inorganic hybrids. Here we report the synthesis and characterization of a novel POSS possessing eight isocyanate groups via the hydrosilylation of octakis(hydridodimethylsiloxy)octasilsesquioxane (Q8M8H) and m-isopropenyl-alpha,alpha'-dimethylbenzyl isocyanate (m-TMI). The suitability of this new macromer to the synthesis of a organic-hybrids has been explored by forming a new type of highly cross-linked polyurethane elastomer via reaction of the macromer with poly(ethylene glycol) using dibutyltin dilaurate catalyst. PMID:12440890

  3. Isocyanate- and phosgene-free routes to polyfunctional cyclic carbonates and green polyurethanes by fixation of carbon dioxide.

    PubMed

    Blattmann, Hannes; Fleischer, Maria; Bähr, Moritz; Mülhaupt, Rolf

    2014-07-01

    The catalytic chemical fixation of carbon dioxide by carbonation of oxiranes, oxetanes, and polyols represents a very versatile green chemistry route to environmentally benign di- and polyfunctional cyclic carbonates as intermediates for the formation of non-isocyanate poly-urethane (NIPU). Two synthetic pathways lead to NIPU thermoplastics and thermosets: i) polycondensation of diacarbamates or acyclic dicarbonates with diols or diamines, respectively, and ii) polyaddition by ring-opening polymerization of di- and polyfunctional cyclic carbonates with di- and polyamines. The absence of hazardous and highly moisture-sensitive isocyanates as intermediates eliminates the need for special safety precautions, drying and handling procedures. Incorporated into polymer backbones and side chains, carbonate groups enable facile tailoring of a great variety of urethane-functional polymers. As compared with conventional polyurethanes, ring-opening polymerization of polyfunctional cyclic carbonates affords polyhydroxyurethanes with unconventional architectures including NIPUs containing carbohydrate segments. NIPU/epoxy hybrid coatings can be applied on wet surfaces and exhibit improved adhesion, thermal stability and wear resistance. Combining chemical with biological carbon dioxide fixation affords 100% bio-based NIPUs derived from plant oils, terpenes, carbohydrates, and bio polyols. Biocompatible and biodegradable NIPU as well as NIPU biocomposites hold great promise for biomedical applications.

  4. New aliphatic glycerophosphoryl-containing polyurethanes: synthesis, platelet adhesion and elution cytotoxicity studies.

    PubMed

    Acetti, Daniela; D'Arrigo, Paola; Giordano, Carmen; Macchi, Piero; Servi, Stefano; Tessaro, Davide

    2009-04-01

    in this study new poly(ether)urethanes (PeUs) based on aliphatic diisocyanates were synthesized with phospholipid-like residues as chain extenders. The primary objective was to prepare new polyurethanes from diisocyanates that are less toxic than the aromatic ones widely used in medical-grade polyurethanes, in order to investigate the effect of the different aromatic or aliphatic hard segment content on the final properties of the materials. Some glycerophospho residues were simultaneously introduced to enhance the hemocompatibility of these materials. Polymers were prepared by a conventional two-step solution polymerization procedure using hexamethylene diisocyanate (HDi) and dodecametilendiisocyanate (DDi) and poly(1,4-butanediol) with molecular weight 1000 to form prepolymers, which were subsequently polymerized with 1-glycerophosphorylcholine (1-GPC) or glycerophosphorylserine (GPS) to act as chain extenders. The reference polymers bearing 1,4-butandiol (BD) were also synthesized. The polymers obtained were characterized by fourier transform infrared spectroscopy (fT-iR), nuclear magnetic resonance (1H nmR), and differential scanning calorimetry (DSC). The hemocompatibility of synthesized segmented polyurethanes was preliminarily investigated by platelet-rich plasma contact studies and related scanning electron microscopy (Sem) photographs as well as by cell viability assay after cell exposure to material elutions to assess the effect of any toxic leachables coming out from the samples. Two of the polymers gave interesting results, suggesting the desirability of further investigation into their possible use in biomedical devices. PMID:19569028

  5. Self-assembled aliphatic chain extended polyurethane nanobiohybrids: emerging hemocompatible biomaterials for sustained drug delivery.

    PubMed

    Mishra, Abhinay; Singh, Sunil K; Dash, Debabrata; Aswal, Vinod K; Maiti, Biswajit; Misra, Manjusri; Maiti, Pralay

    2014-05-01

    Novel polyurethanes (PUs) have been synthesized using an aliphatic diisocyanate and aliphatic chain extenders with varying chain length. Nanocomposites of PUs have been prepared by dispersing 2-D nanoclay in poly-ol followed by prepolymerization and subsequent chain extension using various chain extenders. Systematic improvement in toughness and adequate enhancement in stiffness in the presence of nanoclay has been observed for PUs with longer chain extenders, and these new classes of nanocomposites exhibit no toughness-stiffness trade-off. Bottom-up self-assembly starting from the molecular level to micron-scale crystallite has been revealed through electronic structure calculation, X-ray diffraction, small-angle neutron scattering, atomic force microscopy and optical images. The role of hydrogen bonding has been revealed for this type of supramolecular assembly, and in the presence of organically modified nanoclay hydrogen bonding contributes to the formation of bigger clusters of nanocomposites. Controlled biodegradation of PU and its nanocomposites has been investigated in enzymatic media. Biocompatibility of these novel nanocomposites has been extensively verified through platelet adhesion, aggregation and hemolysis assay. Sustained drug delivery by biocompatible pristine PU and its nanocomposites has been demonstrated either by controlling the crystallite size of the polyurethane through alteration of the aliphatic chain length of the extender or by incorporating disc-like nanoclay, creating a tortuous path that results in delayed diffusion. Hence, the developed nanohybrids are potential biomaterials for tissue engineering and drug delivery. PMID:24374322

  6. Clinical biodurability of aliphatic polyether based polyurethanes as peritoneal dialysis catheters.

    PubMed

    Crabtree, John H

    2003-01-01

    Thermoplastic polyurethane elastomers are the most important implantable grade polyurethanes in medical applications. An aliphatic polyether based polyurethane, Tecoflex (TF; Thermedics, Inc., Woburn, MA), is used in the construction of a proprietary peritoneal dialysis (PD) catheter. Information is limited regarding the biostability of the TF polymer in the clinical environment as a PD catheter. This report presents the clinical experience regarding the biodurability of 104 catheter implants. The extracorporeal tubing segments of all TF catheters eventually developed aesthetically offensive discoloration, opaqueness, and surface tackiness. Catheter breaks in the external segment occurred in 27% of devices that survived longer than 28 months. Mupirocin ointment at the catheter skin exit site caused swelling and deformity of the TF in one case. Three catheters extruded as a result of Dacron cuffs separating from the tubing wall. Catheters removed for other reasons were frequently found to have loose cuffs, especially if the devices were implanted for several years. Causes and possible mechanisms for observed failures are discussed. The durability of biomaterials used in construction of PD catheters is of vital importance for successful long-term functioning. The TF polymer embodied as a PD catheter represents a mismatch of the material and its mission. Fabrication of PD catheters from higher grade polyurethanes possessing greater biostability should be explored. Silicone rubber appears to remain the most durable material to date for PD catheter construction. PMID:12790378

  7. Clinical biodurability of aliphatic polyether based polyurethanes as peritoneal dialysis catheters.

    PubMed

    Crabtree, John H

    2003-01-01

    Thermoplastic polyurethane elastomers are the most important implantable grade polyurethanes in medical applications. An aliphatic polyether based polyurethane, Tecoflex (TF; Thermedics, Inc., Woburn, MA), is used in the construction of a proprietary peritoneal dialysis (PD) catheter. Information is limited regarding the biostability of the TF polymer in the clinical environment as a PD catheter. This report presents the clinical experience regarding the biodurability of 104 catheter implants. The extracorporeal tubing segments of all TF catheters eventually developed aesthetically offensive discoloration, opaqueness, and surface tackiness. Catheter breaks in the external segment occurred in 27% of devices that survived longer than 28 months. Mupirocin ointment at the catheter skin exit site caused swelling and deformity of the TF in one case. Three catheters extruded as a result of Dacron cuffs separating from the tubing wall. Catheters removed for other reasons were frequently found to have loose cuffs, especially if the devices were implanted for several years. Causes and possible mechanisms for observed failures are discussed. The durability of biomaterials used in construction of PD catheters is of vital importance for successful long-term functioning. The TF polymer embodied as a PD catheter represents a mismatch of the material and its mission. Fabrication of PD catheters from higher grade polyurethanes possessing greater biostability should be explored. Silicone rubber appears to remain the most durable material to date for PD catheter construction.

  8. Biomechanical studies on aliphatic physically crosslinked poly(urethane urea) for blood contact applications.

    PubMed

    Thomas, Vinoy; Muthu, Jayabalan

    2008-07-01

    Hydrophobic and physically crosslinked (virtually crosslinked through hydrogen bonding) aliphatic poly(urethane urea)s were developed and characterized for its biomechanical properties. The aging under induced-stress (bend samples) condition reveals resistance of poly(urethane urea) to environmental stress corrosion cracking (ESC) in hydrolytic media, Ringer's solution and phosphate buffered saline at 50 degrees C. The strain-induced (20% tensile strain) and aged polymer in hydrolytic enzyme medium, papain and in buffer reveals increase of elastic modulus in papain enzyme and papain buffer. The increase of elastic modulus is attributed to unidirectional reorganisation of chains under continually strained conditions. The polymer exposed in boiling alcoholic potassium hydroxide solution (accelerated hydrolytic chemical degradation) reveals no degradation. A comparative evaluation of poly(ether urethane urea)s reveals inferior properties. Poly(ether urethane urea)s polymer undergo hydrolytic degradation in boiling alcoholic potassium hydroxide solution. The candidate poly(urethane urea) HFL 18-PUU is more promising elastomer for long-term biomechanically sensitive blood contact applications such as heart valve and blood pump diaphragm of left ventricular assist device.

  9. Biomechanical studies on aliphatic physically crosslinked poly(urethane urea) for blood contact applications.

    PubMed

    Thomas, Vinoy; Muthu, Jayabalan

    2008-07-01

    Hydrophobic and physically crosslinked (virtually crosslinked through hydrogen bonding) aliphatic poly(urethane urea)s were developed and characterized for its biomechanical properties. The aging under induced-stress (bend samples) condition reveals resistance of poly(urethane urea) to environmental stress corrosion cracking (ESC) in hydrolytic media, Ringer's solution and phosphate buffered saline at 50 degrees C. The strain-induced (20% tensile strain) and aged polymer in hydrolytic enzyme medium, papain and in buffer reveals increase of elastic modulus in papain enzyme and papain buffer. The increase of elastic modulus is attributed to unidirectional reorganisation of chains under continually strained conditions. The polymer exposed in boiling alcoholic potassium hydroxide solution (accelerated hydrolytic chemical degradation) reveals no degradation. A comparative evaluation of poly(ether urethane urea)s reveals inferior properties. Poly(ether urethane urea)s polymer undergo hydrolytic degradation in boiling alcoholic potassium hydroxide solution. The candidate poly(urethane urea) HFL 18-PUU is more promising elastomer for long-term biomechanically sensitive blood contact applications such as heart valve and blood pump diaphragm of left ventricular assist device. PMID:18305906

  10. Porous bioactive scaffold of aliphatic polyurethane and hydroxyapatite for tissue regeneration.

    PubMed

    Wang, Li; Li, Yubao; Zuo, Yi; Zhang, Li; Zou, Qin; Cheng, Lin; Jiang, Hong

    2009-04-01

    In this study, a new hydroxyapatite (HA)/polyurethane (PU) composite porous scaffold was developed by in situ polymerization. Aliphatic isophorone diisocyanate as a nontoxic and safe agent was adopted to produce the rigid segment in polyurethane polymerization. Hydroxyapatite powder was compounded in a PU polymer matrix during the polymeric process. The macrostructure and morphology as well as mechanical strength of the scaffolds were characterized by FTIR, XRD, DSC and SEM. The results show that the isophorone diisocyanate can react mildly with hydroxyl (-OH) groups of castor oil and a mild foaming action caused by the release of CO2 gas occurred simultaneously in the reactive process, thus producing a uniform porous structure of HA/PU scaffold. The HA/PU composite scaffold with a high HA content of about 60 wt% has a porosity of more than 78% and a pore size from 100 microm to 800 microm. The HA/PU scaffold exhibited good cytocompatibility estimated by co-culturing the scaffold with MG63 cells through MTT test. The porous composite scaffold has good homogenization and a perfect three-dimensional structure for cell migration and bone tissue ingrowth, and should have good prospects for bone tissue regeneration. PMID:19208942

  11. Immunological evaluation of four arc welders exposed to fumes from ignited polyurethane (isocyanate) foam: antibodies and immune profiles

    SciTech Connect

    Broughton, A.; Thrasher, J.D.; Gard, Z.

    1988-01-01

    Four arc welders having a flu-like illness with multiple health complaints following an exposure to high concentrations of isocyanate fumes from ignited polyurethane foam underwent immunological tests as follows: ELISA antibody assays, activated lymphocyte profiles, and lymphocyte blastogenesis. ELISA procedures revealed the presence of antibodies to hexamethylene diisocyanate (HDI) and formaldehyde (F) conjugated to human serum albumin (HDI-SA and F-SA). The results from the activated lymphocyte profiles showed deviations from the norm as follows: three welders had elevated helper/suppressor (H/S) ratios; all four had elevated percentages of Tal positive cells; two had decreases in B cells; and one had low total white cell and lymphocyte counts. In contrast, the percentage and absolute numbers of ILS receptor cells were normal in the four subjects. T cell blastogenesis to PHA, Con A and PWM resulted in the following: T-cells from one subject responded normally; in another, a high response (212% of controls) to PHA occurred with normal mitogenesis to Con A and PWM. In the remaining two welders, the T cells responded abnormally low (50 to 75% of controls) to the three mitogens. In conclusion, the existence of IgG antibodies to HDI-SA and F-SA, the altered activated immune profiles, the elevated Tal cells, and the abnormal blastogenesis are interpreted as being linked with the episode of HDI and F exposure and the subsequent flu-like illness of the four welders.

  12. Residual Isocyanates in Medical Devices and Products: A Qualitative and Quantitative Assessment

    PubMed Central

    Franklin, Gillian; Harari, Homero; Ahsan, Samavi; Bello, Dhimiter; Sterling, David A.; Nedrelow, Jonathan; Raynaud, Scott; Biswas, Swati; Liu, Youcheng

    2016-01-01

    We conducted a pilot qualitative and quantitative assessment of residual isocyanates and their potential initial exposures in neonates, as little is known about their contact effect. After a neonatal intensive care unit (NICU) stockroom inventory, polyurethane (PU) and PU foam (PUF) devices and products were qualitatively evaluated for residual isocyanates using Surface SWYPE™. Those containing isocyanates were quantitatively tested for methylene diphenyl diisocyanate (MDI) species, using UPLC-UV-MS/MS method. Ten of 37 products and devices tested, indicated both free and bound residual surface isocyanates; PU/PUF pieces contained aromatic isocyanates; one product contained aliphatic isocyanates. Overall, quantified mean MDI concentrations were low (4,4′-MDI = 0.52 to 140.1 pg/mg) and (2,4′-MDI = 0.01 to 4.48 pg/mg). The 4,4′-MDI species had the highest measured concentration (280 pg/mg). Commonly used medical devices/products contain low, but measurable concentrations of residual isocyanates. Quantifying other isocyanate species and neonatal skin exposure to isocyanates from these devices and products requires further investigation. PMID:27773989

  13. Physicochemical and biological properties of nano-hydroxyapatite-reinforced aliphatic polyurethanes membranes.

    PubMed

    Liu, Haohuai; Zhang, Li; Li, Jidong; Zou, Qin; Zuo, Yi; Tian, Weidong; Li, Yubao

    2010-01-01

    Polymer nano-composite membranes, based on aliphatic biodegradable polyurethane (PU) elastomers and nano-hydroxyapatite (n-HA), were prepared by solvent casting and freeze-drying. The PU matrix was synthesized from 4,4'-dicyclohexylmethane diisocyanate (H(12) MDI), poly(ethylene glycol) (PEG), castor oil (CO) and 1,4-butandiol (BDO). The n-HA/PU membranes were characterized by SEM, XRD, IR, TG, mechanical test and in vitro biocompatibility. The results revealed that incorporation of 30 wt% n-HA into the PU matrix increased the tensile strength nearly by 186% and the elongation-at-break by 107% compared to pure PU. The addition of n-HA had the slight positive effect on the thermal stability of PU. Cell culture and MTT assays showed that the incorporation of n-HA into the PU matrix provided a favourable environment for initial cell adhesion, maintained cell viability and cell proliferation. These results suggested that the n-HA/PU composite membrane might be a prospective biodegradable guided bone regeneration (GBR) membrane for future applications. PMID:20537245

  14. Biological evaluation of porous aliphatic polyurethane/hydroxyapatite composite scaffolds for bone tissue engineering.

    PubMed

    Yang, Wanxun; Both, Sanne K; Zuo, Yi; Birgani, Zeinab Tahmasebi; Habibovic, Pamela; Li, Yubao; Jansen, John A; Yang, Fang

    2015-07-01

    Biomaterial scaffolds meant to function as supporting structures to osteogenic cells play a pivotal role in bone tissue engineering. Recently, we synthesized an aliphatic polyurethane (PU) scaffold via a foaming method using non-toxic components. Through this procedure a uniform interconnected porous structure was created. Furthermore, hydroxyapatite (HA) particles were introduced into this process to increase the bioactivity of the PU matrix. To evaluate the biological performances of these PU-based scaffolds, their influence on in vitro cellular behavior and in vivo bone forming capacity of the engineered cell-scaffold constructs was investigated in this study. A simulated body fluid test demonstrated that the incorporation of 40 wt % HA particles significantly promoted the biomineralization ability of the PU scaffolds. Enhanced in vitro proliferation and osteogenic differentiation of the seeded mesenchymal stem cells were also observed on the PU/HA composite. Next, the cell-scaffold constructs were implanted subcutaneously in a nude mice model. After 8 weeks, a considerable amount of vascularized bone tissue with initial marrow stroma development was generated in both PU and PU/HA40 scaffold. In conclusion, the PU/HA composite is a potential scaffold for bone regeneration applications.

  15. Platelet adhesion and human umbilical vein endothelial cell cytocompatibility of biodegradable segmented polyurethanes prepared with 4,4'-methylene bis(cyclohexyl isocyanate), poly(caprolactone) diol and butanediol or dithioerythritol as chain extenders.

    PubMed

    Chan-Chan, L H; Vargas-Coronado, R F; Cervantes-Uc, J M; Cauich-Rodríguez, J V; Rath, R; Phelps, E A; García, A J; San Román Del Barrio, J; Parra, J; Merhi, Y; Tabrizian, M

    2013-08-01

    Biodegradable segmented polyurethanes were prepared with poly(caprolactone) diol as a soft segment, 4,4'-methylene bis(cyclohexyl isocyanate) (HMDI) and either butanediol or dithioerythritol as chain extenders. Platelet adhesion was similar in all segmented polyurethanes studied and not different from Tecoflex® although an early stage of activation was observed on biodegradable segmented polyurethane prepared with dithioerythritol. Relative viability was higher than 80% on human umbilical vein endothelial cells in contact with biodegradable segmented polyurethane extracts after 1, 2 and 7 days. Furthermore, both biodegradable segmented polyurethane materials supported human umbilical vein endothelial cell adhesion, spreading, and viability similar to Tecoflex® medical-grade polyurethane. These biodegradable segmented polyurethanes represent promising materials for cardiovascular applications.

  16. Organic acid-catalyzed polyurethane formation via a dual-activated mechanism: unexpected preference of N-activation over O-activation of isocyanates.

    PubMed

    Sardon, Haritz; Engler, Amanda C; Chan, Julian M W; García, Jeannette M; Coady, Daniel J; Pascual, Ana; Mecerreyes, David; Jones, Gavin O; Rice, Julia E; Horn, Hans W; Hedrick, James L

    2013-10-30

    A systematic study of acid organocatalysts for the polyaddition of poly(ethylene glycol) to hexamethylene diisocyanate in solution has been performed. Among organic acids evaluated, sulfonic acids were found the most effective for urethane formations even when compared with conventional tin-based catalysts (dibutyltin dilaurate) or 1,8-diazabicyclo[5.4.0]undec-7-ene. In comparison, phosphonic and carboxylic acids showed considerably lower catalytic activities. Furthermore, sulfonic acids gave polyurethanes with higher molecular weights than was observed using traditional catalyst systems. Molecular modeling was conducted to provide mechanistic insight and supported a dual activation mechanism, whereby ternary adducts form in the presence of acid and engender both electrophilic isocyanate activation and nucleophilic alcohol activation through hydrogen bonding. Such a mechanism suggests catalytic activity is a function of not only acid strength but also inherent conjugate base electron density. PMID:24083673

  17. Determination of airborne isocyanates generated during the thermal degradation of car paint in body repair shops.

    PubMed

    Boutin, Michel; Dufresne, André; Ostiguy, Claude; Lesage, Jacques

    2006-06-01

    Polyurethanes are widely used in car paint formulations. During thermal degradation, such polymeric systems can generate powerful asthmatic sensitizing agents named isocyanates. In body repair shops, the thermal degradation of car paint can occur during abrasive processes that generate enough heat to involve release of isocyanates in air. An environmental monitoring study was performed in two body repair training schools and in a body repair shop to evaluate the workers' exposure to isocyanates during cutting, grinding and orbital sanding operations. For sampling, cassettes containing two 1-(2-methoxyphenyl)piperazine (MOPIP)-coated glass fiber filters (MFs) ( approximately 5 mg of MOPIP per filter) and bubblers containing 15 ml of MOPIP solution in toluene (1.0 mg ml(-1)) backed at the outlet with cassettes containing two MFs were used. Tandem mass spectrometry was used to analyze the MOPIP derivatives of isocyanic acid (HNCO), all the linear aliphatic isocyanates ranging from methyl isocyanate (Me-i) to hexyl isocyanate, all the alkenyl isocyanates ranging from propylene isocyanate to hexylene isocyanate, 1,6-hexamethylene diisocyanate (HDI), trans- and cis-isophorone diisocyanate (IPDI), 2,4- and 2,6-toluene diisocyanate (TDI), 2,4'-; 2,2'- and 4,4'-methylenediphenyl diisocyanate (MDI), phenyl isocyanate (Ph-i) and p-toluene isocyanate (p-Tol-i). The instrumental detection limits (LOD) were in the 0.13-0.75 microg of NCO per m(3) range for 15 l air samples converted into 3 ml liquid samples. The isocyanate concentrations detected in the workers' breathing zone were in the 1.07-9.80 microg of NCO per m(3) range for cutting, 0.63-3.62 microg of NCO per m(3) range for grinding and 0-1.29 microg of NCO per m(3) range for sanding. However, a rapid decrease of the isocyanate concentration was observed while moving away from the emission source. Among the isocyanates detected the most abundant were the monomers (MDI, HDI, TDI and IPDI) and Me-i.

  18. Workers' exposure to isocyanates

    SciTech Connect

    Lesage, J.; Goyer, N.; Desjardins, F.; Vincent, J.Y.; Perrault, G. )

    1992-02-01

    A model of exposure to isocyanates, based on knowledge of industrial processes and starting materials and the results of industrial hygiene surveys, is proposed. This model of exposure suggests the concentration and physical form of airborne isocyanate monomers and oligomers. A new sampling and analytical system was developed that is capable of determining the physical and chemical characteristics of occupational exposure to a variety of aliphatic and aromatic isocyanates as required by the exposure model. The sampling system consisted of a dual-filter 37-mm cassette, in which the first filter captured aerosol phase contaminants and the second captured vapor phase isocyanates through derivatization with 9-(N-methylaminomethyl) anthracene (MAMA). Urea derivative recovery by the sampling system, isocyanate-MAMA reactivity, and linearity of the calibration curve were evaluated in the laboratory. The practicality of the system was evaluated during field trials. Sampling times are reduced to 15 min, and the detection limit for TDI, HDI, and MDI was 1.0 micrograms/m3. A partial validation of the new sampling system was performed for HDI vapor by comparison to a standard method in field trials and for TDI vapor in a controlled test atmosphere. The analytical system may also be used to measure the concentration of oligomeric isocyanates. Airborne concentrations of isocyanates were measured in two foam plants, nine paint shops, and two foundries to verify the usefulness of the model. Exposure in foam plants was predominantly to gaseous monomeric isocyanates. Exposure to oligomer isocyanates was higher than expected in paint shops. Both monomer and oligomer isocyanates were undetectable in foundries.

  19. Biologically inert synthetic dural substitutes. Appraisal of a medical-grade aliphatic polyurethane and a polysiloxane-carbonate block copolymer.

    PubMed

    Sakas, D E; Charnvises, K; Borges, L F; Zervas, N T

    1990-12-01

    Two types of artificial membranes, a medical-grade aliphatic polyurethane and a polysiloxane-carbonate block copolymer, were tested as substitutes for dura in 24 and 12 rabbits, respectively. The films were placed either epidurally, subdurally, or as dural grafts in equal subgroups of animals. The postoperative course was uneventful with no manifestations of convulsive disorder or cerebrospinal fluid leak. The animals were sacrificed 3, 6, or 9 months after implantation of the artificial membranes. Both types of artificial membranes were easily removed from the underlying nervous and the other surrounding tissues. The histological examination failed to reveal adhesions, neomembrane formations, or any type of foreign body reactions to the polyurethane film. The implantation of the polysiloxane-carbonate film caused no reaction when it was applied epidurally. As a dural graft, the polysiloxane-carbonate copolymer induced the formation of a thin neomembrane of one to two layers of fibroblasts which formed a watertight seal of the dural defect. A similar thin neomembrane was found to encase this artificial membrane in the group of animals in which it was implanted subdurally. There was no foreign body reaction to the polysiloxane-carbonate film. The authors conclude that these materials hold promise as dural substitutes or in the prevention of spinal dural scarring, and should be evaluated clinically.

  20. [Isocyanates: occupational exposures and disorders].

    PubMed

    Baur, X

    2003-09-01

    Isocyanates are extensively used for the production of different foams and elastomers. They also serve as glues, lacquer hardeners, inks, adhesives, fillers, finishes, sealants, coating and insulation materials. Usually, their application results in inhalative, partly also in cutaneous uptake. This review describes occupational exposures to isocyanates as well as hazardous effects. Isocyanates are used in the automotive/mechanical engineering/building and construction/mining/casting/electricity and electronic/plastics/printing/timber and furniture/white goods and textile industry, partly also in medicine. Hazardous exposures to thermal degradation products of isocyanate-based polyurethanes and other materials have also be taken into consideration. Obstructive airway diseases are the major disorder caused by isocyanates. Rare cases suffer from extrinsic allergic alveolitis or eczema. In addition to regulation-based primary prevention qualitative medical surveillance mostly prevents disorders. There is also a need for the establishment of a validated biomonitoring of endangered employees. PMID:13680473

  1. [Isocyanates: occupational exposures and disorders].

    PubMed

    Baur, X

    2003-09-01

    Isocyanates are extensively used for the production of different foams and elastomers. They also serve as glues, lacquer hardeners, inks, adhesives, fillers, finishes, sealants, coating and insulation materials. Usually, their application results in inhalative, partly also in cutaneous uptake. This review describes occupational exposures to isocyanates as well as hazardous effects. Isocyanates are used in the automotive/mechanical engineering/building and construction/mining/casting/electricity and electronic/plastics/printing/timber and furniture/white goods and textile industry, partly also in medicine. Hazardous exposures to thermal degradation products of isocyanate-based polyurethanes and other materials have also be taken into consideration. Obstructive airway diseases are the major disorder caused by isocyanates. Rare cases suffer from extrinsic allergic alveolitis or eczema. In addition to regulation-based primary prevention qualitative medical surveillance mostly prevents disorders. There is also a need for the establishment of a validated biomonitoring of endangered employees.

  2. FTIR and molecular mechanics studies of H-bonds in aliphatic polyurethane and polyamide-66 model molecules.

    PubMed

    Wang, Guoqing; Zhang, Chunxia; Guo, Xiaohe; Ren, Zhiyong

    2008-02-01

    Model aliphatic polyurethane (APU) hard segment based on 1,6-hexamethylene diisocyanate (HDI) and 1,4-butanediol (BDO) were prepared. FTIR and molecular mechanics (MM) simulation were used to conduct the systematic studies on APU and polyamide-66 (PA-66) whose sole difference lies in the alkoxyl oxygen. It was found that the introduction of the alkoxyl not only increases the conformations in APU, makes it a possible H-bond acceptor, but also weakens the H-bond between NH and O=C in APU. There are two conformers stably existed in APU with lowest energy, leading to eight H-bond complexes based on NH as donor and (1) O=C as acceptor, and another two complexes based on (2) alkoxyl O and (3) urethane N as acceptors, whereas there is only one stable conformer in PA-66, leading to one H-bond complex. One predominant H-bond complex has been found in APU with probability of about 95%. The simulated results are consistent with the nuNH and nuC=O band shifting in FTIR.

  3. FTIR and molecular mechanics studies of H-bonds in aliphatic polyurethane and polyamide-66 model molecules

    NASA Astrophysics Data System (ADS)

    Wang, Guoqing; Zhang, Chunxia; Guo, Xiaohe; Ren, Zhiyong

    2008-02-01

    Model aliphatic polyurethane (APU) hard segment based on 1,6-hexamethylene diisocyanate (HDI) and 1,4-butanediol (BDO) were prepared. FTIR and molecular mechanics (MM) simulation were used to conduct the systematic studies on APU and polyamide-66 (PA-66) whose sole difference lies in the alkoxyl oxygen. It was found that the introduction of the alkoxyl not only increases the conformations in APU, makes it a possible H-bond acceptor, but also weakens the H-bond between NH and O dbnd C in APU. There are two conformers stably existed in APU with lowest energy, leading to eight H-bond complexes based on NH as donor and (1) O dbnd C as acceptor, and another two complexes based on (2) alkoxyl O and (3) urethane N as acceptors, whereas there is only one stable conformer in PA-66, leading to one H-bond complex. One predominant H-bond complex has been found in APU with probability of about 95%. The simulated results are consistent with the νNH and νC dbnd O band shifting in FTIR.

  4. FTIR and molecular mechanics studies of H-bonds in aliphatic polyurethane and polyamide-66 model molecules.

    PubMed

    Wang, Guoqing; Zhang, Chunxia; Guo, Xiaohe; Ren, Zhiyong

    2008-02-01

    Model aliphatic polyurethane (APU) hard segment based on 1,6-hexamethylene diisocyanate (HDI) and 1,4-butanediol (BDO) were prepared. FTIR and molecular mechanics (MM) simulation were used to conduct the systematic studies on APU and polyamide-66 (PA-66) whose sole difference lies in the alkoxyl oxygen. It was found that the introduction of the alkoxyl not only increases the conformations in APU, makes it a possible H-bond acceptor, but also weakens the H-bond between NH and O=C in APU. There are two conformers stably existed in APU with lowest energy, leading to eight H-bond complexes based on NH as donor and (1) O=C as acceptor, and another two complexes based on (2) alkoxyl O and (3) urethane N as acceptors, whereas there is only one stable conformer in PA-66, leading to one H-bond complex. One predominant H-bond complex has been found in APU with probability of about 95%. The simulated results are consistent with the nuNH and nuC=O band shifting in FTIR. PMID:17590387

  5. Slow curing of aliphatic polyisocyanate paints in automotive refinishing: a potential source for skin exposure.

    PubMed

    Bello, Dhimiter; Sparer, Judy; Redlich, Carrie A; Ibrahim, Karim; Stowe, Meredith H; Liu, Youcheng

    2007-06-01

    Two-component, polyurethane paints containing aliphatic isocyanates are widely used in autobody spray painting. Such isocyanates can cause asthma, and skin exposure may be an important route of sensitization and may contribute to the development of isocyanate asthma. Autobody workers are frequently in contact with recently painted, dried auto parts. It is not known how fast the newly painted car surfaces are fully cured, that is, for how long unbound, isocyanate species remain on painted surfaces after initial drying. To address this question, scrap sections of auto bodies were painted and dried by autobody shop painters following regular practice. Routinely used paints were sprayed 23 different times on the parts. Drying was accomplished by baking the part in a paint spray booth by heating it with a heat lamp or air drying in the shop. The 23 sprayed surfaces were sampled at regular time intervals after drying to determine the presence of free NCO groups using the semiquantitative SWYPE technique. Quantitative isocyanate analysis was also performed on two sprayed parts using NIOSH method 5525. Geometric mean curing time of 23 painted surfaces was 56.4 hr (range: 0.8 hrs to 32 days). Unbound isocyanate species of similar composition to the original bulk material remained present on the majority of sampled painted surfaces for up to 120 hours for typical paint formulations and for 1 month for others. The actual curing of polyurethane paints in autobody refinishing can be a slow process. Unbound isocyanates may remain on the surface of painted car parts for prolonged periods (days to weeks) after dried. Such surfaces are an under-recognized potential source of skin exposure to autobody workers. PMID:17474030

  6. 21 CFR 177.1680 - Polyurethane resins.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Polyurethane resins. 177.1680 Section 177.1680... Contact Surfaces § 177.1680 Polyurethane resins. The polyurethane resins identified in paragraph (a) of..., polyurethane resins are those produced when one or more of the isocyanates listed in paragraph (a)(1) of...

  7. Methyl isocyanate

    Integrated Risk Information System (IRIS)

    Methyl isocyanate ; CASRN 624 - 83 - 9 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic

  8. Autoclavable highly cross-linked polyurethane networks in ophthalmology.

    PubMed

    Bruin, P; Meeuwsen, E A; van Andel, M V; Worst, J G; Pennings, A J

    1993-11-01

    Highly cross-linked aliphatic polyurethane networks have been prepared by the bulk step reaction of low molecular weight polyols and hexamethylenediisocyanate (HDI). These polyurethane networks are optically transparent, colourless and autoclavable amorphous glassy thermosets, which are suited for use in ophthalmic applications such as intraocular lenses and keratoprostheses. The properties of these glassy polyurethanes, obtained from the reaction of the low molecular weight polyols triisopropanolamine (TIPA) or tetrakis (2-hydroxypropyl)ethylenediamine (Quadrol) and HDI in stoichiometric proportions, have been investigated in more detail. The glassy Quadrol/HDI-based polyurethane exhibits a reduction in ultimate glass transition temperature from 85 to 48 degrees C by uptake of 1% of water, and good ultimate mechanical properties (tensile strength 80-85 MPa, elongation at break ca 15%, modulus ca 1.5 GPa). IR spectra of these hydrophobic polyurethane networks revealed the absence of an isocyanate absorption, indicating that all isocyanates, apparently, had reacted during the cross-linking reaction. The biocompatibility could be increased by grafting tethered polyacrylamide chains onto the surface during network formation. These transparent cross-linked polyurethanes did not transmit UV light up to 400 nm, by incorporation of a small amount of the UV absorbing chromophore Coumarin 102, and could be sterilized simply by autoclaving. They were implanted in rabbit eyes, either in the form of small circular disks or in the form of a keratoprosthesis (artificial cornea). It was shown that the material was well tolerated by the rabbit eyes. Serious opacification of the cornea, a direct result of an adverse reaction to the implant, was never seen. Even 1 yr after implantation of a polyurethane keratoprosthesis the eye was still 'quiet'. PMID:7508760

  9. Diamine curing agents for polyurethanes

    NASA Technical Reports Server (NTRS)

    Bell, V. L.; St. Clair, T. L.

    1975-01-01

    Three aromatic diamines have properties that make them promising candidates as curing agents for converting isocyanates to polyurethanes with higher adhesive strengths, higher softening temperatures, better toughness, and improved abrasion resistance.

  10. Optimization of the structure of polyurethanes for bone tissue engineering applications.

    PubMed

    Bil, Monika; Ryszkowska, Joanna; Woźniak, Piotr; Kurzydłowski, Krzysztof J; Lewandowska-Szumieł, Małgorzata

    2010-07-01

    Polyurethanes containing 22-70 wt.% hard segments were developed and evaluated for bone tissue engineering applications. Aliphatic poly(ester-urethanes) were synthesised from poly(epsilon-caprolactone) diol with different molecular masses (M= approximately 530, 1250 and 2000 Da), cycloaliphatic diisocyanate 4,4'-methylenebis(cyclohexyl isocyanate) and ethylene glycol as a chain extender. Changes in macromolecule order with increasing hard segment content were observed via modulated differential scanning calorimetry. Depending on the hard segment content, a gradual variation in polyurethane surface properties was revealed by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and static contact angle measurements. As the hard segments content increased the polyurethane surface exhibited more phase separation, a higher content of urethane moieties and higher hydrophilicity. The biocompatibility results indicated that proliferation of human bone-derived cells (HBDC) cultured in vitro improved with increasing hard segment content while the osteogenic potential of HBDC decreased with increasing hard segment content. PMID:19723595

  11. Polyurethane synthesis reactions in asphalts

    SciTech Connect

    Bukowski, A.; Gretkiewicz, J.

    1982-04-01

    A series of asphalt-polyurethane composites was prepared by means of polyurethane synthesis in asphalt and carried out in melt. The applied materials were asphalts of differentiated group components content, polyester polyols of chain structure from linear to strongly branched, 2,4-tolylene diisocyanate, 4,4-methylenebis(phenyl isocyanate), and tinorganic catalyst. The asphalt components react with isocyanates to a minimal degree. The influence of the applied substrates, temperature, and polyurethane content in the system on the basic kinetic relations characterizing the process is presented. Polyurethane synthesis in asphalts does not differ in a fundamental way from the obtaining of polyurethanes, especially when their content in the composition is significant, 20 wt% and more.

  12. [2+2+2] cyclotrimerization of alkynes and isocyanates/isothiocyanates catalyzed by ruthenium-alkylidene complexes.

    PubMed

    Alvarez, Silvia; Medina, Sandra; Domínguez, Gema; Pérez-Castells, Javier

    2013-10-01

    Ruthenium carbene catalysts are able to catalyze crossed [2+2+2] cyclotrimerizations of α,ω-diynes with isocyanates, isothiocyanates, and carbon disulfide. Both aliphatic and aromatic isocyanates can be used to produce fused 2-pyridones, although aliphatic isocyanates were more reactive. Aromatic isocyanates give better results when they bear electron-donating substituents. The reaction of unsymmetrical α,ω-diynes gave a product only with the substituent adjacent to the 2-pyridone nitrogen. Isothiocyanates gave thiopyranimines upon reaction with the C═S bond, whereas CS2 reacted efficiently to give a thioxothiopyrane.

  13. Liquid chromatographic determination of residual isocyanate monomers in plastics intended for food contact use.

    PubMed

    Damant, A P; Jickells, S M; Castle, L

    1995-01-01

    A liquid chromatographic (LC) method was developed for the analysis of 10 isocyanates in polyurethane articles and laminates intended for food use. Residual isocyanates are extracted by dichloromethane with concurrent derivatization by 9-(methylaminomethyl)anthracene. The resultant derivatives are analyzed by reversed-phase LC with fluorescence detection. Separation of the isocyanates was studied and optimized. Quantitation uses 1-naphthyl isocyanate as internal standard and standard addition to the food package. Validation demonstrated the method to have good precision (+/- 2-5%) and recovery (83-95%) for samples spiked with isocyanates at 0.1 mg/kg. The limit of detection was 0.03 mg/kg. Analysis of 19 commercial polyurethane or laminate food packages demonstrated that the method was not prone to interferences. Residues of diphenylmethane-4,4'-diisocyanate were detected in 5 packages and ranged from 0.14 to 1.08 mg/kg. PMID:7756886

  14. Liquid chromatographic determination of residual isocyanate monomers in plastics intended for food contact use.

    PubMed

    Damant, A P; Jickells, S M; Castle, L

    1995-01-01

    A liquid chromatographic (LC) method was developed for the analysis of 10 isocyanates in polyurethane articles and laminates intended for food use. Residual isocyanates are extracted by dichloromethane with concurrent derivatization by 9-(methylaminomethyl)anthracene. The resultant derivatives are analyzed by reversed-phase LC with fluorescence detection. Separation of the isocyanates was studied and optimized. Quantitation uses 1-naphthyl isocyanate as internal standard and standard addition to the food package. Validation demonstrated the method to have good precision (+/- 2-5%) and recovery (83-95%) for samples spiked with isocyanates at 0.1 mg/kg. The limit of detection was 0.03 mg/kg. Analysis of 19 commercial polyurethane or laminate food packages demonstrated that the method was not prone to interferences. Residues of diphenylmethane-4,4'-diisocyanate were detected in 5 packages and ranged from 0.14 to 1.08 mg/kg.

  15. Polyurethane Masks Large Areas in Electroplating

    NASA Technical Reports Server (NTRS)

    Beasley, J. L.

    1985-01-01

    Polyurethane foam provides effective mask in electroplating of copper or nickel. Thin layer of Turco maskant painted on area to be masked: Layer ensures polyurethane foam removed easily after served its purpose. Component A, isocyanate, and component B, polyol, mixed together and brushed or sprayed on mask area. Mixture reacts, yielding polyurethane foam. Foam prevents deposition of nickel or copper on covered area. New method saves time, increases productivity and uses less material than older procedures.

  16. Advances in plastic recycling. Volume 1: Recycling of polyurethanes

    SciTech Connect

    Frisch, K.C.; Klempner, D.; Prentice, G.

    1999-07-01

    ``Recycling of Polyurethanes'', the first volume in the Advances in Plastics Recycling series, is focused on the physical and chemical recycling of polyurethanes, with attention given to energy conversion. A compilation of the present ongoing studies on recycling of urethane and, in general, isocyanate-based polymers, the focus is on thermosetting urethane polymers. Contents include: Recycling of Polyurethane Plastics in the European Automotive Industry; Present State of Polyurethane Recycling in Europe; Processing Overview of Bonded Polyurethane Foam; Mechanical Recycling of Polyurethane Scrap; Ecostream{trademark}--A Technology Beyond Recycling; Recycling of Flexible polyurethane Foam; General purpose Adhesives Prepared from Chemically Recycled Waste Rigid Polyurethane Foams; and Utilization of Isocyanate Binders in Recycling of Scrap Automotive Headliners.

  17. Synthesis and properties of radiation modified thermally cured castor oil based polyurethanes

    NASA Astrophysics Data System (ADS)

    Mortley, Aba; Bonin, H. W.; Bui, V. T.

    2007-12-01

    Thermally cured polyurethanes were prepared from castor oil and hexamethylene diisocyanate (HMDI). Due to the long aliphatic chain of the castor oil component of polyurethane, thermal curing of castor oil based polyurethane (COPU) is limited by increasing polymer viscosity. To enhance further crosslinking, COPUs were exposed to doses up to 3.0 MGy produced by the mixed ionizing radiation field of a SLOWPOKE-2 research nuclear reactor. The physico-mechanical properties of castor oil based polyurethanes (COPU), unirradiated and irradiated, were characterized by mechanical tensile tests. A four-fold increase in modulus and tensile strength values from 0.930 to 4.365 MPa and 0.149 to 0.747 MPa, respectively, suggests improved physico-mechanical properties resulting from radiation. The changing areas of the carbonyl and the NH absorbance peaks and the disappearance of the isocyanate peak in the FTIR spectra as radiation progressed, indicates increased hydrogen bonding and intermolecular crosslinking, which is in agreement with the mechanical tests. Unchanging 13C solid state NMR spectra imply limited sample degradation with increasing radiation.

  18. Isocyanate asthma: respiratory symptoms caused by diphenyl-methane di-isocyanate

    PubMed Central

    Tanser, A. R.; Bourke, M. P.; Blandford, A. G.

    1973-01-01

    Tanser, A. R., Bourke, M. P., and Blandford, A. G. (1973).Thorax, 28, 596-600. Isocyanate asthma: respiratory symptoms caused by diphenyl-methane di-isocyanate. We investigated 57 employees of a factory where diphenyl-methane di-isocyanate (MDI) was used to prepare the materials for making rigid polyurethane foam. Four employees had developed hypersensitivity to MDI. Two had severe, and one moderate asthma, while the fourth had symptoms resembling the delayed hypersensitivity type of reaction. Ten other employees had experienced unpleasant, mainly respiratory, irritant effects from MDI vapour. A past history of bronchitis or of allergy was found more commonly in those with symptoms from MDI than in those without symptoms. It is not known if MDI causes permanent damage to the respiratory tract. The most severely affected cases in the present series had normal spirometric values after recovery, and no persisting symptoms. MDI is safer than other isocyanates used in industry but may cause both major and minor illness. It should be handled with the same precautions as those used with the more toxic compounds. PMID:4784381

  19. An FTIR investigation of isocyanate skin absorption using in vitro guinea pig skin.

    PubMed

    Bello, Dhimiter; Smith, Thomas J; Woskie, Susan R; Streicher, Robert P; Boeniger, Mark F; Redlich, Carrie A; Liu, Youcheng

    2006-05-01

    Isocyanates may cause contact dermatitis, sensitization and asthma. Dermal exposure to aliphatic and aromatic isocyanates can occur in various exposure settings. The fate of isocyanates on skin is an important unanswered question. Do they react and bind to the outer layer of skin or do they penetrate through the epidermis as unreacted compounds? Knowing the kinetics of these processes is important in developing dermal exposure sampling or decontamination strategies, as well as understanding potential health implications such exposure may have. In this paper the residence time of model isocyanates on hairless guinea pig skin was investigated in vitro using attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectrometry. Model isocyanates tested were octyl isocyanate, polymeric hexamethylene diisocyanate isocyanurate (pHDI), polymeric isophorone diisocyanate isocyanurate (pIPDI) and methylenediphenyl diisocyanate (MDI). Isocyanates in ethyl acetate (30 microL) were spiked directly on the skin to give 0.2-1.8 micromol NCO cm(-2) (NCO = -N=C=O), and absorbance of the isocyanate group and other chemical groups of the molecule were monitored over time. The ATR-FTIR findings showed that polymeric isocyanates pHDI and pIPDI may remain on the skin as unreacted species for many hours, with only 15-20% of the total isocyanate group disappearing in one hour, while smaller compounds octyl isocyanate and MDI rapidly disappear from the skin surface (80+% in 30 min). Isocyanates most likely leave the skin surface by diffusion predominantly, with minimal reaction with surface proteins. The significance of these findings and their implications for dermal exposure sampling and isocyanate skin decontamination are discussed. PMID:16688353

  20. An FTIR investigation of isocyanate skin absorption using in vitro guinea pig skin.

    PubMed

    Bello, Dhimiter; Smith, Thomas J; Woskie, Susan R; Streicher, Robert P; Boeniger, Mark F; Redlich, Carrie A; Liu, Youcheng

    2006-05-01

    Isocyanates may cause contact dermatitis, sensitization and asthma. Dermal exposure to aliphatic and aromatic isocyanates can occur in various exposure settings. The fate of isocyanates on skin is an important unanswered question. Do they react and bind to the outer layer of skin or do they penetrate through the epidermis as unreacted compounds? Knowing the kinetics of these processes is important in developing dermal exposure sampling or decontamination strategies, as well as understanding potential health implications such exposure may have. In this paper the residence time of model isocyanates on hairless guinea pig skin was investigated in vitro using attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectrometry. Model isocyanates tested were octyl isocyanate, polymeric hexamethylene diisocyanate isocyanurate (pHDI), polymeric isophorone diisocyanate isocyanurate (pIPDI) and methylenediphenyl diisocyanate (MDI). Isocyanates in ethyl acetate (30 microL) were spiked directly on the skin to give 0.2-1.8 micromol NCO cm(-2) (NCO = -N=C=O), and absorbance of the isocyanate group and other chemical groups of the molecule were monitored over time. The ATR-FTIR findings showed that polymeric isocyanates pHDI and pIPDI may remain on the skin as unreacted species for many hours, with only 15-20% of the total isocyanate group disappearing in one hour, while smaller compounds octyl isocyanate and MDI rapidly disappear from the skin surface (80+% in 30 min). Isocyanates most likely leave the skin surface by diffusion predominantly, with minimal reaction with surface proteins. The significance of these findings and their implications for dermal exposure sampling and isocyanate skin decontamination are discussed.

  1. Effects of the Acrylic Polyol Structure and the Selectivity of the Employed Catalyst on the Performance of Two-Component Aqueous Polyurethane Coatings

    PubMed Central

    Cakic, Suzana; Lacnjevac, Caslav; Stamenkovic, Jakov; Ristic, Nikola; Takic, Ljiljana; Barac, Miroljub; Gligoric, Miladin

    2007-01-01

    Two kinds of aqueous acrylic polyols (single step and multi step synthesis type) have been investigated for their performance in the two-component aqueous polyurethane application, by using more selective catalysts. The aliphatic polyfunctional isocyanates based on hexamethylen diisocyanates have been employed as suitable hardeners. The complex of zirconium, commercially known as K-KAT®XC-6212, and manganese (III) complexes with mixed ligands based on the derivative of maleic acid have been used as catalysts in this study. Both of the aqueous polyols give good results, in terms of application and hardness, when elevated temperatures and more selective catalysts are applied. A more selective catalyst promotes the reaction between the isocyanate and polyol component. This increases the percentage of urethane bonds and the degree of hardness in the films formed from the two components of aqueous polyurethane lacquers. The polyol based on the single step synthesis route is favourable concerning potlife and hardness. The obtained results show that the performance of the two-component aqueous polyurethane coatings depends on the polymer structure of the polyols as well as on the selectivity of the employed catalyst.

  2. Structural elucidation of isocyanate-peptide adducts using tandem mass spectrometry.

    PubMed

    Hettick, Justin M; Ruwona, Tinashe B; Siegel, Paul D

    2009-08-01

    Diisocyanates are highly reactive chemical compounds widely used in the manufacture of polyurethanes. Although diisocyanates have been identified as causative agents of allergic respiratory diseases, the specific mechanism by which these diseases occur is largely unknown. To better understand the chemical species produced when isocyanates are reacted with model peptides, tandem mass spectrometry was employed to unambiguously identify the binding site of four commercially-relevant isocyanates on model peptides. In each case, the isocyanates react preferentially with the N-terminus of the peptide. No evidence of side-chain/isocyanate adduct formation exclusive of the N-terminus was observed. However, significant intra-molecular diisocyanate crosslinking was observed between the N-terminal amine and a side-chain amine of arginine, when Arg was located within two residues of the N-terminus. Addition of multiple isocyanates to the peptide occurs via polymerization of the isocyanate at the N-terminus, rather than via addition of multiple isocyanate molecules to varied residues within the peptide. The direct observation of isocyanate binding to the N-terminus of peptides under these experimental conditions is in good agreement with previous studies on the relative reaction rate of isocyanate with amino acid functional groups.

  3. Biological monitoring for isocyanates.

    PubMed

    Cocker, John

    2011-03-01

    Isocyanates are reactive chemicals and thousands of workers may be exposed to them during their manufacture and use in a wide range of products. They are classed as sensitizers and are a major cause of occupational asthma in the UK. Workplace exposure limits are low and control of exposure often depends on personal respiratory protection. Biological monitoring is increasingly used to assess exposure and the efficacy of control measures, including the behavioural aspects of controls. Biological monitoring methods are available for the most common isocyanates hexamethylene diisocyanate, toluene diisocyanate, isophorone diisocyanate, and methylenediphenyl diisocyanate. They are based on the analysis of hexamethylene diamine, toluene diamine, isopherone diamine, and methylenediamine released after hydrolysis of isocyanate-protein adducts in urine or blood. Volunteer and occupational studies show good correlations between inhalation exposure to isocyanate monomers and isocyanate-derived diamines in urine or blood. However, occupational exposure to isocyanates is often to a mixture of monomers and oligomers so there is some uncertainty comparing biological monitoring results with airborne exposure to 'total NCO'. Nevertheless, there is a substantial body of work demonstrating the utility of biological monitoring as a tool to assess exposure and the efficacy of controls, including how they are used in practice. Non-health-based biological monitoring guidance values are available to help target when and where further action is required. Occupational hygienists will need to use their knowledge and experience to determine the relative contributions of different routes of exposure and how controls can be improved to reduced the risk of ill health.

  4. Method of making thermally removable polyurethanes

    DOEpatents

    Loy, Douglas A.; Wheeler, David R.; McElhanon, James R.; Saunders, Randall S.; Durbin-Voss, Marvie Lou

    2002-01-01

    A method of making a thermally-removable polyurethane material by heating a mixture of a maleimide compound and a furan compound, and introducing alcohol and isocyanate functional groups, where the alcohol group and the isocyanate group reacts to form the urethane linkages and the furan compound and the maleimide compound react to form the thermally weak Diels-Alder adducts that are incorporated into the backbone of the urethane linkages during the formation of the polyurethane material at temperatures from above room temperature to less than approximately 90.degree. C. The polyurethane material can be easily removed within approximately an hour by heating to temperatures greater than approximately 90.degree. C. in a polar solvent. The polyurethane material can be used in protecting electronic components that may require subsequent removal of the solid material for component repair, modification or quality control.

  5. Handbook of polyurethanes

    SciTech Connect

    Szycher, M.

    1999-04-01

    This book serves as the first source of information of useful polymers. This new book thoroughly covers the entire spectrum of polyurethanes--from current technology to buyer's information. The contents include: basic concepts in PU chemistry and technology; structure-property relations in PU; isocyanate chemistry; polyols; chain extenders; flexible and semi-flexible-foams; rigid PU foams; rigid foam and surfactants; catalysts; thermoplastic elastomers; reaction injection molding; adhesives; water borne; health and safety; radiation curable adhesives and coatings; processing methods; compounding ingredients; copolymers, polybends, and IPN=S; coatings and solutions; castables, sealants, and caulking compounds; medical applications; raw material suppliers; and processing systems.

  6. Determination of isocyanic acid in air.

    PubMed

    Karlsson, D; Dalene, M; Skarping, G; Marand, A

    2001-08-01

    A method is presented for the determination of isocyanic acid (ICA), HNCO, in air samples as a di-n-butylamine (DBA) derivative. The method is based on sampling in midget impinger flasks containing 10 ml of 0.01 mol l-1 DBA in toluene. Quantification was made using liquid chromatography (LC) and electrospray mass spectrometry (MS) monitoring positive ions. The instrumental detection limit for the LC-MS was 10 fmol of ICA-DBA. ICA was generated by thermal decomposition of urea. A standard solution containing the DBA derivatives of ICA was prepared by collecting the emitted ICA in an impinger flask containing DBA. ICA in the reference solution was characterised by LC and time-of-flight (TOF) MS and quantified by LC chemiluminescent nitrogen detection (LC-CLND). The instrumental detection limit for the LC-CLND was 1 ng of nitrogen. ICA was emitted during thermal degradation of PFU resins and polyurethane (PUR) lacquers, from car metal sheets. ICA was the most dominant isocyanate and in PUR coating up to 8% of the total weight was emitted as ICA and for PFU resins up to 14% was emitted as ICA. When air samples were collected in an iron foundry during casting in sand moulds with furan resins, concentrations of ICA in the range 50-700 micrograms m-3 were found in the working atmosphere. PMID:11523446

  7. Isocyanate exposures in autobody shop work: the SPRAY study.

    PubMed

    Sparer, Judy; Stowe, Meredith H; Bello, Dhimiter; Liu, Youcheng; Gore, Rebecca J; Youngs, Fred; Cullen, Mark R; Redlich, Carrie A; Woskie, Susan R

    2004-09-01

    Isocyanates, known to cause respiratory sensitization and asthma, are widely used in automotive refinishing where exposures to aliphatic polyisocyanates occur by both inhalation and skin contact. The work reported here, the characterization of isocyanate exposure in the autobody industry, was part of an epidemiologic study of workers in 37 autobody shops in Connecticut. This article describes workplaces, tasks, and controls, and outlines the frequency, duration, and intensity of isocyanate exposures. Personal air samples taken outside of respirators had median concentrations of 66.5 microg NCO/m3 for primer, 134.4 microg (NCO)/m3 for sealer, and 358.5 microg NCO/m3 for clearcoat. Forty-eight percent of primer, 66% of sealer, and 92% of clearcoat samples exceeded the United Kingdom Health and Safety Executive guideline for isocyanate, though none exceeded the National Institute for Occupational Safety and Health (NIOSH) recommended exposure limit for monomer. Nonisocyanate-containing primers and sealers are used in more than half the shops, but nonisocyanate clearcoats are rare. Eighty-two percent of personal samples taken within a spray booth exceeded the U.K. guideline: 81% of those in downdraft spray booths, 74% in semidowndraft booths, and 92% in crossdraft booths. Only 8% of shops reported that spraying is done exclusively in spray booths. All painters wore some type of respirator. In 30% of shops, painters used supplied air respirators; the rest relied on half face organic vapor cartridge respirators with N95 overspray pads. All shops provided some type of gloves, usually latex, not recommended for isocyanate protection. Despite improvements in autobody shop materials, practices, and controls, there are still opportunities for substantial exposures to isocyanates. PMID:15559329

  8. Analytical approaches to identify potential migrants in polyester-polyurethane can coatings.

    PubMed

    Louise Bradley, Emma; Driffield, Malcolm; Guthrie, James; Harmer, Nick; Thomas Oldring, Peter Kenneth; Castle, Laurence

    2009-12-01

    The safety of a polyester-polyurethane can coating has been assessed using a suite of complementary analytical methods to identify and estimate the concentrations of potential chemical migrants. The polyester was based on phthalic acids and aliphatic diols. The polyisocyanate cross-linking agent was 1-isocyanato-3-isocyanatomethyl-3,5,5-trimethyl cyclohexane homopolymer (IPDI) blocked with methylethylketone oxime (MEKO) to make a one-part formulation. The overall migrate, obtained using solvent extraction of cured films, comprised almost completely of 12 cyclic and one linear polyester oligomer up to molecular weight 800 and containing up to six monomer units. These 13 oligomers covered a total of 28 isomeric forms. Other minor components detected were plasticisers and surfactants as well as impurities present in the starting materials. There was no detectable residue of either the blocked isocyanate (<0.01 microg/dm(2)) used as the starting substance or the unblocked isocyanate (<0.02 microg/dm(2)). The level of extractable IPDI was used as an indicator of the completeness of cure in experimental coatings. These studies revealed that there was an influence of time, temperature and catalyst content. Polymerisation was also influenced by the additives used and by the ageing of the wet coating formulation over several months. These studies allow parameters to be specified to ensure that commercial production coatings receive a full cure giving low migration characteristics. PMID:19787516

  9. Analytical approaches to identify potential migrants in polyester-polyurethane can coatings.

    PubMed

    Louise Bradley, Emma; Driffield, Malcolm; Guthrie, James; Harmer, Nick; Thomas Oldring, Peter Kenneth; Castle, Laurence

    2009-12-01

    The safety of a polyester-polyurethane can coating has been assessed using a suite of complementary analytical methods to identify and estimate the concentrations of potential chemical migrants. The polyester was based on phthalic acids and aliphatic diols. The polyisocyanate cross-linking agent was 1-isocyanato-3-isocyanatomethyl-3,5,5-trimethyl cyclohexane homopolymer (IPDI) blocked with methylethylketone oxime (MEKO) to make a one-part formulation. The overall migrate, obtained using solvent extraction of cured films, comprised almost completely of 12 cyclic and one linear polyester oligomer up to molecular weight 800 and containing up to six monomer units. These 13 oligomers covered a total of 28 isomeric forms. Other minor components detected were plasticisers and surfactants as well as impurities present in the starting materials. There was no detectable residue of either the blocked isocyanate (<0.01 microg/dm(2)) used as the starting substance or the unblocked isocyanate (<0.02 microg/dm(2)). The level of extractable IPDI was used as an indicator of the completeness of cure in experimental coatings. These studies revealed that there was an influence of time, temperature and catalyst content. Polymerisation was also influenced by the additives used and by the ageing of the wet coating formulation over several months. These studies allow parameters to be specified to ensure that commercial production coatings receive a full cure giving low migration characteristics.

  10. A laboratory investigation of the effectiveness of various skin and surface decontaminants for aliphatic polyisocyanates.

    PubMed

    Bello, Dhimiter; Woskie, Susan R; Streicher, Robert P; Stowe, Meredith H; Sparer, Judy; Redlich, Carrie A; Cullen, Mark R; Liu, Youcheng

    2005-07-01

    Isocyanates may cause contact dermatitis and respiratory sensitization leading to asthma. Dermal exposure to aliphatic isocyanates in auto body shops is very common. However, little is known about the effectiveness of available commercial products used for decontaminating aliphatic polyisocyanates. This experimental study evaluated the decontamination effectiveness of aliphatic polyisocyanates for several skin and surface decontaminants available for use in the auto body industry. The efficiency of two major decontamination mechanisms, namely (i) consumption of free isocyanate groups via chemical reactions with active hydrogen components of the decontaminant and (ii) physical removal processes such as dissolution were studied separately for each decontaminant. Considerable differences were observed among surface decontaminants in their rate of isocyanate consumption, of which those containing free amine groups performed the best. Overall, Pine-Sol(R) MEA containing monoethanolamine was the most efficient surface decontaminant, operating primarily via chemical reaction with the isocyanate group. Polypropylene glycol (PPG) had the highest physical removal efficiency and the lowest reaction rate with isocyanates. All tested skin decontaminants performed similarly, accomplishing decontamination primarily via physical processes and removing 70-80% of isocyanates in one wiping. Limitations of these skin decontaminants are discussed and alternatives presented. In vitro testing using animal skins and in vivo testing with field workers are being conducted to further assess the efficiency and identify related determinants. PMID:15986052

  11. Influence of prepolymer composition on polyurethane morphology

    NASA Astrophysics Data System (ADS)

    Krishnamoorthy, Jayaraman; Jeong, Young Gyu; Hashida, Tomoko; Hsu, Shaw Ling

    2004-03-01

    Polyurethane chemistry is one of the most studied subjects. Yet many aspects remain unexplained. Polyurethanes are synthesized by the reaction of diisocyanate with diol in the presence of nucleophilic catalysts. Polyurethane prepolymers are obtained by reacting the polyester diol / polyether diol with diisocyanate, with [NCO] / [OH] > 1, resulting in isocyanate-terminated polyester/polyether mixture. Prepolymers thus synthesized can be cured at a later stage to realize various morphologies and structures. Though the initial composition and the final morphology are known, little is known about the intermediate prepolymer mixture. Due to the different reactivity of primary and secondary hydroxyl groups in the polyester and polyether towards isocyanate, prepolymer has a non-random distribution in terms of composition as blends and copolymers. Our aim is to characterize the prepolymer by different techniques and study how the different prepolymer composition, with varying polyester and polyether ratio, affects the morphology and phase separation kinetics of the final product.

  12. Pro/Con debate: Is occupational asthma induced by isocyanates an immunoglobulin E-mediated disease?

    PubMed

    Wisnewski, A V; Jones, M

    2010-08-01

    Isocyanates, low-molecular weight chemicals essential to polyurethane production, are one of the most common causes of occupational asthma, yet the mechanisms by which exposure leads to disease remain unclear. While isocyanate asthma closely mirrors other Type I Immune Hypersensitivity (Allergic) disorders, one important characteristic of hypersensitivity ('allergen'-specific IgE) is reportedly absent in a large portion of affected individuals. This variation from common environmental asthma (which typically is induced by high-molecular weight allergens) is important for two reasons. (1) Allergen-specific IgE is an important mediator of many of the symptoms of bronchial hyper-reactivity in 'allergic asthma'. Lack of allergen-specific IgE in isocyanate hypersensitive individuals suggests differences in pathogenic mechanisms, with potentially unique targets for prevention and therapy. (2) Allergen-specific IgE forms the basis of the most commonly used diagnostic tests for hypersensitivity (skin prick and RAST). Without allergen-specific IgE, isocyanates may go unrecognized as the cause of asthma. In hypersensitive individuals, chronic exposure can lead to bronchial hyperreactivity that persists years after exposure ceases. Thus, the question of whether or not isocyanate asthma is an IgE-mediated disease, has important implications for disease screening/surveillance, diagnosis, treatment and prevention. The present Pro/Con Debate, addresses contemporary, controversial issues regarding IgE in isocyanate asthma.

  13. Macrocyclization of Unprotected Peptide Isocyanates.

    PubMed

    Vinogradov, Alexander A; Choo, Zi-Ning; Totaro, Kyle A; Pentelute, Bradley L

    2016-03-18

    A chemistry for the facile two-component macrocyclization of unprotected peptide isocyanates is described. Starting from peptides containing two glutamic acid γ-hydrazide residues, isocyanates can be readily accessed and cyclized with hydrazides of dicarboxylic acids. The choice of a nucleophilic linker allows for the facile modulation of biochemical properties of a macrocyclic peptide. Four cyclic NYAD-1 analogues were synthesized using the described method and displayed a range of biological activities. PMID:26948900

  14. Macrocyclization of Unprotected Peptide Isocyanates.

    PubMed

    Vinogradov, Alexander A; Choo, Zi-Ning; Totaro, Kyle A; Pentelute, Bradley L

    2016-03-18

    A chemistry for the facile two-component macrocyclization of unprotected peptide isocyanates is described. Starting from peptides containing two glutamic acid γ-hydrazide residues, isocyanates can be readily accessed and cyclized with hydrazides of dicarboxylic acids. The choice of a nucleophilic linker allows for the facile modulation of biochemical properties of a macrocyclic peptide. Four cyclic NYAD-1 analogues were synthesized using the described method and displayed a range of biological activities.

  15. Characterization of blocked isocyanates

    NASA Astrophysics Data System (ADS)

    Mirčeva, A.; Janežič, M.; Žigon, M.; Malavašič, T.

    1992-03-01

    An ionomer crosslinker on the basis of partly blocked hexamethylene isocyanurate was synthesized and characterized by FTIR and NMR spectroscopy and by gel permeation chromatography. To determine the selectivity of the blocking reaction. model compounds were also prepared. Deblocking and curing courses were studied by FTIR thermal methods. The selectivity of the blocking reaction was found to be poor and therefore the obtained ionomer crosslinker consisted of different monomer and oligomer components. Deblocking and curing were highly temperature dependent. Curing was more efficient in one-pack systems consisting of the ionomer crosslinker and of an OH groups rich ionomer polyurethane resin.

  16. Rigid zeolite containing polyurethane foams

    DOEpatents

    Frost, Charles B.

    1985-01-01

    A closed cell rigid polyurethane foam has been prepared which contains up to about 60% by weight of molecular sieves capable of sorbing molecules with effective critical diameters of up to about 10 .ANG.. The molecular sieve component of the foam can be preloaded with catalysts or with reactive compounds that can be released upon activation of the foam to control and complete crosslinking after the foam is formed. The foam can also be loaded with water or other flame-retarding agents, after completion. Up to about 50% of the weight of the isocyanate component of the foam can be replaced by polyimide resin precursors for incorporation into the final polymeric network.

  17. Rigid zeolite containing polyurethane foams

    DOEpatents

    Frost, C.B.

    1984-05-18

    A closed cell rigid polyurethane foam has been prepared which contains up to about 60% by weight of molecular sieves capable of sorbing molecules with effective critical diameters of up to about 10 A. The molecular sieve component of the foam can be preloaded with catalysts or with reactive compounds that can be released upon activation of the foam to control and complete crosslinking after the foam is formed. The foam can also be loaded with water or other flame-retarding agents, after completion. Up to about 50% of the weight of the isocyanate component of the foam can be replaced by polyimide resin precursors for incorporation into the final polymeric network.

  18. Radiation induced effects in segmented poly(siloxaneurethaneureas) based on aliphatic and aromatic diisocyanates

    NASA Astrophysics Data System (ADS)

    Przybytniak, Grażyna; Kornacka, Ewa; Kozakiewicz, Janusz; Przybylski, Jarosław

    2007-12-01

    Poly(siloxaneurethaneureas) (PSURURs) prepared from aromatic and aliphatic isocyanates were investigated upon exposure to ionising radiation. Radicals are formed both in siloxane and urethane segments. In comparison with aliphatic analogues it was found that in aromatic PSURURs: (1) concentration of all radicals is lower, (2) relative concentration of methylene radicals formed in siloxane units is higher, (3) the radiation yield of H 2 is more than three times smaller and (4) it seems that efficiency of cross-linking is less significant.

  19. Sampling of respirable isocyanate particles.

    PubMed

    Gylestam, Daniel; Gustavsson, Marcus; Karlsson, Daniel; Dalene, Marianne; Skarping, Gunnar

    2014-04-01

    An advanced design of a denuder impactor (DI) sampler has been developed for characterization of possible airborne isocyanate exposure in different particle size fractions. The sampler is equipped with 12 different parallel denuder tubes, 4 impaction stages with the cut-off values (d50) of: 9.5, 4, 2.5 and 1 µm, and an end filter that collects particles < 1 µm. All collecting parts were impregnated with di-n-butylamine DBA as the reagent in a mixture with acetic acid. The performance of the DI sampler was studied on a standard atmosphere containing gas and particulate isocyanates. The isocyanate atmosphere was generated by liquid permeation of 2,4-, 2,6-Toluene Diisocyanate (TDI), 1,6-Hexamethylene Diisocyanate (HDI) and Isophorone Diisocyanate (IPDI). 4,4'-Methylene Diphenyl Diisocyanate (MDI) particles were generated by heating of technical MDI and condensing the mixture of gas and particle-borne MDI in an atmosphere containing mixed salt particles. The study was performed in a 0.85 m3 environmental chamber with stainless steel walls. With the advancement of the DI sampler it is now possible to collect isocyanate particle samples for up to 320 min. The performance of the DI sampler is essentially unaffected by the humidity. The DI sampler and the ASSET EZ4-NCO sampler (Sigma-Aldrich/Supelco, Bellefonte, PA, USA) gave similar results. Sample losses within the DI sampler are low. In the environmental chamber it was observed that the particle distribution may be affected by the humidity and ageing. A scanning mobility particle sizer (SMPS) was used to separate a flow of selected fractions containing MDI particles from mixed MDI and salt particles. The particle-size distribution had a maximum at about 300 nm, but later in the environmental chamber 1 µm dominated. The distribution was very different as compared to with only NaCl or MDI present. The biological relevance for studying isocyanate nano particles is significant as these have the possibility to reach the

  20. Determination of isocyanate biomarkers in construction site workers.

    PubMed

    Sabbioni, Gabriele; Wesp, Hansjörg; Lewalter, Jürgen; Rumler, Richard

    2007-01-01

    4,4'-Methylenediphenyl diisocyanate (MDI) is the most important isocyanate in the manufacture of polyurethanes, dyes, pigments and adhesives. High concentrations of isocyanates are a potent respiratory irritant. Therefore, it is important to develop methods to monitor exposure to such compounds. We monitored biological samples from 40 non-exposed and 45 exposed construction site workers. 4,4'-Methylenedianiline (MDA) and N-acetyl-4,4'-MDA (AcMDA) were determined from untreated urine (U-MDA, U-AcMDA) and MDA was analysed from acid-treated urine (U-MDA-tot). Haemoglobin (Hb) adducts of MDA (Hb-MDA) were determined in all workers. The levels of biomarkers decreased in the following order: U-MDA-tot>U-AcMDA>U-MDA>Hb-MDA. The same order was found for the percentage of samples, which were found positive in exposed workers: 100%, 91%, 91%, 27%. The urine levels U-MDA-tot correlate with U-MDA, U-AcMDA and Hb-MDA with r=0.79, 0.86 and 0.39, respectively (Spearman rank order, p<0.01). U-AcMDA correlates with U-MDA and Hb-MDA with r=0.77 and 0.47, respectively (p<0.01). U-MDA correlates with Hb-MDA (r=0.38, p<0.05). The levels in the controls were significantly lower than in the exposed workers for all compounds (Mann-Whitney test, p<0.01). The median isocyanate-specific IgE-level was higher in the exposed workers, but the difference was statistically not significant. The change of the biomarker levels was compared in a group of workers (n=20), which were analysed prior to isocyanate exposure and after the exposure for approximately 4-7 months. All urine MDA metabolites and the Hb-adduct levels increased significantly (Wilcoxon sign test, p<0.01). Total IgE increased significantly after the exposure with isocyanate activity (p<0.01). With the present work it could be shown that outdoor workers are exposed to a similar extent as workers from a MDI factory.

  1. Size-separated sampling and analysis of isocyanates in workplace aerosols. Part I. Denuder--cascade impactor sampler.

    PubMed

    Dahlin, Jakob; Spanne, Mårten; Karlsson, Daniel; Dalene, Marianne; Skarping, Gunnar

    2008-07-01

    Isocyanates in the workplace atmosphere are typically present both in gas and particle phase. The health effects of exposure to isocyanates in gas phase and different particle size fractions are likely to be different due to their ability to reach different parts in the respiratory system. To reveal more details regarding the exposure to isocyanate aerosols, a denuder-impactor (DI) sampler for airborne isocyanates was designed. The sampler consists of a channel-plate denuder for collection of gaseous isocyanates, in series with three-cascade impactor stages with cut-off diameters (d(50)) of 2.5, 1.0 and 0.5 mum. An end filter was connected in series after the impactor for collection of particles smaller than 0.5 mum. The denuder, impactor plates and the end filter were impregnated with a mixture of di-n-butylamine (DBA) and acetic acid for derivatization of the isocyanates. During sampling, the reagent on the impactor plates and the end filter is continuously refreshed, due to the DBA release from the impregnated denuder plates. This secures efficient derivatization of all isocyanate particles. The airflow through the sampler was 5 l min(-1). After sampling, the samples containing the different size fractions were analyzed using liquid chromatography-mass spectrometry (LC-MS)/MS. The DBA impregnation was stable in the sampler for at least 1 week. After sampling, the DBA derivatives were stable for at least 3 weeks. Air sampling was performed in a test chamber (300 l). Isocyanate aerosols studied were thermal degradation products of different polyurethane polymers, spraying of isocyanate coating compounds and pure gas-phase isocyanates. Sampling with impinger flasks, containing DBA in toluene, with a glass fiber filter in series was used as a reference method. The DI sampler showed good compliance with the reference method, regarding total air levels. For the different aerosols studied, vast differences were revealed in the distribution of isocyanate in gas and

  2. A method of test for residual isophorone diisocyanate trimer in new polyester-polyurethane coatings on light metal packaging using liquid chromatography with tandem mass spectrometric detection.

    PubMed

    Driffield, Malcolm; Bradley, Emma L; Castle, Laurence

    2007-02-01

    A method of test for residual isophorone diisocyanate (IPDI) trimer in experimental formulation polyester-polyurethane (PEPU) thermoset coatings on metal food packaging is described. The method involves extraction of coated panels using acetonitrile containing dibutylamine for concurrent derivatisation, and then high performance liquid chromatography with electrospray ionisation tandem mass spectrometric detection (LC-MS/MS). Single laboratory validation was carried out using three different experimental PEPU-based coatings. The calibrations were linear, the analytical recovery was good, no interferences were seen, and substance identification criteria were met. The detection limit of the method is around 0.02 micro g/100 cm(2) of coating, which for a typical sized can and assuming complete migration of any residual IPDI trimer, corresponds to about 0.2 micro g/kg food or beverage. Separate studies indicated that, even if migration occurred at such low levels, the IPDI trimer would not be expected to persist in canned aqueous or fatty foodstuffs as it would hydrolyse to the corresponding aliphatic amine or react with food components to destroy the isocyanate moiety. The method of test developed here for residual IPDI trimer in thermoset polyester-polyurethane coatings should prove to be a valuable tool for investigating the cure kinetics of these novel coatings and help to guide the development of enhanced formulations. PMID:17178416

  3. A method of test for residual isophorone diisocyanate trimer in new polyester-polyurethane coatings on light metal packaging using liquid chromatography with tandem mass spectrometric detection.

    PubMed

    Driffield, Malcolm; Bradley, Emma L; Castle, Laurence

    2007-02-01

    A method of test for residual isophorone diisocyanate (IPDI) trimer in experimental formulation polyester-polyurethane (PEPU) thermoset coatings on metal food packaging is described. The method involves extraction of coated panels using acetonitrile containing dibutylamine for concurrent derivatisation, and then high performance liquid chromatography with electrospray ionisation tandem mass spectrometric detection (LC-MS/MS). Single laboratory validation was carried out using three different experimental PEPU-based coatings. The calibrations were linear, the analytical recovery was good, no interferences were seen, and substance identification criteria were met. The detection limit of the method is around 0.02 micro g/100 cm(2) of coating, which for a typical sized can and assuming complete migration of any residual IPDI trimer, corresponds to about 0.2 micro g/kg food or beverage. Separate studies indicated that, even if migration occurred at such low levels, the IPDI trimer would not be expected to persist in canned aqueous or fatty foodstuffs as it would hydrolyse to the corresponding aliphatic amine or react with food components to destroy the isocyanate moiety. The method of test developed here for residual IPDI trimer in thermoset polyester-polyurethane coatings should prove to be a valuable tool for investigating the cure kinetics of these novel coatings and help to guide the development of enhanced formulations.

  4. [FTIR spectra study on the film of polyurethane coated urea controlled-release fertilizer].

    PubMed

    Wu, Shu; Li, Qing-shan; Ru, Tie-jun; Wang, Li-min; Xing, Guang-zhong; Wang, Jin-ming

    2011-03-01

    The polyurethane films were prepared to wrap the urea in order to achieve a desirable release rate by mixing isocyanate, polyols and wax. The effect of wax, urea and isocyanate on the structure and properties of the films was investigated by FTIR. The structural changes were monitored as the polyurethane films together with the wrapped urea were immersed into ammonia water for 28 days, which is used to model soil conditions. The FTIR results showed that the width and intensity of the NH-free band increased remarkably with time, and all kinds of carbonly bands shifted to high wavenumber and their intensity increased obviously. The results suggest that the structure of the polyurethane films was destroyed more heavily in soil than in water, and this explains the relatively fast release rate of urea in soil. It was observed that the increase in the chemical crosslinking density in the polyurethane films can effectively decrease the release rate of the urea nitrogen in soil.

  5. Recycling polyurethanes

    SciTech Connect

    1995-08-01

    This article reports on the PolyUrethane Recycle and Recovery Council`s continuing evaluation of the technical and commercial viability of polyurethane recovery and recycling technologies. In North America, 240,000 tonnes of post-industrial and 16,000 tonnes of post-consumer polyurethane foam was recycled into carpet rebound underlay and other applications in 1993. Demand was so great in North America that 60,000 t of primarily post-industrial scarp was imported from Europe and the Far East. Polyurethane from the seats of the 9 million vehicles scrapped each year could yield 82,000 t of flexible post-consumer foam scrap: instrument and door panels could yield another 10,000 t of semi-flexible scrap.

  6. Composition for producing polyurethane resin at ambient temperature

    SciTech Connect

    Kamatani, Y.; Nishino, K.; Tanaka, M.; Yamazaki, K.

    1984-06-26

    Disclosed is a composition for polyurethane resins which is ordinarily of two-package type and curable at ambient temperature and which comprises an isocyanate component having oxadiazinetrione ring as a curing agent and a polyol component, having in the molecule, at least one of a tertiary amino group, a quaternary ammonium group and a salt-formed carboxyl group as a main component. The composition has excellent curability and provides cured products excellent in adhesiveness and physical properties.

  7. Theory analysis of mass spectra of long-chain isocyanates.

    PubMed

    Liu, Dongliang; Hao, Ce; Zhang, Hua; Qiao, Weihong; Li, Zongshi; Yu, Guanghui; Yan, Kelu; Guo, Yuliang; Cheng, Lvbo

    2008-07-01

    Electron impact mass spectra of four long-chain isocyanates, lauryl isocyanate, tetradecyl isocyanate, hexadecyl isocyanate and octadecyl isocyanate, were obtained with a GCT high-resolution time-of-flight mass spectrometer. The four isocyanates studied gave a common base peak of m/z 99, which suggested the formation of a stable six-membered ring structure to decentralize the positive charge. Quantum-mechanical energy calculation justified that the six-membered ring base peak had the lowest energy. The positive charge assigned during the fragmentation of the radical cation, and the relative intensity of the fragment ion peaks, were explained by quantum-mechanical calculations as well.

  8. NMR Investigation of Filler Effects of (Gamma) Irradiation in Polyurethane Adhesives

    SciTech Connect

    Chinn, S C; Gjersing, E L; Maxwell, R S; Cohenour, R

    2007-06-11

    Polyurethane and polyester elastomers have been used for decades in a wide variety of applications, from seat cushion foams to prosthetic materials to high performance adhesives. Adiprene LW-520 is a polyurethane-based adhesive used in a number of U. S. Department of Energy applications. Several investigations have been performed to determine aging properties of polyurethanes. For example, {sup 1}H nuclear magnetic resonance (NMR) relaxation times have been shown to be sensitive to thermal degradation in polyurethanes. Detailed information about the exact nature of the oxidative thermal degradation in related materials has also been obtained via {sup 17}O and {sup 13}C NMR, with additional insight into morphological changes being obtained using {sup 1}H spin diffusion experiments. Radiation has also been shown to change the physical and mechanical properties of the polymers; in fact many polyurethanes are cured using radiation to affect the isocyanate and free radical reactive groups, thus controlling the properties such as thermal or solvent resistance.

  9. Intrinsically radiopaque polyurethanes with chain extender 4,4'-isopropylidenebis [2-(2,6-diiodophenoxy)ethanol] for biomedical applications.

    PubMed

    Dawlee, S; Jayabalan, M

    2015-05-01

    Radiopaque polyurethanes are used for medical applications as it allows post-operative assessment of the biomaterial devices using X-ray. Inherently, radiopaque polyurethanes based on polytetramethylene glycol (PTMG), polypropylene glycol, 4,4'-methylenebis(phenyl isocyanate), and a new iodinated chain extender 4,4'-isopropylidenebis[2-(2,6-diiodophenoxy)ethanol] with flexible spacers were synthesized and characterized. The iodinated polyurethanes were clear, optically transparent, and had high molecular weights. The polyurethanes also possessed excellent radiopacity and high thermal stability. The biocompatibility of the most promising iodinated polyurethane was evaluated both in vitro (cytotoxicity evaluation by direct contact and MTT assay, using L929 mouse fibroblast cells) and in vivo (toxicology studies in rabbits and subcutaneous implantation in rats). The material was nontoxic and well tolerated by the animals. Thus, these radiopaque and transparent polyurethanes are expected to have potential for various biomedical applications.

  10. Vibration and DFT analysis of 2-methyl-3-nitrophenyl isocyanate and 4-methyl-2-nitrophenyl isocyanate.

    PubMed

    Tonannavar, J; Prasannakumar, Sushanti; Savanur, J; Yenagi, Jayashree

    2012-09-01

    Vibrational spectra of 2-methyl-3-nitrophenyl isocyanate and 4-methyl-2-nitrophenyl isocyanate, in the spectral region 4000-100 cm(-1), have been measured and assigned. Conformational and harmonic frequency analyses have been performed at B3LYP/6-311G(∗) level of calculations. The two stable conformers, cis and trans, have been computed for each of the molecules. It has been determined that the trans conformer has lower energy than the cis by 3.954 kJ/mol for 2-methyl-3-nitrophenyl isocyanate; whereas the cis conformer has lower energy than the trans by 10.230 kJ/mol for 4-methyl-2-nitrophenyl isocyanate. The vibration structure of 2-methyl-3-nitrophenyl isocyanate conforms to the combined behavior of its both conformers from which the deviation is shown by the structure of 4-methyl-2-nitrophenyl isocyanate which follows only the trans conformer. The occurrence of symmetric mode of the methyl group at higher frequency near 2944-20 cm(-1) is attributed to the phenyl ring strain caused by the substituents. As for the other stretching and bending modes, mutually exclusive pattern appears to work for the molecules: The nitro group's non-coplanarity with the phenyl ring is more evident in 4-methyl-2-nitrophenyl isocyanate where the asymmetric mode was assigned to the band at 1569cm(-1), whereas the symmetric mode at lower frequency 1339cm(-1). Occasional doublet appearance of the strong asymmetric absorption near 2282cm(-1) due to isocyanate moiety has been observed in the present study and is assumed to arise from the torsional vibration motion of the moiety rendered by the small energy gap between the conformers of 2-methyl-3-nitrophenyl isocyanate.

  11. Assessment of the Biological Pathways Targeted by Isocyanate Using N-Succinimidyl N-Methylcarbamate in Budding Yeast Saccharomyces cerevisiae

    PubMed Central

    Azad, Gajendra Kumar; Singh, Vikash; Tomar, Raghuvir S.

    2014-01-01

    Isocyanates, a group of low molecular weight aromatic and aliphatic compounds possesses the functional isocyanate group. They are highly toxic in nature hence; we used N-succinimidyl N-methylcarbamate (NSNM), a surrogate chemical containing a functional isocyanate group to understand the mode of action of this class of compounds. We employed budding yeast Saccharomyces cerevisiae as a model organism to study the pathways targeted by NSNM. Our screening with yeast mutants revealed that it affects chromatin, DNA damage response, protein-ubiquitylation and chaperones, oxidative stress, TOR pathway and DNA repair processes. We also show that NSNM acts as an epigenetic modifier as its treatment causes reduction in global histone acetylation and formation of histone adducts. Cells treated with NSNM exhibited increase in mitochondrial membrane potential as well as intracellular ROS levels and the effects were rescued by addition of reduced glutathione to the medium. We also report that deletion of SOD1 and SOD2, the superoxide dismutase in Saccharomyces cerevisiae displayed hypersensitivity to NSNM. Furthermore, NSNM treatment causes rapid depletion of total glutathione and reduced glutathione. We also demonstrated that NSNM induces degradation of Sml1, a ribonucleotide reductase inhibitor involved in regulating dNTPs production. In summary, we define the various biological pathways targeted by isocyanates. PMID:24664350

  12. Assessment of the biological pathways targeted by isocyanate using N-succinimidyl N-methylcarbamate in budding yeast Saccharomyces cerevisiae.

    PubMed

    Azad, Gajendra Kumar; Singh, Vikash; Tomar, Raghuvir S

    2014-01-01

    Isocyanates, a group of low molecular weight aromatic and aliphatic compounds possesses the functional isocyanate group. They are highly toxic in nature hence; we used N-succinimidyl N-methylcarbamate (NSNM), a surrogate chemical containing a functional isocyanate group to understand the mode of action of this class of compounds. We employed budding yeast Saccharomyces cerevisiae as a model organism to study the pathways targeted by NSNM. Our screening with yeast mutants revealed that it affects chromatin, DNA damage response, protein-ubiquitylation and chaperones, oxidative stress, TOR pathway and DNA repair processes. We also show that NSNM acts as an epigenetic modifier as its treatment causes reduction in global histone acetylation and formation of histone adducts. Cells treated with NSNM exhibited increase in mitochondrial membrane potential as well as intracellular ROS levels and the effects were rescued by addition of reduced glutathione to the medium. We also report that deletion of SOD1 and SOD2, the superoxide dismutase in Saccharomyces cerevisiae displayed hypersensitivity to NSNM. Furthermore, NSNM treatment causes rapid depletion of total glutathione and reduced glutathione. We also demonstrated that NSNM induces degradation of Sml1, a ribonucleotide reductase inhibitor involved in regulating dNTPs production. In summary, we define the various biological pathways targeted by isocyanates.

  13. Accidental exposure to isocyanate fumes in a group of firemen.

    PubMed Central

    Axford, A T; McKerrow, C B; Jones, A P; Le Quesne, P M

    1976-01-01

    A total of 35 firemen involved in fighting a fire in a factory in which polyurethane foam was made were exposed to fumes of toluene di-isocyanate from two large storage tanks which were damaged during the fire, resulting in massive spillage. Most of the men experienced symptoms during the fire or during the three weeks after it. The symptoms were mainly gastrointestinal, respiratory, or neurological. Altogether 15 men described gastrointestinal symptoms which subsided within two days of onset. Respiratory symptoms were described by 31 men and were most pronounced during the three days after the fire, thereafter tending to improve. The neurological findings are described separately. When the men were reviewed at six months there was a suggestion that some of them might have sustained long-term damage to the respiratory tract, and almost four years later 20 men had persistent respiratory symptoms. Serial measurements of ventilatory capacity revealed a marked decline in the first six months although this was not sustained. PMID:179561

  14. Novel glutathione conjugates of phenyl isocyanate identified by ultra-performance liquid chromatography/electrospray ionization mass spectrometry and nuclear magnetic resonance.

    PubMed

    Johansson Mali'n, Tove; Lindberg, Sandra; Åstot, Crister

    2014-01-01

    Phenyl isocyanate is a highly reactive compound that is used as a reagent in organic synthesis and in the production of polyurethanes. The potential for extensive occupational exposure to this compound makes it important to elucidate its reactivity towards different nucleophiles and potential targets in the body. In vitro reactions between glutathione and phenyl isocyanate were studied. Three adducts of glutathione with phenyl isocyanate were identified using ultra-performance liquid chromatography/electrospray ionization mass spectrometry and nuclear magnetic resonance (NMR). Mass spectrometric data for these adducts have not previously been reported. Nucleophilic attack on phenyl isocyanate occurred via either the cysteinyl thiol group or the glutamic acid α-amino group of glutathione. In addition, a double adduct was formed by the reaction of both these moieties. NMR analysis confirmed the proposed structure of the double adduct, which has not previously been described. These results suggest that phenyl isocyanate may react with free cysteines, the α-amino group and also with lysine residues whose side chain contains a primary amine.

  15. Studies on polyurethane adhesives and surface modification of hydrophobic substrates

    NASA Astrophysics Data System (ADS)

    Krishnamoorthy, Jayaraman

    This thesis work deals with (a) Curing of reactive, hot-melt polyurethane adhesives and (b) Adsorption studies using different interactions. Research on polyurethanes involves characterization of polyurethane prepolymers and a novel mechanism to cure isocyanate-terminated polyurethane prepolymer by a "trigger" mechanism. Curing of isocyanate-terminated polyurethane prepolymers has been shown to be influenced by morphology and environmental conditions such as temperature and relative humidity. Although the initial composition, final morphology and curing kinetics are known, information regarding the intermediate prepolymer mixture is yet to be established. Polyurethane prepolymers prepared by the reaction of diisocyanates with the primary hydroxyls of polyester diol (PHMA) and secondary hydroxyls of polyether diol (PPG) were characterized. The morphology and crystallization kinetics of a polyurethane prepolymer was compared with a blend of PPG prepolymer (the product obtained by the reaction of PPG with diisocyanate) and a PHMA prepolymer (the product obtained by the reaction of PHMA with diisocyanate) to study the effect of copolymer formed in the polyurethane prepolymer on the above-mentioned properties. Although the morphology of the polyurethane prepolymer is determined in the first few minutes of application, the chemical curing of isocyanate-terminated prepolymer occurs over hours to days. In the literature, different techniques are described to follow the curing kinetics. But there is no established technique to control the curing of polyurethane prepolymer. To make the curing process independent of environmental factors, a novel approach using a trigger mechanism was designed and implemented by using ammonium salts as curing agents. Ammonium salts that are stable at room temperature but decompose on heating to yield active hydrogen-containing compounds, NH3 and H2O, were used as 'Trojan horses' to cure the prepolymer chemically. Research on adsorption

  16. Evaluating Dimethyldiethoxysilane for use in Polyurethane Crosslinked Silica Aerogels

    NASA Technical Reports Server (NTRS)

    Randall, Jason P.; Meador, Mary Ann B.; Jana, Sadhan C.

    2008-01-01

    Silica aerogels are highly porous materials which exhibit exceptionally low density and thermal conductivity. Their "pearl necklace" nanostructure, however, is inherently weak; most silica aerogels are brittle and fragile. The strength of aerogels can be improved by employing an additional crosslinking step using isocyanates. In this work, dimethyldiethoxysilane (DMDES) is evaluated for use in the silane backbone of polyurethane crosslinked aerogels. Approximately half of the resulting aerogels exhibited a core/shell morphology of hard crosslinked aerogel surrounding a softer, uncrosslinked center. Solid state NMR and scanning electron microscopy results indicate the DMDES incorporated itself as a conformal coating around the outside of the secondary silica particles, in much the same manner as isocyanate crosslinking. Response surface curves were generated from compression data, indicating levels of reinforcement comparable to that in previous literature, despite the core/shell morphology.

  17. Polyols and polyurethanes from the liquefaction of lignocellulosic biomass.

    PubMed

    Hu, Shengjun; Luo, Xiaolan; Li, Yebo

    2014-01-01

    Polyurethanes (PUs), produced from the condensation polymerizations between polyols and isocyanates, are one of the most versatile polymer families. Currently, both polyols and isocyanates are largely petroleum derived. Recently, there have been extensive research interests in developing bio-based polyols and PUs from renewable resources. As the world's most abundant renewable biomass, lignocellulosic biomass is rich in hydroxyl groups and has potential as a feedstock to produce bio-based polyols and PUs. Lignocellulosic biomass can be converted to liquid polyols for PU applications through acid- or base-catalyzed atmospheric liquefaction processes using polyhydric alcohols as liquefaction solvents. Biomass liquefaction-derived polyols can be used to prepare various PU products, such as foams, films and adhesives. The properties of biomass liquefaction-derived polyols and PUs depend on various factors, such as feedstock characteristics, liquefaction conditions, and PU formulations.

  18. Cellulose based hybrid hydroxylated adducts for polyurethane foams

    NASA Astrophysics Data System (ADS)

    De Pisapia, Laura; Verdolotti, Letizia; Di Mauro, Eduardo; Di Maio, Ernesto; Lavorgna, Marino; Iannace, Salvatore

    2012-07-01

    Hybrid flexible polyurethane foams (HPU) were synthesized by using a hybrid hydroxilated adduct (HHA) based on renewable resources. In particular the HHA was obtained by dispersing cellulose wastes in colloidal silica at room temperature, pressure and humidity. The colloidal silica was selected for its ability of modifying the cellulose structure, by inducing a certain "destructurization" of the crystalline phase, in order to allow cellulose to react with di-isocyanate for the final synthesis of the polyurethane foam. In fact, cellulose-polysilicate complexes are engaged in the reaction with the isocyanate groups. This study provides evidence of the effects of the colloidal silica on the cellulose structure, namely, a reduction of the microfiber cellulose diameter and the formation of hydrogen bonds between the polysilicate functional groups and the hydroxyl groups of the cellulose, as assessed by IR spectroscopy and solid state NMR. The HHA was added to a conventional polyol in different percentages (between 5 and 20%) to synthesize HPU in presence of catalysts, silicone surfactant and diphenylmethane diisocyanate (MDI). The mixture was expanded in a mold and cured for two hours at room temperature. Thermal analysis, optical microscopy and mechanical tests were performed on the foams. The results highlighted an improvement of thermal stability and a decrease of the cell size with respect neat polyurethane foam. Mechanical tests showed an improvement of the elastic modulus and of the damping properties with increasing HHA amount.

  19. Photochemical activation of extremely weak nucleophiles: highly fluorinated urethanes and polyurethanes from polyfluoro alcohols.

    PubMed

    Soto, Marc; Sebastián, Rosa María; Marquet, Jordi

    2014-06-01

    An efficient and environmentally friendly photoreaction between phenyl isocyanate or pentafluorophenyl isocyanate and polyfluorinated alcohols and diols is described for the first time. New highly fluorinated urethanes and diurethanes, derived from aromatic isocyanates, are produced in good yields in a photoreaction that is apparently governed by the acidic properties of the polyfluoro alcohols and diols. The wettability properties of the new polyfluorinated diurethanes have been tested, some of them showing significantly high values of hydrophobicity and oleophobicity. This new photoreaction has also been tested in the production of a model polyfluorinated polyurethane, establishing the influence of the irradiation power in the outcome of the process, and directly achieving a molecular weight distribution corresponding to a number-average DP(n) = 12 and a highest DP(n) = 20 after 4 h of irradiation (DP(n): "number-average degree of polymerization").

  20. Polyurethane foams obtained from residues of PET manufacturing and modified with carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Stiebra, L.; Cabulis, U.; Knite, M.

    2016-04-01

    In this work we report the preparation of rigid microcellular polyurethane/carbon nanotube nanocomposites with different CNT loadings (0.09-0.46%) and various isocyanate indexes (110-260). Water was used as a blowing agent for samples. Density of all obtained samples - 200 ± 10 kg/m3. Electrical properties, as well as heat conductivity, cellular structure and mechanical properties of these nanocomposites were investigated.

  1. Method for providing a low density high strength polyurethane foam

    SciTech Connect

    Whinnery, Jr., Leroy L.; Goods, Steven H.; Skala, Dawn M.; Henderson, Craig C.; Keifer, Patrick N.

    2013-06-18

    Disclosed is a method for making a polyurethane closed-cell foam material exhibiting a bulk density below 4 lbs/ft.sup.3 and high strength. The present embodiment uses the reaction product of a modified MDI and a sucrose/glycerine based polyether polyol resin wherein a small measured quantity of the polyol resin is "pre-reacted" with a larger quantity of the isocyanate in a defined ratio such that when the necessary remaining quantity of the polyol resin is added to the "pre-reacted" resin together with a tertiary amine catalyst and water as a blowing agent, the polymerization proceeds slowly enough to provide a stable foam body.

  2. Evaluation of sunlight stability of polyurethane elastomers for maxillofacial use. I.

    PubMed

    Chu, C C; Fischer, T E

    1978-05-01

    The evaluation of the efficiency of polymer additives with special emphasis on uv absorbers and antioxidants in polyurethane elastomers has been completed. Aliphatic polyurethanes were chosen for this study because their properties closely relate to the requirements of maxillofacial prosthesis. The polyurethane elastomers were either synthesized by ourselves or formulated according to the manufacturer's recommendation. Eleven different types of uv absorbes, coupled with one antioxidant, were incorporated into the polyurethane systems. The Atlas twin-lamp carbon arc Weatherometer was used as the source of uv. The samples were periodically withdrawn for examination of yellowing and tackiness. It was found that, although the incorporation of uv stabilizers enhanced the uv resistance of polyurethanes, the problem of tackiness resulting from uv aging was not solved satisfactorily. The phenomenon of yellowing, however, was significantly improved, mainly due to the aliphatic structure of polyurethanes. The most promising uv absorbers are Tinuvin 770 and the combination of Tinuvin 328, ZnO, and an antioxidant. Their effectiveness in other polyurethane systems is not known and further research is underway to explore this field. Hopefully, these findings will greatly assist the successful application polyurethane elastomers in maxillofacial prosthesis. PMID:670257

  3. Evaluation of sunlight stability of polyurethane elastomers for maxillofacial use. I.

    PubMed

    Chu, C C; Fischer, T E

    1978-05-01

    The evaluation of the efficiency of polymer additives with special emphasis on uv absorbers and antioxidants in polyurethane elastomers has been completed. Aliphatic polyurethanes were chosen for this study because their properties closely relate to the requirements of maxillofacial prosthesis. The polyurethane elastomers were either synthesized by ourselves or formulated according to the manufacturer's recommendation. Eleven different types of uv absorbes, coupled with one antioxidant, were incorporated into the polyurethane systems. The Atlas twin-lamp carbon arc Weatherometer was used as the source of uv. The samples were periodically withdrawn for examination of yellowing and tackiness. It was found that, although the incorporation of uv stabilizers enhanced the uv resistance of polyurethanes, the problem of tackiness resulting from uv aging was not solved satisfactorily. The phenomenon of yellowing, however, was significantly improved, mainly due to the aliphatic structure of polyurethanes. The most promising uv absorbers are Tinuvin 770 and the combination of Tinuvin 328, ZnO, and an antioxidant. Their effectiveness in other polyurethane systems is not known and further research is underway to explore this field. Hopefully, these findings will greatly assist the successful application polyurethane elastomers in maxillofacial prosthesis.

  4. Size selective isocyanate aerosols personal air sampling using porous plastic foams

    NASA Astrophysics Data System (ADS)

    Khanh Huynh, Cong; Duc, Trinh Vu

    2009-02-01

    As part of a European project (SMT4-CT96-2137), various European institutions specialized in occupational hygiene (BGIA, HSL, IOM, INRS, IST, Ambiente e Lavoro) have established a program of scientific collaboration to develop one or more prototypes of European personal samplers for the collection of simultaneous three dust fractions: inhalable, thoracic and respirable. These samplers based on existing sampling heads (IOM, GSP and cassettes) use Polyurethane Plastic Foam (PUF) according to their porosity to support sampling and separator size of the particles. In this study, the authors present an original application of size selective personal air sampling using chemical impregnated PUF to perform isocyanate aerosols capturing and derivatizing in industrial spray-painting shops.

  5. Studies on nonlinear optical polyurethanes containing heterocyclic chromophores

    NASA Astrophysics Data System (ADS)

    Kariduraganavar, M. Y.; Tambe, S. M.; Tasaganva, R. G.; Kittur, A. A.; Kulkarni, S. S.; Inamdar, S. R.

    2011-02-01

    This paper presents the synthesis of highly stable nitro-substituted thiazole, benzothiazole and thiadiazole chromophores. With these, a series of second-order nonlinear optical (NLO) responsive polyurethanes were successfully synthesized from tolylene-2,4-diisocyanate (TDI) and 4,4'-methylenedi(phenyl isocyanate) (MDI). Molecular structural characterization of these polyurethanes was achieved by 1H NMR, FT-IR, GPC and analytical data. The weight-average molecular weights ( Mw) of the resulting polyurethanes were determined by GPC and ranged between 22,100 and 26,700. All the polyurethanes were highly soluble in aprotic solvents such as tetrahydrofuran, cyclohexanone, N, N-dimethylformamide, N, N-dimethylacetamide, dimethylsulphoxide, N-methyl-2-pyrolidinone, etc. The thermal behaviour of these polyurethanes was investigated using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Their glass transition temperatures were in the range 140-165 °C and most of the polymers showed high thermal stability. With an in situ poling and temperature ramping technique, the optimal temperatures ( Topts) for corona poling were determined for the largest second-order NLO response. The second harmonic generation (SHG) coefficients ( d33) of the poled polyurethane films range from 62.21 to 103.11 pm/V at 1064 nm. All the poled films showed outstanding orientational stability up to 120 °C without any measurable decay in the SHG signal. Of these, the polyurethane with nitro-substituted benzothiazole moiety ( IIb) showed the best dynamical thermal stability of the poling-induced dipole alignment up to ˜150 °C.

  6. Polyurethane-foam-component incompatibilities. [As access deterrent

    SciTech Connect

    Wischmann, K.B.

    1982-01-01

    Access deterrent foams are generated by mixing separately stored and pressurized isocyanate and polyol components upon demand. This specially designed rigid polyurethane foam system must survive ambient storage and still give acceptable foams. The polyol component, a polypropylene oxide diol adduct of phosphoric acid, in the presence of moisture apparently hydrolyzes to phosphoric acid which attacks the container and alters the foaming action. The phosphate ester adduct's fire-retardant characteristics were sacrificed in favor of a superior aging polyol component. Thus, a second foam formulation which did not contain any phosphoric acid adducts while exhibiting virtually identical foaming properties was aged under accelerated conditions. These conditions consisted of aging at room temperature, 60 and 71/sup 0/C, whereby lifetime predictions could be made by Arrhenius modeling. Specifically, the amine equivalent was followed in the isocyanate component while acid number and hydroxyl equivalent were determined in the polyol component. Interestingly, the isocyanate behaved in a predictable manner; however, again problems were encountered with the polyol component. A reaction between the polyol and the blowing agent, Freon 11, was found to give high acid content abruptly following a temperature dependent initiation period. Attempts to add inhibitors to lengthen this initiation period failed. These unsolved incompatibility problems have resulted in a foam system of uncertain quality and unknown lifetime. A third foam system is currently under investigation. 4 figures, 5 tables.

  7. Carter-Wallace debuts new polyurethane condom in U.S.

    PubMed

    1999-07-01

    Condom users in the US will have a choice in male polyurethane condoms when Carter-Wallace of Cranbury, New Jersey, introduces its first polyurethane condom, the Trojan Supra Microsheer, in July 1999. The Trojan condom joins the Durex Avanti from the London International Group of London, England, as the only nonlatex synthetic male condoms available in the US. The sole female condom, Reality, from the Female Health Co. of Chicago, is also made of polyurethane. The condom is manufactured through a dipping process of an aliphatic polyurethane material, which results in a condom that has higher tensile strength and break force than a latex condom. Furthermore, condoms manufactured from polyurethane and other plastics enhance sensitivity, do not cause allergic reactions, and are compatible with oil-based lubricants. Sensicon Corporation and Mayer Laboratories are also planning to introduce nonlatex condoms in the country. PMID:12295380

  8. [FTIR spectra study on the film of polyurethane coated urea controlled-release fertilizer].

    PubMed

    Wu, Shu; Li, Qing-shan; Ru, Tie-jun; Wang, Li-min; Xing, Guang-zhong; Wang, Jin-ming

    2011-03-01

    The polyurethane films were prepared to wrap the urea in order to achieve a desirable release rate by mixing isocyanate, polyols and wax. The effect of wax, urea and isocyanate on the structure and properties of the films was investigated by FTIR. The structural changes were monitored as the polyurethane films together with the wrapped urea were immersed into ammonia water for 28 days, which is used to model soil conditions. The FTIR results showed that the width and intensity of the NH-free band increased remarkably with time, and all kinds of carbonly bands shifted to high wavenumber and their intensity increased obviously. The results suggest that the structure of the polyurethane films was destroyed more heavily in soil than in water, and this explains the relatively fast release rate of urea in soil. It was observed that the increase in the chemical crosslinking density in the polyurethane films can effectively decrease the release rate of the urea nitrogen in soil. PMID:21595206

  9. Nuclear magnetic resonance studies on covalent modification of amino acids thiol and amino residues by monofunctional aryl 13C-isocyanates, models of skin and respiratory sensitizers: transformation of thiocarbamates into urea adducts.

    PubMed

    Fleischel, Olivier; Giménez-Arnau, Elena; Lepoittevin, Jean-Pierre

    2009-06-01

    Exposure to aryl isocyanates, intermediates in the manufacture of polyurethanes, provokes lung sensitization and asthma but also occupational allergic contact dermatitis, sensitization occurring from a single accidental exposure. The initial step in the sensitization process is believed to be the covalent binding of the -N triple bond C triple bond O group with nucleophilic residues on proteins. While a wide knowledge exists on the reactivity of skin sensitizers toward amino acids, little is known about respiratory sensitizers such as aryl isocyanates. (13)C-Labeled monofunctional aryl isocyanates were synthesized, and their reactivities toward nucleophilic amino acids, GSH, and a model peptide were studied by (13)C and [(1)H-(13)C] NMR spectroscopy. An acetonitrile/buffer solution was used as a solvent to avoid the hampering of the follow up of the reactivity by the isocyanate hydrolysis competing reaction. The compounds reacted with thiol groups, through the formation of thiocarbamate bonds and with amino groups to form urea derivatives. The reactivity was confirmed with GSH, containing both free amino and thiol groups, and with a model peptide, particularly in the case of the reaction with lysine. The use of (13)C NMR to follow the aryl isocyanates reversible conjugation with thiol groups is also reported. Particularly, it is shown that thiocarbamate adducts can be converted into adducts of the urea kind by reaction with amino groups. These results confirmed the hypothesis by which thiol-containing peptides/proteins may act as carriers of isocyanates for possible reaction at a later time and/or place with other nucleophiles and confirmed the role of lysine as a good competing nucleophilic amino acid. The reactivity of aryl isocyanates with thiol and amino groups needs thus to be considered in their assigned sensitization processes.

  10. Intramolecular Alkene Aminocarbonylation Using Concerted Cycloadditions of Amino-Isocyanates.

    PubMed

    Ivanovich, Ryan A; Clavette, Christian; Vincent-Rocan, Jean-François; Roveda, Jean-Grégoire; Gorelsky, Serge I; Beauchemin, André M

    2016-06-01

    The ubiquity of nitrogen heterocycles in biologically active molecules challenges synthetic chemists to develop a variety of tools for their construction. While developing metal-free hydroamination reactions of hydrazine derivatives, it was discovered that carbazates and semicarbazides can also lead to alkene aminocarbonylation products if nitrogen-substituted isocyanates (N-isocyanates) are formed in situ as reactive intermediates. At first this reaction required high temperatures (150-200 °C), and issues included competing hydroamination and N-isocyanate dimerization pathways. Herein, improved conditions for concerted intramolecular alkene aminocarbonylation with N-isocyanates are reported. The use of βN-benzyl carbazate precursors allows the effective minimization of N-isocyanate dimerization. Diminished dimerization leads to higher yields of alkene aminocarbonylation products, to reactivity at lower temperatures, and to an improved scope for a reaction sequence involving alkene aminocarbonylation followed by 1,2-migration of the benzyl group. Furthermore, fine-tuning of the blocking (masking) group on the N-isocyanate precursor, and reaction conditions relying on base catalysis for N-isocyanate formation from simpler precursors resulted in room temperature reactivity, consequently minimizing the competing hydroamination pathway. Collectively, this work highlights that controlled reactivity of aminoisocyanates is possible, and provides a broadly applicable alkene aminocarbonylation approach to heterocycles possessing the β-aminocarbonyl motif. PMID:27112602

  11. Intramolecular Alkene Aminocarbonylation Using Concerted Cycloadditions of Amino-Isocyanates.

    PubMed

    Ivanovich, Ryan A; Clavette, Christian; Vincent-Rocan, Jean-François; Roveda, Jean-Grégoire; Gorelsky, Serge I; Beauchemin, André M

    2016-06-01

    The ubiquity of nitrogen heterocycles in biologically active molecules challenges synthetic chemists to develop a variety of tools for their construction. While developing metal-free hydroamination reactions of hydrazine derivatives, it was discovered that carbazates and semicarbazides can also lead to alkene aminocarbonylation products if nitrogen-substituted isocyanates (N-isocyanates) are formed in situ as reactive intermediates. At first this reaction required high temperatures (150-200 °C), and issues included competing hydroamination and N-isocyanate dimerization pathways. Herein, improved conditions for concerted intramolecular alkene aminocarbonylation with N-isocyanates are reported. The use of βN-benzyl carbazate precursors allows the effective minimization of N-isocyanate dimerization. Diminished dimerization leads to higher yields of alkene aminocarbonylation products, to reactivity at lower temperatures, and to an improved scope for a reaction sequence involving alkene aminocarbonylation followed by 1,2-migration of the benzyl group. Furthermore, fine-tuning of the blocking (masking) group on the N-isocyanate precursor, and reaction conditions relying on base catalysis for N-isocyanate formation from simpler precursors resulted in room temperature reactivity, consequently minimizing the competing hydroamination pathway. Collectively, this work highlights that controlled reactivity of aminoisocyanates is possible, and provides a broadly applicable alkene aminocarbonylation approach to heterocycles possessing the β-aminocarbonyl motif.

  12. The Synergize effect of Chain extender to Phosporic acid catalyst to the ultimate property of Soy-Polyurethane

    NASA Astrophysics Data System (ADS)

    Elvistia Firdaus, Flora

    2016-04-01

    The polyurethanes (PUs) foam were made from vegetable oil; a soybean based polyol. The foams were categorized into flexible and semi rigid. This research is manufacturally designed polyurethane foams by a process requiring the reaction of mixture of 2, 4- and 2, 6-Toluene di Isocyanate isomers, soy polyol in the presence of other ingredients. The objective of this work was to functionalized soy-polyol using phosporic acid catalyst and chain extender, study their collaborative reaction in producing ultimate property of PU foam. Correlates the foam morphology images in accordance to mechanical properties of foams.

  13. Preparation and characterization of polyurethane foams using a palm oil-based polyol.

    PubMed

    Tanaka, Ryohei; Hirose, Shigeo; Hatakeyama, Hyoe

    2008-06-01

    Polyurethane (PU) foams were prepared using a palm oil-based polyol (PO-p). At the first stage, palm oil was converted to monoglycerides as a new type of polyol by glycerolysis. A yield of the product reached 70% at reaction temperature of 90 degrees C by using an alkali catalyst and a solvent. At the second stage, PU foams were prepared from mixtures of the polyol and polyethylene glycol (PEG) or diethylene glycol (DEG) and an isocyanate compound. Characterization of the foams was carried out by thermal and mechanical analyses. The analyses showed that the chain motion of polyurethane becomes more flexible at the higher PO-p content in the whole polymer, which indicates that the monoglyceride molecules work as soft segments. The study here may lead to a development of a new type of polyurethane foams using palm oil as a raw material. PMID:17698355

  14. Effect of Diisocyanate Structure on Thermal Properties and Microstructure of Polyurethanes Based on Polyols Derived from Renewable Resources

    NASA Astrophysics Data System (ADS)

    Corcuera, MaAngeles; Rueda, Lorena; Fernández d'Arlas, Borja; Saralegui, Ainara; Marieta, Cristina; Arbelaiz, Aitor; Mondragon, Iñaki; Eceiza, Arantxa

    2010-06-01

    Polyols derived from renewables resources are good candidates to obtaining segmented polyurethane elastomers. Diisocyanates with different chemical structure, aliphatic and aromatic, have been used to synthesize by a two step polymerization procedure polyurethane elastomers with different hard segment content. Microphase separation and thermal stability have been studied using attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The analysis of the H-bonded and non H-bonded urethane carbonyl stretching vibration in the amide I region, the glass transition temperature of the soft and hard segments and the melting temperature and enthalpies of hard segment reveal that aliphatic diisocyanate based polyurethanes present higher phase separation degree and harder segment crystallinity and also superior thermal stability than aromatic diisocyanate-based polyurethanes.

  15. Highly fluorinated polyurethanes

    NASA Technical Reports Server (NTRS)

    Stump, E. C., Jr.; Rochow, S. E. (Inventor)

    1973-01-01

    The reaction perfluorinated hydroxyl terminated polyether with diisocyanate to form polyurethane is discussed. Data are given on the resin's oxidation stability, chemical resistance, and low temperature flexibility.

  16. Metal-free metathesis reaction of C-chiral allylic sulfilimines with aryl isocyanates: construction of chiral nonracemic allylic isocyanates.

    PubMed

    Grange, Rebecca L; Evans, P Andrew

    2014-08-27

    We report the facile and efficient metal-free metathesis reaction of C-chiral allylic sulfilimines with aryl isocyanates. This process facilitates the room temperature construction of an array of chiral nonracemic allylic isocyanates, which are versatile intermediates for the construction of unsymmetrical ureas, carbamates, thiocarbamates and amides. Furthermore, the sulfilimine/isocyanate metathesis reaction with 4,4'-methylene diphenyl diisocyanate (4,4'-MDI) circumvents harsh reaction conditions and/or hazardous reagents employed with more classical methods for the preparation of this important functional group.

  17. Toxicity of inhaled methyl isocyanate vapor

    SciTech Connect

    Ferguson, J.S.

    1988-01-01

    The toxicity of inhaled isocyanate (MIC) vapor was evaluated using several bioassays designed to investigate the toxicity of airborne chemicals. Two methods which measure changes in respiratory rate and identify characteristic breathing patterns in mice were used to evaluate the potency of MIC as a sensory and pulmonary irritant. Using the CO{sub 2} challenge method in conjunction with the measurement of airflow (V) and tidal volume (VT), the pulmonary effects and subsequent recovery process following a single exposure to MIC were studied in guinea pigs for a period of one year. Flow-volume loops were also obtained by plotting V vs. VT. Measurement of O{sub 2} uptake and CO{sub 2} output were also performed to determine the acute and chronic effects of MIC exposure on gas exchange. Lastly, guinea pigs and mice were exposed to {sup 14}C-MIC in an effort to determine uptake and fate of inhaled MIC.

  18. Polyurethane Filler for Electroplating

    NASA Technical Reports Server (NTRS)

    Beasley, J. L.

    1984-01-01

    Polyurethane foam proves suitable as filler for slots in parts electroplated with copper or nickel. Polyurethane causes less contamination of plating bath and of cleaning and filtering tanks than wax fillers used previously. Direct cost of maintenance and indirect cost of reduced operating time during tank cleaning also reduced.

  19. Methyl isocyanate and carcinogenesis: bridgeable gaps in scientific knowledge.

    PubMed

    Senthilkumar, Chinnu Sugavanam; Sah, Nand Kishore; Ganesh, Narayanan

    2012-01-01

    Methyl isocyanate may have a role in cancer etiology, although the link is unclear. There is evidence in the literature that it can induce cancer in animals but the carcinogenic potency is weak. Pheochromocytoma of adrenal medulla and acinar cell tumors of pancreas have been observed in methyl isocyanate exposed animals. Conversely, emerging data from population-based epidemiological studies are contradictory since there is no evidence of such cancers in methyl isocyanate exposed humans. Recently, we reported a high prevalence of breast and lung cancers in such a population in Bhopal. In vitro findings appearing in the latest scientific literature suggest that genomic instability is caused by methyl isocyanate analogs in lung, colon, kidney, ovary epithelial cells, and that hepatocytes may undergo oncogenic transformation, have obvious implications. The conflicting information prompted us to present this update over the last three decades on methyl isocyanate-induced cancers after an extensive literature search using PubMed. While the pertinent literature remains limited, with a scarcity of strong laboratory analyses and field-epidemiological investigations, our succinct review of animal and human epidemiological data including in vitro evidences, should hopefully provide more insight to researchers, toxicologists, and public health professionals concerned with validation of the carcinogenicity of methyl isocyanate in humans.

  20. Farnesol-modified biodegradable polyurethanes for cartilage tissue engineering.

    PubMed

    Eglin, David; Grad, Sibylle; Gogolewski, Sylwester; Alini, Mauro

    2010-01-01

    A bifunctionalized 3,7,11-trimethyl-2,6,10-dodecatrien-1-diaminobutane amide (isoprenoid) was obtained from 3,7,11-trimethyl-2,6,10-dodecatrien-1-ol (farnesol) in a three-step synthesis. The bifunctionalized isoprenoid was characterized using infrared spectroscopy and (1)H and (13)C nuclear magnetic resonance spectroscopy and was covalently incorporated (0.12 mmol x g(-1)) into the biodegradable aliphatic polyurethane formed on the polycondensation reaction of poly(epsilon-caprolactone) diol, 1,4,3,6-dianhydro-D-sorbitol and 1,6-hexamethylene diisocyanate. Although the covalent incorporation of the isoprenoid molecule into the polyurethane chain modified the surface chemistry of the polymer, it did not affect the viability of attached chondrocytes. Porous 3D scaffolds were produced from the modified and unmodified biodegradable segmented polyurethanes by a salt leaching-phase-inverse technique. The scaffolds were seeded with bovine chondrocytes encapsulated in fibrin gel and cultured in vitro for 14 days. The incorporation of bifunctional isoprenoid into the polyurethane affected the morphology of the scaffolds produced, when compared with the morphology of the scaffolds produced using the same technique from the unmodified polyurethane. As a consequence, there was more uniform cell seeding and more homogeneous distribution of the synthesized extracellular matrix throughout the scaffold resulting in a reduced cell/tissue layer at the edges of the constructs. However, glycosaminoglycan (GAG), DNA content, and chondrocytes phenotype in the scaffolds produced from these two polyurethane formulations did not vary significantly. The findings suggest that the change of surface characteristics and the more open pore structure of the scaffolds produced from the isoprenoid-modified polyurethane are beneficial for the seeding efficiency and the homogeneity of the tissue engineered constructs. PMID:19191318

  1. Surface free energy of polyurethane coatings with improved hydrophobicity.

    PubMed

    Król, Piotr; Król, Bożena

    2012-07-01

    The polarity of polyurethane coats was studied on the basis of the goniometric method for determination of wetting angle values, on the basis of calculated surface free energy (SFE) values by the van Oss-Good and Owens-Wendt methods, and on the basis of polarity measurements with the use of the (1)H NMR spectra. Test polyurethanes were synthesised in the reaction of methylene diphenyl 4,4'-diisocyanate (MDI) or 3-izocyanatomethyl -3,5,5- trimethylcyclohexyl isocyanate (IPDI) and polyoxyethylene glycols or polyesters poly(ε-caprolactone) diols and poly(ethyleneadipate) diol with different molecular weights, and some diols as chain extenders, in dioxane. The type of raw material was found to significantly affect the phase structure of the obtained polyurethane elastomers and to control physical interactions within those structures, thus influencing the SFE values. Fundamental reduction in the SFE value of a coating below 28 mJ/m(2) was achieved by the use of 2,2,3,3-tetrafluoro-1,4-butanediol as the urethane prepolymer chain extender.

  2. Platelet adhesion onto segmented polyurethane surfaces modified by carboxybetaine.

    PubMed

    Yuan, J; Zhang, J; Zhou, J; Yuan, Y L; Shen, J; Lin, S C

    2003-01-01

    Polyurethanes are widely used as blood-contacting biomaterials due to their good biocompatibility and mechanical properties. Nevertheless, their blood compatibility is still not adequate for more demanding applications. Surface modification is an effective way to improve the hemocompatibility for biomaterials. The purpose of present study was to synthesize a novel nonthrombogenic biomaterial by modifying the surface of polyurethane with Zwitterions of carboxybetaine monomer. The films of polyurethane were grafted with two kinds of carboxybetaine by a three-step procedure. In the first step, the film surfaces were treated with hexamethylene diisocyanate (HDI) in toluene at 50 degrees C in the presence of di-n-butyl tin dilaurate (DBTDL) as a catalyst. The extent of the reaction was measured by ATR-FT-IR spectra: a maximum number of free NCO group was obtained after a reaction time of 90 min. In the second step, the hydroxyl group of N,N-dimethylethylethanolamine (DMEA) or 4-dimethylamino-1-butanol (DMBA) was allowed to react in toluene with isocyanate groups bound on surface. In the third step, carboxybetaines were formed in the surface through the ring-opening reaction between tertiary amine of DMEA or DMBA and beta-propiolactone (PL). It was characterized by ATR-FT-IR and XPS that the grafted surfaces were composed of carboxybetaine. The results of the contact angle measurements showed that they were strongly hydrophilic. Platelet adhesion tests showed that films grafted carboxybetaine have good blood compatibility, as featured by the low platelet adhesion. PMID:14870938

  3. Phosphonic Acid-Functionalized Polyurethane Dispersions with Improved Adhesion Properties.

    PubMed

    Breucker, Laura; Landfester, Katharina; Taden, Andreas

    2015-11-11

    A facile route to phosphorus-functionalized polyurethane dispersions (P-PUDs) with improved adhesion properties is presented. (Bis)phosphonic acid moieties serve as adhesion promoting sites that are covalently attached via an end-capping reaction to isocyanate-reactive polyurethane particles under aqueous conditions. The synthetic approach circumvents solubility issues, offers great flexibility in terms of polyurethane composition, and allows for the synthesis of semicrystalline systems with thermomechanical response due to reversible physical cross-linking. Differential scanning calorimetry (DSC) is used to investigate the effect of functionalization on the semicrystallinity. The end-capping conversion was determined via inductively-coupled plasma optical emission spectroscopy (ICP-OES) and was surprisingly found to be almost independent of the stoichiometry of reaction, suggesting an adsorption-dominated process. Particle charge detection (PCD) experiments reveal that a dense surface coverage of phosphonic acid groups can be attained and that, at high functionalization degrees, the phosphonic adhesion moieties are partially dragged inside the colloidal P-PUD particle. Quartz crystal microbalance with dissipation (QCMD) investigations conducted with hydroxyapatite (HAP) and stainless steel sensors as model surfaces show a greatly enhanced affinity of the aqueous P-PUDs and furthermore indicate polymer chain rearrangements and autonomous film formation under wet conditions. Due to their facile synthesis, significantly improved adhesion, and variable film properties, P-PUD systems such as the one described here are believed to be of great interest for multiple applications, e.g., adhesives, paints, anticorrosion, or dentistry. PMID:26491881

  4. The formation of high-purity isocyanurate through proazaphosphatrane-catalysed isocyanate cyclo-trimerisation: computational insights.

    PubMed

    Gibb, Jack N; Goodman, Jonathan M

    2013-01-01

    Polyurethane foams are widely used materials and control of their physical properties is a significant challenge. Management of cyclo-trimerisation during the polymerisation process is vital when tailoring the mechanical properties of the foam. Proazaphosphatranes are known to efficiently catalyse the cyclo-trimerisation of organic isocyanates, giving high purity isocyanurate with little uretdione by-product. The mechanism of this catalysis was previously unknown, although some zwitterionic intermediates have been identified spectroscopically. We have investigated a nucleophilic-catalysis reaction pathway involving sequential addition of methyl isocyanate to activated zwitterionic intermediates using density functional theory calculations. Evidence for significant transannulation by the proazaphosphatrane nitrogen was found for all intermediates, offering stabilisation of the phosphonium cation. Steric crowding at the proazaphosphatrane nucleophilic phosphorus gives rise to a preference for direct isocyanurate formation rather than via the uretdione, in sharp contrast to the uncatalysed system which has been found to preferentially proceed via the kinetic uretdione product. The investigations suggest the mechanism of proazaphosphatrane catalysed cyclo-oligomerisation does not proceed via the uretdione product, and hence why little of this impurity is observed experimentally.

  5. Ferrocenoyl piperazide as derivatizing agent for the analysis of isocyanates and related compounds using liquid chromatography/electrochemistry/mass spectrometry (LC/EC/MS).

    PubMed

    Seiwert, Bettina; Henneken, Hartmut; Karst, Uwe

    2004-12-01

    Ferrocenoyl piperazide is introduced as a new pre-column derivatizing agent for the analysis of various isocyanates in air samples using reversed-phase liquid chromatographic separation, electrochemical oxidation/ionization, and mass spectrometry. The nonpolar derivatives can be separated well using a phenyl-modified stationary phase and a formic acid/ammonium formate buffer of pH 3, which yields excellent separations, especially for one problematic group of isocyanates consisting of 2,4- and 2,6-toluylenediisocyanate (2,4- and 2,6-TDI) and hexamethylenediisocyanate (HDI). Electrochemical oxidation at low potentials (0.5 V versus Pd/H(2)) leads to formation of charged products, which are nebulized in a commercial atmospheric pressure chemical ionization (APCI) source, with the corona discharge operated only at low voltage. Limits of detection between 6 and 20 nmol/L are obtained for the isocyanate derivatives, and calibration is linear over at least two decades of concentration. The method is applied for the analysis of air after thermal degradation of a polyurethane foam, and it is demonstrated that it is suitable as well for the analysis of carboxylic acid chlorides and of isothiocyanates.

  6. 40 CFR 721.3364 - Aliphatic ether.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Aliphatic ether. 721.3364 Section 721... Aliphatic ether. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as an aliphatic ether (PMN P-93-1381) is subject to reporting under...

  7. 40 CFR 721.3364 - Aliphatic ether.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Aliphatic ether. 721.3364 Section 721... Aliphatic ether. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as an aliphatic ether (PMN P-93-1381) is subject to reporting under...

  8. Isocyanate and VOC exposure analysis using Flexane®.

    PubMed

    Blake, Charles L; Johnson, Giffe T; Abritis, Alison J; Lieckfield, Robert; Harbison, Raymond D

    2012-08-01

    Flexane® 80 is a trowelable urethane product used in combination with cleaners and primers to effect rubber conveyor belt repairs. These products are of concern due to the potential for worker exposure to isocyanates and volatile organic compounds (VOCs). Small chamber experiments were used to identify chemicals liberated to the ambient air from each of the Flexane®-related products. A new sample collection method using treated cotton sleeves as a surrogate skin surface to assess potential dermal exposure to isocyanates during mixing and application of the Flexane® product was validated. Six simulations of a worst case scenario were performed by an experienced belt repair technician in a walk-in laboratory exposure chamber. Analysis of air samples from the large chamber simulations did not detect airborne isocyanates. The average airborne VOC concentrations were below established occupational exposure levels. Dermal sleeve samples detected intermittent and low levels of isocyanates from self-application while wearing gloves having surface residues of uncured Flexane®. The data strongly suggest that the normal and intended use of Flexane® putty, and its associated products under worst case or typical working conditions is not likely to result in worker VOC or isocyanate exposure levels sufficient to produce adverse health effects. PMID:22627177

  9. DNA photoreacts by nucleobase ring cleavage to form labile isocyanates.

    PubMed

    Buschhaus, Laura; Rolf, Josefin; Kleinermanns, Karl

    2013-11-14

    Differential infrared absorption spectroscopy was used to study the formation of isocyanates and further photo-products in the oligonucleotides dG10, dC10 and dT10 and in their mononucleosides by ultraviolet light at 266 nm. We find that α-cleavage takes place in oligonucleotides and mononucleosides both in films and in solution. The very intense and spectrally isolated isocyanate (N=C=O) asymmetric stretch vibration at 2277 cm(-1) is used as a spectroscopic marker for detection of the photo-product. The band disappears upon reaction with small amounts of water vapour as expected for isocyanates. Quantum yields for isocyanate formation by nucleobase ring cleavage in the α-position to the carbonyl group are ∼5 × 10(-5) in the mononucleosides and up to 5 × 10(-4) in the oligonucleotides. In the mixed oligonucleotides dG10/dC10 and dA10/dT10 the quantum yield of α-cleavage drops by a factor of 10 compared to the single oligonucleotides. Implications for DNA repair and photo-induced DNA-protein cross-linking via isocyanate reaction with NH2 groups of amino acids are discussed.

  10. Isocyanate and VOC exposure analysis using Flexane®.

    PubMed

    Blake, Charles L; Johnson, Giffe T; Abritis, Alison J; Lieckfield, Robert; Harbison, Raymond D

    2012-08-01

    Flexane® 80 is a trowelable urethane product used in combination with cleaners and primers to effect rubber conveyor belt repairs. These products are of concern due to the potential for worker exposure to isocyanates and volatile organic compounds (VOCs). Small chamber experiments were used to identify chemicals liberated to the ambient air from each of the Flexane®-related products. A new sample collection method using treated cotton sleeves as a surrogate skin surface to assess potential dermal exposure to isocyanates during mixing and application of the Flexane® product was validated. Six simulations of a worst case scenario were performed by an experienced belt repair technician in a walk-in laboratory exposure chamber. Analysis of air samples from the large chamber simulations did not detect airborne isocyanates. The average airborne VOC concentrations were below established occupational exposure levels. Dermal sleeve samples detected intermittent and low levels of isocyanates from self-application while wearing gloves having surface residues of uncured Flexane®. The data strongly suggest that the normal and intended use of Flexane® putty, and its associated products under worst case or typical working conditions is not likely to result in worker VOC or isocyanate exposure levels sufficient to produce adverse health effects.

  11. Polyurethane-Foam Maskant

    NASA Technical Reports Server (NTRS)

    Bodemeijer, R.

    1985-01-01

    Brown wax previously used to mask hardware replaced with polyurethane foam in electroplating and electroforming operations. Foam easier to apply and remove than wax and does not contaminate electrolytes.

  12. Copper-Catalyzed Cascade Substitution/Cyclization of N-Isocyanates: A Synthesis of 1-Aminobenzimidazolones.

    PubMed

    An, Jing; Alper, Howard; Beauchemin, André M

    2016-07-15

    A copper-catalyzed cascade reaction of in situ generated nitrogen-substituted isocyanates (N-isocyanates) and 2-iodoanilines has been developed. The cascade relies on the base-catalyzed substitution of masked N-isocyanates, followed by Cu(I)-catalyzed coupling to afford a variety of 1-aminobenzimidazolones in moderate to excellent yields. This is the first example of a transition-metal-catalyzed cascade reaction involving N-isocyanate intermediates. PMID:27341005

  13. Copper-Catalyzed Cascade Substitution/Cyclization of N-Isocyanates: A Synthesis of 1-Aminobenzimidazolones.

    PubMed

    An, Jing; Alper, Howard; Beauchemin, André M

    2016-07-15

    A copper-catalyzed cascade reaction of in situ generated nitrogen-substituted isocyanates (N-isocyanates) and 2-iodoanilines has been developed. The cascade relies on the base-catalyzed substitution of masked N-isocyanates, followed by Cu(I)-catalyzed coupling to afford a variety of 1-aminobenzimidazolones in moderate to excellent yields. This is the first example of a transition-metal-catalyzed cascade reaction involving N-isocyanate intermediates.

  14. Synthesis and characterization of polyurethane ionomers, blends and urethane-urea aerogel hybrids

    NASA Astrophysics Data System (ADS)

    Wang, Mingzhe

    The chemical and physical properties of alkali, alkaline metal and selected transition metal polyurethane ionomers were investigated. A new synthesis was developed for carboxylated polyurethane anionomers, and it was employed to synthesize a range of ionomers. Thus, a series of polyurethane ionomers was prepared in which the molecular weight of a constituent diol, the concentration of carboxylic acid sites, and the nature of the cations was varied. The analogous materials with equivalent nominal stoichiometries were synthesized by the standard method of preparing the acid-form polymer and of replacing the protons for metal ions. The novel synthesis employs a multiphase reaction between isocyanate-terminated prepolymers and solid, anhydrous microcrystalline metal salts of a carboxylic acid diol. This required the development of new synthesis of these starting materials. The materials studied are based on polyether diols, acid-containing diols and a saturated diisocyanate. The novel synthesis is more than twenty times as fast as the standard method under the same conditions. The spectroscopic and mechanical properties of the polyurethane ionomers synthesized in both ways were studied and contrasted. Those prepared by the new method have greater spatial homogeneity, resulting in lower scattering loss in the ultraviolet-visible range. They also exhibited values of E ' (the real elastic modulus) that are as much as an order of magnitude greater than those made by the standard method. In addition, the temperature dependence of Fin the -25 ˜ +75°C range is remarkably low. Studies of the structural properties by infrared spectroscopy, small angle x-ray scattering, thermal analysis, gel permeation chromatography and scanning electron microscopy were used to elucidate their molecular structures and intermolecular interactions. The rates of key synthetic reactions and the thermal stability of the metal containing polyurethane ionomers were studied by thermal analysis. The

  15. Second harmonic generation and photochromic grating in polyurethane films containing diazo isoxazole chromophore

    NASA Astrophysics Data System (ADS)

    Marański, Krzysztof; Kucharski, Stanisław; Ortyl, Ewelina; Nunzi, Jean-Michel; Ahmadi-Kandjani, Sohrab; Dabos-Seignon, Sylvie; Chan, Siu-Wai; Barille, Regis

    2008-08-01

    The chromophoric intermediate: 2,2'-({4-[( E)-(5-methylisoxazol-3-yl)diazenyl]phenyl}-imino)diethanol was used in polyaddition reaction with di-isocyanate to obtain a new polyurethane polymeric material showing nonlinear optical and photochromic properties. The maximum absorption band of the polymer film was at 418 nm. The illumination of the film with crossed beams of the 488 nm Ar + laser yielded surface relief grating of regular structure. Measurement of the frequency doubling signal with 1064 nm laser indicated the polymer as interesting material for photooptical applications. The measured nonlinear optical coefficient, d33, reached 90.2 pm/V.

  16. Bio-based polyurethane foams from renewable resources

    NASA Astrophysics Data System (ADS)

    Stanzione, M.; Russo, V.; Sorrentino, A.; Tesser, R.; Lavorgna, M.; Oliviero, M.; Di Serio, M.; Iannace, S.; Verdolotti, L.

    2016-05-01

    In the last decades, bio-derived natural materials, such as vegetable oils, polysaccharides and biomass represent a rich source of hydroxyl precursors for the synthesis of polyols which can be potentially used to synthesize "greener" polyurethane foams. Herein a bio-based precursor (obtained from succinic acid) was used as a partial replacement of conventional polyol to synthesize PU foams. A mixture of conventional and bio-based polyol in presence of catalysts, silicone surfactant and diphenylmethane di-isocyanate (MDI) was expanded in a mold and cured for two hours at room temperature. Experimental results highlighted the suitability of this bio-precursor to be used in the production of flexible PU foams. Furthermore the chemo-physical characterization of the resulting foams show an interesting improvement in thermal stability and elastic modulus with respect to the PU foams produced with conventional polyol.

  17. Guided desaturation of unactivated aliphatics

    NASA Astrophysics Data System (ADS)

    Voica, Ana-Florina; Mendoza, Abraham; Gutekunst, Will R.; Fraga, Jorge Otero; Baran, Phil S.

    2012-08-01

    The excision of hydrogen from an aliphatic carbon chain to produce an isolated olefin (desaturation) without overoxidation is one of the most impressive and powerful biosynthetic transformations for which there are no simple and mild laboratory substitutes. The versatility of olefins and the range of reactions they undergo are unsurpassed in functional group space. Thus, the conversion of a relatively inert aliphatic system into its unsaturated counterpart could open new possibilities in retrosynthesis. In this article, the invention of a directing group to achieve such a transformation under mild, operationally simple, metal-free conditions is outlined. This ‘portable desaturase’ (TzoCl) is a bench-stable, commercial entity (Aldrich, catalogue number L510092) that is facile to install on alcohol and amine functionalities to ultimately effect remote desaturation, while leaving behind a synthetically useful tosyl group.

  18. Guided Desaturation of Unactivated Aliphatics

    PubMed Central

    Voica, Ana-Florina; Mendoza, Abraham; Gutekunst, Will R.; Fraga, Jorge Otero; Baran, Phil S.

    2012-01-01

    The excision of hydrogen from an aliphatic carbon chain to produce an isolated olefin (desaturation) without over-oxidation is one of the most impressive and powerful biosynthetic transformations for which there are no simple and mild laboratory substitutes. The versatility of olefins and the range of reactions they undergo is unsurpassed in functional group space. Thus, the conversion of a relatively inert aliphatic system to its unsaturated counterpart can open new possibilities in retrosynthesis. In this article, the invention of a directing group to achieve such a transformation under mild, operationally simple, metal-free conditions is outlined. This “portable desaturase” (TzoCl) is a bench-stable, commercial entity (Aldrich, cat # L510092) that is facile to install on alcohol and amine functionalities to ultimately effect remote desaturation, while leaving behind a synthetically useful tosyl group. PMID:22824894

  19. Aliphatic hydrocarbons of the fungi.

    NASA Technical Reports Server (NTRS)

    Weete, J. D.

    1972-01-01

    Review of studies of aliphatic hydrocarbons which have been recently detected in the spores of phytopathogenic fungi, and are found to be structurally very similar to the alkanes of higher plants. It appears that the hydrocarbon components of the few mycelial and yeast forms reported resemble the distribution found in bacteria. The occurence and distribution of these compounds in the fungi is discussed. Suggested functional roles of fungal spore alkanes are presented.

  20. Cell–material interactions on biphasic polyurethane matrix

    PubMed Central

    Dicesare, Patrick; Fox, Wade M.; Hill, Michael J.; Krishnan, G. Rajesh; Yang, Shuying; Sarkar, Debanjan

    2013-01-01

    Cell–matrix interaction is a key regulator for controlling stem cell fate in regenerative tissue engineering. These interactions are induced and controlled by the nanoscale features of extracellular matrix and are mimicked on synthetic matrices to control cell structure and functions. Recent studies have shown that nanostructured matrices can modulate stem cell behavior and exert specific role in tissue regeneration. In this study, we have demonstrated that nanostructured phase morphology of synthetic matrix can control adhesion, proliferation, organization and migration of human mesenchymal stem cells (MSCs). Nanostructured biodegradable polyurethanes (PU) with segmental composition exhibit biphasic morphology at nanoscale dimensions and can control cellular features of MSCs. Biodegradable PU with polyester soft segment and hard segment composed of aliphatic diisocyanates and dipeptide chain extender were designed to examine the effect polyurethane phase morphology. By altering the polyurethane composition, morphological architecture of PU was modulated and its effect was examined on MSC. Results show that MSCs can sense the nanoscale morphology of biphasic polyurethane matrix to exhibit distinct cellular features and, thus, signifies the relevance of matrix phase morphology. The role of nanostructured phases of a synthetic matrix in controlling cell–matrix interaction provides important insights for regulation of cell behavior on synthetic matrix and, therefore, is an important tool for engineering tissue regeneration. PMID:23255285

  1. Combinatorics of aliphatic amino acids.

    PubMed

    Grützmann, Konrad; Böcker, Sebastian; Schuster, Stefan

    2011-01-01

    This study combines biology and mathematics, showing that a relatively simple question from molecular biology can lead to complicated mathematics. The question is how to calculate the number of theoretically possible aliphatic amino acids as a function of the number of carbon atoms in the side chain. The presented calculation is based on earlier results from theoretical chemistry concerning alkyl compounds. Mathematical properties of this number series are highlighted. We discuss which of the theoretically possible structures really occur in living organisms, such as leucine and isoleucine with a chain length of four. This is done both for a strict definition of aliphatic amino acids only involving carbon and hydrogen atoms in their side chain and for a less strict definition allowing sulphur, nitrogen and oxygen atoms. While the main focus is on proteinogenic amino acids, we also give several examples of non-proteinogenic aliphatic amino acids, playing a role, for instance, in signalling. The results are in agreement with a general phenomenon found in biology: Usually, only a small number of molecules are chosen as building blocks to assemble an inconceivable number of different macromolecules as proteins. Thus, natural biological complexity arises from the multifarious combination of building blocks.

  2. Lewis acid-promoted reactions of zirconacyclopentadienes with isocyanates. A one-pot three-component synthesis of multiply-substituted iminocyclopentadienes from one isocyanate and two alkynes.

    PubMed

    Lu, Jiang; Mao, Guoliang; Zhang, Wenxiong; Xi, Zhenfeng

    2005-10-14

    Multiply-substituted iminocyclopentadienes were formed from Lewis acid-promoted reactions of zirconacyclopentadienes and isocyanates via a one-pot three-component coupling process; the C=O double bond of the RN=C=O moiety in the isocyanate was cleaved, and the isocyanates behaved formally as a one-carbon unit with Lewis acid-dependent and substituent-dependent reactions being realized.

  3. Biomarkers of exposure, antibodies, and respiratory symptoms in workers heating polyurethane glue.

    PubMed Central

    Skarping, G; Dalene, M; Svensson, B G; Littorin, M; Akesson, B; Welinder, H; Skerfving, S

    1996-01-01

    OBJECTIVES: The pathogenic basis of respiratory disorders associated with isocyanates are still obscure. One reason for this is the lack of good estimates of human exposure. In this study exposure was estimated by measurement of isocyanate metabolites in biological samples. METHODS: In a factory using isocyanate based polyurethane (PUR) glue, isocyanate concentrations in air were measured by liquid chromatography. Samples from 174 employees were analysed for metabolites of 4,4'-methylene diphenyl diisocyanate (MDI) in plasma (P-MDX) and urine (U-MDX). After hydrolysis, 4,4'-methylenedianiline was measured by gas chromatography-mass spectrometry (GC-MS). The employees were screened for work related respiratory symptoms and tested for specific immunoglobulin E (IgE) and IgG antibodies directed against isocyanate conjugated to human serum albumin. RESULTS: The time weighted isocyanate concentrations in air were low (MDI < 0.2-7; hexamethylene diisocyanate (HDI) < 0.1-0.7; 2,6-toluene diisocyanate (TDI) < 0.1 microgram/m3). All subjects had detectable P-MDX and U-MDX. There were significant associations between the estimates of exposure to thermal degradation products of an MDI based glue and P-MDX (range < or = 0.10-5.5 micrograms/l); and U-MDX (< or = 0.04-5.0 micrograms/g creatinine); in cases of heavy exposure. P-MDX and U-MDX were associated with each other (r = 0.64; P = 0.0001), work related symptoms (P-MDX: P = 0.03; Mann-Whitney U test), and serum concentrations of MDI specific IgG antibodies (r = 0.26; P = 0.0007). Unexpectedly, high P-MDX and U-MDX concentrations were also encountered in workers cutting textile (P-MDX 2.4-4.5 micrograms/l; U-MDX 0.81-3.8 micrograms/g creatinine); the reason is still unknown. Equally unexpected, there were significant negative associations between P-MDX and liver function tests. CONCLUSIONS: The results clearly show the value of biomarkers for isocyanate exposure; in particular, P-MDX is useful. Further, these results show

  4. Exposure to MDI during the process of insulating buildings with sprayed polyurethane foam.

    PubMed

    Crespo, J; Galán, J

    1999-08-01

    Buildings are often insulated with sprayed-in-place polyurethane foam in spite of the fact that few studies have been carried out on exposure levels to isocyanates during the spraying process. This paper is meant to provide new data on personal exposure to methylene-bis (4-phenylisocyanate) (MDI) while dwellings and office buildings are being insulated with polyurethane foam. An impinger using a 1-(2-methoxyphenyl)piperazine toluene solution as absorbent was used to take personal samples for the sprayer and helper during indoor and outdoor applications. The analytical results show that the levels of exposure were significant, especially for the sprayer, with values of up to 0.077 mg m-3 and 0.400 mg m-3 during outdoor and indoor applications, respectively. The helper's exposure was always lower.

  5. Adsorption efficiency of respirator filter cartridges for isocyanates.

    PubMed

    Gustavsson, Marcus; Meiby, Elinor; Gylestam, Daniel; Dahlin, Jakob; Spanne, Mårten; Karlsson, Daniel; Dalene, Marianne; Skarping, Gunnar; Tveterås, Björn Oscar; Pedersen, Age Engen

    2010-06-01

    In some industries, the temperature and the humidity will vary greatly between different work places, such as outdoor work in arctic or tropical climates. There is therefore a need to test respirator filters at conditions that simulate conditions that are relevant for the industries that they are used in. Filter cartridges were exposed to controlled atmospheres of varying isocyanate concentration, air humidity, and temperature in an exposure chamber. For isocyanic acid (ICA) and methyl isocyanate (MIC), the exposure concentrations were between 100 and 200 p.p.b., monitored using a proton transfer reaction mass spectrometer. ICA and MIC were generated by continuous thermal degradation of urea and dimethylurea. The breakthrough was studied by collecting air samples at the outlet of the filter cartridges using impinger flasks or dry samplers with di-n-butylamine as derivatization reagent for isocyanates followed by liquid chromatography tandem mass spectrometry (LC-MS/MS) analysis. For hexamethylene diisocyanate (HDI) and isophorone diisocyanate (IPDI), the exposure concentrations were between 4 and 20 p.p.b. and were generated by wet membrane permeation. To reveal the profile of adsorption in different layers of the respirator filters, representative samples from each of the layers were hydrolyzed. The hydrolysis products hexamethylene diamine and isophorone diamine were determined after derivatization with pentafluoropropionic anhydride (PFPA) followed by LC-MS/MS analysis. The two filter types studied efficiently absorbed both ICA and MIC. There was no trend of impaired performance throughout 48-h exposure tests. Even when the filters were exposed to high concentrations (approximately 200 p.p.b.) of ICA and MIC for 96 h, the isocyanates were efficiently absorbed with only a limited breakthrough. The majority of the HDI and IPDI (>90%) were absorbed in the top layers of the absorbant, but HDI and IPDI penetrated farther down into the respirator filters during 120 h

  6. Adsorption efficiency of respirator filter cartridges for isocyanates.

    PubMed

    Gustavsson, Marcus; Meiby, Elinor; Gylestam, Daniel; Dahlin, Jakob; Spanne, Mårten; Karlsson, Daniel; Dalene, Marianne; Skarping, Gunnar; Tveterås, Björn Oscar; Pedersen, Age Engen

    2010-06-01

    In some industries, the temperature and the humidity will vary greatly between different work places, such as outdoor work in arctic or tropical climates. There is therefore a need to test respirator filters at conditions that simulate conditions that are relevant for the industries that they are used in. Filter cartridges were exposed to controlled atmospheres of varying isocyanate concentration, air humidity, and temperature in an exposure chamber. For isocyanic acid (ICA) and methyl isocyanate (MIC), the exposure concentrations were between 100 and 200 p.p.b., monitored using a proton transfer reaction mass spectrometer. ICA and MIC were generated by continuous thermal degradation of urea and dimethylurea. The breakthrough was studied by collecting air samples at the outlet of the filter cartridges using impinger flasks or dry samplers with di-n-butylamine as derivatization reagent for isocyanates followed by liquid chromatography tandem mass spectrometry (LC-MS/MS) analysis. For hexamethylene diisocyanate (HDI) and isophorone diisocyanate (IPDI), the exposure concentrations were between 4 and 20 p.p.b. and were generated by wet membrane permeation. To reveal the profile of adsorption in different layers of the respirator filters, representative samples from each of the layers were hydrolyzed. The hydrolysis products hexamethylene diamine and isophorone diamine were determined after derivatization with pentafluoropropionic anhydride (PFPA) followed by LC-MS/MS analysis. The two filter types studied efficiently absorbed both ICA and MIC. There was no trend of impaired performance throughout 48-h exposure tests. Even when the filters were exposed to high concentrations (approximately 200 p.p.b.) of ICA and MIC for 96 h, the isocyanates were efficiently absorbed with only a limited breakthrough. The majority of the HDI and IPDI (>90%) were absorbed in the top layers of the absorbant, but HDI and IPDI penetrated farther down into the respirator filters during 120 h

  7. Regulation of isocyanate-induced apoptosis, oxidative stress, and inflammation in cultured human neutrophils: isocyanate-induced neutrophils apoptosis.

    PubMed

    Mishra, P K; Khan, S; Bhargava, A; Panwar, H; Banerjee, S; Jain, S K; Maudar, K K

    2010-06-01

    Implications of environmental toxins on the regulation of neutrophil function are being significantly appraised. Such effects can be varied and markedly different depending on the type and extent of chemical exposure, which results in direct damage to the immune system. Isocyanates with functional group (-NCO), are considered as highly reactive molecules with diverse industrial applications. However, patho-physiological implications resulting from their occupational and accidental exposures have not been well delineated. The present study was carried out to assess the immunotoxic response of isocyanates and their mode of action at a molecular level on cultured human neutrophils isolated from healthy human volunteers. Studies were conducted to evaluate both dose- and time-dependent (n = 3) response using N-succinimidyl N-methylcarbamate, a chemical entity that mimics the effects of methyl isocyanate in vitro. Measure of apoptosis through annexin-V-FITC/PI assay, active caspase-3, apoptotic DNA ladder assay and mitochondrial depolarization; induction of oxidative stress by CM-H(2)DCFDA and formation of 8'-hydroxy-2'-deoxyguanosine; and levels of antioxidant defense system enzyme glutathione reductase, multiplex cytometric bead array analysis to quantify the secreted cytokine levels (interleukin-8, interleukin-1beta, interleukin-6, interleukin-10, interferon-gamma, tumor necrosis factor, and interleukin-12p70) parameters were evaluated. Our results demonstrate that isocyanates induce neutrophil apoptosis via activation of mitochondrial-mediated pathway along with reactive oxygen species production; depletion in antioxidant defense states; and elevated pro-inflammatory cytokine response.

  8. The role of nanocrystalline cellulose on the microstructure of foamed castor-oil polyurethane nanocomposites.

    PubMed

    Cordero, Andrés Ignacio; Amalvy, Javier Ignacio; Fortunati, Elena; Kenny, José María; Chiacchiarelli, Leonel Matías

    2015-12-10

    Nanocrystalline cellulose (CNC), obtained by sulphuric acid hydrolysis, was used to synthesize polyurethane foams (PUFs) based on a functionalized castor oil polyol and a Methylene diphenyl diisocyanate (MDI). Formulations with varying isocyanate index (FI) and NCO number were prepared. At 0.5 wt.%, SEM's of the fractured surface underlined that the CNC acted both as a nucleation agent and as a particulate surfactant with cell geometries and apparent density changing selectively. The chemical structure of the PUF (FTIR) changed after the incorporation of CNC by a relative change of the amount of urea, urethane and isocyanurate groups. A low NCO number and isocyanate index contributed to the migration of the CNC to the Hard Segment (HS), acting as reinforcement and improving substantially the compressive mechanical properties (Ec and σc improvements of 63 and 50%, respectively). For a high NCO number or isocyanate index, the CNC migrated to the Soft Segment (SS), without causing a reinforcement effect. The migration of the CNC was also detected with DSC, TGA and DMA, furtherly supporting the hypothesis that a low NCO number and index contributed both to the formation of a microstructure with a higher content of urethane groups.

  9. The role of nanocrystalline cellulose on the microstructure of foamed castor-oil polyurethane nanocomposites.

    PubMed

    Cordero, Andrés Ignacio; Amalvy, Javier Ignacio; Fortunati, Elena; Kenny, José María; Chiacchiarelli, Leonel Matías

    2015-12-10

    Nanocrystalline cellulose (CNC), obtained by sulphuric acid hydrolysis, was used to synthesize polyurethane foams (PUFs) based on a functionalized castor oil polyol and a Methylene diphenyl diisocyanate (MDI). Formulations with varying isocyanate index (FI) and NCO number were prepared. At 0.5 wt.%, SEM's of the fractured surface underlined that the CNC acted both as a nucleation agent and as a particulate surfactant with cell geometries and apparent density changing selectively. The chemical structure of the PUF (FTIR) changed after the incorporation of CNC by a relative change of the amount of urea, urethane and isocyanurate groups. A low NCO number and isocyanate index contributed to the migration of the CNC to the Hard Segment (HS), acting as reinforcement and improving substantially the compressive mechanical properties (Ec and σc improvements of 63 and 50%, respectively). For a high NCO number or isocyanate index, the CNC migrated to the Soft Segment (SS), without causing a reinforcement effect. The migration of the CNC was also detected with DSC, TGA and DMA, furtherly supporting the hypothesis that a low NCO number and index contributed both to the formation of a microstructure with a higher content of urethane groups. PMID:26428106

  10. Dermal and inhalation exposure to methylene bisphenyl isocyanate (MDI) in iron foundry workers.

    PubMed

    Liljelind, I; Norberg, C; Egelrud, L; Westberg, H; Eriksson, K; Nylander-French, L A

    2010-01-01

    Diisocyanates are a group of chemically reactive agents, which are used in the production of coatings, adhesives, polyurethane foams, and parts for the automotive industry and as curing agents for cores in the foundry industry. Dermal and inhalation exposure to methylene bisphenyl isocyanate (MDI) is associated with respiratory sensitization and occupational asthma. However, limited research has been performed on the quantitative evaluation of dermal and inhalation exposure to MDI in occupationally exposed workers. The objective of this research was to quantify dermal and inhalation exposure levels in iron foundry workers. Workers involved in mechanized moulding and mechanized production of cores were monitored: 12 core makers, 2 core-sand preparers, and 5 core installers. Personal breathing-zone levels of MDI were measured using impregnated filter sampling. Dermal exposure to MDI was measured using a tape-strip technique. Three or five consecutive tape-strip samples were collected from five exposed skin areas (right and left forefingers, left and right wrists, and forehead). The average personal air concentration was 0.55 microg m(-3), 50-fold lower than the Swedish occupational exposure limit of 30 microg m(-3). The core makers had an average exposure of 0.77 microg m(-3), which was not significantly different from core installers' and core-sand preparers' average exposure of 0.16 microg m(-3) (P = 0.059). Three core makers had a 10-fold higher inhalation exposure than the other core makers. The core makers' mean dermal exposure at different skin sites varied from 0.13 to 0.34 microg while the two other groups' exposure ranged from 0.006 to 0.062 microg. No significant difference was observed in the MDI levels between the skin sites in a pairwise comparison, except for left forefinger compared to left and right wrist (P < 0.05). In addition, quantifiable but decreasing levels of MDI were observed in the consecutive tape strip per site indicating MDI penetration

  11. Dermal and inhalation exposure to methylene bisphenyl isocyanate (MDI) in iron foundry workers.

    PubMed

    Liljelind, I; Norberg, C; Egelrud, L; Westberg, H; Eriksson, K; Nylander-French, L A

    2010-01-01

    Diisocyanates are a group of chemically reactive agents, which are used in the production of coatings, adhesives, polyurethane foams, and parts for the automotive industry and as curing agents for cores in the foundry industry. Dermal and inhalation exposure to methylene bisphenyl isocyanate (MDI) is associated with respiratory sensitization and occupational asthma. However, limited research has been performed on the quantitative evaluation of dermal and inhalation exposure to MDI in occupationally exposed workers. The objective of this research was to quantify dermal and inhalation exposure levels in iron foundry workers. Workers involved in mechanized moulding and mechanized production of cores were monitored: 12 core makers, 2 core-sand preparers, and 5 core installers. Personal breathing-zone levels of MDI were measured using impregnated filter sampling. Dermal exposure to MDI was measured using a tape-strip technique. Three or five consecutive tape-strip samples were collected from five exposed skin areas (right and left forefingers, left and right wrists, and forehead). The average personal air concentration was 0.55 microg m(-3), 50-fold lower than the Swedish occupational exposure limit of 30 microg m(-3). The core makers had an average exposure of 0.77 microg m(-3), which was not significantly different from core installers' and core-sand preparers' average exposure of 0.16 microg m(-3) (P = 0.059). Three core makers had a 10-fold higher inhalation exposure than the other core makers. The core makers' mean dermal exposure at different skin sites varied from 0.13 to 0.34 microg while the two other groups' exposure ranged from 0.006 to 0.062 microg. No significant difference was observed in the MDI levels between the skin sites in a pairwise comparison, except for left forefinger compared to left and right wrist (P < 0.05). In addition, quantifiable but decreasing levels of MDI were observed in the consecutive tape strip per site indicating MDI penetration

  12. Degradability in vitro of polyurethanes based on synthetic atactic poly[(R,S)-3-hydroxybutyrate].

    PubMed

    Brzeska, J; Janeczek, H; Janik, H; Kowalczuk, M; Rutkowska, M

    2015-01-01

    The aim of the present study was to determine the degradability of aliphatic polyurethanes, based on a different amount of synthetic, atactic poly[(R,S)-3-hydroxybutyrate] (a-PHB), in hydrolytic (phosphate buffer) and oxidative (H2O2/CoCl2) solutions. The soft segments were built with atactic poly[(R,S)-3-hydroxybutyrate] and polycaprolactone or polyoxytetramethylenediols, whereas hard segments were the reaction product of 4,4'-methylenedicyclohexyl diisocyanate and 1,4-butanediol.The selected properties - density and morphology of polymer surfaces - which could influence the sensitivity of polymers to degradation processes - were analyzed.The analysis of molecular mass (GPC), thermal properties (DSC) and the sample weight changes were undertaken to estimate the degree of degradability of polymer samples after incubation in environments studied.Investigated polyurethanes were amorphous with the very low amount of crystalline phases of hard segments.The polyurethane synthesized with a poly[(R,S)-3-hydroxybutyrate] and polyoxytetramethylenediol at a molar ratio of NCO:OH=3.7:1 (prepolymer step) appeared as the most sensitive for both degradative solutions. Its weight and molecular mass losses were the highest in comparison to other investigated polyurethanes.It could be expected that playing with the amount of poly[(R,S)-3-hydroxybutyrate] in polyurethane synthesis the rate of polyurethane degradation after immersion in living body would be modeled.

  13. Dynamics of Segmented Polyurethane Elastomers Using Dielectric Spectroscopy

    NASA Astrophysics Data System (ADS)

    Runt, James; Fragiadakis, Daniel; Castagna, Alicia; Choi, Taeyi

    2009-03-01

    This investigation focuses on the molecular dynamics of segmented polyurethane copolymers with different hard segment contents (30 to 52 wt percent) and soft segment chemistries. Methylene bis(p-phenyl isocyanate) and 1,4-butanediol constitute the hard segments in all materials under investigation, while soft segments include poly(tetramethylene oxide) and a 80-20 mixture of poly(dimethylsiloxane) and poly(hexamethylene oxide). The dynamics of these materials were explored over a wide temperature and frequency range using dielectric spectroscopy. In addition to investigating the details of segmental and local processes, three dielectric relaxations above Tg were observed for the first time in segmented polyurethanes, and their origin discussed in the presentation. For example, the highest temperature process is assigned to Maxwell-Wagner-Sillars interfacial polarization. The strength of the MWS process is a sensitive indicator of the change in microphase-separated character. It disappears at a temperature similar to that at which the small-angle X-ray scattering maximum disappears, indicating the transformation to the single phase state.

  14. Synthesis and surface properties of environmentally responsive segmented polyurethanes.

    PubMed

    Vaidya, Ashish; Chaudhury, Manoj K

    2002-05-01

    Polyurethanes, containing well-defined assemblies of perfluoro-polyether (PFPE or hexafluoropropene oxide oligomer), polydimethylsiloxane (PDMS), and polyethylene glycol (PEG) segments, exhibit oleophobic, hydrophobic, and hydrophilic properties in response to the polarity of the contacting medium. These polymers were prepared by reacting hydroxy(polyethyleneoxy)-propylether-terminated PDMS block copolymer (HO-PEG-PDMS-PEG-OH) with 4,4'-methylene-bis(phenylene isocyanate) (MDI) in the presence of dibutyltin dilaurate catalyst, followed by reaction with 1,2-diol functional PFPE and chain extension with 2,2,3,3-tetrafluoro-1,4-butanediol (FB). The oleophobic and hydrophobic properties of the segmented polyurethanes (SPU) are due to the segregation of PFPE segments at the polymer-air interface. Wettability studies revealed that the same surface becomes hydrophilic, presumably due to the segregation of the PEG segments at the polymer-water interface. This hydrophobic-to-hydrophilic transformation of the surface prevails not only when the polymer is in contact with liquid water but with water vapor as well. The understanding of the reconstruction mechanism of this novel family of SPU surfaces would furnish valuable information for various applications where dynamic transformation of surface activity is desired. PMID:16290591

  15. Synthesis and surface properties of environmentally responsive segmented polyurethanes.

    PubMed

    Vaidya, Ashish; Chaudhury, Manoj K

    2002-05-01

    Polyurethanes, containing well-defined assemblies of perfluoro-polyether (PFPE or hexafluoropropene oxide oligomer), polydimethylsiloxane (PDMS), and polyethylene glycol (PEG) segments, exhibit oleophobic, hydrophobic, and hydrophilic properties in response to the polarity of the contacting medium. These polymers were prepared by reacting hydroxy(polyethyleneoxy)-propylether-terminated PDMS block copolymer (HO-PEG-PDMS-PEG-OH) with 4,4'-methylene-bis(phenylene isocyanate) (MDI) in the presence of dibutyltin dilaurate catalyst, followed by reaction with 1,2-diol functional PFPE and chain extension with 2,2,3,3-tetrafluoro-1,4-butanediol (FB). The oleophobic and hydrophobic properties of the segmented polyurethanes (SPU) are due to the segregation of PFPE segments at the polymer-air interface. Wettability studies revealed that the same surface becomes hydrophilic, presumably due to the segregation of the PEG segments at the polymer-water interface. This hydrophobic-to-hydrophilic transformation of the surface prevails not only when the polymer is in contact with liquid water but with water vapor as well. The understanding of the reconstruction mechanism of this novel family of SPU surfaces would furnish valuable information for various applications where dynamic transformation of surface activity is desired.

  16. Preparation of porous polyurethane particles and their use in enzyme immobilization.

    PubMed

    Wang, X; Ruckenstein, E

    1993-01-01

    Porous polyurethane particles were prepared as follows: (1) Two low molecular weight polymers, namely, poly[methylene(polyphenyl isocyanate)] and poly(propylene glycol) were mixed with stirring at room temperature and allowed to react. (2) The reacted mixture was dispersed with stirring in mineral oil containing small amounts of water, the catalyst dibutyltin dilaurate, and CaCO3 powder. In the presence of the catalyst, the reaction between the two polymers proceeded to completion. Small particles of polyurethane are thus formed which contain mineral oil and CaCO3 as porogens. The particles obtained, separated by filtration, were treated with a solution of HCl in order to generate additional pores, extracted with benzene to eliminate the mineral oil present in the pores, and finally subjected to drying and sieving. The particles were investigated by scanning electron microscopy (SEM), infrared (IR) spectroscopy, and specific surface area measurements. Lipase from Candida rugosa was immobilized by adsorption on the porous polyurethane particles and cross-linked with glutaraldehyde to enhance the stability of the immobilization. The biocatalytic particles were used for the hydrolysis of triacylglycerides. The high activity of the immobilized enzyme, which per enzyme molecule can be higher than that of the free enzyme, reveals that the porous polyurethane particles constitute excellent supports for lipase.

  17. Experiments to populate and validate a processing model for polyurethane foam :

    SciTech Connect

    Mondy, Lisa Ann; Rao, Rekha Ranjana; Shelden, Bion; Soehnel, Melissa Marie; O'Hern, Timothy J.; Grillet, Anne; Celina, Mathias Christopher; Wyatt, Nicholas B.; Russick, Edward Mark; Bauer, Stephen J.; Hileman, Michael Bryan; Urquhart, Alexander; Thompson, Kyle Richard; Smith, David Michael

    2014-03-01

    We are developing computational models to elucidate the expansion and dynamic filling process of a polyurethane foam, PMDI. The polyurethane of interest is chemically blown, where carbon dioxide is produced via the reaction of water, the blowing agent, and isocyanate. The isocyanate also reacts with polyol in a competing reaction, which produces the polymer. Here we detail the experiments needed to populate a processing model and provide parameters for the model based on these experiments. The model entails solving the conservation equations, including the equations of motion, an energy balance, and two rate equations for the polymerization and foaming reactions, following a simplified mathematical formalism that decouples these two reactions. Parameters for the polymerization kinetics model are reported based on infrared spectrophotometry. Parameters describing the gas generating reaction are reported based on measurements of volume, temperature and pressure evolution with time. A foam rheology model is proposed and parameters determined through steady-shear and oscillatory tests. Heat of reaction and heat capacity are determined through differential scanning calorimetry. Thermal conductivity of the foam as a function of density is measured using a transient method based on the theory of the transient plane source technique. Finally, density variations of the resulting solid foam in several simple geometries are directly measured by sectioning and sampling mass, as well as through x-ray computed tomography. These density measurements will be useful for model validation once the complete model is implemented in an engineering code.

  18. Development and application of a dichotomous vapor/aerosol sampler for HDI-derived total reactive isocyanate group.

    PubMed

    Rando, R J; Poovey, H G

    1999-01-01

    A dichotomous vapor/aerosol sampler was developed for measurement of HDI (1,6-hexamethylene diisocyanate)-derived total reactive isocyanate group (TRIG). The sampler consisted of an impactor or cyclone inlet, followed by an annular diffusional denuder, and a glass-fiber filter backup. The denuder walls and backup filter were each coated with 20 mg tributylphosphate and 1 mg MAMA reagent (9-N-methylamino-methylanthracene). After collection, MAMA-derivatized isocyanates were desorbed from the sampler and determined by high-performance liquid chromatography with dual-wavelength ultraviolet absorbance and fluorescence detection. Test atmospheres of HDI vapor and of HDI/HDI-biuret aerosols were generated in the laboratory and sampled with the optimized dichotomous sampler. Vapor phase HDI was completely collected by the diffusional denuder. When a mixture of HDI-biuret and HDI (approximately 30 ppb) was nebulized and collected with the dichotomous sampler, approximately 78% of the HDI was in the vapor phase, whereas about 22% was associated with the aerosol fraction. The dichotomous sampler was then used to measure vapor and condensed phase TRIG in a paint spray booth during application of a polyurethane paint. Measured levels of TRIG during the spraying operation averaged 391 +/- 154 micrograms/m3. Concentrations of HDI monomer averaged only 14 +/- 6.5 micrograms/m3. HDI-biuret was the largest component of TRIG found in these samples and was completely in the condensed aerosol phase. In contrast, the majority of the HDI was in the vapor phase, but significant (15-26%) amounts were measured in the aerosol fraction of the paint overspray. Thus, significant partitioning of HDI between vapor and condensed phases was demonstrated in both the laboratory and field, even when its concentration was well below the vapor saturation point.

  19. Development and application of a dichotomous vapor/aerosol sampler for HDI-derived total reactive isocyanate group.

    PubMed

    Rando, R J; Poovey, H G

    1999-01-01

    A dichotomous vapor/aerosol sampler was developed for measurement of HDI (1,6-hexamethylene diisocyanate)-derived total reactive isocyanate group (TRIG). The sampler consisted of an impactor or cyclone inlet, followed by an annular diffusional denuder, and a glass-fiber filter backup. The denuder walls and backup filter were each coated with 20 mg tributylphosphate and 1 mg MAMA reagent (9-N-methylamino-methylanthracene). After collection, MAMA-derivatized isocyanates were desorbed from the sampler and determined by high-performance liquid chromatography with dual-wavelength ultraviolet absorbance and fluorescence detection. Test atmospheres of HDI vapor and of HDI/HDI-biuret aerosols were generated in the laboratory and sampled with the optimized dichotomous sampler. Vapor phase HDI was completely collected by the diffusional denuder. When a mixture of HDI-biuret and HDI (approximately 30 ppb) was nebulized and collected with the dichotomous sampler, approximately 78% of the HDI was in the vapor phase, whereas about 22% was associated with the aerosol fraction. The dichotomous sampler was then used to measure vapor and condensed phase TRIG in a paint spray booth during application of a polyurethane paint. Measured levels of TRIG during the spraying operation averaged 391 +/- 154 micrograms/m3. Concentrations of HDI monomer averaged only 14 +/- 6.5 micrograms/m3. HDI-biuret was the largest component of TRIG found in these samples and was completely in the condensed aerosol phase. In contrast, the majority of the HDI was in the vapor phase, but significant (15-26%) amounts were measured in the aerosol fraction of the paint overspray. Thus, significant partitioning of HDI between vapor and condensed phases was demonstrated in both the laboratory and field, even when its concentration was well below the vapor saturation point. PMID:10635539

  20. A base-mediated self-propagative Lossen rearrangement of hydroxamic acids for the efficient and facile synthesis of aromatic and aliphatic primary amines.

    PubMed

    Ohtsuka, Naoya; Okuno, Moriaki; Hoshino, Yujiro; Honda, Kiyoshi

    2016-10-14

    A variety of aromatic and aliphatic hydroxamic acids were converted to the corresponding primary amines via base-mediated rearrangement. This rearrangement could proceed with less than 1 equiv. of K2CO3 in polar solvents under thermal conditions with no external reagents. This rearrangement has several features including no external activating agents needed for promoting the rearrangement, less than one equivalent of a base is sufficient for the reaction, and a clean reaction in which only carbon dioxide is produced as a by-product. A self-propagating mechanism via an isocyanate intermediate is proposed and elementary reaction steps, namely, chain propagation reactions are supported by experiments. PMID:27605448

  1. A base-mediated self-propagative Lossen rearrangement of hydroxamic acids for the efficient and facile synthesis of aromatic and aliphatic primary amines.

    PubMed

    Ohtsuka, Naoya; Okuno, Moriaki; Hoshino, Yujiro; Honda, Kiyoshi

    2016-10-14

    A variety of aromatic and aliphatic hydroxamic acids were converted to the corresponding primary amines via base-mediated rearrangement. This rearrangement could proceed with less than 1 equiv. of K2CO3 in polar solvents under thermal conditions with no external reagents. This rearrangement has several features including no external activating agents needed for promoting the rearrangement, less than one equivalent of a base is sufficient for the reaction, and a clean reaction in which only carbon dioxide is produced as a by-product. A self-propagating mechanism via an isocyanate intermediate is proposed and elementary reaction steps, namely, chain propagation reactions are supported by experiments.

  2. Bacterial isolates degrading aliphatic polycarbonates.

    PubMed

    Suyama, T; Hosoya, H; Tokiwa, Y

    1998-04-15

    Bacteria that degrade an aliphatic polycarbonate, poly(hexamethylene carbonate), were isolated from river water in Ibaraki. Prefecture, Japan, after enrichment in liquid medium containing poly(hexamethylene carbonate) suspensions as carbon source, and dilution to single cells. Four of the strains, 35L, WFF52, 61A and 61B2, degraded poly(hexamethylene carbonate) on agar plate containing suspended poly(hexamethylene carbonate). Degradation of poly(hexamethylene carbonate) was confirmed by gel permeation chromatography. Besides poly(hexamethylene carbonate), the strains were found to degrade poly(tetramethylene carbonate). The strains were characterized morphologically, physiologically, and by 16S rDNA sequence analysis. Strains 35L and WFF52 were tentatively identified as Pseudomonas sp. and Variovorax sp., respectively, while strains 61A and 61B2 constitute an unidentified branch within the beta subclass of the Proteobacteria.

  3. A chronic eosinophilic pneumonia case with long exposure to isocyanates.

    PubMed

    Yalcin, Funda; Sak, Zafer Hasan Ali; Boyaci, Nurefsan; Gencer, Mehmet

    2014-10-01

    Chronic eosinophilic pneumonia (CEP) is a disease with unknown etiology, characterized by peripheral blood eosinophilia and abnormal eosinophil accumulation in the lungs. A 43-year-old male with 30 years history of exposure to isocyanates was admitted with the complaint of sputum, cough, progressive dyspnoea, and weight loss. Physical examination revealed bilaterally decreased breath sounds and extensive rales. On laboratory analysis; leukocytosis (12.3 10(3)/proportional variant L), hypereosinophilia (30%), elevated CRP and RF (1000 IU/ml), and IgE levels (1160 IU/ml) in the serum were observed. Chest radiograph and computed tomography on admission showed reticulonodular pattern at both lung fields. Pulmonary function tests assumed a restrictive pattern and a low diffusing capacity. Bronchoalveolar lavage revealed a marked eosinophilia (50%). Transbronchial lung biopsy indicated eosinophilic pneumonia. In this case we aimed to describe a rare case of CEP probably caused by exposure to isocyanate.

  4. Divergent Reactivity of N-Isocyanates with Primary and Secondary Amines: Access to Pyridazinones and Triazinones.

    PubMed

    Derasp, Joshua S; Vincent-Rocan, Jean-François; Beauchemin, André M

    2016-02-19

    Cascade reactions for the synthesis of 1,2,4-triazinones and 5-aminopyridazinones are reported using α-ketocarbazones as N-isocyanate precursors and exploiting the divergent reactivity observed with primary and secondary amines. Triazinones were formed with primary amines, likely through addition of the amine on the N-isocyanate, followed by cyclization (condensation) on the ketone. In contrast, such cyclization is impossible for secondary amines; this allows in situ formation of enamines, which, upon cyclization, generate 5-amino pyridazinones. This sequence further illustrates the versatility of N-isocyanates in heterocyclic synthesis and provides a rare example of carbon nucleophiles reacting with N-isocyanates.

  5. Improvement on wear resistance property of polyurethane film by compositing plasma-treated multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Ogawa, Daisuke; Nakamura, Keiji

    2016-01-01

    We investigated the effect of plasma-treated multi-walled carbon nanotubes (CNTs) that are composited into a polyurethane (PU) film. In this journal article, we especially focused on one of mechanical properties of PU film, the wear resistance, to find how the plasma-treated CNTs give contributions to improve the resistance. Our experimental results showed that plasma-treated CNTs enhanced the wear resistance, in particular, when the CNTs treated with the plasma that was made of nitrogen-oxygen mixture gas. Then, we made measurements with infrared absorption spectroscopy to find the possible causes of the improvement. The measurement showed that the surface of the CNTs treated with nitrogen-oxygen plasma had an indication of isocyanate group, which generally hardens PU film. The plasma likely attached the functional group on CNTs, and then the CNTs added extra wear resistance of a polyurethane film.

  6. Lymphocyte Gene Expression Characteristic of Immediate Airway Responses (IAR) and Methacholine (MCH) Hyperresponsiveness in Mice Sensitized and Challenged with Isocyanates

    EPA Science Inventory

    Exposure to isocyanates has been associated with occupational airway diseases, including asthma. Previously we reported on respiratory and immune responses following dermal sensitization and intranasal challenge of BALB/c mice with 6 different isocyanates. The purpose of this st...

  7. Isocyanates and Work-Related Asthma: Findings From California, Massachusetts, Michigan, and New Jersey, 1993–2008

    PubMed Central

    Lefkowitz, Daniel; Pechter, Elise; Fitzsimmons, Kathleen; Lumia, Margaret; Stephens, Alicia C.; Davis, Letitia; Flattery, Jennifer; Weinberg, Justine; Harrison, Robert J.; Reilly, Mary Jo; Filios, Margaret S.; White, Gretchen E.; Rosenman, Kenneth D.

    2015-01-01

    Background Isocyanates remain a leading cause of work-related asthma (WRA). Methods Two independent data systems were analyzed for the period 1993–2008: (1) State-based WRA case surveillance data on persons with isocyanate-induced WRA from four states, and (2) Occupational Safety and Health Administration (OSHA) Integrated Management Information System (IMIS) isocyanate air sampling results. Results We identified 368 cases of isocyanate-induced WRA from 32 industries and 678 OSHA isocyanate air samples with detectable levels from 31 industries. Seventeen industries were unique to one or the other dataset. Conclusion Isocyanate-induced WRA continues to occur in a wide variety of industries. Two data systems uncovered industries with isocyanate exposures and/or illness. Improved control measures and standards, including medical surveillance, are needed. More emphasis is needed on task-specific guidance, spill clean-up procedures, skin and respiratory protection, and targeted medical monitoring to mitigate the hazards of isocyanate use. PMID:26351141

  8. Electrically conductive rigid polyurethane foam

    DOEpatents

    Neet, T.E.; Spieker, D.A.

    1983-12-08

    A rigid, moldable polyurethane foam comprises about 2 to 10 weight percent, based on the total foam weight, of a carbon black which is CONDUCTEX CC-40-220 or CONDUCTEX SC, whereby the rigid polyurethane foam is electrically conductive and has essentially the same mechanical properties as the same foam without carbon black added.

  9. Electrically conductive rigid polyurethane foam

    DOEpatents

    Neet, Thomas E.; Spieker, David A.

    1985-03-19

    A rigid, polyurethane foam comprises about 2-10 weight percent, based on the total foam weight, of a carbon black which is CONDUCTEX CC-40-220 or CONDUCTEX SC, whereby the rigid polyurethane foam is electrically conductive and has essentially the same mechanical properties as the same foam without carbon black added.

  10. Anaerobic digestion of aliphatic polyesters.

    PubMed

    Šmejkalová, Pavla; Kužníková, Veronika; Merna, Jan; Hermanová, Soňa

    2016-01-01

    Anaerobic processes for the treatment of plastic materials waste represent versatile and effective approach in environmental protection and solid waste management. In this work, anaerobic biodegradability of model aliphatic polyesters, poly(L-lactic acid) (PLA), and poly(ɛ-caprolactone) (PCL), in the form of powder and melt-pressed films with varying molar mass, was studied. Biogas production was explored in batch laboratory trials at 55 ± 1°C under a nitrogen atmosphere. The inoculum used was thermophilic digested sludge (total solids concentration of 2.9%) from operating digesters at the Central Waste Water Treatment Plant in Prague, Czech Republic. Methanogenic biodegradation of PCLs typically yielded from 54 to 60% of the theoretical biogas yield. The biodegradability of PLAs achieved from 56 to 84% of the theoretical value. High biogas yield (up to 677 mL/g TS) with high methane content (more than 60%), comparable with conventionally processed materials, confirmed the potential of polyester samples for anaerobic treatment in the case of their exploitation in agriculture or as a packaging material in the food industry.

  11. Anaerobic digestion of aliphatic polyesters.

    PubMed

    Šmejkalová, Pavla; Kužníková, Veronika; Merna, Jan; Hermanová, Soňa

    2016-01-01

    Anaerobic processes for the treatment of plastic materials waste represent versatile and effective approach in environmental protection and solid waste management. In this work, anaerobic biodegradability of model aliphatic polyesters, poly(L-lactic acid) (PLA), and poly(ɛ-caprolactone) (PCL), in the form of powder and melt-pressed films with varying molar mass, was studied. Biogas production was explored in batch laboratory trials at 55 ± 1°C under a nitrogen atmosphere. The inoculum used was thermophilic digested sludge (total solids concentration of 2.9%) from operating digesters at the Central Waste Water Treatment Plant in Prague, Czech Republic. Methanogenic biodegradation of PCLs typically yielded from 54 to 60% of the theoretical biogas yield. The biodegradability of PLAs achieved from 56 to 84% of the theoretical value. High biogas yield (up to 677 mL/g TS) with high methane content (more than 60%), comparable with conventionally processed materials, confirmed the potential of polyester samples for anaerobic treatment in the case of their exploitation in agriculture or as a packaging material in the food industry. PMID:27191559

  12. Stable Polyurethane Coatings for Electronic Circuits

    NASA Technical Reports Server (NTRS)

    Morris, D. E.

    1983-01-01

    Alkane-based polyurethanes resist deterioration while maintaining good dielectric properties. Weight loss after prolonged immersion in hot water far less for alkane-based polyurethanes than for more common ether based polyurethanes, at any given oxygen content. Major uses of polyurethanes are as connector potting materials and conformal coatings for printed circuit boards.

  13. 21 CFR 177.1680 - Polyurethane resins.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Polyurethane resins. 177.1680 Section 177.1680... Components of Single and Repeated Use Food Contact Surfaces § 177.1680 Polyurethane resins. The polyurethane...) For the purpose of this section, polyurethane resins are those produced when one or more of...

  14. 21 CFR 177.1680 - Polyurethane resins.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Polyurethane resins. 177.1680 Section 177.1680... Components of Single and Repeated Use Food Contact Surfaces § 177.1680 Polyurethane resins. The polyurethane...) For the purpose of this section, polyurethane resins are those produced when one or more of...

  15. Synthesis of Substituted Furan/Pyrrole-3-carboxamides through a Tandem Nucleopalladation and Isocyanate Insertion.

    PubMed

    Rajesh, Manda; Puri, Surendra; Kant, Ruchir; Sridhar Reddy, Maddi

    2016-09-01

    Access to furanyl- and pyrrolyl-3-carboxamides from readily available 3-alkyne-1,2-diols and 1-amino-3-alkyn-2-ols using isocyanate as amido surrogate is demonstrated. The approach constitutes a successful unprecedented combination of heteropalladation and isocyanate insertion, a new avenue for novel amide bond constructions. The mechanism likely involves a 6-membered oxaaminopalladacycle as the key intermediate. PMID:27532221

  16. Cobalt(III)-Catalyzed C-H Bond Amidation with Isocyanates.

    PubMed

    Hummel, Joshua R; Ellman, Jonathan A

    2015-05-15

    The first examples of cobalt(III)-catalyzed C-H bond addition to isocyanates are described, providing a convergent strategy for arene and heteroarene amidation. Using a robust air- and moisture-stable catalyst, this transformation demonstrates a broad isocyanate scope and good functional-group compatibility and has been performed on gram scale.

  17. Cobalt(III)-Catalyzed C–H Bond Amidation with Isocyanates

    PubMed Central

    Hummel, Joshua R.; Ellman, Jonathan A.

    2015-01-01

    The first examples of cobalt(III)-catalyzed C–H bond addition to isocyanates are described, providing a convergent strategy for arene and heteroarene amidation. Using a robust air- and moisture-stable catalyst, this transformation demonstrates broad isocyanate scope, good functional-group compatibility and has been performed on gram scale. PMID:25945401

  18. A new general pathway for synthesis of reference compounds of N-terminal valine-isocyanate adducts.

    PubMed

    Davies, Ronnie; Rydberg, Per; Westberg, Emelie; Motwani, Hitesh V; Johnstone, Erik; Törnqvist, Margareta

    2010-03-15

    Adducts to Hb could be used as biomarkers to monitor exposure to isocyanates. Particularly useful is the measurement of carbamoylation of N-terminal valines in Hb, after detachment as hydantoins. The synthesis of references from the reactive isocyanates, especially diisocyanates, has been problematic due to side reactions and polymerization of the isocyanate starting material. A simpler, safer, and more general method for the synthesis of valine adducts of isocyanates has been developed using N-[(4-nitrophenyl)carbamate]valine methylamide (NPCVMA) as the key precursor to adducts of various mono- and diisocyanates of interest. By reacting NPCVMA with a range of isocyanate-related amines, carbamoylated valines are formed without the use of the reactive isocyanates. The carbamoylated products synthesized here were cyclized with good yields of the formed hydantoins. The carbamoylated derivative from phenyl isocyanate also showed quantitative yield in a test with cyclization under the conditions used in blood. This new pathway for the preparation of N-carbamoylated model compounds overcomes the above-mentioned problems in the synthesis and is a general and simplified approach, which could make such reference compounds of adducts to N-terminal valine from isocyanates accessible for biomonitoring purposes. The synthesized hydantoins corresponding to adducts from isocyanic acid, methyl isocyanate, phenyl isocyanate, and 2,6-toluene diisocyanate were characterized by LC-MS analysis. The background level of the hydantoin from isocyanic acid in human blood was analyzed with the LC-MS conditions developed.

  19. Melt electrospinning of biodegradable polyurethane scaffolds.

    PubMed

    Karchin, Ari; Simonovsky, Felix I; Ratner, Buddy D; Sanders, Joan E

    2011-09-01

    Electrospinning from a melt, in contrast to from a solution, is an attractive tissue engineering scaffold manufacturing process as it allows for the formation of small diameter fibers while eliminating potentially cytotoxic solvents. Despite this, there is a dearth of literature on scaffold formation via melt electrospinning. This is likely due to the technical challenges related to the need for a well-controlled high-temperature setup and the difficulty in developing an appropriate polymer. In this paper, a biodegradable and thermally stable polyurethane (PU) is described specifically for use in melt electrospinning. Polymer formulations of aliphatic PUs based on (CH(2))(4)-content diisocyanates, polycaprolactone (PCL), 1,4-butanediamine and 1,4-butanediol (BD) were evaluated for utility in the melt electrospinning process. The final polymer formulation, a catalyst-purified PU based on 1,4-butane diisocyanate, PCL and BD in a 4/1/3M ratio with a weight-average molecular weight of about 40kDa, yielded a nontoxic polymer that could be readily electrospun from the melt. Scaffolds electrospun from this polymer contained point bonds between fibers and mechanical properties analogous to many in vivo soft tissues. PMID:21640853

  20. Chemoselective Schwartz Reagent Mediated Reduction of Isocyanates to Formamides.

    PubMed

    Pace, Vittorio; de la Vega-Hernández, Karen; Urban, Ernst; Langer, Thierry

    2016-06-01

    Addition of the in situ generated Schwartz reagent to widely available isocyanates constitutes a chemoselective, high-yielding, and versatile approach to the synthesis of variously functionalized formamides. Steric and electronic factors or the presence of sensitive functionalities (esters, nitro groups, nitriles, alkenes) do not compromise the potential of the method. Full preservation of the stereochemical information contained in the starting materials is observed. The use of formamides in the nucleophilic addition of organometallic reagents (Chida-Sato allylation, Charette-Huang addition to imidoyl triflate activated amides, Matteson homologation of boronic esters) is briefly investigated. PMID:27218199

  1. Prevalence of asthma among inhabitants in the vicinity of a polyurethane factory in Finland

    SciTech Connect

    Nuorteva, P.; Assmuth, T.; Haahtela, T.; Ahti, J.; Kurvonen, E.; Nieminen, T.; Saarainen, T.; Seppaelae, K.Ve.; Veide, P.; Viholainen, S.

    1987-08-01

    Because toluene diisocyanate (TDI) is a strong sensitizer for asthma among workers in polyurethane factories, it is mostly extracted from the factory premises. The influence of such emissions on the prevalence of asthma among the people living in the vicinity of a polyurethane factory in Kouvola, Southern Finland, was studied through a questionnaire survey sent to 6807 persons living around the factory and in a control area; of these 4182 (61%) responded. In the study area near the factory there were 68 cases of asthma out of 3153 respondents (2.2%). In the control area there were 25 cases out of 1029 respondents (2.4%). The difference is insignificant (chi 2 = 0.27). Among the middle-aged the prevalence was significantly higher in the control area (chi 2 = 6.8). There was some indication of a lower asthma prevalence in the zone nearest to the factory, possibly due to its psychologically repellent effect on asthmatics, causing them to move away. Serum samples from 62 asthma patients out of 68 contacted (91%) were received and analyzed for TDI, HDI, and MDI. A positive result for the isocyanates was observed in only one patient who had been exposed in his occupation outside the factory. It was concluded that the polyurethane factory did not have a noticeable influence upon the prevalence of asthma in its surroundings.

  2. Spectroscopic Characteristics of Highly Selective Manganese Catalysis in Acqueous Polyurethane Systems

    PubMed Central

    Cakic, Suzana; Lacnjevac, Caslav; Nikolic, Goran; Stamenkovic, Jakov; Rajkovic, Milos B.; Gligoric, Miladin; Barac, Miroljub

    2006-01-01

    The latest investigations on producing more efficient catalytic aqueous polyurethane systems are in the domain of metal complexes with mixed ligands. In our previous research works, the high selectivity for the isocyanate-hydroxyl reaction in aqueous polyurethane systems has been shown by the manganese(III) mixed-ligand complexes. The two new complexes have been prepared with two acetylacetonate (acac) ligands and one maleate ligand and its hydroxylamine derivative of the general formula [Mn(C5H7O2)2L]. Their structures have been established by using the fundamental analyses, the FTIR and UV/VIS spectroscopic methods, as well as the magnetic measurements. In order to explain the different selectivity of the manganese(III) mixed-ligand complexes, the UV and ESR spectroscopy have been employed to determine the kinetics of the complexes' decomposition. The thermal stability of the complexes has been determined by way of the dynamic TG method at the heating rate of 5°C·min-1 and at the temperature ranged 20-550°C. It suggests the decomposition of the complexes by loss of acid ligand. The main factor in the selective catalysis control in the aqueous polyurethane systems is the nature of the acid ligands and their impact on the manganese(II)/manganese(III) equilibrium.

  3. Design of Xylose-Based Semisynthetic Polyurethane Tissue Adhesives with Enhanced Bioactivity Properties.

    PubMed

    Balcioglu, Sevgi; Parlakpinar, Hakan; Vardi, Nigar; Denkbas, Emir Baki; Karaaslan, Merve Goksin; Gulgen, Selam; Taslidere, Elif; Koytepe, Suleyman; Ates, Burhan

    2016-02-01

    Developing biocompatible tissue adhesives with high adhesion properties is a highly desired goal of the tissue engineering due to adverse effects of the sutures. Therefore, our work involves synthesis, characterization, adhesion properties, protein adsorption, in vitro biodegradation, in vitro and in vivo biocompatibility properties of xylose-based semisynthetic polyurethane (NPU-PEG-X) bioadhesives. Xylose-based semisynthetic polyurethanes were developed by the reaction among 4,4'-methylenebis(cyclohexyl isocyanate) (MCI), xylose and polyethylene glycol 200 (PEG). Synthesized polyurethanes (PUs) showed good thermal stability and high adhesion strength. The highest values in adhesion strength were measured as 415.0 ± 48.8 and 94.0 ± 2.8 kPa for aluminum substrate and muscle tissue in 15% xylose containing PUs (NPU-PEG-X-15%), respectively. The biodegradation of NPU-PEG-X-15% was also determined as 19.96 ± 1.04% after 8 weeks of incubation. Relative cell viability of xylose containing PU was above 86%. Moreover, 10% xylose containing NPU-PEG-X (NPU-PEG-X-10%) sample has favorable tissue response, and inflammatory reaction between 1 and 6 weeks implantation period. With high adhesiveness and biocompatibility properties, NPU-PEG-X can be used in the medical field as supporting materials for preventing the fluid leakage after abdominal surgery or wound closure.

  4. Site-Selective Modification of Cellulose Nanocrystals with Isophorone Diisocyanate and Formation of Polyurethane-CNC Composites.

    PubMed

    Girouard, Natalie M; Xu, Shanhong; Schueneman, Gregory T; Shofner, Meisha L; Meredith, J Carson

    2016-01-20

    The unequal reactivity of the two isocyanate groups in an isophorone diisocyante (IPDI) monomer was exploited to yield modified cellulose nanocrystals (CNCs) with both urethane and isocyanate functionality. The chemical functionality of the modified CNCs was verified with ATR-FTIR analysis and elemental analysis. The selectivity for the secondary isocyanate group using dibutyl tin dilaurate (DBTDL) as the reaction catalyst was confirmed with (13)C NMR. The modified CNCs showed improvements in the onset of thermal degradation by 35 °C compared to the unmodified CNCs. Polyurethane composites based on IPDI and a trifunctional polyether alcohol were synthesized using unmodified (um-CNC) and modified CNCs (m-CNC). The degree of nanoparticle dispersion was qualitatively assessed with polarized optical microscopy. It was found that the modification step facilitated superior nanoparticle dispersion compared to the um-CNCs, which resulted in increases in the tensile strength and work of fracture of over 200% compared to the neat matrix without degradation of elongation at break. PMID:26713564

  5. Role of vitamin D-binding protein in isocyanate-induced occupational asthma.

    PubMed

    Kim, Sung-Ho; Choi, Gil-Soon; Nam, Young-Hee; Kim, Joo-Hee; Hur, Gyu-Young; Kim, Seung-Hyun; Park, Sang Myun; Park, Hae-Sim

    2012-05-31

    The development of a serological marker for early diagnosis of isocyanate-induced occupational asthma (isocyanate-OA) may improve clinical outcome. Our previous proteomic study found that expression of vitamin D-binding protein (VDBP) was upregulated in the patients with isocyanate-OA. In the present study, we evaluated the clinical relevance of VDBP as a serological marker in screening for isocyanate-OA among exposed workers and its role in the pathogenesis of isocyanate-OA. Three study groups including 61 patients with isocyanate-OA (group I), 180 asymptomatic exposed controls (AECs, group II), 58 unexposed healthy controls (NCs, group III) were enrolled in this study. The baseline serum VDBP level was significantly higher in group I compared with groups II and III. The sensitivity and specificity for predicting the phenotype of isocyanate-OA with VDBP were 69% and 81%, respectively. The group I subjects with high VDBP (≥311 μg/ml) had significantly lower PC(20) methacholine levels than did subjects with low VDBP. The in vitro studies showed that TDI suppressed the uptake of VDBP into RLE-6TN cells, which was mediated by the downregulation of megalin, an endocytic receptor of the 25-hydroxycholecalciferol-VDBP complex. Furthermore, toluene diisocyanate (TDI) increased VEGF production and secretion from this epithelial cells by suppression of 1,25-dihydroxycholecalciferol [1,25(OH)(2)D(3)] production. The findings of this study suggest that the serum VDBP level may be used as a serological marker for the detection of isocyanate-OA among workers exposed to isocyanate. The TDI-induced VEGF production/ secretion was reversed by 1,25(OH)(2)D(3) treatment, which may provide a potential therapeutic strategy for patients with isocyanate-OA.

  6. Electrospun nanofibrous scaffolds of segmented polyurethanes based on PEG, PLLA and PTMC blocks: Physico-chemical properties and morphology.

    PubMed

    Trinca, Rafael Bergamo; Abraham, Gustavo A; Felisberti, Maria Isabel

    2015-11-01

    Biocompatible polymeric scaffolds are crucial for successful tissue engineering. Biomedical segmented polyurethanes (SPUs) are an important and versatile class of polymers characterized by a broad spectrum of compositions, molecular architectures, properties and applications. Although SPUs are versatile materials that can be designed by different routes to cover a wide range of properties, they have been infrequently used for the preparation of electrospun nanofibrous scaffolds. This study reports the preparation of new electrospun polyurethane scaffolds. The segmented polyurethanes were synthesized using low molar masses macrodyols (poly(ethylene glycol), poly(l-lactide) and poly(trimethylene carbonate)) and 1,6-hexane diisocyanate and 1,4-butanodiol as isocyanate and chain extensor, respectively. Different electrospinning parameters such as solution properties and processing conditions were evaluated to achieve smooth, uniform bead-free fibers. Electrospun micro/nanofibrous structures with mean fiber diameters ranging from 600nm to 770nm were obtained by varying the processing conditions. They were characterized in terms of thermal and dynamical mechanical properties, swelling degree and morphology. The elastomeric polyurethane scaffolds exhibit interesting properties that could be appropriate as biomimetic matrices for soft tissue engineering applications. PMID:26249621

  7. Electrospun nanofibrous scaffolds of segmented polyurethanes based on PEG, PLLA and PTMC blocks: Physico-chemical properties and morphology.

    PubMed

    Trinca, Rafael Bergamo; Abraham, Gustavo A; Felisberti, Maria Isabel

    2015-11-01

    Biocompatible polymeric scaffolds are crucial for successful tissue engineering. Biomedical segmented polyurethanes (SPUs) are an important and versatile class of polymers characterized by a broad spectrum of compositions, molecular architectures, properties and applications. Although SPUs are versatile materials that can be designed by different routes to cover a wide range of properties, they have been infrequently used for the preparation of electrospun nanofibrous scaffolds. This study reports the preparation of new electrospun polyurethane scaffolds. The segmented polyurethanes were synthesized using low molar masses macrodyols (poly(ethylene glycol), poly(l-lactide) and poly(trimethylene carbonate)) and 1,6-hexane diisocyanate and 1,4-butanodiol as isocyanate and chain extensor, respectively. Different electrospinning parameters such as solution properties and processing conditions were evaluated to achieve smooth, uniform bead-free fibers. Electrospun micro/nanofibrous structures with mean fiber diameters ranging from 600nm to 770nm were obtained by varying the processing conditions. They were characterized in terms of thermal and dynamical mechanical properties, swelling degree and morphology. The elastomeric polyurethane scaffolds exhibit interesting properties that could be appropriate as biomimetic matrices for soft tissue engineering applications.

  8. Assessment of exposure to TDI and MDI during polyurethane foam production in Poland using integrated theoretical and experimental data.

    PubMed

    Kupczewska-Dobecka, Małgorzata; Czerczak, Sławomir; Brzeźnicki, Sławomir

    2012-09-01

    The aim of this study was to develop an optimal strategy for the assessment of inhalation exposure to isocyanates such as TDI and MDI in the production of polyurethane foam by integration of theoretical and experimental data. ECETOC TRA and EASE predictive models were used to determine the estimated levels of exposure to isocyanates. The results of our study suggest that both applications EASE and ECETOC TRA can be used as a screening 1st Tier tool in this case study. PROC12 ECETOC TRA category can be linked to exposure on TDI during polyurethane foam manufacturing because it is working properly and exceeds 90th percentile measured concentration with factor 3 and the maximum measured value with factor 1, 5. The value estimated by using category PROC2 is underestimated so this category should not be linked to this scenario. At the same time, the applications of EASE overstate the expected concentrations although the scenario "Use in closed process" seems to underestimate the exposure at the "lower end". For MDI the both models estimate exposure in a conservative manner.

  9. Synthesis and characterization of poly-O-methyl-[n]-polyurethane from a d-glucamine-based monomer.

    PubMed

    Kolender, Adriana A; Arce, Silvina M; Varela, Oscar

    2011-09-01

    Aminoalditol 1-amino-1-deoxy-D-sorbitol (1) was readily converted into 2,3,4,5-tetra-O-methyl derivative 5, a key precursor of a sugar-based [n]-polyurethane. For the polymerization, the free amino or primary hydroxyl groups of 5 were selectively activated and employed as starting monomers in two alternative procedures. Thus, the amino function of 5 was converted into the isocyanate derivative by treatment with di-tert-butyltricarbonate, and polymerized in situ in the presence of Zr(IV) acetylacetonate. The resulting poly(1-amino-1-deoxy-2,3,4,5-tetra-O-methyl-D-sorbitol)urethane (8) had a moderate molecular weight and showed the presence of urea units. The alternative synthesis of 8 involved the activation of the free hydroxyl group of 5 as the corresponding phenylcarbonate. The polymerization of this α-amino-ω-phenylcarbonate alditol monomer does not require a metal catalyst. The resulting material exhibited an improved molecular weight and higher purity than that obtained via the isocyanate. [n]-polyurethane 8 was highly soluble in water as well as in common organic solvents (chloroform, acetone, ethyl acetate, etc) and was obtained as an amorphous material which was characterized thermally and spectroscopically. PMID:21645884

  10. Experiments on the Multiphase Chemistry of Isocyanic Acid, HNCO.

    NASA Astrophysics Data System (ADS)

    Roberts, J. M.; Liu, Y.

    2015-12-01

    Isocyanic acid, HNCO, has emerged as a potentially important reduced nitrogen compound that is emitted in wildfires, and may have health effect implications. The extent of the health effects depends on the solubility of HNCO in aqueous and non-aqueous solutions and the relative rates of hydrolysis versus carbamylation reactions (for example: HNCO + ROH => H2NC(O)OR). We report here results of studies of HNCO solubility and its reaction in buffered aqueous solutions (pH3), tridecane, and n-octanol at temperatures over the range 5 to 37°C. From these data, the heats of solution and activation energy of hydrolysis are estimated, and a partition coefficient between n-octanol and water at 25°C is greater than 1 for low pH solutions, indicating appreciable portioning to a non-polar phase, but HNCO will be distributed mostly in the aqueous phase at neutral pH. In addition, it was found that the rate of reaction of HNCO with n-octanol was competitive with hydrolysis under physiologically relevant conditions (pH7.4, 37°C), indicating that carbamylation of ROH groups could be significant. Based on these results, research on the carbamylation of other functional groups, and solubility and reaction studies of other isocyanates (e.g. CH3NCO) are warranted. The implications of this multi-phase chemistry for global exposures to wildfire emissions will be discussed.

  11. Cell cycle deregulation by methyl isocyanate: Implications in liver carcinogenesis.

    PubMed

    Panwar, Hariom; Raghuram, Gorantla V; Jain, Deepika; Ahirwar, Alok K; Khan, Saba; Jain, Subodh K; Pathak, Neelam; Banerjee, Smita; Maudar, Kewal K; Mishra, Pradyumna K

    2014-03-01

    Liver is often exposed to plethora of chemical toxins. Owing to its profound physiological role and central function in metabolism and homeostasis, pertinent succession of cell cycle in liver epithelial cells is of prime importance to maintain cellular proliferation. Although recent evidence has displayed a strong association between exposures to methyl isocyanate (MIC), one of the most toxic isocyanates, and neoplastic transformation, molecular characterization of the longitudinal effects of MIC on cell cycle regulation has never been performed. Here, we sequentially delineated the status of different proteins arbitrating the deregulation of cell cycle in liver epithelial cells treated with MIC. Our data reaffirms the oncogenic capability of MIC with elevated DNA damage response proteins pATM and γ-H2AX, deregulation of DNA damage check point genes CHK1 and CHK2, altered expression of p53 and p21 proteins involved in cell cycle arrest with perturbation in GADD-45 expression in the treated cells. Further, alterations in cyclin A, cyclin E, CDK2 levels along with overexpression of mitotic spindle checkpoints proteins Aurora A/B, centrosomal pericentrin protein, chromosomal aberrations, and loss of Pot1a was observed. Thus, MIC impacts key proteins involved in cell cycle regulation to trigger genomic instability as a possible mechanism of developmental basis of liver carcinogenesis.

  12. One-Pot Synthesis of Aza-Diketopiperazines Enabled by Controlled Reactivity of N-Isocyanate Precursors.

    PubMed

    Ivanovich, Ryan A; Vincent-Rocan, Jean-François; Elkaeed, Eslam B; Beauchemin, André M

    2015-10-01

    A one-pot sequence for the synthesis of aza-diketopiperazines is reported, involving carbazate acylation with chloroacetyl chloride, SN2 with a primary amine, N-isocyanate formation, and cyclization. Nitrogen-substituted isocyanates (N-isocyanates) are a rare class of amphoteric isocyanate with high, but severely underdeveloped synthetic potential. This approach highlights that βN-acyl carbazates can act as blocked (masked) N-isocyanates, thus allowing a challenging intermolecular SN2 reaction of a primary amine to proceed while the N-isocyanate is "protected", and then cyclization once it is unmasked. Control experiments show that the alternate pathway--N-isocyanate substitution and then cyclization by an intramolecular SN2 reaction--is not operating.

  13. Prevention Guidance for Isocyanate-Induced Asthma Using Occupational Surveillance Data

    PubMed Central

    Reeb-Whitaker, Carolyn; Anderson, Naomi J.; Bonauto, David K.

    2013-01-01

    Data from Washington State's work-related asthma surveillance system were used to characterize isocyanate-induced asthma cases occurring from 1999 through 2010. Injured worker interviews and medical records were used to describe the industry, job title, work process, workers’ compensation cost, and exposure trends associated with 27 cases of isocyanate-induced asthma. The majority (81%) of cases were classified within the surveillance system as new-onset asthma while 19% were classified as work-aggravated asthma. The workers’ compensation cost for isocyanate-induced asthma cases was $1.7 million; this was 14% of the total claims cost for all claims in the asthma surveillance system. The majority of cases (48%) occurred from paint processes, followed by foam application or foam manufacturing (22%). Nine of the asthma cases associated with spray application occurred during application to large or awkward-shaped objects. Six workers who did not directly handle isocyanates (indirect exposure) developed new-onset asthma. Two cases suggest that skin contact and processes secondary to the isocyanate spray application, such as cleanup, contributed to immune sensitization. Surveillance data provide insight for the prevention of isocyanate-induced respiratory disease. Key observations are made regarding the development of work-related asthma in association with a) paint application on large objects difficult to ventilate, b) indirect exposure to isocyanates, c) exposure during secondary or cleanup processes, and d) reports of dermal exposure. PMID:24116665

  14. Imbalance of mitochondrial-nuclear cross talk in isocyanate mediated pulmonary endothelial cell dysfunction.

    PubMed

    Panwar, Hariom; Jain, Deepika; Khan, Saba; Pathak, Neelam; Raghuram, Gorantla V; Bhargava, Arpit; Banerjee, Smita; Mishra, Pradyumna K

    2013-01-01

    Mechanistic investigations coupled with epidemiology, case-control, cohort and observational studies have increasingly linked isocyanate exposure (both chronic and acute) with pulmonary morbidity and mortality. Though ascribed for impairment in endothelial cell function, molecular mechanisms of these significant adverse pulmonary outcomes remains poorly understood. As preliminary studies conducted in past have failed to demonstrate a cause-effect relationship between isocyanate toxicity and compromised pulmonary endothelial cell function, we hypothesized that direct exposure to isocyanate may disrupt endothelial structural lining, resulting in cellular damage. Based on this premise, we comprehensively evaluated the molecular repercussions of methyl isocyanate (MIC) exposure on human pulmonary arterial endothelial cells (HPAE-26). We examined MIC-induced mitochondrial oxidative stress, pro-inflammatory cytokine response, oxidative DNA damage response and apoptotic index. Our results demonstrate that exposure to MIC, augment mitochondrial reactive oxygen species production, depletion in antioxidant defense enzymes, elevated pro-inflammatory cytokine response and induced endothelial cell apoptosis via affecting the balance of mitochondrial-nuclear cross talk. We herein delineate the first and direct molecular cascade of isocyanate-induced pulmonary endothelial cell dysfunction. The results of our study might portray a connective link between associated respiratory morbidities with isocyanate exposure, and indeed facilitate to discern the exposure-phenotype relationship in observed deficits of pulmonary endothelial cell function. Further, understanding of inter- and intra-cellular signaling pathways involved in isocyanate-induced endothelial damage would not only aid in biomarker identification but also provide potential new avenues to target specific therapeutic interventions.

  15. Prevention guidance for isocyanate-induced asthma using occupational surveillance data.

    PubMed

    Reeb-Whitaker, Carolyn; Anderson, Naomi J; Bonauto, David K

    2013-01-01

    Data from Washington State's work-related asthma surveillance system were used to characterize isocyanate-induced asthma cases occurring from 1999 through 2010. Injured worker interviews and medical records were used to describe the industry, job title, work process, workers' compensation cost, and exposure trends associated with 27 cases of isocyanate-induced asthma. The majority (81%) of cases were classified within the surveillance system as new-onset asthma while 19% were classified as work-aggravated asthma. The workers' compensation cost for isocyanate-induced asthma cases was $1.7 million; this was 14% of the total claims cost for all claims in the asthma surveillance system. The majority of cases (48%) occurred from paint processes, followed by foam application or foam manufacturing (22%). Nine of the asthma cases associated with spray application occurred during application to large or awkward-shaped objects. Six workers who did not directly handle isocyanates (indirect exposure) developed new-onset asthma. Two cases suggest that skin contact and processes secondary to the isocyanate spray application, such as cleanup, contributed to immune sensitization. Surveillance data provide insight for the prevention of isocyanate-induced respiratory disease. Key observations are made regarding the development of work-related asthma in association with a) paint application on large objects difficult to ventilate, b) indirect exposure to isocyanates, c) exposure during secondary or cleanup processes, and d) reports of dermal exposure.

  16. Different respiratory phenotypes are associated with isocyanate exposure in spray painters.

    PubMed

    Pronk, A; Preller, L; Doekes, G; Wouters, I M; Rooijackers, J; Lammers, J-W; Heederik, D

    2009-03-01

    Associations have been observed between exposure to isocyanates, consisting mainly of oligomers, and respiratory symptoms and isocyanate specific sensitisation in spray painters. The aim of the present study was to assess associations between isocyanate exposure and more objective respiratory effect measures such as bronchial hyperresponsiveness (BHR), baseline spirometry and exhaled nitric oxide (eNO) in a subset of spray painters. Methacholine challenge and eNO measurements were performed in 229 workers. Questionnaires and blood samples were obtained. Specific immunoglobulin (Ig)E and IgG to hexamethylene di-isocyanate were assessed in serum using various assays. Personal exposure was estimated by combining personal task-based inhalatory exposure measurements and time-activity information. Workers with higher isocyanate exposure were more often hyperresponsive (prevalence ratio comparing the 75th versus 25th percentile of exposure 1.8). In addition, significant exposure-related decreased forced expiratory volume in one second (FEV(1)), FEV(1)/forced vital capacity ratio and flow-volume parameters independent of BHR were found. BHR was more prevalent among sensitised workers. This was statistically significant for only IgG-ImmunoCAP (Phadia, Uppsala, Sweden) positive workers. eNO was not associated with exposure although slightly elevated eNO levels in specific IgG positive subjects were found. The current study provides evidence that exposure to isocyanate oligomers is related to asthma with bronchial hyperresponsiveness as a hallmark, but also shows independent chronic obstructive respiratory effects resulting from isocyanate exposure.

  17. Flame retardant spandex type polyurethanes

    NASA Technical Reports Server (NTRS)

    Howarth, J. T.; Sheth, S.; Sidman, K. R.; Massucco, A. A. (Inventor)

    1978-01-01

    Flame retardant elastomeric compositions were developed, comprised of: (1) spandex type polyurethane having incorporated into the polymer chain, halogen containing polyols; (2) conventional spandex type polyurethanes in physical admixture flame retardant additives; and (3) fluoroelastomeric resins in physical admixture with flame retardant additives. Methods of preparing fibers of the flame retardant elastomeric materials are presented and articles of manufacture comprised of the elastomeric materials are mentioned.

  18. Fabrication of polyurethane and polyurethane based composite fibres by the electrospinning technique for soft tissue engineering of cardiovascular system.

    PubMed

    Kucinska-Lipka, J; Gubanska, I; Janik, H; Sienkiewicz, M

    2015-01-01

    Electrospinning is a unique technique, which provides forming of polymeric scaffolds for soft tissue engineering, which include tissue scaffolds for soft tissues of the cardiovascular system. Such artificial soft tissues of the cardiovascular system may possess mechanical properties comparable to native vascular tissues. Electrospinning technique gives the opportunity to form fibres with nm- to μm-scale in diameter. The arrangement of obtained fibres and their surface determine the biocompatibility of the scaffolds. Polyurethanes (PUs) are being commonly used as a prosthesis of cardiovascular soft tissues due to their excellent biocompatibility, non-toxicity, elasticity and mechanical properties. PUs also possess fine spinning properties. The combination of a variety of PU properties with an electrospinning technique, conducted at the well tailored conditions, gives unlimited possibilities of forming novel polyurethane materials suitable for soft tissue scaffolds applied in cardiovascular tissue engineering. This paper can help researches to gain more widespread and deeper understanding of designing electrospinable PU materials, which may be used as cardiovascular soft tissue scaffolds. In this paper we focus on reagents used in PU synthesis designed to increase PU biocompatibility (polyols) and biodegradability (isocyanates). We also describe suggested surface modifications of electrospun PUs, and the direct influence of surface wettability on providing enhanced biocompatibility of scaffolds. We indicate a great influence of electrospinning parameters (voltage, flow rate, working distance) and used solvents (mostly DMF, THF and HFIP) on fibre alignment and diameter - what impacts the biocompatibility and hemocompatibility of such electrospun PU scaffolds. Moreover, we present PU modifications with natural polymers with novel approach applied in electrospinning of PU scaffolds. This work may contribute with further developing of novel electrospun PUs, which may be

  19. Fabrication of polyurethane and polyurethane based composite fibres by the electrospinning technique for soft tissue engineering of cardiovascular system.

    PubMed

    Kucinska-Lipka, J; Gubanska, I; Janik, H; Sienkiewicz, M

    2015-01-01

    Electrospinning is a unique technique, which provides forming of polymeric scaffolds for soft tissue engineering, which include tissue scaffolds for soft tissues of the cardiovascular system. Such artificial soft tissues of the cardiovascular system may possess mechanical properties comparable to native vascular tissues. Electrospinning technique gives the opportunity to form fibres with nm- to μm-scale in diameter. The arrangement of obtained fibres and their surface determine the biocompatibility of the scaffolds. Polyurethanes (PUs) are being commonly used as a prosthesis of cardiovascular soft tissues due to their excellent biocompatibility, non-toxicity, elasticity and mechanical properties. PUs also possess fine spinning properties. The combination of a variety of PU properties with an electrospinning technique, conducted at the well tailored conditions, gives unlimited possibilities of forming novel polyurethane materials suitable for soft tissue scaffolds applied in cardiovascular tissue engineering. This paper can help researches to gain more widespread and deeper understanding of designing electrospinable PU materials, which may be used as cardiovascular soft tissue scaffolds. In this paper we focus on reagents used in PU synthesis designed to increase PU biocompatibility (polyols) and biodegradability (isocyanates). We also describe suggested surface modifications of electrospun PUs, and the direct influence of surface wettability on providing enhanced biocompatibility of scaffolds. We indicate a great influence of electrospinning parameters (voltage, flow rate, working distance) and used solvents (mostly DMF, THF and HFIP) on fibre alignment and diameter - what impacts the biocompatibility and hemocompatibility of such electrospun PU scaffolds. Moreover, we present PU modifications with natural polymers with novel approach applied in electrospinning of PU scaffolds. This work may contribute with further developing of novel electrospun PUs, which may be

  20. Microbial degradation of aliphatic and aliphatic-aromatic co-polyesters.

    PubMed

    Shah, Aamer Ali; Kato, Satoshi; Shintani, Noboru; Kamini, Numbi Ramudu; Nakajima-Kambe, Toshiaki

    2014-04-01

    Biodegradable plastics (BPs) have attracted much attention since more than a decade because they can easily be degraded by microorganisms in the environment. The development of aliphatic-aromatic co-polyesters has combined excellent mechanical properties with biodegradability and an ideal replacement for the conventional nondegradable thermoplastics. The microorganisms degrading these polyesters are widely distributed in various environments. Although various aliphatic, aromatic, and aliphatic-aromatic co-polyester-degrading microorganisms and their enzymes have been studied and characterized, there are still many groups of microorganisms and enzymes with varying properties awaiting various applications. In this review, we have reported some new microorganisms and their enzymes which could degrade various aliphatic, aromatic, as well as aliphatic-aromatic co-polyesters like poly(butylene succinate) (PBS), poly(butylene succinate)-co-(butylene adipate) (PBSA), poly(ε-caprolactone) (PCL), poly(ethylene succinate) (PES), poly(L-lactic acid) (PLA), poly(3-hydroxybutyrate) and poly(3-hydoxybutyrate-co-3-hydroxyvalterate) (PHB/PHBV), poly(ethylene terephthalate) (PET), poly(butylene terephthalate) (PBT), poly(butylene adipate-co-terephthalate (PBAT), poly(butylene succinate-co-terephthalate) (PBST), and poly(butylene succinate/terephthalate/isophthalate)-co-(lactate) (PBSTIL). The mechanism of degradation of aliphatic as well as aliphatic-aromatic co-polyesters has also been discussed. The degradation ability of microorganisms against various polyesters might be useful for the treatment and recycling of biodegradable wastes or bioremediation of the polyester-contaminated environments.

  1. Reactive N-protonated isocyanate species stabilized by bis(μ-hydroxo)divanadium(IV)-substituted polyoxometalate.

    PubMed

    Uehara, Kazuhiro; Fukaya, Keisuke; Mizuno, Noritaka

    2012-07-27

    O- or N-protonated? The bis(μ-hydroxo)divanadium(IV)-substituted γ-Keggin-type polyoxometalate (see picture, left) (TBA)(4)[γ-SiV(IV)(2)W(10)O(36)(μ-OH)(4)] (TBA = tetra(n-butyl)ammonium) was synthesized and characterized by X-ray crystallography. Its reaction with phenyl isocyanate gave (TBA)(4)[γ-SiV(IV)(2)W(10)O(38)(μ-OH)(2)(PhNHCO)(2)], which contains two N-protonated phenyl isocyanate species and catalyzes the cyclotrimerization of phenyl isocyanate.

  2. [Preparation and characterization of nano-hydroxyapatite/polyurethane composite bio-film].

    PubMed

    Dong, Zhihong; Li, Yubao; Zhang, Li; Zou, Qin

    2009-06-01

    Through Hydroxyl (-OH) reacting with isocyanate group (-NCO), 13 Wt% nano-hydroxyapatite (n-HA)/polyurethane (PU) composite guided bone regeneration membrane was synthesized by use of solvent evaporation method. Its surface character was analyzed by XRD, IR, TG, contact angle, water absorption, elongation and combustion test and SEM. The results indicate that nano-HA/PU has good homogeneity,the interface between the inorganic mineral and organic polymer is optimized to create proper combination; that n-HA crystals are similar to the apatite crystals in natural bone, HA/PU composite membrane has good hydrophilicity mechanical behavior; and that many pores are observed on the membrane which help cells' metabolism. So the HA/PU composite membrane, thus prepared, has the potential for use in guided bone regeneration and tissue engineering.

  3. Sustained-release microsphere formulation containing an agrochemical by polyurethane polymerization during an agitation granulation process.

    PubMed

    Terada, Takatoshi; Tagami, Manabu; Ohtsubo, Toshiro; Iwao, Yasunori; Noguchi, Shuji; Itai, Shigeru

    2016-07-25

    In this report, a new solventless microencapsulation method by synthesizing polyurethane (PU) from polyol and isocyanate during an agglomeration process in a high-speed mixing apparatus was developed. Clothianidin (CTD), which is a neonicotinoid insecticide and highly effective against a wide variety of insect pests, was used as the model compound. The microencapsulated samples covered with PU (CTD microspheres) had a median diameter of <75μm and sustained-release properties. The CTD microspheres were analyzed by synchrotron X-ray computed tomography measurements. Multiple cores of CTD and other solid excipient were dispersed in PU. Although voids appeared in the CTD microspheres after CTD release, the spherical shape of the microspheres remained stable and no change in its framework was observed. The experimental release data were highly consistent with the Baker-Lonsdale model derived from drug release of spherical monolithic dispersions and consistent with the computed tomography measurements. PMID:27246815

  4. Synthesis of palm-based polyurethane-LiClO{sub 4} via prepolymerization

    SciTech Connect

    Sien, Jason Wong Chee; Badri, Khairiah Haji; Su’ait, Mohd Sukor; Hassan, Nurul Izzati

    2015-09-25

    Palm-based polyurethane (pPU) with varying lithium salt (LiClO{sub 4}) content was synthesized. Higher loading percentage of LiClO{sub 4} in the pPU led to the inhibition of prepolymerization process from taking place. Hydrogen bonded C=O was detected in the FTIR spectrum indicating the hydrogen bonding between the urethane bonds. Ordered complexed C=O was observed in the FTIR spectrum confirming the complex formation between urethane bond and Li{sup +} ion. DSC thermogram showed the increase in the LiClO{sub 4} content could increase the glass transition temperature. SEM micrographs exhibited that more bubbles were formed when the LiClO{sub 4} increased from 10 to 30wt% indicating the reaction between free isocyanate groups with moisture presence in the salt due to the hygroscopic properties of LiClO{sub 4}.

  5. Conductive polyurethane composites containing polyaniline-coated nano-silica.

    PubMed

    Liu, Bo-Tau; Syu, Jhan-Rong; Wang, De-Hua

    2013-03-01

    In this study, we used 1.2-Aminopropyltriethoxysilane (APTS) as a coupling agent to synthesize silica-polyaniline (PANI) core-shell nanoparticles. The core-shell nanoparticles and PANI oligomers were reacted with isocyanates to prepare the conductive polyurethane (PU)-PANI-silica nanocomposites. The core-shell-nanoparticle structure shows significant enhancement on electrical properties of the conductive nanocomposites even though only 0.0755-wt.% PANI was coated on the nano-silica. The surface resistance of the nanocomposite containing 5 wt.% PANI can reduce to ~10(8) Ω/sq, lowering two orders in contrast to the nanocomposite without the core-shell structure. In comparison with the neat PU, tensile strength and elongation of the nanocomposite containing silica-PANI core-shell nanoparticles can increase 3.1 and 3.8 times, respectively. We suspect that the extraordinary enhancement of electrical and mechanical properties may result from the fact that contact probability among PANI moieties and chemical bonding between particles and PU matrix increase due to the PANI coated on the surface of silica. PMID:23261334

  6. Formation, structure and morphology of polyurethane-metal interphases

    NASA Astrophysics Data System (ADS)

    Wehlack, C.; Possart, W.

    2009-09-01

    Thin films (few 10 nm to some μm) of different two-part polyurethane adhesive systems (polyether resins and aromatic isocyanate hardener) are characterised on the native metal surfaces of gold, aluminium, copper and steel, thus acting as a model for the interphase in technically relevant material compounds. It is investigated in how far the curing processes, the resulting chemical structure and the morphology of the polymer films differ from the bulk. The comparison of films on the different metals and with the bulk provides conclusions on the properties of the interphase at polymer-metal contacts. The variation of the film thickness gives access to microstructure gradients. The chemical structure of the films is characterised by IR spectroscopy during curing at room temperature (RT kinetics) and in the cured state. Furthermore, microscopic (e.g. SFM) and additional spectroscopic techniques (e.g. XPS) characterise the films and their surface with respect to morphology, composition, homogeneity and topography. The results reveal specific features in the interphase caused by adhesive interactions, catalysis, phase separation and transport phenomena on the different metal surfaces. Remarkable quantitative differences can be seen in the chemical structure formation of thin PU films with respect to reaction rate and final degree of cure.

  7. Synthesis and characterisation of coating polyurethane cationomers containing fluorine built-in hard urethane segments

    PubMed Central

    Król, Bożena; Pikus, Stanisław; Chmielarz, Paweł; Skrzypiec, Krzysztof

    2010-01-01

    Polyurethane cationomers were synthesised in the reaction of 4,4’-methylenebis(phenyl isocyanate) with polyoxyethylene glycol (M = 2,000) or poly(tetrafluoroethyleneoxide-co-difluoromethylene oxide) α,ω-diisocyanate and N-methyl diethanolamine. Amine segments were built-in to the urethane-isocyanate prepolymer in the reaction with 1-bromobutane or formic acid, and then they were converted to alkylammonium cations. The obtained isocyanate prepolymers were then extended in the aqueous medium that yielded stable aqueous dispersions which were applied on the surfaces of test poly(tetrafluoroethylene) plates. After evaporation of water, the dispersions formed thin polymer coatings. 1H, 13C NMR and IR spectral methods were employed to confirm chemical structures of synthesised cationomers. Based on 1H NMR and IR spectra, the factors κ and α were calculated, which represented the polarity level of the obtained cationomers. The DSC, wide angle X-ray scattering and atom force microscopy methods were employed for the microstructural assessment of the obtained materials. Changes were discussed in the surface free energy and its components, as calculated independently according to the method suggested by van Oss–Good, in relation to chemical and physical structures of cationomers as well as morphology of coating surfaces obtained from those cationomers. Fluorine incorporated into cationomers (about 30%) contributed to lower surface free energy values, down to about 15 mJ/m2. That was caused by gradual weakening of long-range interactions within which the highest share is taken by dispersion interactions. PMID:20927181

  8. Modeling of hexamethylene diisocyanate and psychrometric parameters and other effective factors in the polyurethane factories

    PubMed Central

    Mirmohammadi, Mirtaghi; Ibrahim, M. H.; Saraji, J. N.

    2010-01-01

    Background: Diisocyanates are widely used in surface coatings, polyurethane (PUR) foams, adhesives, resins, elastomers, binders, and sealants. Isocyanate exposure is irritative to the skin, mucous membranes, eyes, and respiratory tract. The most common adverse health outcome associated with isocyanate exposure is asthma due to sensitization. Objective: The goal of this study is to find statistical predictive model to determine the relationship between airborne hexamethylene diisocyanate (HDI) and selective psychrometric variables. Materials and Methods: All air samplers (by midget impinger) were collected by mini personal sampler pump fixed to work stations near the source of pollution. The air samples and psychrometric parameters were separately collected and determined in a working shift for three periods of 2 h, each at a flow rate of 2 l/min in an impinger containing a solution of reagent of dimethyl sulfoxide in tryptamine [US National Instituteof Occupational Safety and Health (NIOSH), 1994]. Results: There was a significant correlation between HDI concentration and relative humidity and dry bulb temperature (P < 0.05). No significant correlation was seen between altitude and dimension of PUR factories (P > 0.05). Conclusions: The finding of the study may be a useful initial tool in estimating possible HDI pollution situation in the PUR workplaces, based on simple psychrometric factors (indoor air temperature and relative humidity). PMID:21461158

  9. Gelatin-Modified Polyurethanes for Soft Tissue Scaffold

    PubMed Central

    Kucińska-Lipka, Justyna; Janik, Helena

    2013-01-01

    Recently, in the field of biomaterials for soft tissue scaffolds, the interest of their modification with natural polymersis growing. Synthetic polymers are often tough, and many of them do not possess fine biocompatibility. On the other hand, natural polymers are biocompatible but weak when used alone. The combination of natural and synthetic polymers gives the suitable properties for tissue engineering requirements. In our study, we modified gelatin synthetic polyurethanes prepared from polyester poly(ethylene-butylene adipate) (PEBA), aliphatic 1,6-hexamethylene diisocyanate (HDI), and two different chain extenders 1,4-butanediol (BDO) or 1-ethoxy-2-(2-hydroxyethoxy)ethanol (EHEE). From a chemical point of view, we replaced expensive components for building PU, such as 2,6-diisocyanato methyl caproate (LDI) and 1,4-diisocyanatobutane (BDI), with cost-effective HDI. The gelatin was added in situ (in the first step of synthesis) to polyurethane to increase biocompatibility and biodegradability of the obtained material. It appeared that the obtained gelatin-modified PU foams, in which chain extender was BDO, had enhanced interactions with media and their hydrolytic degradation profile was also improved for tissue engineering application. Furthermore, the gelatin introduction had positive impact on gelatin-modified PU foams by increasing their hemocompatibility. PMID:24363617

  10. Polyurethane-maleamides for cardiovascular applications: synthesis and properties.

    PubMed

    Petrini, P; De Ponti, S; Farè, S; Tanzi, M C

    1999-12-01

    Several polyurethane-maleamides (PUMAs) containing polyether or polycarbonate soft segments, and aromatic or aliphatic hard segments were synthesized by solution or bulk polymerization, using maleic acid (MA) or a mixture of MA and butanediol as chain extenders. Using this process, activated double bonds are introduced into the polymer chains and the base polyurethanes may undergo further modification via specific grafting, thus improving their tissue compatibility. PUMAs chemicophysical properties were evaluated by gel permeation chromatography (GPC), intrinsic viscosity analyses, differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FT-IR) and tensile mechanical tests. Polycarbonate diol (PCU)-based PUMAs showed higher molecular weights than polyether diol (PEU)-based ones. The use of butanediol in mixture with maleic acid led to an increase of molecular weights. FT-IR confirmed the presence of the bands related to the amide groups and to the conjugated double bond, yet more evident for the polymer obtained in solution. The higher crystallinity shown by this polymer was also indicative of a better phase separation. All the PCU-PUMAs exhibited similar tensile properties with a higher stiffness than PEU-PUMAs. Among the PEU-PUMAs, the highest tensile properties were shown by the polymer obtained in solution, and by the one derived from a mixture of maleic acid and butanediol.

  11. Chitin based polyurethanes using hydroxyl terminated polybutadiene. Part I: molecular engineering.

    PubMed

    Zia, Khalid Mahmood; Mahmood, Kashif; Zuber, Mohammad; Jamil, Tahir; Shafiq, Muhammad

    2013-08-01

    Chitin based polyurethanes (PUs) using hydroxyl terminated polybutadiene (HTPB) as soft segment were prepared and the structure of the proposed PU was confirmed using FTIR spectrometer. PU prepolymer was prepared using HTPB and toluene-2,4-diisocyanate (TDI), and the chain was extended with different proportions of 1,4-butane diol (BDO) and chitin. During the detailed FTIR study, it was observed that tri-functional character of chitin results in the formation of network structure due to crosslinking of the material, whereas bi-functional aliphatic diol based polyurethane produced linear PU. Hydrogen bonding between the hard segments was identified by the IR spectroscopy. The scanning electron microscope (SEM) analysis also confirmed the cross-linked structure. PMID:23643975

  12. CCN activity of aliphatic amine secondary aerosol

    NASA Astrophysics Data System (ADS)

    Tang, X.; Price, D.; Praske, E.; Vu, D.; Purvis-Roberts, K.; Silva, P. J.; Cocker, D. R., III; Asa-Awuku, A.

    2014-01-01

    Aliphatic amines can form secondary aerosol via oxidation with atmospheric radicals (e.g. hydroxyl radical and nitrate radical). The particle composition can contain both secondary organic aerosol (SOA) and inorganic salts. The fraction of organic to inorganic materials in the particulate phase influences aerosol hygroscopicity and cloud condensation nuclei (CCN) activity. SOA formed from trimethylamine (TMA) and butylamine (BA) reactions with hydroxyl radical (OH) is composed of organic material of low hygroscopicity (single hygroscopicity parameter, κ ≤ 0.25). Secondary aerosol formed from the tertiary aliphatic amine (TMA) with N2O5 (source of nitrate radical, NO3), contains less volatile compounds than the primary aliphatic amine (BA) aerosol. TMA + N2O5 form semi-volatile organics in low RH conditions that have κ ~ 0.20, indicative of slightly soluble organic material. As RH increases, several inorganic amine salts are formed as a result of acid-base reactions. The CCN activity of the humid TMA-N2O5 aerosol obeys Zdanovskii, Stokes, and Robinson (ZSR) ideal mixing rules. Higher CCN activity (κ > 0.3) was also observed for humid BA+N2O5 aerosols compared with dry aerosol (κ ~ 0.2), as a result of the formation of inorganic salts such as NH4NO3 and butylamine nitrate (C4H11N · HNO3). Compared with TMA, BA+N2O5 reactions produce more volatile aerosols. The BA+N2O5 aerosol products under humid experiments were found to be very sensitive to the temperature within the stream-wise continuous flow thermal gradient CCN counter. The CCN counter, when set above a 21 °C temperature difference, evaporates BA+N2O5 aerosol formed at RH ≥ 30%; κ ranges from 0.4 to 0.7 and is dependent on the instrument supersaturation (ss) settings. The aerosol behaves non-ideally, hence simple ZSR rules cannot be applied to the CCN results from the primary aliphatic amine system. Overall, aliphatic amine aerosol systems κ ranges from 0.2 < κ < 0.7. This work indicates that

  13. Developing an Efficient and General Strategy for Immobilization of Small Molecules onto Microarrays Using Isocyanate Chemistry.

    PubMed

    Zhu, Chenggang; Zhu, Xiangdong; Landry, James P; Cui, Zhaomeng; Li, Quanfu; Dang, Yongjun; Mi, Lan; Zheng, Fengyun; Fei, Yiyan

    2016-01-01

    Small-molecule microarray (SMM) is an effective platform for identifying lead compounds from large collections of small molecules in drug discovery, and efficient immobilization of molecular compounds is a pre-requisite for the success of such a platform. On an isocyanate functionalized surface, we studied the dependence of immobilization efficiency on chemical residues on molecular compounds, terminal residues on isocyanate functionalized surface, lengths of spacer molecules, and post-printing treatment conditions, and we identified a set of optimized conditions that enable us to immobilize small molecules with significantly improved efficiencies, particularly for those molecules with carboxylic acid residues that are known to have low isocyanate reactivity. We fabricated microarrays of 3375 bioactive compounds on isocyanate functionalized glass slides under these optimized conditions and confirmed that immobilization percentage is over 73%. PMID:26999137

  14. Rh(III)-Catalyzed C-H Amidation of Indoles with Isocyanates.

    PubMed

    Jeong, Taejoo; Han, Sangil; Mishra, Neeraj Kumar; Sharma, Satyasheel; Lee, Seok-Yong; Oh, Joa Sub; Kwak, Jong Hwan; Jung, Young Hoon; Kim, In Su

    2015-07-17

    The rhodium(III)-catalyzed direct amidation of indoles and pyrroles with aryl and alkyl isocyanates is described. These transformations provide a facile and efficient construction of C2-amidated N-heterocyclic scaffolds.

  15. Developing an Efficient and General Strategy for Immobilization of Small Molecules onto Microarrays Using Isocyanate Chemistry

    PubMed Central

    Zhu, Chenggang; Zhu, Xiangdong; Landry, James P.; Cui, Zhaomeng; Li, Quanfu; Dang, Yongjun; Mi, Lan; Zheng, Fengyun; Fei, Yiyan

    2016-01-01

    Small-molecule microarray (SMM) is an effective platform for identifying lead compounds from large collections of small molecules in drug discovery, and efficient immobilization of molecular compounds is a pre-requisite for the success of such a platform. On an isocyanate functionalized surface, we studied the dependence of immobilization efficiency on chemical residues on molecular compounds, terminal residues on isocyanate functionalized surface, lengths of spacer molecules, and post-printing treatment conditions, and we identified a set of optimized conditions that enable us to immobilize small molecules with significantly improved efficiencies, particularly for those molecules with carboxylic acid residues that are known to have low isocyanate reactivity. We fabricated microarrays of 3375 bioactive compounds on isocyanate functionalized glass slides under these optimized conditions and confirmed that immobilization percentage is over 73%. PMID:26999137

  16. Developing an Efficient and General Strategy for Immobilization of Small Molecules onto Microarrays Using Isocyanate Chemistry.

    PubMed

    Zhu, Chenggang; Zhu, Xiangdong; Landry, James P; Cui, Zhaomeng; Li, Quanfu; Dang, Yongjun; Mi, Lan; Zheng, Fengyun; Fei, Yiyan

    2016-03-16

    Small-molecule microarray (SMM) is an effective platform for identifying lead compounds from large collections of small molecules in drug discovery, and efficient immobilization of molecular compounds is a pre-requisite for the success of such a platform. On an isocyanate functionalized surface, we studied the dependence of immobilization efficiency on chemical residues on molecular compounds, terminal residues on isocyanate functionalized surface, lengths of spacer molecules, and post-printing treatment conditions, and we identified a set of optimized conditions that enable us to immobilize small molecules with significantly improved efficiencies, particularly for those molecules with carboxylic acid residues that are known to have low isocyanate reactivity. We fabricated microarrays of 3375 bioactive compounds on isocyanate functionalized glass slides under these optimized conditions and confirmed that immobilization percentage is over 73%.

  17. [Asthma due to isocyanates in a theoretically non-exposed worker].

    PubMed

    Kopferschmitt-Kubler, M C; Bessot, J C; Charles, P; Blaumeiser-Kapps, M; Pauli, G

    1991-01-01

    We report a case of isocyanate induced asthma in a patient who had been previously exposed to isocyanate and had become a porter in a factory producing polyurethene foam. The test for exposure to TDI was positive. The recognition of occupational asthma was nevertheless challenged and the patient was not considered to be carrying out work involving exposure to the inhalation of isocyanates. The effect of a change of job in the development of occupational asthma, and the risk of asthma induced by isocyanates despite inhaled concentrations inferior to the VME, the difficulty of obtaining a recognition of occupational asthma when the working conditions fulfilled do not exactly correspond to those labelled in the schedule for occupational diseases, are discussed in this paper.

  18. 40 CFR 721.10534 - Brominated aliphatic alcohol (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Brominated aliphatic alcohol (generic... Specific Chemical Substances § 721.10534 Brominated aliphatic alcohol (generic). (a) Chemical substance and... aliphatic alcohol (PMN P-12-260) is subject to reporting under this section for the significant new...

  19. 40 CFR 721.10534 - Brominated aliphatic alcohol (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Brominated aliphatic alcohol (generic... Specific Chemical Substances § 721.10534 Brominated aliphatic alcohol (generic). (a) Chemical substance and... aliphatic alcohol (PMN P-12-260) is subject to reporting under this section for the significant new...

  20. 40 CFR 721.2270 - Aliphatic dicarboxylic acid salt.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Aliphatic dicarboxylic acid salt. 721... Substances § 721.2270 Aliphatic dicarboxylic acid salt. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as aliphatic dicarboxylic...

  1. 40 CFR 721.2270 - Aliphatic dicarboxylic acid salt.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Aliphatic dicarboxylic acid salt. 721... Substances § 721.2270 Aliphatic dicarboxylic acid salt. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as aliphatic dicarboxylic...

  2. 40 CFR 721.2270 - Aliphatic dicarboxylic acid salt.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Aliphatic dicarboxylic acid salt. 721... Substances § 721.2270 Aliphatic dicarboxylic acid salt. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as aliphatic dicarboxylic...

  3. 40 CFR 721.2270 - Aliphatic dicarboxylic acid salt.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Aliphatic dicarboxylic acid salt. 721... Substances § 721.2270 Aliphatic dicarboxylic acid salt. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as aliphatic dicarboxylic...

  4. 40 CFR 721.3520 - Aliphatic polyglycidyl ether.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Aliphatic polyglycidyl ether. 721.3520... Substances § 721.3520 Aliphatic polyglycidyl ether. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance aliphatic polyglycidyl ether (PMN P-89-1036) is subject...

  5. 40 CFR 721.3520 - Aliphatic polyglycidyl ether.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Aliphatic polyglycidyl ether. 721.3520... Substances § 721.3520 Aliphatic polyglycidyl ether. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance aliphatic polyglycidyl ether (PMN P-89-1036) is subject...

  6. 40 CFR 721.6140 - Dialkyldithiophosphoric acid, aliphatic amine salt.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ..., aliphatic amine salt. 721.6140 Section 721.6140 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.6140 Dialkyldithiophosphoric acid, aliphatic amine salt. (a) Chemical... as a dialkyldithiophosphoric acid, aliphatic amine salt (P-90-1839) is subject to reporting...

  7. 40 CFR 721.6140 - Dialkyldithiophosphoric acid, aliphatic amine salt.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ..., aliphatic amine salt. 721.6140 Section 721.6140 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.6140 Dialkyldithiophosphoric acid, aliphatic amine salt. (a) Chemical... as a dialkyldithiophosphoric acid, aliphatic amine salt (P-90-1839) is subject to reporting...

  8. 40 CFR 721.6140 - Dialkyldithiophosphoric acid, aliphatic amine salt.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ..., aliphatic amine salt. 721.6140 Section 721.6140 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.6140 Dialkyldithiophosphoric acid, aliphatic amine salt. (a) Chemical... as a dialkyldithiophosphoric acid, aliphatic amine salt (P-90-1839) is subject to reporting...

  9. 40 CFR 721.6140 - Dialkyldithiophosphoric acid, aliphatic amine salt.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ..., aliphatic amine salt. 721.6140 Section 721.6140 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.6140 Dialkyldithiophosphoric acid, aliphatic amine salt. (a) Chemical... as a dialkyldithiophosphoric acid, aliphatic amine salt (P-90-1839) is subject to reporting...

  10. 40 CFR 721.6140 - Dialkyldithiophosphoric acid, aliphatic amine salt.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ..., aliphatic amine salt. 721.6140 Section 721.6140 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.6140 Dialkyldithiophosphoric acid, aliphatic amine salt. (a) Chemical... as a dialkyldithiophosphoric acid, aliphatic amine salt (P-90-1839) is subject to reporting...

  11. 40 CFR 721.8090 - Polyurethane polymer.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Polyurethane polymer. 721.8090 Section... Substances § 721.8090 Polyurethane polymer. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as a polyurethane polymer (P-94-47) is...

  12. 40 CFR 721.8090 - Polyurethane polymer.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Polyurethane polymer. 721.8090 Section... Substances § 721.8090 Polyurethane polymer. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as a polyurethane polymer (P-94-47) is...

  13. 40 CFR 721.8090 - Polyurethane polymer.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Polyurethane polymer. 721.8090 Section... Substances § 721.8090 Polyurethane polymer. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as a polyurethane polymer (P-94-47) is...

  14. 21 CFR 177.1680 - Polyurethane resins.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Polyurethane resins. 177.1680 Section 177.1680... Components of Single and Repeated Use Food Contact Surfaces § 177.1680 Polyurethane resins. The polyurethane resins identified in paragraph (a) of this section may be safely used as the food-contact surface...

  15. 40 CFR 721.8095 - Silylated polyurethane.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Silylated polyurethane. 721.8095... Substances § 721.8095 Silylated polyurethane. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as a silylated polyurethane (PMN P-95-1356)...

  16. 40 CFR 721.8095 - Silylated polyurethane.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Silylated polyurethane. 721.8095... Substances § 721.8095 Silylated polyurethane. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as a silylated polyurethane (PMN P-95-1356)...

  17. 40 CFR 721.8095 - Silylated polyurethane.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Silylated polyurethane. 721.8095... Substances § 721.8095 Silylated polyurethane. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as a silylated polyurethane (PMN P-95-1356)...

  18. 40 CFR 721.8095 - Silylated polyurethane.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Silylated polyurethane. 721.8095... Substances § 721.8095 Silylated polyurethane. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as a silylated polyurethane (PMN P-95-1356)...

  19. 40 CFR 721.8095 - Silylated polyurethane.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Silylated polyurethane. 721.8095... Substances § 721.8095 Silylated polyurethane. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as a silylated polyurethane (PMN P-95-1356)...

  20. 21 CFR 177.1680 - Polyurethane resins.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Polyurethane resins. 177.1680 Section 177.1680 Food... of Single and Repeated Use Food Contact Surfaces § 177.1680 Polyurethane resins. The polyurethane resins identified in paragraph (a) of this section may be safely used as the food-contact surface...

  1. 40 CFR 721.8090 - Polyurethane polymer.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Polyurethane polymer. 721.8090 Section... Substances § 721.8090 Polyurethane polymer. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as a polyurethane polymer (P-94-47) is...

  2. 40 CFR 721.8090 - Polyurethane polymer.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Polyurethane polymer. 721.8090 Section... Substances § 721.8090 Polyurethane polymer. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as a polyurethane polymer (P-94-47) is...

  3. [Occupational dermatoses due to polyurethane drugs].

    PubMed

    Rothe, A

    1976-01-01

    Twenty cases of occupational dermatoses caused by isocyanates, especially diphenylmethane diisocyanate (MDI), isophorone diisocyanate (IPDI), toluene diisocyanate (TDI) and tri-isocyanate-triphenylmethane are reported. The handling of patch test substances is described. Personal in test laboratories have to be considered as persons at risk. Findings give some evidence for cross-sensitization between MDI and the corresponding diamine diaminodiphenylmethane. Moreover, it is supposed that MDI may give rise to cross-sensitization to p-phenylene diamine and chemically related compounds.

  4. C-Terminal Modification of Fully Unprotected Peptide Hydrazides via in Situ Generation of Isocyanates.

    PubMed

    Vinogradov, Alexander A; Simon, Mark D; Pentelute, Bradley L

    2016-03-18

    A method for chemo- and regioselective conjugation of nucleophiles to fully unprotected peptides and proteins via in situ generation of C-terminal isocyanates is reported. Oxidation of C-terminal peptide hydrazides in aqueous media followed by Curtius rearrangement of acyl azides reliably generates isocyanates, which react with a variety of external nucleophiles, such as hydrazines, hydrazides, aromatic thiols, and hydroxylamines. Multiple peptides and a 53 kDa protein hydrazide were conjugated to different nucleophiles using this reaction. PMID:26948719

  5. Regioselective piperidine-catalyzed tandem imination-isocyanate annulation to fused tricyclic triazines.

    PubMed

    Barve, Indrajeet J; Chen, Chih-Hau; Kao, Chih-Hsien; Sun, Chung-Ming

    2014-05-12

    A novel tandem imination-isocyanate-mediated annulation was explored. Ionic liquid-immobilized 2-aminobenzimidazoles react sequentially with aldehydes and isocyanates to give highly functionalized benzimidazole-embedded triazines. The second-stage transformation revealed that the formation of triazinone functionality is entirely regioselective to allow rapid assembly of biologically interesting tricyclic skeletons. In conjunction with the application of microwave irradiation and IL support, this method provides an efficient route to access substituted benzoimidazotriazines.

  6. C-Terminal Modification of Fully Unprotected Peptide Hydrazides via in Situ Generation of Isocyanates.

    PubMed

    Vinogradov, Alexander A; Simon, Mark D; Pentelute, Bradley L

    2016-03-18

    A method for chemo- and regioselective conjugation of nucleophiles to fully unprotected peptides and proteins via in situ generation of C-terminal isocyanates is reported. Oxidation of C-terminal peptide hydrazides in aqueous media followed by Curtius rearrangement of acyl azides reliably generates isocyanates, which react with a variety of external nucleophiles, such as hydrazines, hydrazides, aromatic thiols, and hydroxylamines. Multiple peptides and a 53 kDa protein hydrazide were conjugated to different nucleophiles using this reaction.

  7. Mass spectrometric identification of isocyanate-induced modifications of keratins in human skin.

    PubMed

    Hulst, Albert G; Verstappen, Daan R W; van der Riet-Van Oeveren, Debora; Vermeulen, Nico P E; Noort, Daan

    2015-07-25

    In the current paper we show that exposure of human callus to isocyanates leads to covalent modifications within keratin proteins. Mass spectrometric analyses of pronase digests of keratin isolated from exposed callus show that both mono- and di-adducts (for di-isocyanates) are predominantly formed on the ε-amino group of lysine. In addition, numerous modified tryptic keratin fragments were identified, demonstrating rather random lysine modification. Interestingly, preliminary experiments demonstrate that in case of MDI a similar lysine di-adduct was formed with lung elastin. Our data support the hypothesis that skin sensitization through antigenic modifications of skin proteins by isocyanates could play a role in occupational isocyanate-induced asthma. It is further envisaged that the elucidated adducts will also have great potential for use as biomarkers to assess skin exposure to isocyanates. Advantageously, the various lysine adducts display the presence of a characteristic daughter fragment at m/z 173.1 [lysine-NCO](+), enabling generic and rapid screening for exposure to isocyanates.

  8. 2-Methoxyphenyl isocyanate and 2-Methoxyphenyl isothiocyanate: conformers, vibration structure and multiplet Fermi resonance.

    PubMed

    Yenagi, Jayashree; Nandurkar, Anita R; Tonannavar, J

    2012-06-01

    IR and Raman spectral measurements in the region 3500-400/50 cm(-1) have been made for the liquid samples of 2-Methoxyphenyl isocyanate and 2-Methoxyphenyl isothiocyanate. A complete assignment of the measured bands has been proposed as aided by conformational and vibration analyses at B3LYP/6-311++G** level of calculations. Three conformers for 2-Methoxyphenyl isocyanate and two for 2-Methoxyphenyl isothiocyanate have been determined. The tilt of the isocyanate (NCO) and isothiocyanate (NCS) moieties with respect to phenyl ring are in broad agreement with their parents. Stretching mode frequencies of methyl group (-OCH(3)) in 2-Methoxyphenyl isocyanate have been lowered in the 2900-2800 cm(-1); deformation asymmetric modes are IR strong and symmetric one Raman strong. In 2-Methoxyphenyl isothiocyanate, a similar pattern is true for stretching modes but deformation asymmetric modes are IR strong and symmetric mode has not been observed. Multiplet absorption band system near 2200 cm(-1) in 2-Methoxyphenyl isocyanate has been interpreted to be caused by Fermi resonance. A similar pattern in absorption near 2100 cm(-1) in 2-Methoxyphenyl isothiocyanate but more complex Raman band pattern has also been explained through Fermi resonance from heuristic stand-point. Many Raman modes in 1300-1100 cm(-1) are intensified apparently owing to isothiocyanate than isocyanate moiety. Phenyl ring breathing mode is shifted to 1040 cm(-1) as strong Raman; the symmetric stretching mode of O-CH(3) near 1023 cm(-1) as strong absorption.

  9. Renaissance of Aliphatic Polycarbonates: New Techniques and Biomedical Applications

    PubMed Central

    Xu, Jianwen; Feng, Ellva; Song, Jie

    2014-01-01

    Aliphatic polycarbonates were discovered a long time ago, with their conventional applications mostly limited to low molecular weight oligomeric intermediates for copolymerization with other polymers. Recent developments in polymerization techniques have overcome the difficulty in preparing high molecular weight aliphatic polycarbonates. These in turn, along with new functional monomers, have enabled the preparation of a wide range of aliphatic polycarbonates with diverse chemical compositions and structures. This review summarizes the latest polymerization techniques for preparing well-defined functional aliphatic polycarbonates, as well as the new applications of those aliphatic polycarbonates, esecially in the biomedical field. PMID:24994939

  10. CO2 and Sn(II) adducts of N-heterocyclic carbenes as delayed-action catalysts for polyurethane synthesis.

    PubMed

    Bantu, Bhasker; Pawar, Gajanan Manohar; Decker, Ulrich; Wurst, Klaus; Schmidt, Axel M; Buchmeiser, Michael R

    2009-01-01

    Catalytic rivals: Both CO(2)-protected tetrahydropyrimidin-2-ylidene-based N-heterocyclic carbenes (NHCs) and Sn(II)-1,3-dimesitylimidazol-2-ylidene, as well as Sn(II)-1,3-dimesitylimidazolin-2-ylidene complexes (example displayed), have been identified as truly latent catalysts for polyurethane (PUR) synthesis rivaling all existing systems both in activity and latency.A series of CO(2)-protected pyrimidin-2-ylidenes as well as 1,3-dimesitylimidazol-2-ylidene and dimesitylimidazolin-2-ylidene complexes of Sn(II) have been prepared. Selected single-crystal X-ray structures are reported. The new compounds were investigated for their catalytic behavior in polyurethane (PUR) synthesis. All compounds investigated showed excellent catalytic activity, rivaling the industrially most relevant catalyst dibutyltin dilaurate. Even more important, all compounds displayed pronounced latent behavior, in selected cases rivaling and exceeding the industrially relevant latent catalyst phenylmercury neodecanoate both in terms of latency and catalytic activity. This allows for creating one-component PUR systems with improved pot lifetimes. Pseudo-second-order kinetics were found for both CO(2)-protected tetrahyropyrimidin-2-ylidenes and for [SnCl(2)(1,3-dimesityldihydroimidazol-2-ylidene)], indicating a fast pre-catalyst decomposition prior to polyurethane formation. 1,3-Di(2-propyl)tetrahydropyrimidin-2-ylidene was additionally found to be active in the cyclotrimerization of various isocyanates, offering access to a broad variability in polymer structure, that is, creating both urethane and isocyanurate moieties within the same polymer. PMID:19212991

  11. Combinations of Aromatic and Aliphatic Radiolysis.

    PubMed

    LaVerne, Jay A; Dowling-Medley, Jennifer

    2015-10-01

    The production of H(2) in the radiolysis of benzene, methylbenzene (toluene), ethylbenzene, butylbenzene, and hexylbenzene with γ-rays, 2-10 MeV protons, 5-20 MeV helium ions, and 10-30 MeV carbon ions is used as a probe of the overall radiation sensitivity and to determine the relative contributions of aromatic and aliphatic entities in mixed hydrocarbons. The addition of an aliphatic side chain with progressively from one to six carbon lengths to benzene increases the H(2) yield with γ-rays, but the yield seems to reach a plateau far below that found from a simple aliphatic such as cyclohexane. There is a large increase in H(2) with LET (linear energy transfer) for all of the substituted benzenes, which indicates that the main process for H(2) formation is a second-order process and dominated by the aromatic entity. The addition of a small amount of benzene to cyclohexane can lower the H(2) yield from the value expected from a simple mixture law. A 50:50% volume mixture of benzene-cyclohexane has essentially the same H(2) yield as cyclohexylbenzene at a wide variation in LET, suggesting that intermolecular energy transfer is as efficient as intramolecular energy transfer.

  12. Polyurethane Dispersions with Peptide Corona: Facile Synthesis of Stimuli-Responsive Dispersions and Films.

    PubMed

    Breucker, Laura; Schöttler, Susanne; Landfester, Katharina; Taden, Andreas

    2015-08-10

    Peptide-polymer hybrid particles of submicron size yielding stimuli-responsive macroscopic films are presented. A thermoplastic polyurethane (PU) carrying polysiloxane and polyester soft segments serves as core material to obtain flexible, yet semicrystalline films with temperature-sensitivity. The synthesis is based on the high-sheer emulsification of isocyanate-terminated PU prepolymers, which in our model system purposefully lack any ability of colloidal self-stabilization. While emulsification in water leads to immediate coagulation, stable dispersions of polyurethane nanoparticles were formed in aqueous solutions of a hydrolyzed protein from wool. A comparison of dispersion and film properties to nonreactive, otherwise identical dispersions suggests covalent attachment of the peptide to the PU backbone. We show that the colloidal stability of the hybrid particles is completely governed by the peptide corona, and hence pH-triggered coagulation can be employed to induce particle deposition and film formation. Differential scanning calorimetry confirms partial crystallinity in the film and reveals strongly modified crystallization behavior due to the peptide.

  13. Enhanced biocompatibility and antibacterial property of polyurethane materials modified with citric acid and chitosan.

    PubMed

    Liu, Tian-Ming; Wu, Xing-Ze; Qiu, Yun-Ren

    2016-08-01

    Citric acid (CA) and chitosan (CS) were covalently immobilized on polyurethane (PU) materials to improve the biocompatibility and antibacterial property. The polyurethane pre-polymer with isocyanate group was synthesized by one pot method, and then grafted with citric acid, followed by blending with polyethersulfone (PES) to prepare the blend membrane by phase-inversion method so that chitosan can be grafted from the membrane via esterification and acylation reactions eventually. The native and modified membranes were characterized by attenuated total reflectance-Fourier transform infrared spectroscope, X-ray photoelectron spectroscopy, scanning electron microscopy, water contact angle measurement, and tensile strength test. Protein adsorption, platelet adhesion, hemolysis assay, activated partial thromboplastin time, prothrombin time, thrombin time, and adsorption of Ca(2+) were executed to evaluate the blood compatibility of the membranes decorated by CA and CS. Particularly, the antibacterial activities on the modified membranes were evaluated based on a vitro antibacterial test. It could be concluded that the modified membrane had good anticoagulant property and antibacterial property. PMID:27102367

  14. Fluorinated Polyurethanes, Synthesis and Properties.

    PubMed

    Smirnova, Olga; Glazkov, Alexey; Yarosh, Alexander; Sakharov, Alexey

    2016-01-01

    Fluorinated polyurethanes with a glass transition temperature as low as -139 °C and a decomposition onset temperature of 247-330 °C were prepared by a reaction of fluorinated alcohols with aromatic and cycloaliphatic diisocyanates in solution or melt. PMID:27420039

  15. Fluorinated Polyurethanes, Synthesis and Properties.

    PubMed

    Smirnova, Olga; Glazkov, Alexey; Yarosh, Alexander; Sakharov, Alexey

    2016-07-12

    Fluorinated polyurethanes with a glass transition temperature as low as -139 °C and a decomposition onset temperature of 247-330 °C were prepared by a reaction of fluorinated alcohols with aromatic and cycloaliphatic diisocyanates in solution or melt.

  16. Preparation of highly fluorinated polyurethanes

    NASA Technical Reports Server (NTRS)

    Rochow, S. E.; Stump, E. C., Jr.

    1971-01-01

    New polyurethanes, formed from a reaction of a prepolymer diol and a perfluorinated diisocyanate, are nonflammable and possess high corrosion resistance and good low temperature flexibility. Polymer hardness increases rapidly with increasing ratio of diisocaynate to diol, but its glass transition temperature is not adversely affected.

  17. Open-celled polyurethane foam

    NASA Technical Reports Server (NTRS)

    Russell, L. W.

    1970-01-01

    Open-celled polyurethane foam has a density of 8.3 pounds per cubic foot and a compressive strength of 295 to 325 psi. It is useful as a porous spacer in layered insulation and as an insulation material in vacuum tight systems.

  18. Washing Off Polyurethane Foam Insulation

    NASA Technical Reports Server (NTRS)

    Burley, Richard K.; Fogel, Irving

    1990-01-01

    Jet of hot water removes material quickly and safely. Simple, environmentally sound technique found to remove polyurethane foam insulation from metal parts. Developed for (but not limited to) use during rebuilding of fuel system of Space Shuttle main engine, during which insulation must be removed for penetrant inspection of metal parts.

  19. Immunological studies on mice exposed subacutely to methyl isocyanate

    SciTech Connect

    Tucker, A.N.; Bucher, J.R.; Germolec, D.R.; Silver, M.T.; Vore, S.J.; Luster, M.I.

    1987-06-01

    The immunotoxicity of methyl isocyanate (MIC) was evaluated in female B6C3F1 mice exposed via inhalation to 0, 1, or 3 ppm for 6 hr per day on 4 consecutive days. The antibody response to sheep erythrocytes and natural killer cell activity were found to be unaffected by MIC exposure. Although lymphoproliferative responses to mitogens were moderately suppressed by MIC, the differences were not statistically significant. The response of splenic lymphocytes to allogeneic leukocytes in a mixed leukocyte response (MLR) was suppressed in a dose-related fashion and was significantly different from the control response at the 3 ppm level. This effect was thought to be secondary and a result of general toxicity rather than a direct effect of MIC on the immune system. Furthermore, resistance to the infectious agents Listeria monocytogenes, mouse malaria parasite, and influenza virus, or to transplantable tumor cells was not compromised by MIC exposure. Thus, the immune system does not appear to be a primary target for MIC toxicity.

  20. Inception Cohort Study of Workers Exposed to Toluene Diisocyanate at a Polyurethane Foam Factory: Initial One-Year Follow-up

    PubMed Central

    Gui, Wei; Wisnewski, Adam V.; Neamtiu, Iulia; Gurzau, Eugen; Sparer, Judith A.; Stowe, Meredith H.; Liu, Jian; Slade, Martin D.; Rusu, Olivia A.; Redlich, Carrie A.

    2014-01-01

    Background Isocyanates are one of the most commonly reported causes of occupational asthma; however, the risks of developing isocyanate asthma in modern production facilities remain poorly defined. We evaluated TDI exposure and respiratory health among an inception cohort of workers during their first year of employment at a new polyurethane foam production factory. Methods Forty-nine newly hired workers were evaluated pre-employment, 6-months, and 12-months post-employment through questionnaire, spirometry and TDI-specific serology. Airborne TDI levels were monitored by fixed-point air sampling and limited personal sampling. Qualitative surface SWYPE™ tests were performed to evaluate potential sources of skin exposure. Results Airborne TDI levels overall were low; over 90% of fixed-point air measurements were below the limit of detection (0.1 ppb). Over the first year of employment,12 of the 49 original workers (24.5%) were lost to follow-up, no additional workers were enrolled, and seven of the 49 original workers (14.2%) developed either new asthma symptoms (N=3), TDI-specific IgG (N=1), new airflow obstruction (N=1) and/or a decline in FEV1≥ 15% (N=3), findings that could indicate TDI-related health effects.The prevalence of current asthma symptoms was significantly higher in the workers lost to follow-up compared to those who completed the 12 month follow-up (25% vs.2.7%; p=0.04). Conclusions The findings suggest possible early TDI-related health effects in a modern polyurethane production plant. These findings also highlight the need for further longitudinal evaluation of these workers and the challenges of studying workers at risk for isocyanate asthma. PMID:25266741

  1. Inflammatory response to isocyanates and onset of genomic instability in cultured human lung fibroblasts.

    PubMed

    Mishra, P K; Bhargava, A; Raghuram, G V; Gupta, S; Tiwari, S; Upadhyaya, R; Jain, S K; Maudar, K K

    2009-02-10

    Lungs comprise the primary organ exposed to environmental toxic chemicals, resulting in diverse respiratory ailments and other disorders, including carcinogenesis. Carcinogenesis is a multi-stage phenomenon, which involves a series of genetic alterations that begin with genomic instability provoked by certain factors such as inflammation and DNA damage and end with the development of cancer. Isocyanates such as methyl isocyanate are the chief metabolic intermediates in many industrial settings with diverse applications; exposure to them can lead to severe hypersensitive, mutagenic and genotoxic alterations. We examined the molecular mechanisms underlying isocyanate-mediated inflammatory responses and their probable role in the onset of genomic instability in cultured IMR-90 human lung fibroblasts. The isocyanates induced inflammation, resulting in extensive DNA damage, evidenced by increases in ATM, ATR, gammaH2AX, and p53 expression levels. The apoptotic index also increased. Chromosomal anomalies in treated cells included over-expression of centrosome protein and variable amplification of inter-simple sequence repeats, further demonstrating isocyanate-induced genomic instability. This information could be useful in the design of new approaches for risk assessment of potential industrial disasters.

  2. Effect of silica nanoparticles on polyurethane foaming process and foam properties

    NASA Astrophysics Data System (ADS)

    Francés, A. B.; Navarro Bañón, M. V.

    2014-08-01

    Flexible polyurethane foams (FPUF) are commonly used as cushioning material in upholstered products made on several industrial sectors: furniture, automotive seating, bedding, etc. Polyurethane is a high molecular weight polymer based on the reaction between a hydroxyl group (polyol) and isocyanate. The density, flowability, compressive, tensile or shearing strength, the thermal and dimensional stability, combustibility, and other properties can be adjusted by the addition of several additives. Nanomaterials offer a wide range of possibilities to obtain nanocomposites with specific properties. The combination of FPUF with silica nanoparticles could develop nanocomposite materials with unique properties: improved mechanical and thermal properties, gas permeability, and fire retardancy. However, as silica particles are at least partially surface-terminated with Si-OH groups, it was suspected that the silica could interfere in the reaction of poyurethane formation.The objective of this study was to investigate the enhancement of thermal and mechanical properties of FPUF by the incorporation of different types of silica and determining the influence thereof during the foaming process. Flexible polyurethane foams with different loading mass fraction of silica nanoparticles (0-1% wt) and different types of silica (non treated and modified silica) were synthesized. PU/SiO2 nanocomposites were characterized by FTIR spectroscopy, TGA, and measurements of apparent density, resilience and determination of compression set. Addition of silica nanoparticles influences negatively in the density and compression set of the foams. However, resilience and thermal stability of the foams are improved. Silica nanoparticles do not affect to the chemical structure of the foams although they interfere in the blowing reaction.

  3. {Polycyclic aromatic hydrocarbons (PAHs) and aliphatic hydrocarbons in gas and particle phases in two sites of Mexico: MILAGRO project}

    NASA Astrophysics Data System (ADS)

    Amador-Muñoz, O.; Villalobos-Pietrini, R.; Castro, T.; Gaspariano-Larino, R.

    2009-04-01

    Aliphatic hydrocarbons are markers of anthropogenic and biogenic emission sources1; meanwhile PAHs are generated by incomplete combustion sources2. The last ones are important compounds due to their carcinogenic and mutagenic properties3,4. The aim of this study was to identify and quantify aliphatic hydrocarbons and PAHs in gas and particles phases of the atmospheric aerosol and to determine the day and night time behavior during the MILAGRO (Megacity Initiative: Local Global and Research Observations) campaign. The gas phase was collected on polyurethane foam, while particles less than 2.5 m (PM2.5) were collected on glass fiber filters covered with Teflon (TIGF, pallflex) of 8x10 in. Samplings were carried out with a high volume sampler (Tisch) with a flow of 1.13 m3 min-1 at two sites: Instituto Mexicano del Petróleo (T0) and Tecamac (T1) located at North and Northeast of Mexico City, respectively during day (7:00 am-7:00 pm) and night time (7:00 pm-7:00 am) from 1 to 29 of March, 2006. Ninteen PAHs and 23 aliphatic hydrocarbons from n-C13H28 to n-C35H72 were analyzed by gas chromatography coupled to mass spectrometry in impact mode. The samples were spiked with deuterads PAHs and aliphatics hydrocarbons before ultrasound extraction. Medians comparisons were made with Mann-Whitney U test. PAHs with molecular weight (MW) less than 228 g mol-1 were distributed in the gas phase, in both sites. Higher concentrations of PAHs ≥ 228 g mol-1 in PM2.5, were observed during night period (p

  4. [(Salcen)Cr(III) + Lewis base]-catalyzed synthesis of N-aryl-substituted oxazolidinones from epoxides and aryl isocyanates.

    PubMed

    Paddock, Robert L; Adhikari, Debashis; Lord, Richard L; Baik, Mu-Hyun; Nguyen, SonBinh T

    2014-12-14

    [(Salcen)Cr(III) + Lewis base] was found to be a highly active and selective catalyst system in the [2+3] cycloaddition between epoxides and isocyanates to form 5-oxazolidinones. The reaction proceeds to high yield under mild reaction conditions and is applicable to a variety of terminal epoxides and aryl isocyanates.

  5. Spreading coefficients of aliphatic hydrocarbons on water

    SciTech Connect

    Takii, Taichi; Mori, Y.H. . Dept. of Mechanical Engineering)

    1993-11-01

    Experiments have been performed to determine the equilibrium spreading coefficients of some aliphatic hydrocarbons (C[sub 6]C[sub 10]) on water. The thickness of a discrete lens of each hydrocarbon sample floating on a stagnant water pool was measured interferometrically and used to calculate the spreading coefficient of the hydrocarbon with the aid of Langmuir's capillarity theory. The dependences of the spreading coefficient, thus observed, on temperature (0--50 C) and on the number of carbon atoms in the hydrocarbon molecule are in qualitative agreement with the predictions based on the Lifshitz theory of van der Waals forces.

  6. Isocyanate-mediated covalent immobilization of Mucor miehei lipase onto SBA-15 for transesterification reaction.

    PubMed

    Canilho, N; Jacoby, J; Pasc, A; Carteret, C; Dupire, F; Stébé, M J; Blin, J L

    2013-12-01

    Mucor miehei lipase (Mm-L) covalently bind on a hexagonally ordered silica SBA-15 (Santa Barbara Amorphous), previously functionalized with isocyanate moieties, was examined as biocatalyst for transesterification of colza oil with methanol. The isocyanate-mesoporous silica (NCO-SBA-15) was obtained by condensation of silanol with triethoxysilane propyl isocyanate (TPI). The efficiency of the functionalization has been evidenced by infrared, (29)Si and (13)C NMR spectroscopies. The substrate provided a moderate hydrophobic microenvironment together with reactive sites for chemical immobilization of the enzyme. The biocatalyst containing 0.28 g of Mm-L per gram of support afforded a high level of transesterification activity (yield up to 80%) while using 1:1 molar ratio of methanol/colza oil and small amount of water. The biocatalyst showed higher operational stability than the corresponding physisorbed enzyme since it can be reused 6 times against 2 consecutive runs for the physisorbed enzyme.

  7. Catalytic properties of maltogenic α-amylase from Bacillus stearothermophilus immobilized onto poly(urethane urea) microparticles.

    PubMed

    Straksys, Antanas; Kochane, Tatjana; Budriene, Saulute

    2016-11-15

    The immobilization of maltogenic α-amylase from Bacillus stearothermophilus (BsMa) onto novel porous poly(urethane urea) (PUU) microparticles synthesized from poly(vinyl alcohol) and isophorone diisocyanate was performed by covalent attachment to free isocyanate groups from PUU microparticles, or by physical adsorption of enzyme onto the surface of the carrier. The influence of structure, surface area and porosity of microparticles on the catalytic properties of immobilized BsMa was evaluated. The highest efficiency of immobilization of BsMa was found to be 72%. Optimal activity of immobilized BsMa was found to have increased by 10°C compared with the native enzyme. Influence of concentration of sodium chloride on activity of immobilized BsMa was evaluated. High storage and thermal stability and reusability for starch hydrolysis of immobilized enzyme were obtained. Immobilized BsMa has a great potential for biotechnology. PMID:27283635

  8. Catalytic properties of maltogenic α-amylase from Bacillus stearothermophilus immobilized onto poly(urethane urea) microparticles.

    PubMed

    Straksys, Antanas; Kochane, Tatjana; Budriene, Saulute

    2016-11-15

    The immobilization of maltogenic α-amylase from Bacillus stearothermophilus (BsMa) onto novel porous poly(urethane urea) (PUU) microparticles synthesized from poly(vinyl alcohol) and isophorone diisocyanate was performed by covalent attachment to free isocyanate groups from PUU microparticles, or by physical adsorption of enzyme onto the surface of the carrier. The influence of structure, surface area and porosity of microparticles on the catalytic properties of immobilized BsMa was evaluated. The highest efficiency of immobilization of BsMa was found to be 72%. Optimal activity of immobilized BsMa was found to have increased by 10°C compared with the native enzyme. Influence of concentration of sodium chloride on activity of immobilized BsMa was evaluated. High storage and thermal stability and reusability for starch hydrolysis of immobilized enzyme were obtained. Immobilized BsMa has a great potential for biotechnology.

  9. [A case of isocyanate-induced hypersensitivity pneumonitis and a compression-air mask thought to be effective in its prevention].

    PubMed

    Idezuka, J; Ikarashi, H; Nozawa, S; Maruyama, M; Sasagawa, M; Suzuki, E

    1991-07-01

    A 41-year-old paint sprayer, who had worked with polyurethane paint since the spring of 1989, developed exertional dyspnea and dry cough and entered hospital on December 4, 1989. Plain chest X-ray film and a computed tomogram of the lung revealed diffuse micronodular shadows in both lower lung fields. DLco was shown to be significantly decreased in a pulmonary function test. A sample of bronchoalveolar lavage fluid showed increased T lymphocytes and a decreased CD4/8 ratio. A lung biopsy specimen revealed alveolitis, but neither Masson body nor granulomas were seen. Serum antibody specific to TDI-HSA was detected, and an environmental provocation test was positive. From these results, the patient was diagnosed as having isocyanate-induced hypersensitivity pneumonitis. We advised him to wear a compression-air mask when he worked, because he did not want to quit his job. Respiratory symptoms have not been seen since then, but careful observation was thought to be necessary. The involvement of type III humoral and type IV cellular immunity was suspected in this case.

  10. Open-pore polyurethane product

    DOEpatents

    Jefferson, R.T.; Salyer, I.O.

    1974-02-17

    The method is described of producing an open-pore polyurethane foam having a porosity of at least 50% and a density of 0.1 to 0.5 g per cu cm, and which consists of coherent spherical particles of less than 10 mu diam separated by interconnected interstices. It is useful as a filter and oil absorbent. The product is admirably adapted to scavenging of crude oil from the surface of seawater by preferential wicking. The oil-soaked product may then be compressed to recover the oil or burned for disposal. The crosslinked polyurethane structures are remarkably solvent and heat-resistance as compared with known thermoplastic structures. Because of their relative inertness, they are useful filters for gasoline and other hydrocarbon compounds. (7 claims)

  11. Biofiltration of gasoline and diesel aliphatic hydrocarbons.

    PubMed

    Halecky, Martin; Rousova, Jana; Paca, Jan; Kozliak, Evguenii; Seames, Wayne; Jones, Kim

    2015-02-01

    The ability of a biofilm to switch between the mixtures of mostly aromatic and aliphatic hydrocarbons was investigated to assess biofiltration efficiency and potential substrate interactions. A switch from gasoline, which consisted of both aliphatic and aromatic hydrocarbons, to a mixture of volatile diesel n-alkanes resulted in a significant increase in biofiltration efficiency, despite the lack of readily biodegradable aromatic hydrocarbons in the diesel mixture. This improved biofilter performance was shown to be the result of the presence of larger size (C₉-C(12)) linear alkanes in diesel, which turned out to be more degradable than their shorter-chain (C₆-C₈) homologues in gasoline. The evidence obtained from both biofiltration-based and independent microbiological tests indicated that the rate was limited by biochemical reactions, with the inhibition of shorter chain alkane biodegradation by their larger size homologues as corroborated by a significant substrate specialization along the biofilter bed. These observations were explained by the lack of specific enzymes designed for the oxidation of short-chain alkanes as opposed to their longer carbon chain homologues.

  12. Aliphatic hydrocarbons of the Murchison meteorite

    SciTech Connect

    Cronin, J.R.; Pizzarello, S. )

    1990-10-01

    The indigenous organic compounds of carbonaceous chondrites have been difficult to characterize because of problems arising from terrestrial contamination. The fall of the Murchison meteorite (CM2) provided pristine samples which allowed the resolution of some prior ambiguities as, for example, in the case of the amino acids. However, the nature of the aliphatic hydrocarbons has remained unclear. Shortly after the Murchison fall, one laboratory found them to be mainly cycloalkanes; another found, in order of abundance, branched alkanes, olefins, and cycloalkanes; while a third reported predominantly n-alkanes followed by methyl alkanes and olefins. The authors have reinvestigated this question using benzene-methanol as the extraction solvent, silica-gel chromatography for fractionation of the extract, and GC-MS, and IR and NMR spectroscopic techniques for the analyses. When interior samples were obtained and the analyses carried out under conditions that minimized environmental contaminants, they have found the principal aliphatic components of the Murchison meteorite to be a structurally diverse suite of C{sub 15} to C{sub 30} branched alkyl-substituted mono-, di-, and tricyclic alkanes. Comparative analyses were carried out on the Murray (CM2), Allende (CV3), and New Concord (L6) chondrites that illustrate the nature of the contamination problem encountered with carbonaceous chondrites.

  13. Aliphatic hydrocarbons of the Murchison meteorite.

    PubMed

    Cronin, J R; Pizzarello, S

    1990-01-01

    The indigenous organic compounds of carbonaceous chondrites have been difficult to characterize because of problems arising from terrestrial contamination. The fall of the Murchison meteorite (CM2) provided pristine samples which allowed the resolution of some prior ambiguities as, for example, in the case of the amino acids. However, the nature of the aliphatic hydrocarbons has remained unclear. Shortly after the Murchison fall, one laboratory found them to be mainly cycloalkanes; another found, in order of abundance, branched alkanes, olefins, and cycloalkanes; while a third reported predominantly n-alkanes followed by methyl alkanes and olefins. We have reinvestigated this question using benzene-methanol as the extraction solvent, silica-gel chromatography for fractionation of the extract, and GC-MS, and IR and NMR spectroscopic techniques for the analyses. When interior samples were obtained and the analyses carried out under conditions that minimized environmental contaminants, we have found the principal aliphatic components of the Murchison meteorite to be a structurally diverse suite of C15 to C30 branched alkyl-substituted mono-, di-, and tricyclic alkanes. Comparative analyses were carried out on the Murray (CM2), Allende (CV3), and New Concord (L6) chondrites that illustrate the nature of the contamination problem encountered with carbonaceous chondrites.

  14. Gaseous aliphatic aldehydes in Chinese incense smoke

    SciTech Connect

    Lin, J.M.; Wang, L.H. )

    1994-09-01

    Aliphatic aldehydes were found during the combustion of materials. Tobacco smoke contains aldehydes. Fire fighters were exposed to aldehydes when they conducted firefighting. Aldehydes in ambient air come mainly from the incomplete combustion of hydrocarbons and from photochemical reaction. Most aldehydes in ambient air are formaldehyde and acetaldehyde. Formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, and benzaldehyde were found in the atmosphere in Los Angeles. Burning Chinese incense for worshipping deities is a Chinese daily routine. It was suspected to be a factor causing nasopharynegeal cancer. Epidemiological studies correlated it with the high risk of childhood brain tumor and the high risk of childhood leukemia. Ames test identified the mutagenic effect of the smoke from burning Chinese incense. The smoke had bee proved to contain polycyclic aromatic hydrocarbons and aromatic aldehydes. Suspicion about formaldehyde and other alphatic aldehydes was evoked, when a survey of indoor air pollution was conducted in Taipei city. This study determined the presence of aliphatic aldehydes in the smoke from burning Chinese incense under a controlled atmosphere. 12 refs., 5 figs., 2 tabs.

  15. Biodegradation of aliphatic and aromatic polycarbonates.

    PubMed

    Artham, Trishul; Doble, Mukesh

    2008-01-01

    Polycarbonate is one of the most widely used engineering plastics because of its superior physical, chemical, and mechanical properties. Understanding the biodegradation of this polymer is of great importance to answer the increasing problems in waste management of this polymer. Aliphatic polycarbonates are known to biodegrade either through the action of pure enzymes or by bacterial whole cells. Very little information is available that deals with the biodegradation of aromatic polycarbonates. Biodegradation is governed by different factors that include polymer characteristics, type of organism, and nature of pretreatment. The polymer characteristics such as its mobility, tacticity, crystallinity, molecular weight, the type of functional groups and substituents present in its structure, and plasticizers or additives added to the polymer all play an important role in its degradation. The carbonate bond in aliphatic polycarbonates is facile and hence this polymer is easily biodegradable. On the other hand, bisphenol A polycarbonate contains benzene rings and quaternary carbon atoms which form bulky and stiff chains that enhance rigidity. Even though this polycarbonate is amorphous in nature because of considerable free volume, it is non-biodegradable since the carbonate bond is inaccessible to enzymes because of the presence of bulky phenyl groups on either side. In order to facilitate the biodegradation of polymers few pretreatment techniques which include photo-oxidation, gamma-irradiation, or use of chemicals have been tested. Addition of biosurfactants to improve the interaction between the polymer and the microorganisms, and blending with natural or synthetic polymers that degrade easily, can also enhance the biodegradation.

  16. A cascade synthesis of aminohydantoins using in situ-generated N-substituted isocyanates.

    PubMed

    Vincent-Rocan, Jean-François; Clavette, Christian; Leckett, Kyle; Beauchemin, André M

    2015-03-01

    Nitrogen-substituted isocyanates are rarely utilized but powerful building blocks for the development of cascade reactions in heterocyclic synthesis. These reactive amphoteric intermediates can be accessed in situ via an equilibrium that allows controlled reactivity in the presence of bifunctional partners such as α-amino esters. A cascade reaction has been carried out that forms 3-aminohydantoin derivatives using simple phenoxycarbonyl derivatives of hydrazides and hydrazones as precursors of N-substituted-isocyanates. This method allows rapid assembly of complex aminohydantoin derivatives, including analogues of medicinally-relevant compounds, using simple reactants.

  17. Polyurethanes from fluoroalkyl propyleneglycol polyethers

    NASA Technical Reports Server (NTRS)

    Trischler, F. D. (Inventor)

    1969-01-01

    A description is given of highly stable polyurethane polymers prepared by reacting a polyether with a diisocyanate. Compounded stocks of these polymers may be shaped and cured in conventional equipment used in the rubber industry. The solutions are dispersed gels prepared from the polymers and may be used for forming supported or unsupported films for coating fabrics or solid surfaces, and for forming adhesive bonds between a wide variety of plastics, elastomers, fabrics, metals, wood, leather, ceramics and the like.

  18. Polyurethane retainers for ball bearings

    NASA Technical Reports Server (NTRS)

    Christy, R. I.

    1973-01-01

    Evaluation of a new ball bearing retainer material is reported. A special composite polyurethane foam ball retainer has been developed that has virtually zero wear, is chemically inert to hydrocarbon lubricants, and stores up to 60 times as much lubricant per unit volume as the most commonly used retainer material, cotton phenolic. This new retainer concept shows promise of years of ball bearing operation without reoiling, based on life testing in high vacuum.

  19. 77 FR 56639 - Certain New Chemicals; Receipt and Status Information

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-13

    ... polyurethane containing oil, foam. polymer with aromatic isocyanate, polyalkylene- polyalkylene glycol ether with dialkylene glycol (2:1) and polyalkylene- polyalkylene glycol ether with aliphatic triol (3:1), polyalkylene glycol mono(branched alkylaromatic) ether-blocked. P-12-0489 08/01/2012 10/29/2012 CBI...

  20. Is the analysis of histamine and/or interleukin-4 release after isocyanate challenge useful in the identification of patients with IgE-mediated isocyanate asthma?

    PubMed

    Blindow, Silke; Preisser, Alexandra M; Baur, Xaver; Budnik, Lygia T

    2015-07-01

    Isocyanates are a well-known and frequent cause of occupational asthma. The implementation of specific inhalation challenges (SICs) is the gold standard in asthma diagnosis supporting occupational case history, lung function testing, specific skin prick tests and the detection of specific IgE. However, the diagnosis is not always definitive. An interesting new approach, analyses of individual genetic susceptibilities, requires discrimination between a positive SIC reaction arising from IgE-mediated immune responses and one from other pathophysiological mechanisms. Hence, additional refinement tools would be helpful in defining sub-classes of occupational asthma and diagnosis. We used total IgE levels, specific IgE and SIC results for sub-classification of 27 symptomatic isocyanate workers studied. Some mutations in glutathione S-transferases (GSTs) are suspected either to enhance or to decrease the individual risk in the development of isocyanate asthma. Our patient groups were assessed for the point mutations GSTP1*I105V and GSTP1*A114V as well as deletions (null mutations) of GSTM1 and GSTT1. There seems to be a higher risk in developing IgE-mediated reactions when GSTM1 is deleted, while GSTT1 deletions were found more frequently in the SIC positive group. Blood samples taken before SIC, 30-60 min and 24h after SIC, were analyzed for histamine and IL-4, classical markers for the IgE-mediated antigen-specific activation of basophils or mast cells. We suggest that the utility of histamine measurements might provide an additional useful marker reflecting isocyanate-induced cellular reactions (although the sampling times require optimization). The promising measurement of IL-4 is not feasible at present due to the lack of a reliable, validated assay.

  1. 40 CFR 721.4497 - Aliphatic polyisocyanates (generic name).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Aliphatic polyisocyanates (generic name). 721.4497 Section 721.4497 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED... Specific Chemical Substances § 721.4497 Aliphatic polyisocyanates (generic name). (a) Chemical...

  2. Metalloradical-catalyzed aliphatic carbon-carbon activation of cyclooctane.

    PubMed

    Chan, Yun Wai; Chan, Kin Shing

    2010-05-26

    The aliphatic carbon-carbon activation of c-octane was achieved via the addition of Rh(ttp)H to give Rh(ttp)(n-octyl) in good yield under mild reaction conditions. The aliphatic carbon-carbon activation was Rh(II)(ttp)-catalyzed and was very sensitive to porphyrin sterics.

  3. 40 CFR 721.2270 - Aliphatic dicarboxylic acid salt.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Aliphatic dicarboxylic acid salt. 721... Substances § 721.2270 Aliphatic dicarboxylic acid salt. (a) Chemical substance and significant new uses... salt (PMN P-92-1352) is subject to reporting under this section for the significant new uses...

  4. Formulation, Preparation, and Characterization of Polyurethane Foams

    ERIC Educational Resources Information Center

    Pinto, Moises L.

    2010-01-01

    Preparation of laboratory-scale polyurethane foams is described with formulations that are easy to implement in experiments for undergraduate students. Particular attention is given to formulation aspects that are based on the main chemical reactions occurring in polyurethane production. This allows students to develop alternative formulations to…

  5. Microwave-assisted synthesis of cyclodextrin polyurethanes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cyclodextrin (CD) has often been incorporated into polyurethanes in order to facilitate its use in encapsulation or removal of organic species for various applications. In this work a microwave-assisted method has been developed to produce polyurethanes consisting of alpha-, ß-, and gamma-CD and thr...

  6. Aryl isomerization during aliphatic CH bond activation

    SciTech Connect

    Chamberlain, L.R.; Rothwell, I.P.

    1983-03-23

    The transition-metal-stablized benzyne or o-phenylene (n/sup 2/-C/sub 6/H/sub 4/) ligand has been shown to be both an interesting and reactive group. The ligand is normally generated in mononuclear systems by ..beta..- (ortho-) hydrogen abstraction from an aryl group, and this synthetic approach has allowed a stable example to be isolated and structurally characterized. Here the conclusive identification of a benzyne intermediate during the isomerization of a tantalum-aryl compound is reported. The reaction is interesting in that the ortho hydrogen is transferred to the carbon atom of a cyclometalated chelate, the reverse (isomerization) step thus involving the activation of an aliphatic CH bond by the intermediate benzyne.

  7. Stable isotope investigations of chlorinated aliphatic hydrocarbons.

    SciTech Connect

    Abrajano, T.; Heraty, L. J.; Holt, B. D.; Huang, L.; Sturchio, N. C.

    1999-06-01

    Stable isotope ratio measurements for carbon (C) and chlorine (Cl) can be used to elucidate the processes affecting transformation and transportation of chlorinated aliphatic hydrocarbons (CAHs) in the environment. Methods recently developed in our laboratory for isotopic analysis of CAHs have been applied to laboratory measurements of the kinetic isotope effects associated with aerobic degradation of dichloromethane (DCM) and with both anaerobic and aerobic cometabolic degradation of trichlomethene (TCE) in batch and column microbial cultures. These experimental determinations of fractionation factors are crucial for understanding the behavior of CAHs in complex natural systems, where the extent of biotransformation can be masked by dispersion and volatilization. We have also performed laboratory investigations of kinetic isotope effects accompanying evaporation of CAHs, as well as field investigations of natural attenuation and in situ remediation of CAHs in a number of contaminated shallow aquifers at sites operated by the federal government and the private sector.

  8. Isothermal aging of three polyurethane elastomers

    SciTech Connect

    Guess, T.R.

    1996-05-01

    Two polyurethane systems, EN-7 and L-100, have a long history as encapsulants and coatings in Sandia programs. These materials contain significant amounts of toluene diisocyanate (TDI), a suspect human carcinogen. As part of efforts to reduce the use of hazardous materials in the workplace, PET-90A, a polyurethane with less than 0.1% free TDI, was identified as a candidate for new applications and as a replacement for the more hazardous polyurethanes in selected programs. This report documents the results of a two-year accelerated aging study of PET-90A, EN-7, and L-100 polyurethane elastomers to characterize the effect of 135{degrees}F isothermal aging on selected physical, electrical, mechanical and thermal properties. In general, there was very little change in properties over the two year period for the three elastomers. The largest changes occurred in EN-7, which is the polyurethane with the longest service history in Sandia applications.

  9. Validation of transferability of DBA derivatization and LC-MS/MS determination method for isocyanates via an interlaboratory comparison.

    PubMed

    Bobeldijk, Ivana; Karlsson, Daniel; Pronk, Anjoeka; Gonsalves, John; Hekman, Maarten; Van De Lagemaat, Dick; Preller, Liesbeth; Heederik, Dick; Skarping, Gunnar

    2008-11-01

    An adapted method for the quantitative determination of isocyanates in air was implemented and validated in-house. The method was based on air sampling using an impinger flask containing di-n-butylamine (DBA) in toluene and a glass fibre filter in series. The DBA derivatives were determined using liquid chromatography and tandem mass spectrometry. Studied isocyanates were isophorone diisocyanate, isocyanic acid (ICA), methyl isocyanate, ethyl isocyanate, propyl isocyanate, hexamethylene diisocyanate (HDI), 2,6- and 2,4-toluene diisocyanate, 4,4'-methylene diphenyl diisocyanate (MDI), phenyl isocyanate (PhI), MDI oligomers and different HDI adducts. Monitoring of selected reactions resulted in quantifications with correlation coefficients >0.995, within-batch relative standard deviation (RSD) of repeatability was <13% for all analytes. Between-batch RSD (reproducibility) was determined for all the compounds with the exception of the adducts and oligomers and was also <13%. As an additional validation procedure, the method was evaluated by exchanging field (air) and standard samples between two laboratories. The RSDs observed by the two laboratories were comparable. The concentrations determined were between 80 and 120% of each other, depending on the analyte and the individual concentrations. The method was applied in a large field study on exposure of workers in car repair shops and industrial painters with >500 samples.

  10. Transient receptor potential ankyrin 1 antagonists block the noxious effects of toxic industrial isocyanates and tear gases

    PubMed Central

    Bessac, Bret F.; Sivula, Michael; von Hehn, Christian A.; Caceres, Ana I.; Escalera, Jasmine; Jordt, Sven-Eric

    2009-01-01

    The release of methyl isocyanate in Bhopal, India, caused the worst industrial accident in history. Exposures to industrial isocyanates induce lacrimation, pain, airway irritation, and edema. Similar responses are elicited by chemicals used as tear gases. Despite frequent exposures, the biological targets of isocyanates and tear gases in vivo have not been identified, precluding the development of effective countermeasures. We use Ca2+ imaging and electrophysiology to show that the noxious effects of isocyanates and those of all major tear gas agents are caused by activation of Ca2+ influx and membrane currents in mustard oil-sensitive sensory neurons. These responses are mediated by transient receptor potential ankyrin 1 (TRPA1), an ion channel serving as a detector for reactive chemicals. In mice, genetic ablation or pharmacological inhibition of TRPA1 dramatically reduces isocyanate- and tear gas-induced nocifensive behavior after both ocular and cutaneous exposures. We conclude that isocyanates and tear gas agents target the same neuronal receptor, TRPA1. Treatment with TRPA1 antagonists may prevent and alleviate chemical irritation of the eyes, skin, and airways and reduce the adverse health effects of exposures to a wide range of toxic noxious chemicals.—Bessac, B. F., Sivula, M., von Hehn, C. A., Caceres, A. I., Escalera, J., Jordt, S.-E. Transient receptor potential ankyrin 1 antagonists block the noxious effects of toxic industrial isocyanates and tear gases. PMID:19036859

  11. Modification, crosslinking and reactive electrospinning of a thermoplastic medical polyurethane for vascular graft applications.

    PubMed

    Theron, J P; Knoetze, J H; Sanderson, R D; Hunter, R; Mequanint, K; Franz, T; Zilla, P; Bezuidenhout, D

    2010-07-01

    Thermoplastic polyurethanes are used in a variety of medical devices and experimental tissue engineering scaffolds. Despite advances in polymer composition to improve their stability, the correct balance between chemical and mechanical properties is not always achieved. A model compound (MC) simulating the structure of a widely used medical polyurethane (Pellethane) was synthesized and reacted with aliphatic and olefinic acyl chlorides to study the reaction site and conditions. After adopting the conditions to the olefinic modification of Pellethane, processing into flat sheets, and crosslinking by thermal initiation or ultraviolet radiation, mechanical properties were determined. The modified polyurethane was additionally electrospun under ultraviolet light to produce a crosslinked tubular vascular graft prototype. Model compound studies showed reaction at the carbamide nitrogen, and the modification of Pellethane with pentenoyl chloride could be accurately controlled to up to 20% (correlation: rho=0.99). Successful crosslinking was confirmed by insolubility of the materials. Initiator concentrations were optimized and the crosslink densities shown to increase with increasing modification. Crosslinking of Pellethane containing an increasing number of pentenoyl groups resulted in decreases (up to 42%, p<0.01) in the hysteresis and 44% in creep (p<0.05), and in a significant improvement in degradation resistance in vitro. Modified Pellethane was successfully electrospun into tubular grafts and crosslinked using UV irradiation during and after spinning to render them insoluble. Prototype grafts had sufficient burst pressure (>550 mm Hg), and compliances of 12.1+/-0.8 and 6.2+/-0.3%/100 mm Hg for uncrosslinked and crosslinked samples, respectively. It is concluded that the viscoelastic properties of a standard thermoplastic polyurethane can be improved by modification and subsequent crosslinking, and that the modified material may be electrospun and initiated to yield

  12. Development of aliphatic biodegradable photoluminescent polymers

    PubMed Central

    Yang, Jian; Zhang, Yi; Gautam, Santosh; Liu, Li; Dey, Jagannath; Chen, Wei; Mason, Ralph P.; Serrano, Carlos A.; Schug, Kevin A.; Tang, Liping

    2009-01-01

    None of the current biodegradable polymers can function as both implant materials and fluorescent imaging probes. The objective of this study was to develop aliphatic biodegradable photoluminescent polymers (BPLPs) and their associated cross-linked variants (CBPLPs) for biomedical applications. BPLPs are degradable oligomers synthesized from biocompatible monomers including citric acid, aliphatic diols, and various amino acids via a convenient and cost-effective polycondensation reaction. BPLPs can be further cross-linked into elastomeric cross-linked polymers, CBPLPs. We have shown representatively that BPLP-cysteine (BPLP-Cys) and BPLP-serine (BPLP-Ser) offer advantages over the traditional fluorescent organic dyes and quantum dots because of their preliminarily demonstrated cytocompatibility in vitro, minimal chronic inflammatory responses in vivo, controlled degradability and high quantum yields (up to 62.33%), tunable fluorescence emission (up to 725 nm), and photostability. The tensile strength of CBPLP-Cys film ranged from 3.25 ± 0.13 MPa to 6.5 ± 0.8 MPa and the initial Modulus was in a range of 3.34 ± 0.15 MPa to 7.02 ± 1.40 MPa. Elastic CBPLP-Cys could be elongated up to 240 ± 36%. The compressive modulus of BPLP-Cys (0.6) (1:1:0.6 OD:CA:Cys) porous scaffold was 39.60 ± 5.90 KPa confirming the soft nature of the scaffolds. BPLPs also possess great processability for micro/nano-fabrication. We demonstrate the feasibility of using BPLP-Ser nanoparticles (“biodegradable quantum dots”) for in vitro cellular labeling and noninvasive in vivo imaging of tissue engineering scaffolds. The development of BPLPs and CBPLPs represents a new direction in developing fluorescent biomaterials and could impact tissue engineering, drug delivery, bioimaging. PMID:19506254

  13. CYTOKINE MRNA PROFILES FOR ISOCYANATES WITH KNOWN AND UNKNOWN POTENTIAL TO INDUCE RESPIRATORY SENSITIZATION

    EPA Science Inventory

    Cytokine mRNA Profiles for Isocyanates with Known and Unknown Potential to Induce Respiratory Sensitization. Plitnick, L.M., Loveless, S.E., Ladics, G.S., Holsapple, M.P., Smialowicz, R.J., Woolhiser, M.R., Anderson, P.K., Smith, C., Sailstad, D.M. and Selgrade, M.J.K (2002) Tox...

  14. A New Synthesis of Tertiary Alkyl N-Arylcarbamates from Isocyanates.

    ERIC Educational Resources Information Center

    Bailey, William J.; Griffith, James R.

    1978-01-01

    The method involves the dissolution of a small piece of metallic lithium in a small quantity of tertiary alcohol followed by addition to a mixture of the isocyanate and the tertiary alcohol in ether. This should be useful in organic chemistry laboratory courses for the identification of tertiary alcohols. (Author/BB)

  15. Magnetic iron oxide nanoparticle functionalization: isocyanate moiety as a suitable monodentate anchoring group.

    PubMed

    Carrara, Claudio; Sala, Maria C; Caneva, Enrico; Cauteruccio, Silvia; Licandro, Emanuela

    2014-01-17

    A new strategy for anchoring organic molecules onto superparamagnetic iron oxide nanoparticles (SPIONs) using isocyanate containing linkers has been realized. This functional group easily and efficiently reacts with the hydroxyl residues of the nanoparticle surface, leading to the formation of a stable carbamate bond, as confirmed by means of spectroscopic and analytical data.

  16. Determination of isocyanates by capillary electrophoresis with tris(2,2'-bipyridine)ruthenium(II) electrochemiluminescence.

    PubMed

    Li, Haijuan; Shi, Lihong; Liu, Xiaoqing; Niu, Wenxin; Xu, Guobao

    2009-11-01

    CE with tris(2,2'-bipyridyl) ruthenium(II) (Ru(bpy)(3) (2+)) electrochemiluminescence (ECL) detection for the quantitative determination of isocyanates was first reported. Hexamethylene diisocyanate (HDI) and hexyl isocyanate (HI) were used as the model analytes. Commercially available N,N-diethyl-N'-methylethylenediamine was used as the derivatization reagent. It has both a secondary amine group and a tertiary amine group. The secondary amine group can quantitatively react with isocyanate group, and the tertiary amine group can react with Ru(bpy)(3) (2+) to produce strong ECL signal for sensitive detection. The derivatization reaction was almost instantaneous and is much faster than other reported derivative reactions using other derivative reagents. The urea formed was stable. Linear calibration curve was obtained in the range from 0.01 to 10 microM for HDI, and 0.02 to 20 microM for hexyl isocyanate (HI). The detection limit is 0.01 microM for HDI and 0.02 microM for HI. The method is more sensitive than UV-detection and electrochemical detection. For practical application, recovery higher than 90% for HDI and HI was obtained for foam sample.

  17. Enantioselective [2 + 2 + 2] cycloaddition reaction of isocyanates and allenes catalyzed by nickel.

    PubMed

    Miura, Tomoya; Morimoto, Masao; Murakami, Masahiro

    2010-11-17

    The enantioselective intermolecular [2 + 2 + 2] cycloaddition reaction of two molecules of isocyanate and one molecule of allene is catalyzed by a nickel(0)/(S,S)-i-Pr-FOXAP complex, providing an efficient access to enantiomerically enriched dihydropyrimidine-2,4-diones.

  18. Airborne isocyanate exposures in the collision repair industry and a comparison to occupational exposure limits.

    PubMed

    Reeb-Whitaker, Carolyn; Whittaker, Stephen G; Ceballos, Diana M; Weiland, Elisa C; Flack, Sheila L; Fent, Kenneth W; Thomasen, Jennifer M; Trelles Gaines, Linda G; Nylander-French, Leena A

    2012-01-01

    Isocyanate exposure was evaluated in 33 spray painters from 25 Washington State autobody shops. Personal breathing zone samples (n = 228) were analyzed for isophorone diisocyanate (IPDI) monomer, 1,6-hexamethylene diisocyanate (HDI) monomer, IPDI polyisocyanate, and three polyisocyanate forms of HDI. The objective was to describe exposures to isocyanates while spray painting, compare them with short-term exposure limits (STELs), and describe the isocyanate composition in the samples. The composition of polyisocyanates (IPDI and HDI) in the samples varied greatly, with maximum amounts ranging from up to 58% for HDI biuret to 96% for HDI isocyanurate. There was a significant inverse relationship between the percentage composition of HDI isocyanurate to IPDI and to HDI uretdione. Two 15-min STELs were compared: (1) Oregon's Occupational Safety and Health Administration (OR-OSHA) STEL of 1000 μg/m(3) for HDI polyisocyanate, and (2) the United Kingdom's Health and Safety Executive (UK-HSE) STEL of 70 μg NCO/m(3) for all isocyanates. Eighty percent of samples containing HDI polyisocyanate exceeded the OR-OSHA STEL while 98% of samples exceeded the UK-HSE STEL. The majority of painters (67%) wore half-face air-purifying respirators while spray painting. Using the OR-OSHA and the UK-HSE STELs as benchmarks, 21% and 67% of painters, respectively, had at least one exposure that exceeded the respirator's OSHA-assigned protection factor. A critical review of the STELs revealed the following limitations: (1) the OR-OSHA STEL does not include all polyisocyanates, and (2) the UK-HSE STEL is derived from monomeric isocyanates, whereas the species present in typical spray coatings are polyisocyanates. In conclusion, the variable mixtures of isocyanates used by autobody painters suggest that an occupational exposure limit is required that includes all polyisocyanates. Despite the limitations of the STELs, we determined that a respirator with an assigned protection factor of 25 or

  19. Airborne Isocyanate Exposures in the Collision Repair Industry and a Comparison to Occupational Exposure Limits

    PubMed Central

    Reeb-Whitaker, Carolyn; Whittaker, Stephen G.; Ceballos, Diana M.; Weiland, Elisa C.; Flack, Sheila L.; Fent, Kenneth W.; Thomasen, Jennifer M.; Gaines, Linda G. Trelles; Nylander-French, Leena A.

    2014-01-01

    Isocyanate exposure was evaluated in 33 spray painters from 25 Washington State autobody shops. Personal breathing zone samples (n = 228) were analyzed for isophorone diisocyanate (IPDI) monomer, 1,6-hexamethylene diisocyanate (HDI) monomer, IPDI polyisocyanate, and three polyisocyanate forms of HDI. The objective was to describe exposures to isocyanates while spray painting, compare them with short-term exposure limits (STELs), and describe the isocyanate composition in the samples. The composition of polyisocyanates (IPDI and HDI) in the samples varied greatly, with maximum amounts ranging from up to 58% for HDI biuret to 96% for HDI isocyanurate. There was a significant inverse relationship between the percentage composition of HDI isocyanurate to IPDI and to HDI uretdione. Two 15-min STELs were compared: (1) Oregon's Occupational Safety and Health Administration (OR-OSHA) STEL of 1000 μg/m3 for HDI polyisocyanate, and (2) the United Kingdom's Health and Safety Executive (UK-HSE) STEL of 70 μg NCO/m3 for all isocyanates. Eighty percent of samples containing HDI polyisocyanate exceeded the OR-OSHA STEL while 98% of samples exceeded the UKHSE STEL. The majority of painters (67%) wore half-face air-purifying respirators while spray painting. Using the OROSHA and the UK-HSE STELs as benchmarks, 21% and 67% of painters, respectively, had at least one exposure that exceeded the respirator's OSHA-assigned protection factor. A critical review of the STELs revealed the following limitations: (1) the OR-OSHA STEL does not include all polyisocyanates, and (2) the UK-HSE STEL is derived from monomeric isocyanates, whereas the species present in typical spray coatings are polyisocyanates. In conclusion, the variable mixtures of isocyanates used by autobody painters suggest that an occupational exposure limit is required that includes all polyisocyanates. Despite the limitations of the STELs, we determined that a respirator with an assigned protection factor of 25 or

  20. Post-Polymerization Crosslinked Polyurethane Shape-Memory Polymers

    PubMed Central

    Hearon, K.; Gall, K.; Ware, T.; Maitland, D. J.; Bearinger, J. P.; Wilson, T. S.

    2011-01-01

    Novel urethane shape-memory polymers (SMPs) of significant industrial relevance have been synthesized and characterized. Chemically crosslinked SMPs have traditionally been made in a one-step polymerization of monomers and crosslinking agents. However, these new post-polymerization crosslinked SMPs can be processed into complex shapes by thermoplastic manufacturing methods and later crosslinked by heat exposure or by electron beam irradiation. Several series of linear, olefinic urethane polymers were made from 2-butene-1,4-diol, other saturated diols, and various aliphatic diisocyanates. These thermoplastics were melt-processed into desired geometries and thermally crosslinked at 200°C or radiation crosslinked at 50 kGy. The SMPs were characterized by solvent swelling and extraction, differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), tensile testing, and qualitative shape-recovery analysis. Swelling and DMA results provided concrete evidence of chemical crosslinking, and further characterization revealed that the urethanes had outstanding mechanical properties. Key properties include tailorable transitions between 25 and 80°C, tailorable rubbery moduli between 0.2 and 4.2 MPa, recoverable strains approaching 100%, failure strains of over 500% at Tg, and qualitative shape-recovery times of less than 12 seconds at body temperature (37°C). Because of its outstanding thermo-mechanical properties, one polyurethane was selected for implementation in the design of a complex medical device. These post-polymerization crosslinked urethane SMPs are an industrially relevant class of highly processable shape-memory materials. PMID:21572577

  1. Post-Polymerization Crosslinked Polyurethane Shape-Memory Polymers.

    PubMed

    Hearon, K; Gall, K; Ware, T; Maitland, D J; Bearinger, J P; Wilson, T S

    2011-07-01

    Novel urethane shape-memory polymers (SMPs) of significant industrial relevance have been synthesized and characterized. Chemically crosslinked SMPs have traditionally been made in a one-step polymerization of monomers and crosslinking agents. However, these new post-polymerization crosslinked SMPs can be processed into complex shapes by thermoplastic manufacturing methods and later crosslinked by heat exposure or by electron beam irradiation. Several series of linear, olefinic urethane polymers were made from 2-butene-1,4-diol, other saturated diols, and various aliphatic diisocyanates. These thermoplastics were melt-processed into desired geometries and thermally crosslinked at 200°C or radiation crosslinked at 50 kGy. The SMPs were characterized by solvent swelling and extraction, differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), tensile testing, and qualitative shape-recovery analysis. Swelling and DMA results provided concrete evidence of chemical crosslinking, and further characterization revealed that the urethanes had outstanding mechanical properties. Key properties include tailorable transitions between 25 and 80°C, tailorable rubbery moduli between 0.2 and 4.2 MPa, recoverable strains approaching 100%, failure strains of over 500% at T(g), and qualitative shape-recovery times of less than 12 seconds at body temperature (37°C). Because of its outstanding thermo-mechanical properties, one polyurethane was selected for implementation in the design of a complex medical device. These post-polymerization crosslinked urethane SMPs are an industrially relevant class of highly processable shape-memory materials.

  2. Reticulation of Aqueous Polyurethane Systems Controlled by DSC Method

    PubMed Central

    Cakic, Suzana; Lacnjevac, Caslav; Rajkovic, Milos B.; Raskovic, Ljiljana; Stamenkovic, Jakov

    2006-01-01

    The DSC method has been employed to monitor the kinetics of reticulation of aqueous polyurethane systems without catalysts, and with the commercial catalyst of zirconium (CAT®XC-6212) and the highly selective manganese catalyst, the complex Mn(III)-diacetylacetonemaleinate (MAM). Among the polyol components, the acrylic emulsions were used for reticulation in this research, and as suitable reticulation agents the water emulsible aliphatic polyisocyanates based on hexamethylendoisocyanate with the different contents of NCO-groups were employed. On the basis of DSC analysis, applying the methods of Kissinger, Freeman-Carroll and Crane-Ellerstein the pseudo kinetic parameters of the reticulation reaction of aqueous systems were determined. The temperature of the examination ranged from 50°C to 450°C with the heat rate of 0.5°C/min. The reduction of the activation energy and the increase of the standard deviation indicate the catalytic action of the selective catalysts of zirconium and manganese. The impact of the catalysts on the reduction of the activation energy is the strongest when using the catalysts of manganese and applying all the three afore-said methods. The least aberrations among the stated methods in defining the kinetic parameters were obtained by using the manganese catalyst.

  3. Occupational asthma caused by isocyanates: patterns of asthmatic reactions to increasing day-to-day doses.

    PubMed

    Malo, J L; Ghezzo, H; Elie, R

    1999-06-01

    Inhalation challenges to isocyanates are conducted in specialized centers to confirm occupational asthma. The pattern of asthmatic reactions due to consecutively increasing daily doses of isocyanates is unknown. We conducted a study involving 24 subjects who had undergone specific inhalation challenges to isocyanates (toluene diisocyanate [TDI], n = 8; hexamethylene diisocyanate [HDI], n = 10; and methylene diisocyanate [MDI], n = 6) on three or more consecutive days. Challenge tests were given through a closed-circuit apparatus (n = 12) or in small cubicles (n = 12), allowing assessment of the total inhaled dose (concentration x duration). The pattern of asthmatic reactions was described. In addition, dose-response curves were analyzed and tested for their linear and quadratic trends. Four patterns of response were observed: (1) linear (n = 10); (2) minimal effect followed by a brisk change (n = 7); (3) significant change followed by tachyphylaxis or a plateau (n = 4); (4) biphasic (i.e., significant change followed by a reduction in the effect and significant change on the last day of exposure [n = 3]). Subjects with a linear dose-response pattern had been exposed to isocyanates at work for a significantly shorter interval (7.2 +/- 6.7 yr) than subjects with a nonlinear pattern (20.0 +/- 13.1 yr). An analysis of variance covering a 3-d period for all subjects showed a significant linear model for the response (p < 0.0001); there was no quadratic trend. However, when the analysis was done on subjects with four or more days of challenge (n = 10), we found both linear and quadratic significant components. This analysis shows that the most common pattern of asthmatic reactions to inhaled isocyanates generated on consecutive days is linear; however, other patterns are also observed. In some individuals, particularly those in whom more days of challenge are required, we observed in addition to a strong linear component a quadratic component manifested by a brisk change

  4. Spectrophotometry of PRESAGETM polyurethane dosimeters

    NASA Astrophysics Data System (ADS)

    Krstajic, N.; Wai, P.; Adamovics, J.; Doran, S.

    2004-01-01

    Preliminary optical density results on irradiated PRESAGE dosimeter are outlined in this article. PRESAGE is a solid dosimeter, based on a clear polyurethane combined with the leuco-dye leuco-malachite green. The purpose of these measurements was a) to obtain spectra for optimizing the wavelength of a new light source for the equipment and b) to obtain a dose-response relation. 10 PRESAGE cuvettes were given uniform doses from 0.1 to 40 Gy and later read out by spectrophotometer. The instrument used was CAMSPEC M350 Double Beam Spectrophotometer.

  5. Adsorption of halogenated aliphatic contaminants by graphene nanomaterials.

    PubMed

    Zhou, Yang; Apul, Onur Guven; Karanfil, Tanju

    2015-08-01

    In this study, adsorption of ten environmentally halogenated aliphatic synthetic organic compounds (SOCs) by a pristine graphene nanosheet (GNS) and a reduced graphene oxide (rGO) was examined, and their adsorption behaviors were compared with those of a single-walled carbon nanotube (SWCNT) and a granular activated carbon (GAC). In addition, the impacts of background water components (i.e., natural organic matter (NOM), ionic strength (IS) and pH) on the SOC adsorption behavior were investigated. The results indicated HD3000 and SWCNT with higher microporous volumes exhibited higher adsorption capacities for the selected aliphatic SOCs than graphenes, demonstrating microporosity of carbonaceous adsorbents played an important role in the adsorption. Analysis of adsorption isotherms demonstrated that hydrophobic interactions were the dominant contributor to the adsorption of aliphatic SOCs by graphenes. However, π-π electron donor-acceptor and van der Waals interactions are likely the additional mechanisms contributing to the adsorption of aliphatic SOCs on graphenes. Among the three background solution components examined, NOM showed the most influential effect on adsorption of the selected aliphatic SOCs, while pH and ionic strength had a negligible effects. The NOM competition on aliphatic adsorption was less pronounced on graphenes than SWCNT. Overall, in terms of adsorption capacities, graphenes tested in this study did not exhibit a major advantage over SWCNT and GAC for the adsorption of aliphatic SOCs.

  6. Controlled release of dexamethasone acetate from biodegradable and biocompatible polyurethane and polyurethane nanocomposite.

    PubMed

    Da Silva, Gisele Rodrigues; Ayres, Eliane; Orefice, Rodrigo Lambert; Moura, Sandra Aparecida L; Cara, Denise Carmona; Cunha, Armando Da Silva

    2009-06-01

    Polyurethanes and polyurethane nanocomposites can be applied to control the release of drugs previously incorporated into these materials. In this study, dexamethasone acetate (ACT) was incorporated into biodegradable and biocompatible polyurethane and polyurethane containing montmorillonite nanoparticles. Fourier transform infrared spectroscopic technique showed no strong interactions between drug and polymers. Data obtained from X-ray diffraction and small angle X-ray scattering indicated that the incorporation of ACT did not disturb the polymer morphology, but montmorillonite led to a less defined phase separation between hard and soft segments of polyurethane. The in vitro release studies demonstrated that nanoparticles increased the rate of ACT release possibly because these particles have a hydrophilic surface that increases the absorption of water and accelerates the hydrolysis of the polymer. The in vivo short-term biocompatibility studies demonstrated adequate interfacial interaction between polyurethane and subcutaneous tissue and a discreet inflammatory response which was completely resolved in 14 days.

  7. Isocyanate Cross-Linked Silica: Structurally Strong Aerogels

    NASA Technical Reports Server (NTRS)

    Leventis, Nicholas; Sotiriou-Leventis, Chariklia; Zhang, Guo-Hui; Rawashdeh, Abdel-Monem M.

    2002-01-01

    Molecular-level synergism between the silica nanoparticles of pre-formed monoliths and molecular cross-linkers inverts the relative host-guest roles in glass-polymer composites, leading to new strong low-density materials. Attempts to load gels with variable amounts of polyurethane precursors such as di-ISO and diol end-capped polybutylene adipate followed by heat treatment, washing, and supercritical drying led to opaque materials, somewhat stronger than silica but still quite brittle and much inferior to the materials described above. Direct mixing of a diisocyanate and an alcohol-free sol has been attempted recently by Yim et al. Reportedly, that procedure leads to week-long gelation times and requires an at least equally long aging period. In our attempt to add various amounts of di-ISO in a base-catalyzed sol in PC, we also noticed a week-long gelation time. The resulting aerogels were translucent but no less brittle than native silica. According to more recent studies, if propylene carbonate is replaced with acetone, it leads not only to shorter processing times, but also to much stronger gels that can tolerate loads in excess of 40 kg in the arrangement presented. We attribute that behavior to the lower viscosity of acetone, that allows faster diffusion of the di-ISO solution within the pores before di-ISO has time to react with the surface of silica. Further studies are underway to vary the chemical identity of the diisocyanate, as well as the composition and density of silica.

  8. [Polyurethane denture base material "Pentalur" and modified polyurethane compositions: comparative study of mechanical properties].

    PubMed

    Al'ter, Iu M; Tkachuk, A-M P; Poiurovskaia, I Ia; Sutugina, T F; Ogorodnikov, M Iu

    2013-01-01

    Results of laboratory tests of polyurethane based material "Pentalur" conducted to determine its mechanical properties proved the material to meet basic requirements for removable dentures materials. The introduction of simple poluethers with certain molecular weight as well as 1,4-butanediol allows varying polyurethane properties in a fairly wide range. This range of polyurethane mechanical properties along with good biocompatibility opens new possibilities in creation of removable dentures with improved functional properties as well as maxillofacial prosthesis.

  9. CYTOKINE RESPONSES TO DERMAL ISOCYANATE EXPOSURE IN DRAINING LYMPH NODES ARE NOT PREDICTIVE OF AIRWAY RESPONSES AFTER AIRWAY CHALLENGE

    EPA Science Inventory

    Exposure to low molecular weight chemicals including isocyanates has been linked to occupational asthma. A strong need exists for the rapid and accurate identification of chemical respiratory sensitizers. Recently, some investigators have proposed that chemicals may be identified...

  10. Laboratory development and field evaluation of a generic method for sampling and analysis of isocyanates. Revised final report

    SciTech Connect

    McGaughey, J.F.; Foster, S.C.; Merrill, R.G.

    1995-09-01

    The U.S. Environmental Protection Agency (EPA), under the authority of Title III of the Clean Air Act Amendments (CAAA) of 1990, requires the identification and validation of sampling and analytical methods for the isocyanate compounds which are listed among the 189 hazardous air pollutants identified in Title III. In all, three field tests were performed to accomplish the isocyanate field evaluation. The objective of this work was to develop and evaluate the isocyanate sampling and analytical test method through field testing at operating stationary sources. The method was evaluated by collecting flue gas samples for the analysis of the individual isocyanate and evaluating the data for bias and precision. EPA Method 301, Field Validation of Pollutant Measurement Methods from Various Waste Media, was used as the model for the experimental design of this method evaluation project.

  11. Addition of lithium carbenoids to isocyanates: a direct access to synthetically useful N-substituted 2-haloacetamides.

    PubMed

    Pace, Vittorio; Castoldi, Laura; Holzer, Wolfgang

    2013-09-28

    The addition of lithium carbenoids to isocyanates provides a versatile access to N-substituted 2-haloacetamides: the reaction tolerates the presence of variously functionalized substituents on the nitrogen atom, including sterically demanding ones and reactive halogens. No erosion of the enantiopurity was observed in the case of optically active isocyanates. One of the substrates prepared has been employed in Charette's type chemoselective addition of a Grignard reagent to access an α-chloroketone.

  12. Cyclic tetramers of a five-membered palladacycle based on a head-to-tail-linked isocyanate dimer and their reactivity in cyclotrimerization of isocyanates.

    PubMed

    Lee, Seon Gye; Choi, Keun-Young; Kim, Yong-Joo; Park, SuJin; Lee, Soon W

    2015-04-14

    Reactions of [Pd(styrene)(PR3)2], generated from trans-[PdEt2(PR3)2] and styrene, with 2 equiv. of benzyl isocyanate in THF at room-temperature afforded unusual cyclic Pd-tetramers of five-membered rings consisting of organic isocyanate dimers and palladium, [Pd(PR3){-C(O)N(R)C(O)N(R)-}]4 (PR3 = PMe3, ; PR3 = PMe2Ph, ). Additionally, a cyclic trimer, (RNCO)3, (R = benzyl) was produced as a catalytic product. Treatment of the cyclic tetramer () with 4 equiv. of chelated phosphine, such as (1,2-bis(diethylphosphino)ethane) (DEPE) or (1,2-bis(dimethylphosphino)ethane) (DMPE), readily caused conversion to a metallacyclic cis-form, [Pd{N(R)C(O)N(R)C(O)}(P ∼ P)] (P ∼ P = DEPE, ; P ∼ P = DMPE, ) in quantitative yields. In contrast, reactions of Pd(0)-PR3 with 2 equiv. of Ar-NCO (Ar = Ph, p-tolyl, p-ClC6H4) afforded metallacyclic complexes having a dimeric isocyanato moiety, cis-[Pd{C(O)N(Ar)-C(O)N(Ar)}(PR3)2] (PR3 = PMe3 Ar = C6H5, ; p-MeC6H4, ; p-Cl-C6H4, ; PR3 = PMe2Ph, Ar = p-Cl-C6H4, ). Treatment of the palladacyclic complex () with an equimolar amount of chelated phosphine such as DEPE readily caused conversion to a palladacyclic cis-form, [Pd{N(Ar)C(O)N(Ar)C(O)}(DEPE)], in quantitative yield. The catalytic cyclotrimerization of benzyl isocyanate to [Pd(styrene)(PMe3)2] was achieved by varying the molar ratio of R-NCO (R = benzyl). In addition, catalytic cyclotrimerization was performed from the five-membered palladacyclic complexes or the Pd(0)-PR3 complex with excess Ar-NCO.

  13. ANAEROBIC AND AEROBIC TREATMENT OF CHLORINATED ALIPHATIC COMPOUNDS

    EPA Science Inventory

    Biological degradation of 12 chlorinated aliphatic compounds (CACs) was assessed in bench-top reactors and in serum bottle tests. Three continuously mixed daily batch-fed reactor systems were evaluated: anaerobic, aerobic, and sequential-anaerobic-aerobic (sequential). Glucose,...

  14. Phenylethanoid and aliphatic alcohol glycosides from Acanthus ilicifolius.

    PubMed

    Wu, Jun; Zhang, Si; Xiao, Qiang; Li, Qingxin; Huang, Jianshe; Long, Lijuan; Huang, Liangmin

    2003-06-01

    A phenylethanoid glycoside (ilicifolioside A) and an aliphatic alcohol glycoside (ilicifolioside B), have been isolated from the aerial parts of Acanthus ilicifolius, together with eight known compounds. Their structures were determined from spectroscopic analyses.

  15. Transient receptor potential ankyrin 1 antagonists block the noxious effects of toxic industrial isocyanates and tear gases.

    PubMed

    Bessac, Bret F; Sivula, Michael; von Hehn, Christian A; Caceres, Ana I; Escalera, Jasmine; Jordt, Sven-Eric

    2009-04-01

    The release of methyl isocyanate in Bhopal, India, caused the worst industrial accident in history. Exposures to industrial isocyanates induce lacrimation, pain, airway irritation, and edema. Similar responses are elicited by chemicals used as tear gases. Despite frequent exposures, the biological targets of isocyanates and tear gases in vivo have not been identified, precluding the development of effective countermeasures. We use Ca(2+) imaging and electrophysiology to show that the noxious effects of isocyanates and those of all major tear gas agents are caused by activation of Ca(2+) influx and membrane currents in mustard oil-sensitive sensory neurons. These responses are mediated by transient receptor potential ankyrin 1 (TRPA1), an ion channel serving as a detector for reactive chemicals. In mice, genetic ablation or pharmacological inhibition of TRPA1 dramatically reduces isocyanate- and tear gas-induced nocifensive behavior after both ocular and cutaneous exposures. We conclude that isocyanates and tear gas agents target the same neuronal receptor, TRPA1. Treatment with TRPA1 antagonists may prevent and alleviate chemical irritation of the eyes, skin, and airways and reduce the adverse health effects of exposures to a wide range of toxic noxious chemicals.

  16. Transient receptor potential ankyrin 1 antagonists block the noxious effects of toxic industrial isocyanates and tear gases.

    PubMed

    Bessac, Bret F; Sivula, Michael; von Hehn, Christian A; Caceres, Ana I; Escalera, Jasmine; Jordt, Sven-Eric

    2009-04-01

    The release of methyl isocyanate in Bhopal, India, caused the worst industrial accident in history. Exposures to industrial isocyanates induce lacrimation, pain, airway irritation, and edema. Similar responses are elicited by chemicals used as tear gases. Despite frequent exposures, the biological targets of isocyanates and tear gases in vivo have not been identified, precluding the development of effective countermeasures. We use Ca(2+) imaging and electrophysiology to show that the noxious effects of isocyanates and those of all major tear gas agents are caused by activation of Ca(2+) influx and membrane currents in mustard oil-sensitive sensory neurons. These responses are mediated by transient receptor potential ankyrin 1 (TRPA1), an ion channel serving as a detector for reactive chemicals. In mice, genetic ablation or pharmacological inhibition of TRPA1 dramatically reduces isocyanate- and tear gas-induced nocifensive behavior after both ocular and cutaneous exposures. We conclude that isocyanates and tear gas agents target the same neuronal receptor, TRPA1. Treatment with TRPA1 antagonists may prevent and alleviate chemical irritation of the eyes, skin, and airways and reduce the adverse health effects of exposures to a wide range of toxic noxious chemicals. PMID:19036859

  17. Evaluation of antibacterial activity of synthetic aliphatic and aromatic monoacylglycerols.

    PubMed

    Batovska, Daniela; Todorova, Iva; Parushev, Stoyan; Tsvetkova, Iva; Najdenski, Hristo; Ubukata, Makoto

    2008-01-01

    The antibacterial activity of synthetic aliphatic and aromatic monoacylglycerols (MAGs) was studied against two human pathogens: Staphylococcus aureus and Escherichia coli. The active compounds inhibited selectively S. aureus. The most active compounds amongst them were those with medium size aliphatic chain and aromatic MAGs with electron withdrawing substituents at the aryl ring. The introduction of one or two-carbon spacer between the aryl ring and the carboxylic function did not influence antibacterial effectiveness. PMID:19004249

  18. Process for producing peracids from aliphatic hydroxy carboxylic acids

    DOEpatents

    Chum, H.L.; Palasz, P.D.; Ratcliff, M.A.

    1984-12-20

    A process is described for producing peracids from lactic acid-containing solutions derived from biomass processing systems. It consists of adjusting the pH of the solution to about 8 to 9 and removing alkaline residue fractions therefrom to form a solution comprised substantially of lower aliphatic hydroxy acids. The solution is oxidized to produce volatile lower aliphatic aldehydes. The aldehydes are removed as they are generated and converted to peracids.

  19. Process for producing peracids from aliphatic hydroxy carboxylic acids

    DOEpatents

    Chum, Helena L.; Ratcliff, Matthew A.; Palasz, Peter D.

    1986-01-01

    A process for producing peracids from lactic acid-containing solutions derived from biomass processing systems comprising: adjusting the pH of the solution to about 8-9 and removing alkaline residue fractions therefrom to form a solution comprised substantially of lower aliphatic hydroxy acids; oxidizing the solution to produce volatile lower aliphatic aldehydes; removing said aldehydes as they are generated; and converting said aldehydes to peracids.

  20. A Comparative Study of Microphase Separation of Polyurethane Multiblock Copolymers with Different Soft Segment Chemistries.

    NASA Astrophysics Data System (ADS)

    Hernandez, Rebeca; Choi, Taeyi; Weksler, Jadwiga; Padsalgikar, Ajay; Xu, Lichong; Siedlecki, Christopher; Runt, James

    2008-03-01

    We focus in this study on three series of chemically well-defined polyurethanes (PUs) with the same hard segments (MDI-BDO) but different soft segment chemistries of interest in biomedical applications: 1000 g/mol aliphatic polycarbonate, polytetramethylenoxide and a mixed macrodiol of polydimethylsiloxane (PDMS) and polyhexamethylenoxide. Using quantitative small-angle X-ray scattering we demonstrate that the degree of hard/soft segment demixing varies greatly between the materials. For example, the PDMS-based copolymers exhibit a three phase, core-shell morphology, while the other copolymers exhibit a typical two phase structure. Additional analysis was conducted with a number of experimental probes including FTIR to assess inter- and intracomponent hydrogen bonding, and tapping mode AFM to characterize the nanoscale morphology.

  1. Thrombocytopenia associated with environmental exposure to polyurethane

    SciTech Connect

    Michelson, A.D. )

    1991-10-01

    Few chemicals in the environment have been implicated as causes of isolated thrombocytopenia, and the evidence is usually less than convincing because the patients were not rechallenged with the chemical in vivo. In the present paper, a child is reported with the onset of thrombocytopenia in temporal association with environmental exposure to polyurethane. Five years after the initial thrombocytopenia had resolved, an inadvertent in vivo rechallenge with environmental polyurethane resulted in recurrence of the thrombocytopenia. This recurrence, together with the fact that only 1-4% of cases of idiopathic thrombocytopenic purpura in children recur, provided strong evidence for a causal role for the polyurethane exposure in this patient's thrombocytopenia. In summary, environmental exposure to polyurethane should be considered in the differential diagnosis of acquired thrombocytopenia in childhood.

  2. Analysis of lead in polyurethane catalyst

    SciTech Connect

    Ewanowski, L.C.

    1986-04-01

    Lead is an organically-complexed metal that is contained in polyurethane catalyst as lead octoate. This polyurethane catalyst (MHSM 35-Account Number 35-1118) is required in acceptance testing to contain 24 +- 3% total lead. To provide a more rapid and more precise lead analysis, the quantification of lead is being performed by atomic absorption spectrophotometry (AAS). The results are comparable to data collected by Specification Dwg. 4617130. The AAS method eliminates caustic reagents, matrix interferences, and hours of tedious labor.

  3. Polyurethane-based polymer surface modifiers with alkyl ammonium copolyoxetane soft segments: Reaction engineering, surface morphology and antimicrobial behavior

    NASA Astrophysics Data System (ADS)

    Brunson, Kennard Marcellus, Jr.

    Concentrating quaternary (positive) charge at polymer surfaces is important for applications including layer-by-layer polyelectrolyte deposition and antimicrobial coatings. Prior techniques to introduce quaternary charge to the surface involve grafting of quaternary ammonium moieties to a substrate or using polyurethanes with modified hard segments however there are impracticalities involved with these techniques. In the case of the materials discussed, the quaternary charge is introduced via polyurethane based polymer surface modifiers (PSMs) with quaternized soft segments. The particular advantage to this method is that it utilizes the intrinsic phase separation between the hard and soft segments of polyurethanes. This phase separation results in the surface concentration of the soft segments. Another advantage is that unlike grafting, where modification has to take place after device fabrication, these PSMs can be incorporated with the matrix material during device fabrication. The soft segments of these quaternized polyurethanes are produced via ring opening co-polymerization of oxetane monomers which possess either a trifluoroethoxy (3FOx) side chains or a quaternary ammonium side chain (C12). These soft segments are subsequently reacted with 4,4'-(methylene bis (p-cyclohexyl isocyanate)), HMDI and butanediol (BD) to form the PSM. It was initially intended to increase the concentration of quaternary ammonium charge by increasing PSM soft segment molecular weight. Unexpectedly, produced blends with surface microscale phase separation. This observation prompted further investigation of the effect of PSM soft segment molecular weight on phase separation in PSM-base polyurethane blends and the subsequent effects of this phase separation on the biocidal activity. Analysis of the surface morphology via tapping mode atomic force microscopy (TM-AFM) and scanning electron microscopy (SEM) revealed varying complexities in surface morphology as a function of the PSM soft

  4. Synthesis of Industrially Relevant Carbamates towards Isocyanates using Carbon Dioxide and Organotin(IV) Alkoxides.

    PubMed

    Germain, Nicolas; Müller, Imke; Hanauer, Matthias; Paciello, Rocco A; Baumann, Robert; Trapp, Oliver; Schaub, Thomas

    2016-07-01

    A straightforward phosgene-free synthesis of aromatic isocyanates and diisocyanates is disclosed. Theoretical investigations suggested that the insertion of carbon dioxide (CO2 ) by dialkyltin(IV) dialkoxides could be used to convert aromatic amines into aromatic mono- and dicarbamates. Here we show, that methyl phenylcarbamate (MPC) from aniline using organotin(IV) dimethoxide and CO2 can be formed in high yield of up to 92 %, experimentally corroborating the predictions of density functional theory (DFT) calculations. MPC was then separated from the tin oxide residues and converted into phenyl isocyanate. Furthermore, organotin(IV) alkoxides could be regenerated from the tin oxide residues and reused, paving the way for a continuous industrial process. Extension of the scope to the synthesis of diurethanes from toluene 2,4-diamine and 4,4'-methylenedianiline could potentially allow the efficient production of industrially relevant diisocyanates. PMID:27319978

  5. Carbon Nanofiber Incorporated Silica Based Aerogels with Di-Isocyanate Cross-Linking

    NASA Technical Reports Server (NTRS)

    Vivod, Stephanie L.; Meador, Mary Ann B.; Capadona, Lynn A.; Sullivan, Roy M.; Ghosn, Louis J.; Clark, Nicholas; McCorkle, Linda

    2008-01-01

    Lightweight materials with excellent thermal insulating properties are highly sought after for a variety of aerospace and aeronautic applications. (1) Silica based aerogels with their high surface area and low relative densities are ideal for applications in extreme environments such as insulators for the Mars Rover battery. (2) However, the fragile nature of aerogel monoliths prevents their widespread use in more down to earth applications. We have shown that the fragile aerogel network can be cross-linked with a di-isocyanate via amine decorated surfaces to form a conformal coating. (3) This coating reinforces the neck regions between secondary silica particles and significantly strengthens the aerogels with only a small effect on density or porosity. Scheme 1 depicts the cross-linking reaction with the di-isocyanate and exhibits the stages that result in polymer cross-linked aerogel monoliths.

  6. Synthesis of Industrially Relevant Carbamates towards Isocyanates using Carbon Dioxide and Organotin(IV) Alkoxides.

    PubMed

    Germain, Nicolas; Müller, Imke; Hanauer, Matthias; Paciello, Rocco A; Baumann, Robert; Trapp, Oliver; Schaub, Thomas

    2016-07-01

    A straightforward phosgene-free synthesis of aromatic isocyanates and diisocyanates is disclosed. Theoretical investigations suggested that the insertion of carbon dioxide (CO2 ) by dialkyltin(IV) dialkoxides could be used to convert aromatic amines into aromatic mono- and dicarbamates. Here we show, that methyl phenylcarbamate (MPC) from aniline using organotin(IV) dimethoxide and CO2 can be formed in high yield of up to 92 %, experimentally corroborating the predictions of density functional theory (DFT) calculations. MPC was then separated from the tin oxide residues and converted into phenyl isocyanate. Furthermore, organotin(IV) alkoxides could be regenerated from the tin oxide residues and reused, paving the way for a continuous industrial process. Extension of the scope to the synthesis of diurethanes from toluene 2,4-diamine and 4,4'-methylenedianiline could potentially allow the efficient production of industrially relevant diisocyanates.

  7. Isocyanates and human health: Multi-stakeholder information needs and research priorities

    PubMed Central

    Lockey, JE; Redlich, CA; Streicher, R; Pfahles-Hutchens, A; Hakkinen, PJ; Ellison, GL; Harber, P; Utell, M; Holland, J; Comai, A; White, Marc

    2014-01-01

    Objective Outline the knowledge gaps and research priorities identified by a broad-base of stakeholders involved in the planning and participation of an international conference and research agenda workshop on isocyanates and human health held in Potomac, Maryland in April 2013. Methods A multi-modal iterative approach was employed for data collection including pre-conference surveys, review of a 2001 consensus conference on isocyanates, oral and poster presentations, focused break-out sessions, panel discussions and post-conference research agenda workshop. Results Participants included representatives of consumer and worker health, health professionals, regulatory agencies, academic and industry scientists, labor, and trade associations. Conclusions Recommendations were summarized regarding knowledge gaps and research priorities in the following areas: worker and consumer exposures; toxicology, animal models, and biomarkers; human cancer risk; environmental exposure and monitoring; and respiratory epidemiology and disease, and occupational health surveillance. PMID:25563538

  8. Biocompatible polyurethane-based hydrogel.

    PubMed

    Braatz, J A

    1994-07-01

    A polyurethane polymer developed at W. R. Grace has been evaluated for a variety of biomedical applications. The primary property of the polymer exploited for these applications is its ability to prevent protein adsorption when coated on a surface. The prepolymer consists of a trifunctional poly(ethyleneoxide-propylene oxide) triol end capped with isophorone diisocyanate. The prepolymer is reactive with water and can be converted to a hydrogel, a thin coating, or a soluble conjugate with another compound. Each category lends itself to separate biomedical applications which are described in detail. The non-toxic nature of the polymer was demonstrated in a number of systems and suggests its utility in biomedical applications. PMID:7983587

  9. Activated T-lymphocytes and eosinophils in the bronchial mucosa in isocyanate-induced asthma.

    PubMed

    Bentley, A M; Maestrelli, P; Saetta, M; Fabbri, L M; Robinson, D S; Bradley, B L; Jeffery, P K; Durham, S R; Kay, A B

    1992-04-01

    We have studied the phenotype and activation status of leukocytes in the bronchial mucosa in patients with isocyanate-induced asthma. Fiberoptic bronchial biopsy specimens were obtained from nine subjects with occupational (five toluene- and four methylene diisocyanate-sensitive) asthma, 10 subjects with extrinsic asthma, and 12 nonatopic healthy control subjects. Bronchial biopsy specimens were examined by immunohistology with a panel of monoclonal antibodies and the alkaline phosphatase-antialkaline phosphatase method. There was a significant increase in the number of CD25+ cells (interleukin-2 receptor-bearing cells, presumed "activated" T-lymphocytes; p less than 0.01) in isocyanate-induced asthma compared with that of control subjects. There were also significant increases in major basic protein (BMK-13)-positive (p less than 0.02) and EG2-positive (p less than 0.01) cells that represent total and "activated" eosinophil cationic protein-secreting eosinophils, respectively. In agreement with our previous findings, CD25+ (p less than 0.01), BMK-13 (p less than 0.03), and EG2+ (p less than 0.01) cells were also elevated in extrinsic asthma. No significant differences were observed in the numbers of T-lymphocyte phenotypic markers (CD3, CD4, and CD8) between subjects with asthma (isocyanate-induced and extrinsic) and control subjects. Similarly, no significant differences in immunostaining for neutrophil elastase (neutrophils) or CD68 (macrophages) were observed. The results suggest that isocyanate-induced occupational asthma and atopic (extrinsic) asthma have a similar pattern of inflammatory cell infiltrate. The results support the view that T-lymphocyte activation and eosinophil recruitment may be important in asthma of diverse etiology.

  10. An approach to area sampling and analysis for total isocyanates in workplace air.

    PubMed

    Key-Schwartz, R J; Tucker, S P

    1999-01-01

    An approach to sampling and analysis for total isocyanates (monomer plus any associated oligomers of a given isocyanate) in workplace air has been developed and evaluated. Based on a method developed by the Occupational Health Laboratory, Ontario Ministry of Labour, Ontario, Canada, isocyanates present in air are derivatized with a fluorescent reagent, tryptamine, in an impinger and subsequently analyzed via high-performance liquid chromatography (HPLC) with fluorescence detection. Excitation and emission wavelengths are set at 275 and 320 nm, respectively. A modification to the Ontario method was made in the replacement of the recommended impinger solvents (acetonitrile and 2,2,4-trimethylpentane) with dimethyl sulfoxide (DMSO). DMSO has the advantages of being compatible with reversedphase HPLC and not evaporating during sampling, as do the more volatile solvents used in the Ontario method. DMSO also may dissolve aerosol particles more efficiently during sampling than relatively nonpolar solvents. Several formulations containing diisocyanate prepolymers have been tested with this method in the laboratory. This method has been issued as National Institute for Occupational Safety and Health (NIOSH) Method 5522 in the first supplement to the fourth edition of the NIOSH Manual of Analytical Methods. This method is recommended for area sampling only due to possible hazards from contact with DMSO solutions containing isocyanate derivatives. The limits of detection are 0.1 microgram/sample for 2,4-toluene diisocyanate, 0.2 microgram/sample for 2,6-toluene diisocyanate, 0.3 microgram/sample for methylene bisphenyl diisocyanate, and 0.2 microgram/sample for 1,6-hexamethylene diisocyanate.

  11. Catalytic [3 + 2] Cycloaddition through Ring Cleavage of Simple Cyclopropanes with Isocyanates.

    PubMed

    Tsunoi, Shinji; Maruoka, Yoshiaki; Suzuki, Itaru; Shibata, Ikuya

    2015-08-21

    The catalytic synthesis of γ-butyrolactams was established via [3 + 2]-cycloaddition of cyclopropanes with isocyanates. An organotin iodide ate complex, MgBr(+)[Bu2SnBrI2](-), was employed as an effective catalyst. Simple cyclopropanes that lack aryl or vinyl substituents were useful precursors. Even acyl cyclopropanes were applicable. The hybrid characteristics of a tin complex, acidic MgBr(+) with nucleophilic tin iodide, was responsible for the catalytic reaction.

  12. A practical approach to semicarbazone and hydrazone derivatives via imino-isocyanates.

    PubMed

    Garland, Keira; Gan, Wei; Depatie-Sicard, Charlotte; Beauchemin, André M

    2013-08-16

    Complex hydrazone derivatives can be accessed readily from hydrazones upon heating in the presence of nucleophiles. This reactivity likely involves imino-isocyanate intermediates, and a variety of leaving groups can be used at temperatures ranging from 20 to 150 °C. Alcohols, thiols, primary, and secondary amines can be used as nucleophiles, thus providing a simple alternative to the synthesis of hydrazones via condensation on the parent carbonyl precursor and allowing late-stage derivatization.

  13. Ruthenium(II)-catalyzed C-H activation with isocyanates: a versatile route to phthalimides.

    PubMed

    De Sarkar, Suman; Ackermann, Lutz

    2014-10-20

    A cationic ruthenium(II)-complex was utilized in the efficient synthesis of phthalimide derivatives by C-H activation with synthetically useful amides. The reaction proceeded through a mechanistically unique insertion of a cycloruthenated species into a C-Het multiple bond of isocyanate. The novel method also proved applicable for the synthesis of heteroaromatic unsymmetric diamides as well as a potent COX-2 enzyme inhibitor.

  14. Catalytic [3 + 2] Cycloaddition through Ring Cleavage of Simple Cyclopropanes with Isocyanates.

    PubMed

    Tsunoi, Shinji; Maruoka, Yoshiaki; Suzuki, Itaru; Shibata, Ikuya

    2015-08-21

    The catalytic synthesis of γ-butyrolactams was established via [3 + 2]-cycloaddition of cyclopropanes with isocyanates. An organotin iodide ate complex, MgBr(+)[Bu2SnBrI2](-), was employed as an effective catalyst. Simple cyclopropanes that lack aryl or vinyl substituents were useful precursors. Even acyl cyclopropanes were applicable. The hybrid characteristics of a tin complex, acidic MgBr(+) with nucleophilic tin iodide, was responsible for the catalytic reaction. PMID:26247349

  15. Solvent-free sampling with di-n-butylamine for monitoring of isocyanates in air.

    PubMed

    Marand, Asa; Karlsson, Daniel; Dalene, Marianne; Skarping, Gunnar

    2005-04-01

    The solvent-free sampler for airborne isocyanates consisted of a polypropylene tube with an inner wall coated with a glass fibre filter, coupled in series with a 13 mm glass fibre filter. The filters were impregnated with reagent solution containing equimolar amounts of di-n-butylamine (DBA) and acetic acid. Air sampling was performed with an air flow of 0.2 l min(-1). The formed isocyanate-DBA derivatives were determined using liquid chromatography and tandem mass spectrometry. The sampler was investigated in regard to collection principle and extraction of the formed derivatives with good results. The possibility to store the sampler before sampling and to perform long-term sampling was demonstrated. Field extraction of the sampler was not necessary, as there was no difference between immediately extracted samples and stored ones (2 days). In comparative studies, the sampler was evaluated against a reference method, impinger-filter sampling with DBA as reagent. The ratios between the results obtained with the sampler and the reference in a test chamber at a relative humidity (RH) of 45% was in the range of 83-109% for isocyanates formed during thermal decomposition of PUR. At RH 95%, the range was 72-101% with the exception of isocyanic acid. In two field evaluations, the ratios for fast curing 2,4'- and 4,4'-methylene bisphenyl diisocyanate (MDI) was in the range 81-113% and for the 3-ring MDI the range was 54-70%. For the slower curing 1,6-hexamethylene diisocyanate (HDI) and HDI isocyanurate, the ratios were in the range 78-145%. In conclusion, the solvent-free sampler is a convenient alternative in most applications to the more cumbersome impinger-filter sampler.

  16. Environmental isocyanate-induced asthma: morphologic and pathogenetic aspects of an increasing occupational disease.

    PubMed

    Fisseler-Eckhoff, Annette; Bartsch, Holger; Zinsky, Rica; Schirren, Joachim

    2011-09-01

    Occupational diseases affect more and more people every year. According to the International Labour Organization (ILO), in 2000 an estimated amount of at least 160 million people became ill as a result of occupational-related hazards or injuries. Globally, occupational deaths, diseases and injuries account for an estimated loss of 4% of the Gross Domestic Product. Important substances that are related to occupational diseases are isocyanates and their products. These substances, which are used in a lot of different industrial processes, are not only toxic and irritant, but also allergenic. Although the exposure to higher concentrations could be monitored and restricted by technical means, very low concentrations are difficult to monitor and may, over time, lead to allergic reactions in some workers, ending in an occupational disease. In order to prevent the people from sickening, the mechanisms underlying the disease, by patho-physiological and genetical means, have to be known and understood so that high risk groups and early signs in the development of an allergic reaction could be detected before the exposure to isocyanates leads to an occupational disease. Therefore, this paper reviews the so far known facts concerning the patho-physiologic appearance and mechanisms of isocyanate-associated toxic reactions and possible genetic involvement that might trigger the allergic reactions. PMID:22016709

  17. Environmental isocyanate-induced asthma: morphologic and pathogenetic aspects of an increasing occupational disease.

    PubMed

    Fisseler-Eckhoff, Annette; Bartsch, Holger; Zinsky, Rica; Schirren, Joachim

    2011-09-01

    Occupational diseases affect more and more people every year. According to the International Labour Organization (ILO), in 2000 an estimated amount of at least 160 million people became ill as a result of occupational-related hazards or injuries. Globally, occupational deaths, diseases and injuries account for an estimated loss of 4% of the Gross Domestic Product. Important substances that are related to occupational diseases are isocyanates and their products. These substances, which are used in a lot of different industrial processes, are not only toxic and irritant, but also allergenic. Although the exposure to higher concentrations could be monitored and restricted by technical means, very low concentrations are difficult to monitor and may, over time, lead to allergic reactions in some workers, ending in an occupational disease. In order to prevent the people from sickening, the mechanisms underlying the disease, by patho-physiological and genetical means, have to be known and understood so that high risk groups and early signs in the development of an allergic reaction could be detected before the exposure to isocyanates leads to an occupational disease. Therefore, this paper reviews the so far known facts concerning the patho-physiologic appearance and mechanisms of isocyanate-associated toxic reactions and possible genetic involvement that might trigger the allergic reactions.

  18. Isocyanate-functional adhesives for biomedical applications. Biocompatibility and feasibility study for vascular closure applications.

    PubMed

    Hadba, Ahmad R; Belcheva, Nadya; Jones, Fatima; Abuzaina, Ferass; Calabrese, Allison; Kapiamba, Mbiya; Skalla, Walter; Taylor, Jack L; Rodeheaver, George; Kennedy, John

    2011-10-01

    Biodegradable isocyanate-functional adhesives based on poly(ethylene glycol)-adipic acid esters were synthesized, characterized, and evaluated in vitro and in vivo. Two types of formulations, P2TT and P2MT, were developed by functionalization with 2,4-tolylene diisocyanate (TDI) or 4,4'-methylene-bis(phenyl isocyanate) (MDI), respectively, and branching with 1,1,1-trimethylolpropane (TMP). The biocompatibility of the synthesized adhesive formulations was evaluated as per ISO 10993. Cytotoxicity, systemic toxicity, pyrogenicity, genotoxicity (reverse mutation of Salmonella typhimurium and Escherichia coli), hemolysis, intracutaneous reactivity, and delayed-type hypersensitivity were evaluated. All formulations met the requirements of the conducted standard tests. The biological behavior and ability of the adhesive formulations to close an arteriotomy and withstand arterial pressure following partial approximation with a single suture were evaluated in a rat abdominal aorta model. Animals were evaluated at 1, 2, 3, and 4 weeks after surgery. Macroscopic and histopathologic evaluation of explanted arteries suggested that the P2TT formulation had better in vivo performance than the P2MT formulation. Additionally, the P2TT formulation resulted in less tissue reaction than P2MT formulation. To our knowledge, this is the first study demonstrating the potential of this new class of isocyanate-functional degradable adhesives for vascular applications.

  19. Physicochemical and biological properties of a novel injectable polyurethane system for root canal filling

    PubMed Central

    Wang, Jian; Zuo, Yi; Zhao, Minghui; Jiang, Jiaxing; Man, Yi; Wu, Jun; Hu, Yunjiu; Liu, Changlei; Li, Yubao; Li, Jidong

    2015-01-01

    A root canal sealer with antibacterial activity can be efficacious in preventing reinfection that results from residual microorganisms and/or the leakage of microorganisms. In the present study, a series of injectable, self-curing polyurethane (PU)-based antibacterial sealers with different concentrations of silver phosphate (Ag3PO4) were fabricated. Subsequently, their physicochemical properties, antibacterial abilities, and preliminary cytocompatibilities were evaluated. The results indicated that the fabricated PU-based sealers can achieve a high conversion rate in a short amount of time. More than 95% of the isocyanate group of PU sealers with 3 wt% (PU3) and 5 wt% (PU5) concentrations of Ag3PO4 were included in the curing reaction after 7 hours. With the exception of those for film thickness for PU5, the results of setting time, film thickness, and solubility were able to meet the requirements of the International Organization for Standardization. The antibacterial tests showed that PU3 and PU5 exhibit stronger antimicrobial effects than that achieved with 1 wt% Ag3PO4 (PU1) and AH Plus (positive control) against Streptococcus mutans. The cytocompatibility evaluation revealed that the PU1 and PU3 sealers possess good cytocompatibility and low cytotoxicity. These results demonstrate that the PU3 sealer offers good physicochemical and antimicrobial properties along with cytocompatibility, which may hold great application potential in the field of root canal fillings. PMID:25653518

  20. Hydroxyalkylation and polyether polyol grafting of graphene tailored for graphene/polyurethane nanocomposites.

    PubMed

    Appel, Anna-Katharina; Thomann, Ralf; Mülhaupt, Rolf

    2013-08-01

    Graphene functionalization by hydroxyalkylation and grafting with polyether polyols enables polyurethane (PU) nanocomposites formation by in situ polymerization with isocyanates combined with effective covalent interfacial coupling. Functionalized graphene (FG) hydroxylation is achieved either by alkylation, transesterification, or grafting of thermally reduced graphite oxide. In the presence of K2 CO3 as catalyst the reaction of FG-OH with ethylene carbonate at 180 °C affords hydroxyethylated FG, whereas transesterification with castor oil produces riconoleiate-modified FG polyols. In the "grafting-from" process, FG-alkoholate macro initiators initiate the graft polymerization of propylene oxide to produce hybrid FG polyols containing 38 and 59 wt% oligopropylene oxide. In the "grafting-to" process 3-ethyl-3-hydroxymethyl-oxetane is cationically polymerized onto FG-OH, producing novel hyperbranched FG-based polyether polyols. Whereas hydroxylation and grafting of FG greatly improve FG dispersion in organic solvents, polyols and even PU, as confirmed by transmission electron microscopy, matrix reinforcement of FG/PU is impaired by increasing alkyl chain length and polyol graft copolymer content. PMID:23836705

  1. Structure-morphology-rheology relationships in thermoplastic polyurethanes

    NASA Astrophysics Data System (ADS)

    Youn, Yeo-O.

    The effect of thermal history on the phase transitions, morphology, and rheological behavior of six thermoplastic polyurethanes (TPUs) with varying contents of hard segment, each having 4,4'-methylene bis(phenyl isocyanate) and 1,4-butane diol as hard segment and poly(epsilon-caprolactone) diol as soft segment was investigated using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), fourier-transform infrared (FTIR) spectroscopy, and polarizing optical microscopy (POM). Specifically, we conducted dynamic frequency sweep experiments at various temperatures for all six TPUs synthesized, as well as isochronal temperature sweep experiments using the parallel-plate fixture of a cone-and-plate rheometer. In the dynamic frequency sweep experiments, the initial morphology was controlled by heating a specimen to a temperature above the isotropization temperature (Ti) of the hard segment, and then slowly cooled the sample down to a predetermined temperature below the Ti of each TPU specimen. Initial DSC experiments provided information on thermal transition temperatures of each TPU specimen. The rheological measurements are interpreted with the aid of the images from polarized optical microscopy taken under the same thermal histories employed as for the rheological measurements. It was found that thermal history of specimen (L3) had a profound influence on the variations of storage modulus (G ') and loss modulus (G″) with time observed during isothermal annealing, based upon the structural development of spherulitic superstructure of hard segment. The differences in the rheological behavior observed among the different TPUs synthesized in this study are further interpreted with the aid of Fourier transform infrared spectra obtained at various temperatures. It is concluded that hydrogen bonding has a profound influence on the time variations of rheological behavior during measurements. Finally, we have investigated time variations of G ' obtained

  2. In vivo biostability of polyether polyurethanes with fluoropolymer surface modifying endgroups: resistance to biologic oxidation and stress cracking.

    PubMed

    Ward, Bob; Anderson, James; McVenes, Rick; Stokes, Ken

    2006-12-15

    A series of Shore 80A polyether polyurethanes were synthesized with from 0 to 6% fluoropolymer surface modifying endgroups (SME) to provide the bulk properties of the polyurethane with the surface properties of the fluoropolymer. It was theorized that the fluoropolymer would migrate to the surface, forming a monolayer barrier to the oxidants and crack-driving agents released by macrophages and foreign body giant cells in vivo. In a 12-week biostability screening test, samples strained to 400% elongation appeared to be highly stable. In a longer-term study, the fluoropolymer SME significantly delayed, but did not completely prevent the onset of microcracking and the development of environmental stress cracking in strained samples. Even so, the 4 and 6% SME polymers explanted at 2 years performed significantly better than the control. FTIR analysis did not correlate with SME concentration, but increased hydrogen-bonding index and loss of aliphatic ether (autoxidation) did correlate with the visual appearance and density of microcracks. Significant molecular weight reductions were seen for the SME-free control, but were small (within instrumental error) for the polymers with SME. The use of fluoropolymer as a SME does appear to be warranted as a means to improve polyether polyurethane biostability. PMID:16886223

  3. Catalyst-free synthesis of high elongation degradable polyurethanes containing varying ratios of isosorbide and polycaprolactone: physical properties and biocompatibility.

    PubMed

    Park, Hyung-seok; Gong, Myoung-Seon; Knowles, Jonathan C

    2013-02-01

    Biocompatible and biodegradable polyurethanes were prepared with fixed aliphatic diisocyanate level and varying ratios of isosorbide, and PCL diol via a simple one-shot polymerization without a catalyst. The successful synthesis of the polyurethanes was confirmed by gel permeation chromatography, (1)H-nuclear magnetic resonance and Fourier transform-infrared spectroscopies and the thermal properties were determined by differential scanning calorimetry and showed glass transition temperatures of around 30-35 °C. The degradation tests were performed at 37 °C in phosphate buffer solution (approx. pH 7.3) and showed a mass loss of around 5 % after 12 weeks, except for the polymer with the highest isosorbide content which showed an initial rapid mass loss. The in vitro cytocompatibility test results following culture of osteoblasts on the polymer surface showed that relative cell number on all of the polyurethane films after 5 days of cultured on polymer films was lower compared to the proliferation rate on the optimized tissue culture plastic. These polymers offer significant promise due to the simplicity of the synthesis and the controlled degradation. PMID:23183961

  4. Biotransformation of methyl isocyanate in the rat. Evidence for glutathione conjugation as a major pathway of metabolism and implications for isocyanate-mediated toxicities.

    PubMed

    Slatter, J G; Rashed, M S; Pearson, P G; Han, D H; Baillie, T A

    1991-01-01

    S-(N-Methylcarbamoyl)-N-acetylcysteine (AMCC), a chemically labile mercapturic acid conjugate, was identified by liquid chromatography-mass spectrometry (LC-MS) in the urine of rats dosed intraperitoneally with methyl isocyanate (MIC; 45.2 mumol). The corresponding cysteine conjugate, however, was not detected in urine. Following methylation, urine extracts were analyzed by thermospray LC-MS and the AMCC methyl ester was quantified by means of a stable isotope dilution assay procedure which utilized S-(N-methylcarbamoyl)-N-[2H3]-acetylcysteine [( 2H3]AMCC) as internal standard. The results showed that the fraction of the injected dose of MIC which appeared in 24-h urine collections as AMCC was 24.8 +/- 1.9% (mean +/- SD, N = 4). Thus, conjugation of MIC with glutathione (GSH), followed by metabolism of the resulting adduct to AMCC, appears to represent a quantitatively important pathway of biotransformation of MIC in the rat. However, in view of the known carbamoylating properties and in vitro cytotoxicity of S-linked conjugates of MIC, it seems unlikely that the GSH pathway of metabolism fulfills a conventional detoxification role in the case of MIC. In contrast, it is proposed that carbamate thioester conjugates of MIC, which can revert spontaneously to free MIC under physiological conditions, may actually contribute to the multisystem adverse effects of this highly toxic isocyanate in vivo. PMID:1782345

  5. Gas chromatographic method for the determination of residual monomers, 2-(acryloyloxy)ethyl isocyanate and 2-(methacryloyloxy)ethyl isocyanate, as curing agents in an ultraviolet curable adhesive.

    PubMed

    Kim, Byoung-Hyoun; Kim, Nosun; Moon, Dong Cheul

    2014-02-01

    A gas chromatographic method is described for the determination of residual 2-(acryloyloxy)ethyl isocyanate (AOI) and 2-(methacryloyloxy)ethyl isocyanate (MOI) as curing agents in an ultraviolet curable adhesive. Pre-column derivatization was employed in the determination of AOI and MOI as a means of enhancing the response of the flame ionization detector. Urethane derivatives of AOI and MOI were derived using methanol for 30 min at room temperature. The accuracies (n = 5, three concentration levels) were in the range of 113.4 to 126.7%, and precisions (n = 5, three concentration levels) were in the range of 0.8 to 4.3% for AOI-OMe. Furthermore, the accuracies were in the range of 79.5 to 108.6% and the precisions were in the range of 1.0 to 2.4% for MOI-OMe. The correlation coefficients of six calibration standards were all greater than 0.9999 for AOI-OMe and greater than 0.9998 for MOI-OMe over the range from 10 to 100 µg/mL.

  6. Cloud condensation nuclei (CCN) activity of aliphatic amine secondary aerosol

    NASA Astrophysics Data System (ADS)

    Tang, X.; Price, D.; Praske, E.; Vu, D. N.; Purvis-Roberts, K.; Silva, P. J.; Cocker, D. R., III; Asa-Awuku, A.

    2014-06-01

    Aliphatic amines can form secondary aerosol via oxidation with atmospheric radicals (e.g., hydroxyl radical and nitrate radical). The particle can contain both secondary organic aerosol (SOA) and inorganic salts. The ratio of organic to inorganic materials in the particulate phase influences aerosol hygroscopicity and cloud condensation nuclei (CCN) activity. SOA formed from trimethylamine (TMA) and butylamine (BA) reactions with hydroxyl radical (OH) is composed of organic material of low hygroscopicity (single hygroscopicity parameter, κ, ≤ 0.25). Secondary aerosol formed from the tertiary aliphatic amine (TMA) with N2O5 (source of nitrate radical, NO3) contains less volatile compounds than the primary aliphatic amine (BA) aerosol. As relative humidity (RH) increases, inorganic amine salts are formed as a result of acid-base reactions. The CCN activity of the humid TMA-N2O5 aerosol obeys Zdanovskii, Stokes, and Robinson (ZSR) ideal mixing rules. The humid BA + N2O5 aerosol products were found to be very sensitive to the temperature at which the measurements were made within the streamwise continuous-flow thermal gradient CCN counter; κ ranges from 0.4 to 0.7 dependent on the instrument supersaturation (ss) settings. The variance of the measured aerosol κ values indicates that simple ZSR rules cannot be applied to the CCN results from the primary aliphatic amine system. Overall, aliphatic amine aerosol systems' κ ranges within 0.2 < κ < 0.7. This work indicates that aerosols formed via nighttime reactions with amines are likely to produce hygroscopic and volatile aerosol, whereas photochemical reactions with OH produce secondary organic aerosol of lower CCN activity. The contributions of semivolatile secondary organic and inorganic material from aliphatic amines must be considered for accurate hygroscopicity and CCN predictions from aliphatic amine systems.

  7. In vitro oxidation of high polydimethylsiloxane content biomedical polyurethanes: correlation with the microstructure.

    PubMed

    Hernandez, Rebeca; Weksler, Jadwiga; Padsalgikar, Ajay; Runt, James

    2008-11-01

    The resistance to in vitro metal ion oxidation of a polydimethylsiloxane (PDMS)-containing thermoplastic polyurethane elastomer (Elast-Eon) is compared with that of a polyurethane consisting of the same hard segment chemistry and content, but with aliphatic polycarbonate soft segments (PCU). Scanning electron microscopy and attenuated total reflectance Fourier transform infrared spectroscopy were used to assess changes in surface morphology and chemistry. The extent of bulk degradation was assessed indirectly by dynamic mechanical analysis and small-angle X-ray scattering experiments. The findings indicate that Elast-Eon is more resistant to oxidation than the PCU, because of the presence of the PDMS soft segments as well as its phase separated microstructure. The PCU exhibits a rather high degree of intermixing between hard and soft segments, rendering the hard segments dissolved or trapped in the soft phase more susceptible to oxidative conditions. By contrast, we propose that the existence of a completely phase separated PDMS soft phase in Elast-Eon protects the remainder of the segments from oxidation.

  8. New isocyanate-specific albumin adducts of 4,4'-methylenediphenyl diisocyanate (MDI) in rats.

    PubMed

    Kumar, Anoop; Dongari, Nagaraju; Sabbioni, Gabriele

    2009-12-01

    4,4'-Methylenediphenyl diisocyanate (MDI) is the most important of the isocyanates used as intermediates in the chemical industry. Among the main types of damage after exposure to low levels of MDI are lung sensitization and asthma. Albumin adducts of MDI might be involved in the etiology of sensitization reactions. It is, therefore, necessary to have sensitive and specific methods for monitoring the isocyanate exposure of workers. To date, urinary metabolites or protein adducts have been used as biomarkers in workers exposed to MDI. However, with these methods it is not possible to determine whether the biomarkers result from exposure to MDI or to the parent aromatic amine 4,4'-methylenedianiline (MDA). This work presents a procedure for the determination of isocyanate-specific albumin adducts. In a long-term experiment, designed to determine the carcinogenic and toxic effects of MDI, rats were exposed chronically for 3 months, to 0.0 (control), 0.26, 0.70, and 2.06 mg MDI/m(3) as aerosols. Albumin was isolated from plasma, digested with Pronase E, and analyzed by LC-MS/MS. MDI formed adducts with lysine: N(6)-[({4-[4-aminobenzyl]phenyl}amino)carbonyl]lysine (MDI-Lys) and N(6)-[({4-[4-(acetylamino)benzyl]phenyl}amino)carbonyl] lysine (AcMDI-Lys). For the quantitation of the adducts in vivo, isotope dilution mass spectrometry was used to measure the adducts in 2 mg of albumin. The adducts found in vivo (MDI-Lys and AcMDI-Lys) and the corresponding isotope labeled compounds (MDI-[(13)C(6)(15)N(2)]Lys and Ac[(2)H(4)]MDI-Lys) were synthesized and used for quantitation. The MDI-Lys levels increased from 0-24.8 pmol/mg albumin, and the AcMDI-Lys levels increased from 0-1.85 pmol/mg albumin. The mean ratio of MDI-Lys/AcMDI-Lys for each dose level was greater than >20. The albumin adducts correlate with other biomarkers measured in the same rats in the past: urinary metabolites and hemoglobin adducts released after mild base hydrolysis. This method will enable one to

  9. Aliphatic alcohols in spirits inhibit phagocytosis by human monocytes.

    PubMed

    Pál, László; Árnyas, Ervin M; Bujdosó, Orsolya; Baranyi, Gergő; Rácz, Gábor; Ádány, Róza; McKee, Martin; Szűcs, Sándor

    2015-04-01

    A large volume of alcoholic beverages containing aliphatic alcohols is consumed worldwide. Previous studies have confirmed the presence of ethanol-induced immunosuppression in heavy drinkers, thereby increasing susceptibility to infectious diseases. However, the aliphatic alcohols contained in alcoholic beverages might also impair immune cell function, thereby contributing to a further decrease in microbicidal activity. Previous research has shown that aliphatic alcohols inhibit phagocytosis by granulocytes but their effect on human monocytes has not been studied. This is important as they play a crucial role in engulfment and killing of pathogenic microorganisms and a decrease in their phagocytic activity could lead to impaired antimicrobial defence in heavy drinkers. The aim of this study was to measure monocyte phagocytosis following their treatment with those aliphatic alcohols detected in alcoholic beverages. Monocytes were separated from human peripheral blood and phagocytosis of opsonized zymosan particles by monocytes treated with ethanol and aliphatic alcohols individually and in combination was determined. It was shown that these alcohols could suppress the phagocytic activity of monocytes in a concentration-dependent manner and when combined with ethanol, they caused a further decrease in phagocytosis. Due to their additive effects, it is possible that they may inhibit phagocytosis in a clinically meaningful way in alcoholics and episodic heavy drinkers thereby contribute to their increased susceptibility to infectious diseases. However, further research is needed to address this question.

  10. 40 CFR 721.9959 - Polyurethane polymer (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Polyurethane polymer (generic). 721... Substances § 721.9959 Polyurethane polymer (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as a polyurethane polymer (PMN...

  11. 40 CFR 721.9959 - Polyurethane polymer (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Polyurethane polymer (generic). 721... Substances § 721.9959 Polyurethane polymer (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as a polyurethane polymer (PMN...

  12. 40 CFR 721.9959 - Polyurethane polymer (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Polyurethane polymer (generic). 721... Substances § 721.9959 Polyurethane polymer (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as a polyurethane polymer (PMN...

  13. 40 CFR 721.8082 - Polyester polyurethane acrylate.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Polyester polyurethane acrylate. 721... Substances § 721.8082 Polyester polyurethane acrylate. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as polyester polyurethane...

  14. 40 CFR 721.10299 - Polymeric MDI based polyurethanes (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Polymeric MDI based polyurethanes... Specific Chemical Substances § 721.10299 Polymeric MDI based polyurethanes (generic). (a) Chemical... as polymeric MDI based polyurethanes (PMNs P-00-2, P-00-5, and P-00-6) are subject to reporting...

  15. 40 CFR 721.10299 - Polymeric MDI based polyurethanes (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Polymeric MDI based polyurethanes... Specific Chemical Substances § 721.10299 Polymeric MDI based polyurethanes (generic). (a) Chemical... as polymeric MDI based polyurethanes (PMNs P-00-2, P-00-5, and P-00-6) are subject to reporting...

  16. 40 CFR 721.8082 - Polyester polyurethane acrylate.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Polyester polyurethane acrylate. 721... Substances § 721.8082 Polyester polyurethane acrylate. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as polyester polyurethane...

  17. 40 CFR 721.8082 - Polyester polyurethane acrylate.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Polyester polyurethane acrylate. 721... Substances § 721.8082 Polyester polyurethane acrylate. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as polyester polyurethane...

  18. 40 CFR 721.8082 - Polyester polyurethane acrylate.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Polyester polyurethane acrylate. 721... Substances § 721.8082 Polyester polyurethane acrylate. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as polyester polyurethane...

  19. 40 CFR 721.10299 - Polymeric MDI based polyurethanes (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Polymeric MDI based polyurethanes... Specific Chemical Substances § 721.10299 Polymeric MDI based polyurethanes (generic). (a) Chemical... as polymeric MDI based polyurethanes (PMNs P-00-2, P-00-5, and P-00-6) are subject to reporting...

  20. 40 CFR 721.8082 - Polyester polyurethane acrylate.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Polyester polyurethane acrylate. 721... Substances § 721.8082 Polyester polyurethane acrylate. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as polyester polyurethane...

  1. 40 CFR 721.9959 - Polyurethane polymer (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Polyurethane polymer (generic). 721... Substances § 721.9959 Polyurethane polymer (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as a polyurethane polymer (PMN...

  2. 40 CFR 721.9959 - Polyurethane polymer (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Polyurethane polymer (generic). 721... Substances § 721.9959 Polyurethane polymer (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as a polyurethane polymer (PMN...

  3. Catalytic Asymmetric Hydroamination of Unactivated Internal Olefins to Aliphatic Amines

    PubMed Central

    Yang, Yang; Shi, Shi-Liang; Niu, Dawen; Liu, Peng; Buchwald, Stephen L.

    2015-01-01

    Catalytic assembly of enantiopure aliphatic amines from abundant and readily available precursors has long been recognized as a paramount challenge in synthetic chemistry. Herein, we describe a mild and general copper-catalyzed hydroamination that effectively converts unactivated internal olefins, an important yet unexploited class of abundant feedstock chemicals, into highly enantioenriched α-branched amines (≥ 96% enantiomeric excess) featuring two minimally differentiated aliphatic substituents. This method provides a powerful means to access a broad range of advanced, highly functionalized enantioenriched amines of interest in pharmaceutical research and other areas. PMID:26138973

  4. Microwave-assisted synthesis of cyclodextrin polyurethanes.

    PubMed

    Biswas, Atanu; Appell, Michael; Liu, Zengshe; Cheng, H N

    2015-11-20

    Cyclodextrin (CD) has often been incorporated into polyurethanes in order to facilitate its use in encapsulation or removal of organic species for various applications. In this work a microwave-assisted method has been developed to produce polyurethanes consisting of α-, β-, and γ-CD and three common diisocyanates. As compared to conventional heating, this new synthetic method saves energy, significantly reduces reaction time, and gets similar or improved yield. The reaction products have been fully characterized with (13)C, (1)H, and two-dimensional NMR spectroscopy. With suitable stoichiometry of starting CD and diisocyanate, the resulting CD polyurethane is organic-soluble and water-insoluble and is shown to remove Nile red dye and phenol from water. Possible applications include the removal of undesirable materials from process streams, toxic compounds from the environment, and encapsulation of color or fragrance molecules.

  5. Microwave-assisted synthesis of cyclodextrin polyurethanes.

    PubMed

    Biswas, Atanu; Appell, Michael; Liu, Zengshe; Cheng, H N

    2015-11-20

    Cyclodextrin (CD) has often been incorporated into polyurethanes in order to facilitate its use in encapsulation or removal of organic species for various applications. In this work a microwave-assisted method has been developed to produce polyurethanes consisting of α-, β-, and γ-CD and three common diisocyanates. As compared to conventional heating, this new synthetic method saves energy, significantly reduces reaction time, and gets similar or improved yield. The reaction products have been fully characterized with (13)C, (1)H, and two-dimensional NMR spectroscopy. With suitable stoichiometry of starting CD and diisocyanate, the resulting CD polyurethane is organic-soluble and water-insoluble and is shown to remove Nile red dye and phenol from water. Possible applications include the removal of undesirable materials from process streams, toxic compounds from the environment, and encapsulation of color or fragrance molecules. PMID:26344257

  6. Efficient continuous dryer for flexible polyurethane foam and cleaning apparatus

    DOEpatents

    Jody, B.; Daniels, E.; Libera, J.A.

    1999-03-16

    A method of cleaning polyurethane foams where the material is transported through a wash station while alternately soaking the polyurethane foam in an organic solvent and squeezing solvent from the polyurethane foam a number of times. Then the polyurethane foam is sent through a rinse or solvent transfer station for reducing the concentration of solvent in the foam. The rinsed polyurethane foam is sent to a drying station wherein the foam is repeatedly squeezed while being exposed to hot air to remove wet air from the foam. 4 figs.

  7. Efficient continuous dryer for flexible polyurethane foam and cleaning apparatus

    DOEpatents

    Jody, Bassam; Daniels, Edward; Libera, Joseph A.

    1999-01-01

    A method of cleaning polyurethane foams where the material is transported through a wash station while alternately soaking the polyurethane foam in an organic solvent and squeezing solvent from the polyurethane foam a number of times. Then the polyurethane foam is sent through a rinse or solvent transfer station for reducing the concentration of solvent in the foam. The rinsed polyurethane foam is sent to a drying station wherein the foam is repeatedly squeezed while being exposed to hot air to remove wet air from the foam.

  8. Selective synthesis of eight-membered cyclic ureas by the [6 + 2] cycloaddition reaction of 2-vinylazetidines and electron-deficient isocyanates.

    PubMed

    Koya, Shunsuke; Yamanoi, Kenichi; Yamasaki, Ryu; Azumaya, Isao; Masu, Hyuma; Saito, Shinichi

    2009-12-01

    The [6 + 2] cycloaddition reaction of 2-vinylazetidines with electron-deficient isocyanates such as tosyl isocyanate proceeded smoothly in the absence of the catalyst at room temperature, and various cyclic ureas were isolated in good to high yields. Electron-deficient allenes also reacted with the 2-vinylazetidine, and the corresponding azocine derivatives were isolated.

  9. Radiation cross-linking of ethylene vinyl alcohol copolymer functionalized with m-isopropenyl-{alpha},{alpha}-dimethyl benzyl isocyanate

    SciTech Connect

    Ekman, K.B.; Naesman, J.H.

    1993-12-31

    In order to allow radiation cross-linking at low radiation doses, pendant unsaturation was introduced by reactive processing of ethylene vinyl alcohol copolymer and m-isopropenyl-{alpha},{alpha}-dimethyl benzyl isocyanate. Oxygen permeability of ethylene vinyl alcohol copolymer decreased with increasing degree of functionalization, while irradiation of the samples form trapped radicals, which act as oxygen scavengers and consequently no oxygen permeability was detected. However, radical activity was inhibited by annealing the samples at 110{degrees}C for 2.5 h, resulting in a 24% higher oxygen permeability value for the irradiated unfunctionalized copolymer, while the oxygen permeability values of the irradiated functionalized samples were 13% lower. Laminates, of m-isopropenyl-{alpha},{alpha}-dimethyl benzyl isocyanate functionalized ethylene vinyl alcohol copolymer and m-isopropenyl-{alpha},{alpha}-dimethyl benzyl isocyanate functionalized ethylene hydroxyethyl methacrylate copolymer acquired improved adhesive strength both at dry and wet conditions as well as at elevated temperatures upon exposure to radiation.

  10. Investigation of pulmonary function among employees exposed to low levels of monomeric isocyanates and solvents at an automobile finishings plant.

    PubMed

    Schweigert, Michael; Sax, Sol; House, Ron; Henderson, Bruce

    2002-11-01

    There have been reports in the literature of decrements in pulmonary function associated with long-term, low-level monomeric isocyanate exposure combined with solvent exposure. This cross-sectional study examines the relationship between these exposures and pulmonary function in an automobile paint and coating (finishes) plant. A job exposure matrix was developed for isocyanate and solvent exposure; years in a work task were used as a surrogate for exposure. Recent pulmonary function tests were used as the outcome variables; specifically the difference between predicted and actual FEV1 and FVC. The results of the analysis demonstrated no statistically significant relationship between combined isocyanate and solvent exposure and decline in pulmonary function. There was a statistically significant negative correlation between solvent exposure and FEV1 and FVC.

  11. Modeling of skeletal members using polyurethane foam

    SciTech Connect

    Sena, J.M.F.; Weaver, R.W.

    1983-11-01

    At the request of the University of New Mexico's Maxwell Museum of Anthropology, members of the Plastic Section in the Process Development Division at SNLA undertook the special project of the Chaco Lady. The project consisted of polyurethane foam casting of a disinterred female skull considered to be approximately 1000 years old. Rubber latex molds, supplied by the UNM Anthropology Department, were used to produce the polymeric skull requested. The authors developed for the project a modified foaming process which will be used in future polyurethane castings of archaeological artifacts and contemporary skeletal members at the University.

  12. Biobased polyurethanes prepared from different vegetable oils.

    PubMed

    Zhang, Chaoqun; Madbouly, Samy A; Kessler, Michael R

    2015-01-21

    In this study, a series of biobased polyols were prepared from olive, canola, grape seed, linseed, and castor oil using a novel, solvent/catalyst-free synthetic method. The biobased triglyceride oils were first oxidized into epoxidized vegetable oils with formic acid and hydrogen peroxide, followed by ring-opening reaction with castor oil fatty acid. The molecular structures of the polyols and the resulting polyurethane were characterized. The effects of cross-linking density and the structures of polyols on the thermal, mechanical, and shape memory properties of the polyurethanes were also investigated.

  13. Biobased polyurethanes prepared from different vegetable oils.

    PubMed

    Zhang, Chaoqun; Madbouly, Samy A; Kessler, Michael R

    2015-01-21

    In this study, a series of biobased polyols were prepared from olive, canola, grape seed, linseed, and castor oil using a novel, solvent/catalyst-free synthetic method. The biobased triglyceride oils were first oxidized into epoxidized vegetable oils with formic acid and hydrogen peroxide, followed by ring-opening reaction with castor oil fatty acid. The molecular structures of the polyols and the resulting polyurethane were characterized. The effects of cross-linking density and the structures of polyols on the thermal, mechanical, and shape memory properties of the polyurethanes were also investigated. PMID:25541678

  14. A new amine catalyst for polyurethanes

    SciTech Connect

    Ziv, M.H.; Mascioli, R.L.

    1982-05-01

    This article reports on a new amine catalyst for polyurethanes, the X-8154, which is a delayed action polyurethane catalyst. Experimental results indicated that unlike conventional amine catalysts, the X-8154's unique property of delayed initiation followed by rapid complete cure provides excellent processing and high quality parts. Good flow ability of the components in the production of rigid foams yields uniformity of properties necessary for a high quality product. X-8154, by virtue of its ability to delay reactivity, should find broad use in rigid foams, both in appliance and structural applications.

  15. Submillimeter Wave Spectroscopy of Acetyl Isocyanate : CH_3C(O)NCO

    NASA Astrophysics Data System (ADS)

    Margulès, L.; Motiyenko, R. A.; Guillemin, J.-C.; Tercero, Belén; Cernicharo, Jose; Jabri, Atef; Kleiner, Isabelle; Ilyushin, V.

    2014-06-01

    Except isocyanic acid detected in the ISM since 1972, the organo isocyanate derivatives are poorly studied in the millimeter wave domain. This lack of data could be the reason of their non detection in the ISM up to now. We decided to investigate the C_3H_3NO_2 isomer: acetyl isocyanate. Previously measured up to 40 GHz, the cis-conformer exhibits internal rotation motion with a medium barrier value of 360 wn. The trans conformer conformer is calculated to have an energy of 12.55 kJ.mol-1 (1060 wn) higher than the cis one and is not studied here. The measurements were performed in Lille with our solid state devices spectrometer up to 500 GHz. The sample was found to have a poor stability and reacts fastly with metal parts. We should repeat measurements using a flow and a pyrex cell in order to have satisfactory signal to noise ratio. The analysis was performed with RAM36 code which used the Rho Axis Method. The first results and its searche in ORION will be presented. Snyder, L. E.; and Buhl, D.Astrophys. J., 177, (1972) 619 Landsberg, B.M.; and Iqbal, K.J.C.S. Faraday II, 76, (1980) 1208 Uchida, Y.; Toyoda, M.; Kuze, N.; and Sakaizumi, T.J. Mol. Spectrosc., 256, (2009) 163 Ilyushin, V.V. et al;J. Mol. Spectrosc., 259, (2010) 26 This work was supported by the CNES and the Action sur Projets de l'INSU, PCMI. This work was also done under Ukrainian-French CNRS-PICS 6051 project and ANR-13-BS05-0008-02 IMOLABS

  16. Respiratory Symptoms, Sensitization, and Exposure–Response Relationships in Spray Painters Exposed to Isocyanates

    PubMed Central

    Pronk, Anjoeka; Preller, Liesbeth; Raulf-Heimsoth, Monika; Jonkers, Irene C. L.; Lammers, Jan-Willem; Wouters, Inge M.; Doekes, Gert; Wisnewski, Adam V.; Heederik, Dick

    2007-01-01

    Rationale: Associations between oligomeric isocyanate exposure, sensitization, and respiratory disease have received little attention, despite the extensive use of isocyanate oligomers. Objectives: To investigate exposure–response relationships of respiratory symptoms and sensitization in a large population occupationally exposed to isocyanate oligomers during spray painting. Methods: The prevalence of respiratory symptoms and sensitization was assessed in 581 workers in the spray-painting industry. Personal exposure was estimated by combining personal task-based inhalatory exposure measurements and time activity information. Specific IgE and IgG to hexamethylene diisocyanate (HDI) were assessed in serum by ImmunoCAP assay and enzyme immunoassays using vapor and liquid phase HDI–human serum albumin (HDI–HSA) and HSA conjugates prepared with oligomeric HDI. Measurements and Main Results: Respiratory symptoms were more prevalent in exposed workers than among comparison office workers. Log–linear exposure–response associations were found for asthmalike symptoms, chronic obstructive pulmonary disease–like symptoms, and work-related chest tightness (prevalence ratios for an interquartile range increase in exposure of 1.2, 1.3 and 2.0, respectively; P ⩽ 0.05). The prevalence of specific IgE sensitization was low (up to 4.2% in spray painters). Nevertheless, IgE to N100 (oligomeric HDI)–HSA was associated with exposure and work-related chest tightness. The prevalence of specific IgG was higher (2–50.4%) and strongly associated with exposure. Conclusions: The results provide evidence of exposure–response relationships for both work-related and non–work-related respiratory symptoms and specific sensitization in a population exposed to oligomers of HDI. Specific IgE was found in only a minority of symptomatic individuals. Specific IgG seems to be merely an indicator of exposure. PMID:17656675

  17. Isocyanates and isothiocyanates as versatile platforms for accessing (thio)amide-type compounds.

    PubMed

    Pace, Vittorio; Monticelli, Serena; de la Vega-Hernández, Karen; Castoldi, Laura

    2016-08-16

    The addition of carbon (Grignard and organolithium reagents) and hydride nucleophiles (Schwartz reagent) to isocyanates and isothiocyanates constitutes a versatile, direct and high yielding approach to the synthesis of functionalized (thio)amide derivatives including haloamides and formamides. The chemoselective delivery of a nucleophilic (eventually configurationally stable) organometallic species to a given iso(thio)cyanate is the crucial parameter for the success of the strategy. Thus, the influence of the factors governing classical methodologies (e.g. dehydrative condensation) such as steric hindrance and electronic properties of the reactants become practically negligible. PMID:27461156

  18. Improving the antifouling property of polysulfone ultrafiltration membrane by incorporation of isocyanate-treated graphene oxide.

    PubMed

    Zhao, Haiyang; Wu, Liguang; Zhou, Zhijun; Zhang, Lin; Chen, Huanlin

    2013-06-21

    In this paper, isocyanate-treated graphene oxide (iGO), which can be well dispersed in organic solvent, was prepared in a simple manner and showed excellent compatibility with polysulfone (PSF). iGO-PSF ultrafiltration membranes were prepared by the classical phase inversion method. The separation performance and the antifouling property of the prepared membranes were investigated in detail. The antifouling property of the prepared membranes was found to be greatly enhanced by the addition of iGO, and we attributed the enhanced antifouling property to the improved hydrophilicity, the more negative zeta potential and the improved smoothness of the membrane surface.

  19. The Electrical Properties for Phenolic Isocyanate-Modified Bisphenol-Based Epoxy Resins Comprising Benzoate Group.

    PubMed

    Lee, Eun Yong; Chae, Il Seok; Park, Dongkyung; Suh, Hongsuk; Kang, Sang Wook

    2016-03-01

    Epoxy resin has been required to have a low dielectric constant (D(k)), low dissipation factor (Df), low coefficient of thermal expansion (CTE), low water absorption, high mechanical, and high adhesion properties for various applications. A series of novel phenolic isocyanate-modified bisphenol-based epoxy resins comprising benzoate group were prepared for practical electronic packaging applications. The developed epoxy resins showed highly reduced dielectric constants (D(k)-3.00 at 1 GHz) and low dissipation values (Df-0.014 at 1 GHz) as well as enhanced thermal properties. PMID:27455751

  20. The Electrical Properties for Phenolic Isocyanate-Modified Bisphenol-Based Epoxy Resins Comprising Benzoate Group.

    PubMed

    Lee, Eun Yong; Chae, Il Seok; Park, Dongkyung; Suh, Hongsuk; Kang, Sang Wook

    2016-03-01

    Epoxy resin has been required to have a low dielectric constant (D(k)), low dissipation factor (Df), low coefficient of thermal expansion (CTE), low water absorption, high mechanical, and high adhesion properties for various applications. A series of novel phenolic isocyanate-modified bisphenol-based epoxy resins comprising benzoate group were prepared for practical electronic packaging applications. The developed epoxy resins showed highly reduced dielectric constants (D(k)-3.00 at 1 GHz) and low dissipation values (Df-0.014 at 1 GHz) as well as enhanced thermal properties.

  1. Genotoxicity studies of methyl isocyanate in Salmonella, Drosophila, and cultured Chinese hamster ovary cells

    SciTech Connect

    Mason, J.M.; Zeiger, E.; Haworth, S.; Ivett, J.; Valencia, R.

    1987-01-01

    The genotoxic effects of methyl isocyanate (MIC) were investigated using four short-term tests: the Salmonella reversion assay (Ames test), the Drosophila sex-linked recessive lethal assay, and the sister chromatic exchange (SCE) and chromosomal aberration assays in cultured Chinese hamster ovary (CHO) cells. No evidence was found for the induction of mutations in either Salmonella or Drosophila. MIC did, however, induce SCEs and chromosomal aberrations in CHO cells both in the presence and absence of Aroclor-induced rat liver S-9.

  2. Occupational eosinophilic bronchitis in a foundry worker exposed to isocyanate and a baker exposed to flour

    PubMed Central

    Stefano, Fabio Di; Giampaolo, Luca Di; Verna, Nicola; Gioacchino, Mario Di

    2007-01-01

    Eosinophilic bronchitis without asthma may occur as a consequence of occupational exposure. The cases of a foundry worker and a baker who developed symptoms, respectively, due to exposure to isocyanate and flour, are reported. Cough was not associated with variable airflow obstruction or with airway hyper‐responsiveness and was responsive to inhaled corticosteroids. The eosinophilia detectable in their sputum was causally related to the occupational exposure in the workplace. The examination of induced sputum should be used in addition to the objective monitoring of lung function for workers who have asthma‐like symptoms in an occupational setting. PMID:16055615

  3. Applicability of the theory of thermodynamic similarity to predict the enthalpies of vaporization of aliphatic aldehydes

    NASA Astrophysics Data System (ADS)

    Esina, Z. N.; Korchuganova, M. R.

    2015-06-01

    The theory of thermodynamic similarity is used to predict the enthalpies of vaporization of aliphatic aldehydes. The predicted data allow us to calculate the phase diagrams of liquid-vapor equilibrium in a binary water-aliphatic aldehyde system.

  4. Selective stabilization of aliphatic organic carbon by iron oxide

    PubMed Central

    Adhikari, Dinesh; Yang, Yu

    2015-01-01

    Stabilization of organic matter in soil is important for natural ecosystem to sequestrate carbon and mitigate greenhouse gas emission. It is largely unknown what factors govern the preservation of organic carbon in soil, casting shadow on predicting the response of soil to climate change. Iron oxide was suggested as an important mineral preserving soil organic carbon. However, ferric minerals are subject to reduction, potentially releasing iron and decreasing the stability of iron-bound organic carbon. Information about the stability of iron-bound organic carbon in the redox reaction is limited. Herein, we investigated the sorptive interactions of organic matter with hematite and reductive release of hematite-bound organic matter. Impacts of organic matter composition and conformation on its sorption by hematite and release during the reduction reaction were analyzed. We found that hematite-bound aliphatic carbon was more resistant to reduction release, although hematite preferred to sorb more aromatic carbon. Resistance to reductive release represents a new mechanism that aliphatic soil organic matter was stabilized by association with iron oxide. Selective stabilization of aliphatic over aromatic carbon can greatly contribute to the widely observed accumulation of aliphatic carbon in soil, which cannot be explained by sorptive interactions between minerals and organic matter. PMID:26061259

  5. Triphosgene–Amine Base Promoted Chlorination of Unactivated Aliphatic Alcohols

    PubMed Central

    Villalpando, Andrés; Ayala, Caitlan E.; Watson, Christopher B.; Kartika, Rendy

    2014-01-01

    Unactivated α-branched primary and secondary aliphatic alcohols have been successfully transformed into their corresponding alkyl chlorides in high yields upon treatment with a mixture of triphosgene and pyridine in dichloromethane at reflux. These mild chlorination conditions are high yielding, stereospecific, and well tolerated by numerous sensitive functionalities. Furthermore, no nuisance waste products are generated in the course of the reactions. PMID:23496045

  6. Cloud condensation nuclei activity of aliphatic amine secondary aerosol

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aliphatic amines can form secondary aerosol via oxidation with atmospheric radicals (e.g. hydroxyl radical and nitrate radical). The resulting particle composition can contain both secondary organic aerosol (SOA) and inorganic salts. The fraction of organic to inorganic materials in the particulate ...

  7. Selective stabilization of aliphatic organic carbon by iron oxide.

    PubMed

    Adhikari, Dinesh; Yang, Yu

    2015-01-01

    Stabilization of organic matter in soil is important for natural ecosystem to sequestrate carbon and mitigate greenhouse gas emission. It is largely unknown what factors govern the preservation of organic carbon in soil, casting shadow on predicting the response of soil to climate change. Iron oxide was suggested as an important mineral preserving soil organic carbon. However, ferric minerals are subject to reduction, potentially releasing iron and decreasing the stability of iron-bound organic carbon. Information about the stability of iron-bound organic carbon in the redox reaction is limited. Herein, we investigated the sorptive interactions of organic matter with hematite and reductive release of hematite-bound organic matter. Impacts of organic matter composition and conformation on its sorption by hematite and release during the reduction reaction were analyzed. We found that hematite-bound aliphatic carbon was more resistant to reduction release, although hematite preferred to sorb more aromatic carbon. Resistance to reductive release represents a new mechanism that aliphatic soil organic matter was stabilized by association with iron oxide. Selective stabilization of aliphatic over aromatic carbon can greatly contribute to the widely observed accumulation of aliphatic carbon in soil, which cannot be explained by sorptive interactions between minerals and organic matter. PMID:26061259

  8. Introducing Aliphatic Substitution with a Discovery Experiment Using Competing Electrophiles

    ERIC Educational Resources Information Center

    Curran, Timothy P.; Mostovoy, Amelia J.; Curran, Margaret E.; Berger, Clara

    2016-01-01

    A facile, discovery-based experiment is described that introduces aliphatic substitution in an introductory undergraduate organic chemistry curriculum. Unlike other discovery-based experiments that examine substitution using two competing nucleophiles with a single electrophile, this experiment compares two isomeric, competing electrophiles…

  9. A thermostable transketolase evolved for aliphatic aldehyde acceptors.

    PubMed

    Yi, Dong; Saravanan, Thangavelu; Devamani, Titu; Charmantray, Franck; Hecquet, Laurence; Fessner, Wolf-Dieter

    2015-01-11

    Directed evolution of the thermostable transketolase from Geobacillus stearothermophilus based on a pH-based colorimetric screening of smart libraries yielded several mutants with up to 16-fold higher activity for aliphatic aldehydes and high enantioselectivity (>95% ee) in the asymmetric carboligation step. PMID:25415647

  10. Aromatic amines from polyurethane adhesives in food packaging: the challenge of identification and pattern recognition using Quadrupole-Time of Flight-Mass SpectrometryE.

    PubMed

    Pezo, Davinson; Fedeli, Mauro; Bosetti, Osvaldo; Nerín, Cristina

    2012-12-01

    Toxic primary aromatic amines (PAAs) are reaction products from residual isocyanates in polyurethane adhesives. The maximum migration level of the total sum of PAAs is 10 ng g(-1) of food. This paper reports on a method for quantification of 18 PAAs by UHPLC-MS/MS that was optimised and applied to a series of industrial laminates prepared from polyurethane adhesives. Non-intentionally added substances (NIAS), impurities and other migrants were identified by Q-TOF/MS(E). A comparison of the quantitative values obtained by the colorimetric method using NEDA and by UHPLC-MS/MS confirmed that the first method can overestimate the quantification of PAAs. This could be attributed to the impurities and other NIAS present in the plastic laminate. Values of R(2) in the analytical characteristics of UHPLC-MS/MS were obtained, the best value being 0.9964 and the most unfavourable 0.7626. The detection limit (LOD) and the quantification limit (LOQ) were 2 pg g(-1) and 7 pg g(-1), respectively. The stability of the PAAs over time in the acidic simulant in contact with the plastic laminate is also reported. PMID:23176739

  11. Aromatic amines from polyurethane adhesives in food packaging: the challenge of identification and pattern recognition using Quadrupole-Time of Flight-Mass SpectrometryE.

    PubMed

    Pezo, Davinson; Fedeli, Mauro; Bosetti, Osvaldo; Nerín, Cristina

    2012-12-01

    Toxic primary aromatic amines (PAAs) are reaction products from residual isocyanates in polyurethane adhesives. The maximum migration level of the total sum of PAAs is 10 ng g(-1) of food. This paper reports on a method for quantification of 18 PAAs by UHPLC-MS/MS that was optimised and applied to a series of industrial laminates prepared from polyurethane adhesives. Non-intentionally added substances (NIAS), impurities and other migrants were identified by Q-TOF/MS(E). A comparison of the quantitative values obtained by the colorimetric method using NEDA and by UHPLC-MS/MS confirmed that the first method can overestimate the quantification of PAAs. This could be attributed to the impurities and other NIAS present in the plastic laminate. Values of R(2) in the analytical characteristics of UHPLC-MS/MS were obtained, the best value being 0.9964 and the most unfavourable 0.7626. The detection limit (LOD) and the quantification limit (LOQ) were 2 pg g(-1) and 7 pg g(-1), respectively. The stability of the PAAs over time in the acidic simulant in contact with the plastic laminate is also reported.

  12. System Description for the K-25/K-27 D&D Project Polyurethane Foam Delivery System, East Tennessee Technology Park, Oak Ridge, Tennessee

    SciTech Connect

    Boris, G.

    2008-02-21

    The Foam Delivery System used in the decontamination and decommissioning (D&D) project for the K-25/K-27 Buildings at the East Tennessee Technology Park (ETTP) is comprised of a trailer-mounted Gusmer{reg_sign} H20/35 Pro-TEC Proportioning Unit and the associated equipment to convey electrical power, air, and foam component material to the unit. This high-pressure, plural-component polyurethane foam pouring system will be used to fill process gas and non-process equipment/piping (PGE/P) within the K-25/K-27 Buildings with polyurethane foam to immobilize contaminants prior to removal. The system creates foam by mixing isocyanate and polyol resin (Resin) component materials. Currently, the project plans to utilize up to six foaming units simultaneously during peak foaming activities. Also included in this system description are the foam component material storage containers that will be used for storage of the component material drums in a staging area outside of the K-25/K-27 Buildings. The Foam Delivery System and foam component material storage enclosures (i.e., Foaming Component Protective Enclosures) used to store polymeric methylene diphenyl diisocyanate (PMDI) component material are identified as Safety Significant (SS) Structures, Systems and Components (SSC) in the Documented Safety Analysis (DSA) for the project, Documented Safety Analysis for the K-25 and K-27 Facilities at the East Tennessee Technology Park, Oak Ridge, Tennessee, DSA-ET-K-25/K-27-0001.

  13. 40 CFR 721.10608 - Aliphatic diisocyanate polymer with alkanediol and alkylglycol (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Aliphatic diisocyanate polymer with... Significant New Uses for Specific Chemical Substances § 721.10608 Aliphatic diisocyanate polymer with.... (1) The chemical substance identified generically as aliphatic diisocyanate polymer with...

  14. 40 CFR 721.10608 - Aliphatic diisocyanate polymer with alkanediol and alkylglycol (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Aliphatic diisocyanate polymer with... Significant New Uses for Specific Chemical Substances § 721.10608 Aliphatic diisocyanate polymer with.... (1) The chemical substance identified generically as aliphatic diisocyanate polymer with...

  15. 40 CFR 721.7250 - Polyaziridinyl ester of an aliphatic alcohol (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Polyaziridinyl ester of an aliphatic... Specific Chemical Substances § 721.7250 Polyaziridinyl ester of an aliphatic alcohol (generic). (a... generically as a polyaziridinyl ester of an aliphatic alcohol (PMN P-01-97) is subject to reporting under...

  16. Rigid polyurethane and kenaf core composite foams

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Rigid polyurethane foams are valuable in many construction applications. Kenaf is a bast fiber plant where the surface stem skin provides bast fibers whose strength-to-weight ratio competes with glass fiber. The higher volume product of the kenaf core is an under-investigated area in composite appli...

  17. A constitutive theory for rigid polyurethane foam

    SciTech Connect

    Neilsen, M.K.; Krieg, R.D.; Schreyer, H.L.

    1992-12-31

    Rigid, closed-cell, polyurethane foam consists of interconnected polyurethane plates which form cells. When this foam is compressed, it exhibits an initial elastic regime which is followed by a plateau regime in which the load required to compress the foam remains nearly constant. In the plateau regime, cell walls are damaged and large permanent volume changes are generated. As additional load is applied, cell walls are compressed against neighboring cell walls, and the stiffness of the foam increases and approaches a value equal to that of solid polyurethane. When the foam is loaded in tension, the cell walls are damaged and the foam fractures. A constitutive theory for rigid polyurethane foam has been developed. This theory is based on a decomposition of the foam into two parts: a skeleton and a nonlinear elastic continuum in parallel. The skeleton accounts for the foam behavior in the elastic and plateau regimes and is described using a coupled plasticity with continuum damage theory. The nonlinear elastic continuum accounts for the lock-up of the foam due to internal gas pressure and cell wall interactions. This new constitutive theory has been implemented in both static and dynamic finite element codes. Numerical simulations performed using the new constitutive theory are presented.

  18. (Chicken feathers keratin)/polyurethane membranes

    NASA Astrophysics Data System (ADS)

    Saucedo-Rivalcoba, V.; Martínez-Hernández, A. L.; Martínez-Barrera, G.; Velasco-Santos, C.; Castaño, V. M.

    2011-07-01

    Actually, chicken feathers are considered as waste from the poultry industry; however, 90% of feather structure is constituted by a protein called keratin. In this research, the properties of feather keratin and polyurethane are combined in order to synthesize hybrid synthetic-natural membranes. Both polymers are linked by urethane bonds which are similar to peptide bonds found in proteins. Keratin is incorporated onto the polyurethane matrix by dissolving protein in a salt solution (urea and 2-mercaptoethanol) at different concentrations: 11, 13, 15, 17, 19, and 21% (w/w). In order to know the effect of urea on membranes, keratin is incorporated to polyurethane in two ways; as keratin salt solution and after dialyzing. Both membrane types were characterized by Scanning Electron Microscopy (SEM) to observe their morphologic changes. Fourier Transformed Infrared Spectroscopy (FT-IR), Termogravimetric Analysis (TGA), and Differential Scanning Calorimetry (DSC) were used to study membrane structures. Results show that keratin is grafted in polyurethane and, therefore, there is an influence of amino acids through the amino and carboxylic groups (NH and COOH) into the synthetic polymer structure. According with characterization results, the obtained membranes are functional materials that can be useful in diverse applications, among them the separation process can be emphasized.

  19. Polyurethane adhesive with improved high temperature properties

    NASA Technical Reports Server (NTRS)

    Stuckey, J. M.

    1977-01-01

    A polyurethane resin with paste activator, capable of providing useful bond strengths over the temperature range of -184 C to 149 C, is described. The adhesive system has a pot life of over one hour. Tensile shear strength ratings are given for various adhesive formulations.

  20. Measuring Rind Thickness on Polyurethane Foam

    NASA Technical Reports Server (NTRS)

    Johnson, C.; Miller, J.; Brown, H.

    1985-01-01

    Nondestructive test determines rind thickness of polyurethane foam. Surface harness of foam measured by Shore durometer method: hardness on Shore D scale correlates well with rind thickness. Shore D hardness of 20, for example, indicates rind thickness of 0.04 inch (1 millimeter). New hardness test makes it easy to determine rind thickness of sample nondestructively and to adjust fabrication variables accordingly.

  1. Biodegradation Of thermoplastic polyurethanes from vegetable oils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Thermoplastic urethanes based on polyricinoleic acid soft segments and MDI/BD hard segments with varied soft segment concentration were prepared. Soft segment concentration was varied fro, 40 to 70 wt %. Biodegradation was studied by respirometry. Segmented polyurethanes with soft segments based ...

  2. Nonwoven glass fiber mat reinforces polyurethane adhesive

    NASA Technical Reports Server (NTRS)

    Roseland, L. M.

    1967-01-01

    Nonwoven glass fiber mat reinforces the adhesive properties of a polyurethane adhesive that fastens hardware to exterior surfaces of aluminum tanks. The mat is embedded in the uncured adhesive. It ensures good control of the bond line and increases the peel strength.

  3. Development of Lignin-Based Polyurethane Thermoplastics

    SciTech Connect

    Saito, Tomonori; Perkins, Joshua H; Jackson, Daniel C; Trammell, Neil E; Hunt, Marcus A; Naskar, Amit K

    2013-01-01

    In our continued effort to develop value-added thermoplastics from lignin, here we report utilizing a tailored feedstock to synthesize mechanically robust thermoplastic polyurethanes at very high lignin contents (75 65 wt %). The molecular weight and glass transition temperature (Tg) of lignin were altered through cross-linking with formaldehyde. The cross-linked lignin was coupled with diisocyanate-based telechelic polybutadiene as a network-forming soft segment. The appearance of two Tg s, around 35 and 154 C, for the polyurethanes indicates the existence of two-phase morphology, a characteristic of thermoplastic copolymers. A calculated Flory-Huggins interaction parameter of 7.71 also suggests phase immiscibility in the synthesized lignin polyurethanes. An increase in lignin loading increased the modulus, and an increase in crosslink-density increased the modulus in the rubbery plateau region of the thermoplastic. This path for synthesis of novel lignin-based polyurethane thermoplastics provides a design tool for high performance lignin-based biopolymers.

  4. Modeling decomposition of rigid polyurethane foam

    SciTech Connect

    Hobbs, M.L.

    1998-01-01

    Rigid polyurethane foams are used as encapsulants to isolate and support thermally sensitive components within weapon systems. When exposed to abnormal thermal environments, such as fire, the polyurethane foam decomposes to form products having a wide distribution of molecular weights and can dominate the overall thermal response of the system. Decomposing foams have either been ignored by assuming the foam is not present, or have been empirically modeled by changing physical properties, such as thermal conductivity or emissivity, based on a prescribed decomposition temperature. The hypothesis addressed in the current work is that improved predictions of polyurethane foam degradation can be realized by using a more fundamental decomposition model based on chemical structure and vapor-liquid equilibrium, rather than merely fitting the data by changing physical properties at a prescribed decomposition temperature. The polyurethane decomposition model is founded on bond breaking of the primary polymer and formation of a secondary polymer which subsequently decomposes at high temperature. The bond breaking scheme is resolved using percolation theory to describe evolving polymer fragments. The polymer fragments vaporize according to individual vapor pressures. Kinetic parameters for the model were obtained from Thermal Gravimetric Analysis (TGA) from a single nonisothermal experiment with a heating rate of 20 C/min. Model predictions compare reasonably well with a separate nonisothermal TGA weight loss experiment with a heating rate of 200 C/min.

  5. Revealing Stepwise Mechanisms in Dipolar Cycloaddition Reactions: Computational Study of the Reaction between Nitrones and Isocyanates.

    PubMed

    Darù, Andrea; Roca-López, David; Tejero, Tomás; Merino, Pedro

    2016-01-15

    The mechanism of cycloaddition reactions of nitrones with isocyanates has been studied using density functional theory (DFT) methods at the M06-2X/cc-pVTZ level of theory. The exploration of the potential energy surfaces associated with two reactive channels leading to 1,2,4-oxadiazolidin-5-ones and 1,4,2-dioxazolidines revealed that the cycloaddition reaction takes place through a concerted mechanism in gas phase and in apolar solvents but a stepwise mechanism in polar solvents. In stepwise mechanisms, the first step of the reaction is a rare case in which the nitrone oxygen acts as a nucleophile by attacking the central carbon atom of the isocyanate (interacting with the π-system of the C═O bond) to give an intermediate. The corresponding transition structure is stabilized by an attractive electrostatic interaction favored in a polar medium. The second step of the reaction is the rate-limiting one in which the formation of 1,2,4-oxadiazolidin-5-ones or 1,4,2-dioxazolidines is decided. Calculations indicate that formation of 1,2,4-oxadiazolidin-5-ones is favored both kinetically and thermodynamically independently of the solvent, in agreement with experimental observations. Noncovalent interactions (NCI) and topological analysis of the gradient field of electron localization function (ELF) bonding confirmed the observed interactions.

  6. Oligomers with pendant isocyanate groups as adhesives for dentin and other tissues.

    PubMed

    Lee, C H; Brauer, G M

    1989-03-01

    Oligomers containing pendant isocyanate groups were synthesized from various vinyl monomers, m-isopropenyldimethylbenzyl isocyanate (TMI), and 2-isocyanatoethyl methacrylate (IEM). The liquids were characterized by their refractive indices, infrared spectra, and percentage of isocynate groups in the molecule. Adhesive properties of these compounds were compared with those of oligomers prepared from methacrylate esters, IEM, and/or TMI which had been synthesized previously. Bond strengths of the sodium salt of ethylenediamine-tetraacetic acid (Na2EDTA adjusted to pH 7.4) and glutaraldehyde-treated dentin cemented to composite resin with dilute solutions of the oligomers and then stored in water were determined by the procedure of Kemper and Kilian (1975). These adhesive compositions, especially formulations synthesized from vinyl monomers, adhered at least as well to dentin as did other dentin bonding agents. Oligomers synthesized with methacrylate esters bonded more strongly to bone than did other hard-tissue adhesives. These oligomeric compositions are also excellent soft-tissue adhesives. For example, they provide a strong bond between a collagenous substrate (such as calfskin) and cured denture-base resin. Provided that their biological properties prove satisfactory, these compositions could find many applications as hard- and soft-tissue adhesives in clinical dentistry. PMID:2921392

  7. Di-Isocyanate Crosslinked Aerogels with 1, 6-Bis (Trimethoxysilyl) Hexane Incorporated in Silica Backbone

    NASA Technical Reports Server (NTRS)

    Vivod, Stephanie L.; Meador, Mary Ann B.; Nguyen, Baochau N.; Quade, Derek; Randall, Jason; Perry, Renee

    2008-01-01

    Silica aerogels are desirable materials for many applications that take advantage of their light weight and low thermal conductivity. Addition of a conformal polymer coating which bonds with the amine decorated surface of the silica network improves the strength of the aerogels by as much as 200 times. Even with vast improvement in strength they still tend to undergo brittle failure due to the rigid silica backbone. We hope to increase the flexibility and elastic recovery of the silica based aerogel by altering the silica back-bone by incorporation of more flexible hexane links. To this end, we investigated the use of 1,6-bis(trimethoxysilyl)hexane (BTMSH), a polysilsesquioxane precursor3, as an additional co-reactant to prepare silica gels which were subsequently cross-linked with di-isocyanate. Previously, this approach of adding flexibility by BTMSH incorporation was demonstrated with styrene cross-linked aerogels. In our study, we varied silane concentration, mol % of silicon from BTMSH and di-isocyanate concentration by weight percent to attempt to optimize both the flexibility and the strength of the aerogels.

  8. Revealing Stepwise Mechanisms in Dipolar Cycloaddition Reactions: Computational Study of the Reaction between Nitrones and Isocyanates.

    PubMed

    Darù, Andrea; Roca-López, David; Tejero, Tomás; Merino, Pedro

    2016-01-15

    The mechanism of cycloaddition reactions of nitrones with isocyanates has been studied using density functional theory (DFT) methods at the M06-2X/cc-pVTZ level of theory. The exploration of the potential energy surfaces associated with two reactive channels leading to 1,2,4-oxadiazolidin-5-ones and 1,4,2-dioxazolidines revealed that the cycloaddition reaction takes place through a concerted mechanism in gas phase and in apolar solvents but a stepwise mechanism in polar solvents. In stepwise mechanisms, the first step of the reaction is a rare case in which the nitrone oxygen acts as a nucleophile by attacking the central carbon atom of the isocyanate (interacting with the π-system of the C═O bond) to give an intermediate. The corresponding transition structure is stabilized by an attractive electrostatic interaction favored in a polar medium. The second step of the reaction is the rate-limiting one in which the formation of 1,2,4-oxadiazolidin-5-ones or 1,4,2-dioxazolidines is decided. Calculations indicate that formation of 1,2,4-oxadiazolidin-5-ones is favored both kinetically and thermodynamically independently of the solvent, in agreement with experimental observations. Noncovalent interactions (NCI) and topological analysis of the gradient field of electron localization function (ELF) bonding confirmed the observed interactions. PMID:26682934

  9. Alkyl isocyanates as active site-directed inactivators of guinea pig liver transglutaminase.

    PubMed

    Gross, M; Whetzel, N K; Folk, J E

    1975-10-10

    Alkyl isocyanates are effective inactivators of guinea pig liver transglutaminase. Based on the specificity of the reaction the protection against inactivation by glutamine substrate, and the essential nature of calcium for the inactivation reaction, it is concluded that these reagents act as amide substrate analogs and, thus function in an active site-specific manner. Support for the contention that inactivation results from alkyl thiocarbamate ester formation through the single active site sulfhydryl group of the enzyme is (a) the loss of one free--SH group and the incorporation of 1 mol of reagent/mol of enzyme in the reaction, (b) similarity in chemical properties of the inactive enzyme derivative formed to those previously reported for another alkyl thiocarbamoylenzyme and an alkyl thiocarbamoylcysteine derivative, and (c) the finding that labeled peptides from digests of [methyl-14C]thiocarbamoyltransglutaminase and those from digests of iodoacetamide-inactivated enzyme occupy similar positions on peptide maps. Transglutaminase was found to be inactivated neither by urethan anlogs of its active ester substrates nor by urea analogs of its amide substrates. It is concluded on the basis of these findings that inactive carbamoylenzyme derivatives are formed only by direct addition of the transglutaminase active--SH group to the isocyanate C--N double bond, and not, like several serine active site enzymes, by nucleophilic displacement with urethan analogs of substrate, or by nucleophilic displacement with urea analogs of substrate. PMID:240837

  10. Modulation of microsomal membrane associated detoxication enzymes activity by methyl isocyanate (MIC) exposure

    SciTech Connect

    Mishra, A.; Dwivedi, P.D.; Verma, A.S.; Mishra, J.; Sinha, M.; Dutta, K.K.; Ray, P.K. )

    1991-11-01

    In the industrial disaster at Bhopal, India in 1984 the leakage of 40 tons of methyl isocyanate (MIC) gas from a pesticide plant claimed over 2,500 lives and left an estimated population of 15,000 people suffering from a variety of ailments. MIC induced changes in respiratory functions including bronchial asthma, pulmonary oedema, necrosis of alveoli, hypersensitivity, pneumonities and incapacitated pulmonary functions. Reports have also indicated changes in the respiratory tract of animals as a result of exposure to MIC, the lung being the main target organ attacked by MIC. The authors earlier report of the high dose single exposure toxicity to methyl isocyanate leads to alterations in biotransformation enzymes and their isoenzymic pattern. Recently, a drastic decrease in Na{sup +}, K{sup +}, and Mg{sup ++} ATPase enzyme levels by repeated MIC exposure has been shown. The present study further explores the biochemical basis of MIC intoxication with reference to consecutive dose dependent toxicity in terms of alteration in phase 1 and phase 2 membrane bound detoxication enzymes.

  11. Aminolysis of phenyl N-phenylcarbamate via an isocyanate intermediate: theory and experiment.

    PubMed

    Ilieva, Sonia; Nalbantova, Didi; Hadjieva, Boriana; Galabov, Boris

    2013-07-01

    A comprehensive examination of the mechanism of the uncatalyzed and base-catalyzed aminolysis of phenyl N-phenylcarbamate by theoretical quantum mechanical methods at M06-2X/6-311+G(2d,2p) and B3LYP-D3/6-31G(d,p) levels, combined with an IR spectroscopic study of the reaction, was carried out. Three alternative reaction channels were theoretically characterized: concerted, stepwise via a tetrahedral intermediate, and stepwise involving an isocyanate intermediate. In contrast to dominating views, the theoretical results revealed that the reaction pathway through the isocyanate intermediate (E1cB) is energetically favored. These conclusions were supported by an IR spectroscopic investigation of the interactions of phenyl N-phenylcarbamate with several amines possessing varying basicities and nucleophilicities: n-butylamine, diethylamine, triethylamine, N-methylpyrrolidine, and trimethylamine. The reactivity of substituted phenyl N-phenylcarbamates in the aminolysis reaction was rationalized using theoretical and experimental reactivity indexes: electrostatic potential at nuclei (EPN), Hirshfeld and NBO atomic charges, and Hammett constants. The obtained quantitative relationships between these property descriptors and experimental kinetic constants reported in the literature emphasize the usefulness of theoretical parameters (EPN, atomic charges) in characterizing chemical reactivity.

  12. Isocyanic acid in the atmosphere and its possible link to smoke-related health effects

    PubMed Central

    Roberts, James M.; Veres, Patrick R.; Cochran, Anthony K.; Warneke, Carsten; Burling, Ian R.; Yokelson, Robert J.; Lerner, Brian; Gilman, Jessica B.; Kuster, William C.; Fall, Ray; de Gouw, Joost

    2011-01-01

    We measured isocyanic acid (HNCO) in laboratory biomass fires at levels up to 600 parts per billion by volume (ppbv), demonstrating that it has a significant source from pyrolysis/combustion of biomass. We also measured HNCO at mixing ratios up to 200 pptv (parts-per-trillion by volume) in ambient air in urban Los Angeles, CA, and in Boulder, CO, during the recent 2010 Fourmile Canyon fire. Further, our measurements of aqueous solubility show that HNCO is highly soluble, as it dissociates at physiological pH. Exposure levels > 1 ppbv provide a direct source of isocyanic acid and cyanate ion (NCO-) to humans at levels that have recognized health effects: atherosclerosis, cataracts, and rheumatoid arthritis, through the mechanism of protein carbamylation. In addition to the wildland fire and urban sources, we observed HNCO in tobacco smoke, HNCO has been reported from the low-temperature combustion of coal, and as a by-product of urea-selective catalytic reduction (SCR) systems that are being phased-in to control on-road diesel NOx emissions in the United States and the European Union. Given the current levels of exposure in populations that burn biomass or use tobacco, the expected growth in biomass burning emissions with warmer, drier regional climates, and planned increase in diesel SCR controls, it is imperative that we understand the extent and effects of this HNCO exposure. PMID:21576489

  13. Isocyanic acid in the atmosphere and its possible link to smoke-related health effects.

    PubMed

    Roberts, James M; Veres, Patrick R; Cochran, Anthony K; Warneke, Carsten; Burling, Ian R; Yokelson, Robert J; Lerner, Brian; Gilman, Jessica B; Kuster, William C; Fall, Ray; de Gouw, Joost

    2011-05-31

    We measured isocyanic acid (HNCO) in laboratory biomass fires at levels up to 600 parts per billion by volume (ppbv), demonstrating that it has a significant source from pyrolysis/combustion of biomass. We also measured HNCO at mixing ratios up to 200 pptv (parts-per-trillion by volume) in ambient air in urban Los Angeles, CA, and in Boulder, CO, during the recent 2010 Fourmile Canyon fire. Further, our measurements of aqueous solubility show that HNCO is highly soluble, as it dissociates at physiological pH. Exposure levels > 1 ppbv provide a direct source of isocyanic acid and cyanate ion (NCO(-)) to humans at levels that have recognized health effects: atherosclerosis, cataracts, and rheumatoid arthritis, through the mechanism of protein carbamylation. In addition to the wildland fire and urban sources, we observed HNCO in tobacco smoke, HNCO has been reported from the low-temperature combustion of coal, and as a by-product of urea-selective catalytic reduction (SCR) systems that are being phased-in to control on-road diesel NO(x) emissions in the United States and the European Union. Given the current levels of exposure in populations that burn biomass or use tobacco, the expected growth in biomass burning emissions with warmer, drier regional climates, and planned increase in diesel SCR controls, it is imperative that we understand the extent and effects of this HNCO exposure. PMID:21576489

  14. Thermal Expansion of Polyurethane Foam

    NASA Technical Reports Server (NTRS)

    Lerch, Bradley A.; Sullivan, Roy M.

    2006-01-01

    Closed cell foams are often used for thermal insulation. In the case of the Space Shuttle, the External Tank uses several thermal protection systems to maintain the temperature of the cryogenic fuels. A few of these systems are polyurethane, closed cell foams. In an attempt to better understand the foam behavior on the tank, we are in the process of developing and improving thermal-mechanical models for the foams. These models will start at the microstructural level and progress to the overall structural behavior of the foams on the tank. One of the key properties for model characterization and verification is thermal expansion. Since the foam is not a material, but a structure, the modeling of the expansion is complex. It is also exacerbated by the anisoptropy of the material. During the spraying and foaming process, the cells become elongated in the rise direction and this imparts different properties in the rise direction than in the transverse directions. Our approach is to treat the foam as a two part structure consisting of the polymeric cell structure and the gas inside the cells. The polymeric skeleton has a thermal expansion of its own which is derived from the basic polymer chemistry. However, a major contributor to the thermal expansion is the volume change associated with the gas inside of the closed cells. As this gas expands it exerts pressure on the cell walls and changes the shape and size of the cells. The amount that this occurs depends on the elastic and viscoplastic properties of the polymer skeleton. The more compliant the polymeric skeleton, the more influence the gas pressure has on the expansion. An additional influence on the expansion process is that the polymeric skeleton begins to breakdown at elevated temperatures and releases additional gas species into the cell interiors, adding to the gas pressure. The fact that this is such a complex process makes thermal expansion ideal for testing the models. This report focuses on the thermal

  15. Synthesis of biobased polyurethane from oleic and ricinoleic acids as the renewable resources via the AB-type self-condensation approach.

    PubMed

    Palaskar, Dnyaneshwar V; Boyer, Aurélie; Cloutet, Eric; Alfos, Carine; Cramail, Henri

    2010-05-10

    Polyurethane (PU) from methyl oleate (derived from sunflower oil) and ricinoleic acid (derived from castor oil) was synthesized using the AB-type self-polycondensation approach for the first time. In the present work, three novel AB-type monomers, namely, a mixture of 10-hydroxy-9-methoxyoctadecanoyl azide/9-hydroxy-10-methoxyoctadecanoyl azide (HMODAz), 12-hydroxy-9-cis-octadecenoyl azide (HODEAz) and methyl-N-11-hydroxy-9-cis-heptadecen carbamate (MHHDC) were synthesized from methyl oleate and ricinoleic acid using simple reaction steps. Out of these, HMODAz and HODEAz monomers were polymerized by the acyl-azido and hydroxyl AB-type self-condensation approach, while MHHDC monomer was polymerized through AB-type self-condensation via transurethane reaction. The acyl-azido and hydroxyl self-condensations were carried out at various temperatures (50, 60, 80. and 110 degrees C) in bulk with and without catalyst. A FTIR study of the polymerization, using HMODAz at 80 degrees C without catalyst, indicates in situ formation of an intermediate isocyanate group in the first 15-30 min, and further onward, the molar mass increases as observed by SEC analysis. In the case of the MHHDC monomer, a transurethane reaction was used to obtain a similar PU (which was obtained by AB-type acyl-azido and hydroxyl self-condensation of HODEAz) in the presence of titanium tetrabutoxide as a catalyst at 130 degrees C. HMODAz, HODEAz, MHHDC, and corresponding polyurethanes were characterized by FTIR, (1)H NMR, (13)C NMR, and MALDI-TOF mass spectroscopy. Differential scanning calorimetric analysis of polyurethanes derived from HMODAz, HODEAz, and MHHDC showed two different glass transition temperatures for soft segments (at lower temperature) and hard segments (at higher temperature), indicating phase-separated morphology. PMID:20402498

  16. Protonation switching to the least-basic heteroatom of carbamate through cationic hydrogen bonding promotes the formation of isocyanate cations.

    PubMed

    Kurouchi, Hiroaki; Sumita, Akinari; Otani, Yuko; Ohwada, Tomohiko

    2014-07-01

    We found that phenethylcarbamates that bear ortho-salicylate as an ether group (carbamoyl salicylates) dramatically accelerate OC bond dissociation in strong acid to facilitate generation of isocyanate cation (N-protonated isocyanates), which undergo subsequent intramolecular aromatic electrophilic cyclization to give dihydroisoquinolones. To generate isocyanate cations from carbamates in acidic media as electrophiles for aromatic substitution, protonation at the ether oxygen, the least basic heteroatom, is essential to promote CO bond cleavage. However, the carbonyl oxygen of carbamates, the most basic site, is protonated exclusively in strong acids. We found that the protonation site can be shifted to an alternative basic atom by linking methyl salicylate to the ether oxygen of carbamate. The methyl ester oxygen ortho to the phenolic (ether) oxygen of salicylate is as basic as the carbamate carbonyl oxygen, and we found that monoprotonation at the methyl ester oxygen in strong acid resulted in the formation of an intramolecular cationic hydrogen bond (>CO(+) H⋅⋅⋅O<) with the phenolic ether oxygen. This facilitates OC bond dissociation of phenethylcarbamates, thereby promoting isocyanate cation formation. In contrast, superacid-mediated diprotonation at the methyl ester oxygen of the salicylate and the carbonyl oxygen of the carbamate afforded a rather stable dication, which did not readily undergo CO bond dissociation. This is an unprecedented and unknown case in which the monocation has greater reactivity than the dication.

  17. Activation of dinitrogen-derived hafnium nitrides for nucleophilic N-C bond formation with a terminal isocyanate.

    PubMed

    Semproni, Scott P; Chirik, Paul J

    2013-12-01

    Better by Hf: Anion coordination to a bridging hafnocene nitride complex, prepared from CO-induced N2 cleavage, increases the nucleophilicity of the nitrogen atom, thus promoting additional NC bond formation with a typically inert terminal isocyanate ligand. This cascade sequence allows synthesis of otherwise challenging mono-substituted ureas using N2 , CO, and an appropriate electrophile.

  18. Interfacial thiol-isocyanate reactions for functional nanocarriers: a facile route towards tunable morphologies and hydrophilic payload encapsulation.

    PubMed

    Kuypers, Sören; Pramanik, Sumit Kumar; D'Olieslaeger, Lien; Reekmans, Gunter; Peters, Martijn; D'Haen, Jan; Vanderzande, Dirk; Junkers, Thomas; Adriaensens, Peter; Ethirajan, Anitha

    2015-11-11

    Functional nanocarriers were synthesized using an in situ inverse miniemulsion polymerization employing thiol-isocyanate reactions at the droplet interface to encapsulate hydrophilic payloads. The morphology of the nanocarriers is conveniently tunable by varying the reaction conditions and the dispersions are easily transferable to the aqueous phase.

  19. Marine biofouling resistance of polyurethane with biodegradation and hydrolyzation.

    PubMed

    Xu, Wentao; Ma, Chunfeng; Ma, Jielin; Gan, Tiansheng; Zhang, Guangzhao

    2014-03-26

    We have prepared polyurethane with poly(ε-caprolactone) (PCL) as the segments of the main chain and poly(triisopropylsilyl acrylate) (PTIPSA) as the side chains by a combination of radical polymerization and a condensation reaction. Quartz crystal microbalance with dissipation studies show that polyurethane can degrade in the presence of enzyme and the degradation rate decreases with the PTIPSA content. Our studies also demonstrate that polyurethane is able to hydrolyze in artificial seawater and the hydrolysis rate increases as the PTIPSA content increases. Moreover, hydrolysis leads to a hydrophilic surface that is favorable to reduction of the frictional drag under dynamic conditions. Marine field tests reveal that polyurethane has good antifouling ability because polyurethane with a biodegradable PCL main chain and hydrolyzable PTIPSA side chains can form a self-renewal surface. Polyurethane was also used to carry and release a relatively environmentally friendly antifoulant, and the combined system exhibits a much higher antifouling performance even in a static marine environment.

  20. Urinary catheter with polyurethane coating modified by ion implantation

    NASA Astrophysics Data System (ADS)

    Kondyurina, I.; Nechitailo, G. S.; Svistkov, A. L.; Kondyurin, A.; Bilek, M.

    2015-01-01

    A low friction urinary catheter that could be used without a lubricant is proposed in this work. A polyurethane coating was synthesised on the surface of a metal guide wire catheter. Ion implantation was applied to surface modify the polyurethane coating. FTIR ATR, wetting angle, AFM and friction tests were used for analysis. Low friction was found to be provided by the formation of a hard carbonised layer on the polyurethane surface.

  1. Polyurethane sheet: a potential substitute of surgical cotton gauze.

    PubMed

    Shimamoto, Takeshi

    2011-03-07

    Polyurethane sheet is a pure white, soft, and flexible synthetic sponge with a mechanical strength and abrasion resistance equivalent or even superior to other sponge materials. Our study indicates that the blood absorption power of the polyurethane sheet is equivalent to that of the cotton gauze even after repeated use, and it has the potential to decrease the total amount of sponge usage. Further, accurately identifying the bleeding point might be easier with the polyurethane sheet.

  2. Lipstick dermatitis due to C18 aliphatic compounds.

    PubMed

    Hayakawa, R; Matsunaga, K; Suzuki, M; Arima, Y; Ohkido, Y

    1987-04-01

    An 18-year-old girl developed cheilitis. She had a past history of lip cream dermatitis, but the cause was not found. Patch tests with 2 lipsticks were strongly positive. Tests with the ingredients were positive to 2 aliphatic compounds, glyceryl diisostearate and diisostearyl malate. Impurities in the materials were suspected as the cause. Analysis by gas chromatography detected 3 chemicals in glyceryl diisostearate and 1 in diisostearyl malate as impurities. Patch testing with the impurities and glyceryl monoisostearate 0.01% pet in glyceryl diisostearate and isostearyl alcohol 0.25% pet in diisostearyl malate were strongly positive. The characteristics common to the 2 chemicals were liquidity at room temperature, branched C18 aliphatic compound and primary alcohol. Chemicals lacking any of the above 3 features did not react.

  3. Determination of aliphatic hydrocarbons in the alga Himanthalia elongata.

    PubMed

    Punín Crespo, M O; Lage Yusty, M A

    2004-02-01

    The algae considered new foods according to Regulation CE 258/97 need a guarantee of their healthfulness before being in the European market. In this work ten samples of the brown alga Himanthalia elongata have been analyzed with the aim of verifying the absence of aliphatic hydrocarbons, due to the ability of the macroalgae to capture lipophilic organic compounds of the marine water coming from accidental or continuous leaks of raw oil and refined products, which happen each year with the growth of the industrialization and the demand of energy. The fat of the samples were Soxhlet extracted using hexane:dichloromethane (1:1) for 7h. The organic fractions were purified using silica microcolumns. The identification and quantification of the aliphatic hydrocarbons have been carried out using gas chromatography (GC) with flame ionization detector (FID). The total hydrocarbon content was between 14.8 and 40.2 microg g(-1) dry weight. PMID:14759670

  4. Biodegradation of Trihalomethanes and Other Halogenated Aliphatic Compounds

    NASA Technical Reports Server (NTRS)

    Smith, G. B.

    1996-01-01

    The biological dehalogenation of common water pollutants such as trichloromethane (chloroform) and other halogenated aliphatic compounds was the subject of this project. Samples from diverse water environments such as from groundwater contaminated with halogenated compounds and wastewaters from regional treatment plants were studied to identify conditions that favor certain dehalogenation reactions over others. Gene probe analyses of DNA extracted from the dichlormethane-degrading wastewater indicated the presence of the gene coding for dichloromethane dehalogenase, indicating the genetic basis for the dechlorination activity observed. These studies indicate that methanogenic bacteria are the organisms responsible for the chloroform dechlorination. Dechlorination of a common chlorofluorocarbon (CFC-11) was identified in samples taken from a regional aquifer contaminated with halogenated aliphatic compounds.

  5. Aliphatics hydrocarbon content in surface sediment from Jakarta Bay, Indonesia

    NASA Astrophysics Data System (ADS)

    YAzis, M.; Asia, L.; Piram, A.; Doumenq, P.; Syakti, A. D.

    2016-02-01

    Sedimentary aliphatic hydrocarbons content have been studied quantitatively and qualitatively using GC/MS method in eight coastal stations located in the Jakarta Bay, North of Jakarta, Indonesia. The total concentrations n-alkanes have ranged from 480 μg.kg-1to 1,935 μg.kg-1sediment dry weight. Several ratios (e.g. CPI24-32, NAR, TAR, Pr/Phy, n-C17/Pr, n- C18/Phyt,n-C29/n-C17, Ʃn-alkanes/n-C16LMW/HMW, Paq and TMD) were used to evaluate the possible sources of terrestrial-marine inputs of these hydrocarbons in the sediments. The various origins of aliphatic hydrocarbons were generally biogenic, including both terrigenous and marine, with an anthropogenic pyrolytic contribution (petrogenic and biogenic combustion). Two stations (G,H) were thehighest concentration and had potential risk to environment

  6. Sensory and pulmonary irritation of methyl isocyanate in mice and pulmonary irritation and possible cyanidelike effects of methyl isocyanate in guinea pigs

    SciTech Connect

    Alarie, Y.; Ferguson, J.S.; Stock, M.F.; Weyel, D.A.; Schaper, M.

    1987-06-01

    Methyl isocyanate (MIC) was evaluated for sensory and pulmonary irritation in mice. MIC was found to be both a potent sensory and pulmonary irritant in this species. From these results, a safe level of exposure for a period of 8 hr was estimated to be about 0.02 ppm for humans. Guinea pigs were also exposed to MIC for a single 3-hr exposure at a concentration of 37 ppm. During exposure to MIC, coughing was observed in all animals. Pulmonary function was evaluated immediately following exposure and intermittently on the next 35 days using CO/sub 2/ challenges and flow-volume loops. Highly abnormal responses to CO/sub 2/ were observed immediately after exposure in all animals. Six of the eight animals exposed to MIC died. In the two survivors, an apparent recovery was seen during the 5 days following exposure, but a worsening effect was observed at days 21 and 28, with a partial recovery at day 35. The data clearly demonstrated that the primary pulmonary effect of MIC was one of airways obstruction. Oxygen uptake and carbon dioxide output were also measured in the guinea pigs following exposure to MIC. No evidence of a cyanidelike effect was observed, in contrast to a severe depression of oxygen uptake following exposure to hydrogen cyanide.

  7. Manganese-Mediated Coupling Reaction of Vinylarenes and Aliphatic Alcohols

    PubMed Central

    Zhang, Wei; Wang, Nai-Xing; Bai, Cui-Bing; Wang, Yan-Jing; Lan, Xing-Wang; Xing, Yalan; Li, Yi-He; Wen, Jia-Long

    2015-01-01

    Alcohols and alkenes are the most abundant and commonly used organic building blocks in the large-scale chemical synthesis. Herein, this is the first time to report a novel and operationally simple coupling reaction of vinylarenes and aliphatic alcohols catalyzed by manganese in the presence of TBHP (tert-butyl hydroperoxide). This coupling reaction provides the oxyalkylated products of vinylarenes with good regioselectivity and accomplishes with the principles of step-economies. A possible reaction mechanism has also been proposed. PMID:26470633

  8. Room Temperature, Metal-Free Arylation of Aliphatic Alcohols

    PubMed Central

    Ghosh, Raju; Lindstedt, Erik; Jalalian, Nazli; Olofsson, Berit

    2014-01-01

    Diaryliodonium salts are demonstrated as efficient arylating agents of aliphatic alcohols under metal-free conditions. The reaction proceeds at room temperature within 90 min to give alkyl aryl ethers in good to excellent yields. Aryl groups with electron-withdrawing substituents are transferred most efficiently, and unsymmetric iodonium salts give chemoselective arylations. The methodology has been applied to the formal synthesis of butoxycaine. PMID:24808991

  9. Aerobic microorganism for the degradation of chlorinated aliphatic hydrocarbons

    DOEpatents

    Fliermans, Carl B.

    1989-01-01

    A chlorinated aliphatic hydrocarbon-degrading microorganism, having American Type Culture Collection accession numbers ATCC 53570 and 53571, in a biologically pure culture aseptically collected from a deep subsurface habitat and enhanced, mineralizes trichloroethylene and tetrachloroethylene to HCl, H.sub.2 O and Co.sub.2 under aerobic conditions stimulated by methane, acetate, methanol, tryptone-yeast extract, propane and propane-methane.

  10. Manganese-Mediated Coupling Reaction of Vinylarenes and Aliphatic Alcohols.

    PubMed

    Zhang, Wei; Wang, Nai-Xing; Bai, Cui-Bing; Wang, Yan-Jing; Lan, Xing-Wang; Xing, Yalan; Li, Yi-He; Wen, Jia-Long

    2015-01-01

    Alcohols and alkenes are the most abundant and commonly used organic building blocks in the large-scale chemical synthesis. Herein, this is the first time to report a novel and operationally simple coupling reaction of vinylarenes and aliphatic alcohols catalyzed by manganese in the presence of TBHP (tert-butyl hydroperoxide). This coupling reaction provides the oxyalkylated products of vinylarenes with good regioselectivity and accomplishes with the principles of step-economies. A possible reaction mechanism has also been proposed. PMID:26470633

  11. Manganese-Mediated Coupling Reaction of Vinylarenes and Aliphatic Alcohols

    NASA Astrophysics Data System (ADS)

    Zhang, Wei; Wang, Nai-Xing; Bai, Cui-Bing; Wang, Yan-Jing; Lan, Xing-Wang; Xing, Yalan; Li, Yi-He; Wen, Jia-Long

    2015-10-01

    Alcohols and alkenes are the most abundant and commonly used organic building blocks in the large-scale chemical synthesis. Herein, this is the first time to report a novel and operationally simple coupling reaction of vinylarenes and aliphatic alcohols catalyzed by manganese in the presence of TBHP (tert-butyl hydroperoxide). This coupling reaction provides the oxyalkylated products of vinylarenes with good regioselectivity and accomplishes with the principles of step-economies. A possible reaction mechanism has also been proposed.

  12. Value-added conversion of waste cooking oil and post-consumer PET bottles into biodiesel and polyurethane foams.

    PubMed

    Dang, Yu; Luo, Xiaolan; Wang, Feng; Li, Yebo

    2016-06-01

    A sustainable process of value-added utilization of wastes including waste cooking oil (WCO) and post-consumer PET bottles for the production of biodiesel and polyurethane (PU) foams was developed. WCO collected from campus cafeteria was firstly converted into biodiesel, which can be used as vehicle fuel. Then crude glycerol (CG), a byproduct of the above biodiesel process, was incorporated into the glycolysis process of post-consumer PET bottles collected from campus to produce polyols. Thirdly, PU foams were synthesized through the reaction of the above produced polyols with isocyanate in the presence of catalysts and other additives. The characterization of the produced biodiesel demonstrated that its properties meet the specification of biodiesel standard. The effect of crude glycerol loading on the properties of polyols and PU foams were investigated. All the polyols showed satisfactory properties for the production of rigid PU foams which had performance comparable to those of some petroleum-based analogs. A mass balance and a cost analysis for the conversion of WCO and waste PET into biodiesel and PU foams were also discussed. This study demonstrated the potential of WCO and PET waste for the production of value-added products.

  13. FTIR spectroscopic characterization of polyurethane-urea model hard segments (PUUMHS) based on three diamine chain extenders

    NASA Astrophysics Data System (ADS)

    Zhang, Shijie; Ren, Zhiyong; He, Suqing; Zhu, Yan; Zhu, Chengshen

    2007-01-01

    Six polyurethane-urea model hard segments (PUUMHS) were prepared by a solution method based, respectively, on two isocyanates: 4,4'-methylene-diphenyl-diisocyanate (MDI), 4,4'-methylene-dicyclohexyl diisocyanate (HMDI) and three amine chain extenders: ethylene diamine (EDA), methylene-bis-ortho-chloroaniline (MOCA), 2,4-diamino-3,5-dimethylsuphylchlorobenzene (DDSCB). FTIR was used to study their spectroscopic characterization. The main FTIR bands of the six samples were assigned and compared. It was found that most of N-H and C dbnd O are H-bonded in these PUUMHS. However, the N-H in three MDI based PUUMHS is all in the stronger H-bond state than that in their corresponding HMDI based while the C dbnd O in three HMDI based PUUMHS is all in the stronger H-bond state than that in their corresponding MDI based, respectively. In addition, the order of the H-bond strength in HMDI based PUUMHS is MOCA, DDSCB and EDA whether according to νN sbnd H or νC dbnd O band wavenumbers, which is, however, different from that in MDI based PUUMHS. Moreover, the HMDI based PUUMHS shows obvious double amide III bands while the MDI based has only prominent one. The results are discussed according mainly to the different characteristics of the three chain extenders as well as the structure difference between MDI and HMDI.

  14. Value-added conversion of waste cooking oil and post-consumer PET bottles into biodiesel and polyurethane foams.

    PubMed

    Dang, Yu; Luo, Xiaolan; Wang, Feng; Li, Yebo

    2016-06-01

    A sustainable process of value-added utilization of wastes including waste cooking oil (WCO) and post-consumer PET bottles for the production of biodiesel and polyurethane (PU) foams was developed. WCO collected from campus cafeteria was firstly converted into biodiesel, which can be used as vehicle fuel. Then crude glycerol (CG), a byproduct of the above biodiesel process, was incorporated into the glycolysis process of post-consumer PET bottles collected from campus to produce polyols. Thirdly, PU foams were synthesized through the reaction of the above produced polyols with isocyanate in the presence of catalysts and other additives. The characterization of the produced biodiesel demonstrated that its properties meet the specification of biodiesel standard. The effect of crude glycerol loading on the properties of polyols and PU foams were investigated. All the polyols showed satisfactory properties for the production of rigid PU foams which had performance comparable to those of some petroleum-based analogs. A mass balance and a cost analysis for the conversion of WCO and waste PET into biodiesel and PU foams were also discussed. This study demonstrated the potential of WCO and PET waste for the production of value-added products. PMID:27055365

  15. Long-term in vivo biostability of poly(dimethylsiloxane)/poly(hexamethylene oxide) mixed macrodiol-based polyurethane elastomers.

    PubMed

    Simmons, Anne; Hyvarinen, Jari; Odell, Ross A; Martin, Darren J; Gunatillake, Pathiraja A; Noble, Kathryn R; Poole-Warren, Laura A

    2004-09-01

    The long-term biostability of a novel thermoplastic polyurethane elastomer (Elast-Eon 2 80A) synthesized using poly(hexamethylene oxide) (PHMO) and poly(dimethylsiloxane) (PDMS) macrodiols has been studied using an in vivo ovine model. The material's biostability was compared with that of three commercially available control materials, Pellethane 2363-80A, Pellethane 2363-55D and Bionate 55D, after subcutaneous implantation of strained compression moulded flat sheet dumbbells in sheep for periods ranging from 3 to 24 months. Scanning electron microscopy, attenuated total reflectance-Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy were used to assess changes in the surface chemical structure and morphology of the materials. Gel permeation chromatography, differential scanning calorimetry and tensile testing were used to examine changes in bulk characteristics of the materials. The results showed that the biostability of the soft flexible PDMS-based test polyurethane was significantly better than the control material of similar softness, Pellethane 80A, and as good as or better than both of the harder commercially available negative control polyurethanes, Pellethane 55D and Bionate 55D. Changes observed in the surface of the Pellethane materials were consistent with oxidation of the aliphatic polyether soft segment and hydrolysis of the urethane bonds joining hard to soft segment with degradation in Pellethane 80A significantly more severe than that observed in Pellethane 55D. Very minor changes were seen on the surfaces of the Elast-Eon 2 80A and Bionate 55D materials. There was a general trend of molecular weight decreasing with time across all polymers and the molecular weights of all materials decreased at a similar relative rate. The polydispersity ratio, Mw/Mn, increased with time for all materials. Tensile tests indicated that UTS increased in Elast-Eon 2 80A and Bionate 55D following implantation under strained conditions

  16. Synthesis and characterization of shape memory poly (epsilon-caprolactone) polyurethane-ureas

    NASA Astrophysics Data System (ADS)

    Ren, Hongfeng

    content. The SANS results revealed phase separation of hard and soft segments into nano scale domains. The overall objectives of this dissertation were: ■ To improve the recovery stress of linear shape memory polymers. ■ To study the morphology and structure property relationships of shape memory polymers. Chapter 1 reviews the literature on SMAs and SMPs, especially on linear SMPs. Chapter 2 is devoted to SMPUUs with the aliphatic amine 1, 4-Butanediamine (BDA) as chain extender. Chapter 3 reports the effects of different aliphatic diamines as the chain extenders. Chapter 4 covers the results for shape memory polyurethane-ureas with aromatic diamine 4, 4’-Methylenedianiline (MDA) as the chain extender. The effect of different diisocyanates is covered in Chapter 5. Chapter 6-7 show some synthesized polymer systems with unimproved recovery stress or even no shape memory properties. The overall conclusions of this work are reported in Chapter 8.

  17. Reduced platelet adhesion on the surface of polyurethane bearing structure of sulfobetaine.

    PubMed

    Yuan, J; Zhang, J; Zhu, J; Shen, J; Lin, S C; Zhu, W; Fang, J L

    2003-10-01

    Poly(etherurethane)s are widely used as blood-contacting biomaterials due to their good biocompatibility and mechanical properties. Nevertheless, their blood compatibility is still not adequate for the more demanding applications. Surface modification is an effective way to improve the blood compatibility and retain the bulk properties of biomaterials. The purpose of present study was to design and synthesize a novel nonthrombogenic biomaterial by modifying the surface of poly(etherurethane) with zwitterionic monomer. Films of polyurethane were grafted with sulfobetaine by a three-step procedure. In the first step, the film surfaces were treated with hexamethylene diisocyanate (HDI) in toluene at 50 degrees C in the presence of di-n-butyl tin dilaurate (DBTDL) as a catalyst. The extent of the reaction was measured by ATR-IR spectra; a maximum number of free NCO group was obtained after a reaction time of 90 min. In the second step, the hydroxyl group of 4-dimethylamino-1-butanol (DMAB) was allowed to react in toluene with isocyanate groups bound on the surface. In the third step, sulfobetaine was formed on the surface through the ring-opening reaction between tertiary amine of DMAB and 1,3- propane-sultone (PS). It was characterized by ATR-IR, XPS. The data showed that the grafted surfaces were composed of sulfobetaine. The results of the contact angle measurements showed that they were strongly hydrophilic. The state of platelet adhesion and shape variation for the attached platelets was described. The modified surface shows excellent blood compatibility feature by the low platelet adhesion. PMID:14621338

  18. Platelet adhesive resistance of polyurethane surface grafted with zwitterions of sulfobetaine.

    PubMed

    Jiang, Yuan; Qingfeng, Hou; Baolei, Liu; Jian, Shen; Sicong, Lin

    2004-07-01

    A possible approach to improve the blood compatibility of poly(etherurethane)s (PU) involves the covalent attachment of key molecular on its surface. Recently, polymer tailed with zwitterions was found having good blood compatibility. The purpose of present study was to design and synthesis a novel nonthrombogenic biomaterial by modifying the surface of poly(etherurethane) with zwitterions of sulfobetaine via HDI spacer. The films of polyurethane were grafted with sulfobetaine by a three-step procedure. In the first step, the film surfaces were treated with hexamethylene diisocyanate (HDI) in toluene at 50 degrees C in the presence of di-n-butyl tin dilaurate(DBTDL) as a catalyst. The extent of the reaction was measured by ATR-IR spectra; a maximum number of free NCO group was obtained after a reaction time of 2.5 h. In the second step, the primary amine group of N,N-diethylethylenediamine (DEA) or N,N-dimethylethylenediamine (DMA) was allowed to react in toluene with isocyanate groups bound on surface. In the third step, two kinds of sulfobetaines were formed in the surface through the ring-opening reaction between tertiary amine of DMA or DEA and 1,3- propanesultone (PS). The reaction process was monitored with ATR-IR spectra and XPS spectra. The wettability of films was investigated by water contact angle measurement. A platelet adhesion experiment was conducted as a preliminary test to confirm the improved blood compatibility of PU. The number of platelets adhering to PU decreased greatly compared to original after 1 h and 3 h of contact with human plate-rich plasma. PMID:15261019

  19. Biocompatibility and chemical reaction kinetics of injectable, settable polyurethane/allograft bone biocomposites.

    PubMed

    Page, Jonathan M; Prieto, Edna M; Dumas, Jerald E; Zienkiewicz, Katarzyna J; Wenke, Joseph C; Brown-Baer, Pamela; Guelcher, Scott A

    2012-12-01

    Injectable and settable bone grafts offer significant advantages over pre-formed implants due to their ability to be administered using minimally invasive techniques and to conform to the shape of the defect. However, injectable biomaterials present biocompatibility challenges due to the potential toxicity and ultimate fate of reactive components that are not incorporated in the final cured product. In this study the effects of stoichiometry and triethylenediamine (TEDA) catalyst concentration on the reactivity, injectability, and biocompatibility of two component lysine-derived polyurethane (PUR) biocomposites were investigated. Rate constants were measured for the reactions of water (a blowing agent resulting in the generation of pores), polyester triol, dipropylene glycol (DPG), and allograft bone particles with the isocyanate-terminated prepolymer using an in situ attenuated total reflection Fourier transform infrared spectroscopy technique. Based on the measured rate constants, a kinetic model predicting the conversion of each component with time was developed. Despite the fact that TEDA is a well-known urethane gelling catalyst, it was found to preferentially catalyze the blowing reaction with water relative to the gelling reactions by a ratio >17:1. Thus the kinetic model predicted that the prepolymer and water proceeded to full conversion, while the conversions of polyester triol and DPG were <70% after 24h, which was consistent with leaching experiments showing that only non-cytotoxic polyester triol and DPG were released from the reactive PUR at early time points. The PUR biocomposite supported cellular infiltration and remodeling in femoral condyle defects in rabbits at 8weeks, and there was no evidence of an adverse inflammatory response induced by unreacted components from the biocomposite or degradation products from the cured polymer. Taken together, these data underscore the utility of the kinetic model in predicting the biocompatibility of reactive

  20. Investigation of non-isocyanate urethane functional latexes and carbon nanofiller/epoxy coatings

    NASA Astrophysics Data System (ADS)

    Meng, Lei

    This dissertation consists of two parts. In the first part, a new class of non-isocyanate urethane methacrylates was synthesized and the effect of the new monomers on the urethane functional latex was investigated. The second part focused on a comparison of carbon nanofillers in inorganic/organic epoxy coating system for anticorrosive applications. A new class of non-isocyanate urethane methacrylates (UMAs) monomers was synthesized through an environmentally friendly non-isocyanate pathway. The kinetics of seeded semibatch emulsion polymerization of UMAs with methyl methacrylate (MMA) and butyl acrylate (BA) was monitored. The particle size and morphology were investigated by dynamic light scattering (DLS), ultrasound acoustic attenuation spectroscopy (UAAS) and transmission electron microscopy (TEM). The minimum film formation temperature (MFFT), mechanical and viscoelastic properties were studied. It was found that the emulsion polymerization processes all proceeded via Smith-Ewart control, leading to the uniform morphology and particle size. The glass transition temperature (Tg) and the mechanical properties of poly(MMA/BA/UMA) decreased with the increasing chain length of urethane methacrylate monomers due to the increasing flexibility of side chains. Without the effect of Tg, lower MFFT and improved mechanical properties were observed from urethane functional latexes. The improved mechanical properties were due to the increasing particle interaction by forming hydrogen bonding. Furthermore, the effect of urethane functionality in terms of the polymer composition, the location and the concentration was investigated by the batch, single-stage and two-stage semibatch polymerization of 2-[(butylcarbamoyl)oxy]ethyl methacrylate (BEM) with MMA and BA. The core-shell and homogeneous structures were evaluated by TEM, differential scanning calorimetry (DSC), and solid state nuclear magnetic resonance (SS-NMR). The compositional drift was observed from the batch

  1. Biodegradation of aliphatic vs. aromatic hydrocarbons in fertilized arctic soils

    USGS Publications Warehouse

    Braddock, J.F.

    1999-01-01

    A study was carried out to test a simple bioremediation treatment strategy in the Arctic and analyze the influence of fertilization the degradation of aliphatic and aromatic hydrocarbons, e.g., pristine, n-tetradecane, n-pentadecane, 2-methylnaphthalene, naphthalene, and acenaphthalene. The site was a coarse sand pad that once supported fuel storage tanks. Diesel-range organics concentrations were 250-860 mg/kg soil at the beginning of the study. Replicate field plots treated with fertilizer yielded final concentrations of 0, 50, 100, or 200 mg N/kg soil. Soil pH and soil-water potentials decreased due to fertilizer application. The addition of fertilizer considerably increased soil respiration potentials, but not the populations of microorganisms measured. Fertilizer addition also led to ??? 50% loss of measured aliphatic and aromatic hydrocarbons in surface and subsurface soils. For fertilized plots, hydrocarbon loss was not associated with the quantity of fertilizer added. Losses of aliphatic hydrocarbons were ascribed to biotic processes, while losses of aromatic hydrocarbons were due to biotic and abiotic processes.

  2. Isolation of methylene dianiline and aqueous-soluble biodegradation products from polycarbonate-polyurethanes.

    PubMed

    Tang, Y W; Labow, R S; Santerre, J P

    2003-08-01

    Polycarbonate-polyurethanes (PCNUs) have provided the medical device industry with practical alternatives to oxidation-sensitive polyether-urethanes (PEUs). To date, many studies have focused on PCNUs synthesized with 4,4'-methylene diphenyl-diisocyanate (MDI). The relative hydrolytic stability of this class of polyurethanes is actually quite surprising given the inherent hydrolytic potential of the aliphatic carbonate group. Yet, there has been little information reporting on the rationale for the material's demonstrated hydrolytic stability. Recent work has shown that PCNU materials have a strong sensitivity towards hydrolysis when changes are made to their hard segment content and/or chemistry. However, knowledge is specifically lacking in regards of the identification of cleavage sites and the specific nature of the biodegradation products. Using high-performance liquid chromatography, radiolabel tracers and mass spectrometry, the current study provides insight into the distribution of biodegradation products from the enzyme-catalyzed hydrolysis of five different PCNUs. The hydrolytic sensitivity of the materials is shown to be related to the distribution of products, which itself is a direct consequence of unique micro-structures formed within the different materials. While an MDI-based polymer was shown to be the most hydrolytically stable material, it was the only PCNU that produced its diamine analog, in this case 4,4'-methylene dianiline (MDA), as a degradation product. Given the concern over aromatic diamine toxicity, this finding is important and highlights the fact that relative biostability is a distinct issue from that of degradation product toxicity, and that both must be considered separately when assessing the impact of biodegradation on biomaterial in vivo compatibility.

  3. Exposed polyurethane seen as fire hazard

    SciTech Connect

    Weaver, M.

    1982-11-29

    Improperly exposed polyurethane insulation is a fire hazard. Recent fire tragedies underscore the importance of installing approved thermal barriers over the foam. Vendors warn of the need to follow building codes and manufacturer's guidelines, and stress the absence of hazards if this is done. Polyurethane foam requires a high temperature to ignite but, once ignited, flashes intensely. The foam smolders at lower temperatures, however, and gives off combustible gases. The risk is higher in warehouses and other buildings where the foam is often sprayed on the walls and left uncovered and in upholstered furniture. Lawsuits resulted over claims that the material is self-extinguishing. Vendors list commercially available thermal barriers and factors customers should consider before investing in foam. (DCK)

  4. Investigation into reversion of polyurethane encapsulants

    NASA Technical Reports Server (NTRS)

    Lynch, C. R.

    1973-01-01

    The effect of high humidity (95% RH) at 60 C, 70 C, 85 C and 100 C on the solid-to-liquid reversion of polyurethane elastomers (used for potting electrical connectors and conformal coating printed circuit boards) was investigated. Hardness measurements were conducted on eleven elastomers to track reversion for a 101-day period. The primary purpose of the tests was to provide data to predict service life for the polyurethane elastomers. This was not accomplished as the hardness did not deteriorate rapidly enough at the lower test temperatures. The tests did determine that the potting and coating materials most widely used on the S-1C Program are susceptible to reversion but appear adequate for service in the S-1C environment.

  5. Phosphorus and silicon analogs of isocyanic acid: Microwave detection of HPCO and HNSiO

    NASA Astrophysics Data System (ADS)

    Thorwirth, S.; Lattanzi, V.; McCarthy, M. C.

    2015-04-01

    Phosphaketene, HPCO, and silaisocyanic acid, HNSiO, have been characterized in the gas phase for the first time, employing Fourier transform microwave spectroscopy. Besides the parent isotopic species, the rare isotopologs HP13CO, HN29SiO, and HN30SiO were also observed. The molecular parameters derived experimentally agree very well with results of new quantum-chemical calculations performed at the coupled-cluster level of theory. Other derivatives of HNCO, in which one atom is replaced with its third-row counterpart, or two atoms are replaced with their second-row counterparts, may be detectable using the same combined theoretical/experimental approach. Because both isocyanic acid, HNCO, and its sulfur variant HNCS are abundant in molecule-rich astronomical sources, HPCO and HNSiO are good candidates for future radio astronomical searches.

  6. Real-time emission factor measurements of isocyanic acid from light duty gasoline vehicles

    NASA Astrophysics Data System (ADS)

    Brady, J.; Crisp, T. A.; Collier, S.; Kuwayama, T.; Zhang, Q.; Kleeman, M.; Bertram, T. H.

    2013-12-01

    Recent work has demonstrated the potential for vehicle based anthropogenic sources of the carcinogen isocyanic acid (HNCO) in urban environments. Although emission factors for HNCO have recently been measured for light duty diesel vehicles, light duty gasoline vehicles are not well characterized. Here we will present real-time emission factor measurements of HNCO for light duty gasoline vehicles measured at the California Air Resource Board's Haagen-Smit Laboratory in September of 2011 driven on a chassis dynamometer using the California Unified Driving Cycle. Emission factors for HNCO were determined for eight light duty gasoline vehicles utilizing a fast response chemical ionization time-of-flight mass spectrometer and simultaneous real-time measurements of CO, CO2, and NOx. We will discuss the potential production mechanism for HNCO by light duty gasoline vehicles as well as the potential drive cycle dependency of HNCO production.

  7. Twilight Zone Sponges from Guam Yield Theonellin Isocyanate and Psammaplysins I and J†

    PubMed Central

    Wright, Anthony D.; Schupp, Peter J.; Schrör, Jan-Philipp; Engemann, Anna; Rohde, Sven; Kelman, Dovi; de Voogd, Nicole; Carroll, Anthony; Motti, Cherie A.

    2012-01-01

    From the organic extracts of two Guam sponges, Rhaphoxya sp., and Suberea sp., determined to have cytotoxic and chemopreventive activities, three new compounds, theonellin isocyanate (1), psammaplysins I and J (5-6), and six previously reported compounds (2-4, 7-9) were isolated and characterised spectroscopically (1H and 13C NMR, MS, IR, UV, [α]D). The two new compounds (5 and 6) isolated from the Rhaphoxya sp., sponge are rare examples of compounds containing a bromotyramine moiety rather than the more usual dibromo-analogue. For the compounds isolated from the Rhaphoxya sp., this is the first report of the known compounds 2-4 being found in a single sponge. For previously reported compounds 2-4 complete unambiguous 1H and 13C NMR data are provided. PMID:22236331

  8. Twilight zone sponges from Guam yield theonellin isocyanate and psammaplysins I and J.

    PubMed

    Wright, Anthony D; Schupp, Peter J; Schrör, Jan-Philipp; Engemann, Anna; Rohde, Sven; Kelman, Dovi; de Voogd, Nicole; Carroll, Anthony; Motti, Cherie A

    2012-03-23

    From the organic extracts of two Guam sponges, Rhaphoxya sp. and Suberea sp., determined to have cytotoxic and chemopreventive activities, three new compounds, theonellin isocyanate (1) and psammaplysins I and J (5, 6), and six previously reported compounds (2-4, 7-9) were isolated and characterized spectroscopically ((1)H and (13)C NMR, MS, IR, UV, [α](D)). The two new metabolites (5 and 6) isolated from the Suberea sp. sponge are rare examples of compounds containing a bromotyramine moiety rather than the more usual dibromo analogue. For the compounds isolated from the Rhaphoxya sp., this is the first report of the known compounds 2-4 being found in a single sponge. For previously reported compounds 2-4 complete unambiguous (1)H and (13)C NMR data are provided.

  9. THE ROTATIONAL SPECTRUM OF THE UREA\\cdot\\cdot\\cdotISOCYANIC ACID COMPLEX

    NASA Astrophysics Data System (ADS)

    Mullaney, John C.; Medcraft, Chris; Walker, Nick; Legon, Anthony; Lewis-Borrell, Luke; Golding, Bernard T.

    2016-06-01

    A dimer of urea and isocyanic acid has been generated and observed in the gas phase. The complex was generated by laser vaporisation of a rod target containing urea and copper in a 1:1 ratio, then cooled in a supersonic expansion. Six isotopologues of the complex have been characterised using a chirped pulse Fourier-transform microwave spectrometer in the frequency range 6.5-18.5 GHz. The spectra have been fitted to the Hamiltonian for an asymmetric rotor using PGOPHER. Data obtained from the 13C and 15N isotopologues confirms that all nitrogen atoms are close to the a intertial axis while the carbon atoms are not. A tentative structure will be presented.

  10. Photochemical processing of diesel fuel emissions as a large secondary source of isocyanic acid (HNCO)

    NASA Astrophysics Data System (ADS)

    Link, M. F.; Friedman, B.; Fulgham, R.; Brophy, P.; Galang, A.; Jathar, S. H.; Veres, P.; Roberts, J. M.; Farmer, D. K.

    2016-04-01

    Isocyanic acid (HNCO) is a well-known air pollutant that affects human health. Biomass burning, smoking, and combustion engines are known HNCO sources, but recent studies suggest that secondary production in the atmosphere may also occur. We directly observed photochemical production of HNCO from the oxidative aging of diesel exhaust during the Diesel Exhaust Fuel and Control experiments at Colorado State University using acetate ionization time-of-flight mass spectrometry. Emission ratios of HNCO were enhanced, after 1.5 days of simulated atmospheric aging, from 50 to 230 mg HNCO/kg fuel at idle engine operating conditions. Engines operated at higher loads resulted in less primary and secondary HNCO formation, with emission ratios increasing from 20 to 40 mg HNCO/kg fuel under 50% load engine operating conditions. These results suggest that photochemical sources of HNCO could be more significant than primary sources in urban areas.

  11. Cloud partitioning of isocyanic acid (HNCO) and evidence of secondary source of HNCO in ambient air

    NASA Astrophysics Data System (ADS)

    Zhao, R.; Lee, A. K. Y.; Wentzell, J. J. B.; Mcdonald, A. M.; Toom-Sauntry, D.; Leaitch, W. R.; Modini, R. L.; Corrigan, A. L.; Russell, L. M.; Noone, K. J.; Schroder, J. C.; Bertram, A. K.; Hawkins, L. N.; Abbatt, J. P. D.; Liggio, J.

    2014-10-01

    Although isocyanic acid (HNCO) may cause a variety of health issues via protein carbamylation and has been proposed as a key compound in smoke-related health issues, our understanding of the atmospheric sources and fate of this toxic compound is currently incomplete. To address these issues, a field study was conducted at Mount Soledad, La Jolla, CA, to investigate partitioning of HNCO to clouds and fogs using an Acetate Chemical Ionization Mass Spectrometer coupled to a ground-based counterflow virtual impactor. The first field evidence of cloud partitioning of HNCO is presented, demonstrating that HNCO is dissolved in cloudwater more efficiently than expected based on the effective Henry's law solubility. The measurements also indicate evidence for a secondary, photochemical source of HNCO in ambient air at this site.

  12. Theoretical Simulation of isocyanate (NCO) adsorption on the Ag(001) surface

    NASA Astrophysics Data System (ADS)

    Boungou, C. C.; N'dollo, M.; Malonda-Boungou, B. R.; Moussounda, P. S.; Dintzer, T.

    2016-05-01

    The adsorption of isocyanate (NCO) on a Ag (001) surface with different coverages [θ = 0.25, 0.50, 0.75 and 1.00 monolayer (ML)] is studied by using density functional theory and the periodic slab model. Adsorption energies, geometrical parameters and work function changes are calculated. We found that the most energetic sites are the bridge for 0.25 ML and the hollow for 0.50, 0.75 and 1.00 ML. The change in the work function depends on both the adsorption site and the NCO coverage. A detailed analysis of the computed local density of states shows that the NCO π and σ states strongly interact with the Ag (pz, dz2) bands.

  13. Reactive, anomalous compression in shocked polyurethane foams

    NASA Astrophysics Data System (ADS)

    Dattelbaum, Dana M.; Coe, Joshua D.; Kiyanda, Charles B.; Gustavsen, Richard L.; Patterson, Brian M.

    2014-05-01

    We present the results of plate impact experiments performed on 30%-75% porous, polymeric methylene diphenyl diisocyanate polyurethane foams. The combination of new data with those previously obtained on full-density material was used to calibrate complete equations-of-state under both inert and chemically reactive frameworks. Description of unreacted polyurethane was based on a combination of Hayes and P-α models, whereas its decomposition products were predicted via free energy minimization under the assumption of chemical and thermodynamic equilibrium. Correspondence of experiment and theory suggests that polyurethane at all densities decomposes when shocked above some threshold pressure, and that this threshold falls dramatically as a function of initial porosity. The shock locus of foams at 50% or less of theoretical maximum density was found "anomalous" in the sense that final volumes increased with pressure. We attribute this anomaly to chemical decomposition of the initial matrix to a mixture of small-molecule fluids and bulk carbon (graphite or diamond, depending on the initial density).

  14. Reactive, anomalous compression in shocked polyurethane foams

    SciTech Connect

    Dattelbaum, Dana M. Gustavsen, Richard L.; Coe, Joshua D. Kiyanda, Charles B.; Patterson, Brian M.

    2014-05-07

    We present the results of plate impact experiments performed on 30%–75% porous, polymeric methylene diphenyl diisocyanate polyurethane foams. The combination of new data with those previously obtained on full-density material was used to calibrate complete equations-of-state under both inert and chemically reactive frameworks. Description of unreacted polyurethane was based on a combination of Hayes and P-α models, whereas its decomposition products were predicted via free energy minimization under the assumption of chemical and thermodynamic equilibrium. Correspondence of experiment and theory suggests that polyurethane at all densities decomposes when shocked above some threshold pressure, and that this threshold falls dramatically as a function of initial porosity. The shock locus of foams at 50% or less of theoretical maximum density was found “anomalous” in the sense that final volumes increased with pressure. We attribute this anomaly to chemical decomposition of the initial matrix to a mixture of small-molecule fluids and bulk carbon (graphite or diamond, depending on the initial density)

  15. Thermoplastic Polyurethanes with Isosorbide Chain Extender

    SciTech Connect

    Javni, Ivan; Bilic, Olivera; Bilic, Nikola; Petrovic, Zoran; Eastwood, Eric; Zhang, Fan; Ilavsky, Jan

    2015-12-15

    Isosorbide, a renewable diol derived from starch, was used alone or in combination with butane diol (BD) as the chain extender in two series of thermoplastic polyurethanes (TPU) with 50 and 70% polytetramethylene ether glycol (PTMEG) soft segment concentration (SSC), respectively. In the synthesized TPUs, the hard segment composition was systematically varied in both series following BD/isosorbide molar ratios of 100 : 0; 75 : 25; 50 : 50; 25 : 75, and 0 : 100 to examine in detail the effect of chain extenders on properties of segmented polyurethane elastomers with different morphologies. We found that polyurethanes with 50% SSC were hard elastomers with Shore D hardness of around 50, which is consistent with assumed co-continuous morphology. Polymers with 70% SSC displayed lower Shore A hardness of 74–79 (Shore D around 25) as a result of globular hard domains dispersed in the soft matrix. Insertion of isosorbide increased rigidity, melting point and glass transition temperature of hard segments and tensile strength of elastomers with 50% SSC. These effects were weaker or non-existent in 70% SSC series due to the short hard segments and low content of isosorbide. We also found that the thermal stability was lowered by increasing isosorbide content in both series.

  16. Real-time emission factor measurements of isocyanic acid from light duty gasoline vehicles.

    PubMed

    Brady, James M; Crisp, Timia A; Collier, Sonya; Kuwayama, Toshihiro; Forestieri, Sara D; Perraud, Véronique; Zhang, Qi; Kleeman, Michael J; Cappa, Christopher D; Bertram, Timothy H

    2014-10-01

    Exposure to gas-phase isocyanic acid (HNCO) has been previously shown to be associated with the development of atherosclerosis, cataracts and rheumatoid arthritis. As such, accurate emission inventories for HNCO are critical for modeling the spatial and temporal distribution of HNCO on a regional and global scale. To date, HNCO emission rates from light duty gasoline vehicles, operated under driving conditions, have not been determined. Here, we present the first measurements of real-time emission factors of isocyanic acid from a fleet of eight light duty gasoline-powered vehicles (LDGVs) tested on a chassis dynamometer using the Unified Driving Cycle (UC) at the California Air Resources Board (CARB) Haagen-Smit test facility, all of which were equipped with three-way catalytic converters. HNCO emissions were observed from all vehicles, in contrast to the idealized laboratory measurements. We report the tested fleet averaged HNCO emission factors, which depend strongly on the phase of the drive cycle; ranging from 0.46 ± 0.13 mg kg fuel(-1) during engine start to 1.70 ± 1.77 mg kg fuel(-1) during hard acceleration after the engine and catalytic converter were warm. The tested eight-car fleet average fuel based HNCO emission factor was 0.91 ± 0.58 mg kg fuel(-1), within the range previously estimated for light duty diesel-powered vehicles (0.21-3.96 mg kg fuel(-1)). Our results suggest that HNCO emissions from LDGVs represent a significant emission source in urban areas that should be accounted for in global and regional models. PMID:25198906

  17. Real-time emission factor measurements of isocyanic acid from light duty gasoline vehicles.

    PubMed

    Brady, James M; Crisp, Timia A; Collier, Sonya; Kuwayama, Toshihiro; Forestieri, Sara D; Perraud, Véronique; Zhang, Qi; Kleeman, Michael J; Cappa, Christopher D; Bertram, Timothy H

    2014-10-01

    Exposure to gas-phase isocyanic acid (HNCO) has been previously shown to be associated with the development of atherosclerosis, cataracts and rheumatoid arthritis. As such, accurate emission inventories for HNCO are critical for modeling the spatial and temporal distribution of HNCO on a regional and global scale. To date, HNCO emission rates from light duty gasoline vehicles, operated under driving conditions, have not been determined. Here, we present the first measurements of real-time emission factors of isocyanic acid from a fleet of eight light duty gasoline-powered vehicles (LDGVs) tested on a chassis dynamometer using the Unified Driving Cycle (UC) at the California Air Resources Board (CARB) Haagen-Smit test facility, all of which were equipped with three-way catalytic converters. HNCO emissions were observed from all vehicles, in contrast to the idealized laboratory measurements. We report the tested fleet averaged HNCO emission factors, which depend strongly on the phase of the drive cycle; ranging from 0.46 ± 0.13 mg kg fuel(-1) during engine start to 1.70 ± 1.77 mg kg fuel(-1) during hard acceleration after the engine and catalytic converter were warm. The tested eight-car fleet average fuel based HNCO emission factor was 0.91 ± 0.58 mg kg fuel(-1), within the range previously estimated for light duty diesel-powered vehicles (0.21-3.96 mg kg fuel(-1)). Our results suggest that HNCO emissions from LDGVs represent a significant emission source in urban areas that should be accounted for in global and regional models.

  18. The stability and generation pattern of thermally formed isocyanic acid (ICA) in air - potential and limitations of proton transfer reaction-mass spectrometry (PTR-MS) for real-time workroom atmosphere measurements.

    PubMed

    Jankowski, Mikolaj Jan; Olsen, Raymond; Thomassen, Yngvar; Molander, Paal

    2016-07-13

    Isocyanic acid (ICA) in vapour phase has been reported to be of unstable nature, making the occupational hygienic relevance of ICA questionable. The stability of pure ICA in clean air at different humidity conditions was investigated by Fourier transform-infrared spectrometric (FT-IR) measurements. Furthermore, the stability of ICA in a complex atmosphere representative thermal degradation hot-work procedures were examined by performing parallel measurements by proton transfer reaction-mass spectrometric (PTR-MS) instrumentation and off-line denuder air sampling using di-n-butylamine (as a derivatization agent prior to liquid chromatography mass spectrometric (LC-MS) determination). The apparent half-life of ICA in pure ICA atmospheres was 16 to 4 hours at absolute humidity (AH) in the range 4.2 to 14.6 g m(-3), respectively. In a complex atmosphere at an initial AH of 9.6 g m(-3) the apparent half-life of ICA was 8 hours, as measured with the denuder method. Thus, thermally formed ICA is to be considered as a potential occupational hazard with regard to inhalation. The generation pattern of ICA formed during controlled gradient (100-540 °C) thermal decomposition of different polymers in the presence of air was examined by parallel PTR-MS and denuder air sampling. According to measurement by denuder sampling ICA was the dominant aliphatic isocyanate formed during the thermal decomposition of all polymers. The real-time measurements of the decomposed polymers revealed different ICA generation patterns, with initial appearance of thermally released ICA in the temperature range 200-260 °C. The PTR-MS ICA measurements was however affected by mass overlap from other decomposition products at m/z 44, illustrated by a [ICA]Denuder/[ICA]PTR-MS ratio ranging from 0.04 to 0.90. These findings limits the potential use of PTR-MS for real time measurements of thermally released ICA in field, suggesting parallel sampling with short-term sequential off-line methodology. PMID

  19. Molecular simulation of fibronectin adsorption onto polyurethane surfaces

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Polyethylene glycol-based polyurethanes have been widely used in biomedical applications, however are prone to swelling. A natural polyol, castor oil can be incorporated into these polyurethanes to control the degree of the swelling, which alters mechanical properties and protein adsorption characte...

  20. Cryogenic line insulation made from prefabricated polyurethane shells

    NASA Technical Reports Server (NTRS)

    Lerma, G.

    1975-01-01

    Prefabricated polyurethane foam insulation is inexpensive and easily installed on cryogenic lines. Insulation sections are semicircular half shells. Pair of half shells is placed to surround cryogenic line. Cylindrically-shaped knit sock is pulled over insulation then covered with polyurethane resin to seal system.

  1. Storage-stable foamable polyurethane is activated by heat

    NASA Technical Reports Server (NTRS)

    1966-01-01

    Polyurethane foamable mixture remains inert in storage unit activated to produce a rapid foaming reaction. The storage-stable foamable composition is spread as a paste on the surface of an expandable structure and, when heated, yields a rigid open-cell polyurethane foam that is self-bondable to the substrate.

  2. Tests Of Polyurethane And Dichromate Coats On Aluminum

    NASA Technical Reports Server (NTRS)

    Danford, M. D.

    1992-01-01

    Report describes experiments to determine relative effectiveness of new polyurethane and more-conventional dichromate coat in helping to retard corrosion of anodized 6061-T6 aluminum. Concludes by suggesting greater protection against corrosion achieved by combining polyurethane-sealing method with hard-anodizing method and by increasing thickness of coat.

  3. Chemical Grouting Lost-Circulation Zones with Polyurethane Foam

    SciTech Connect

    Mansure, A.J.; Westmoreland, J.J.

    1999-07-12

    Sandia National Laboratories is developing polyurethane foam as a chemical grout for lost circulation zones. In past work polyurethane foam was tried with limited success in laboratory tests and GDO sponsored field tests. Goals were that the foam expanded significantly and harden to a chillable firmness quickly. Since that earlier work there have been improvements in polyurethane chemistry and the causes of the failures of previous tests have been identified. Recent success in applying pure solution grouts (proper classification of polyurethane--Naudts) in boreholes encourages reevaluating its use to control lost circulation. These successes include conformance control in the oil patch (e.g. Ng) and darn remediation projects (Bruce et al.). In civil engineering, polyurethane is becoming the material of choice for sealing boreholes with large voids and high inflows, conditions associated with the worst lost circulation problems. Demonstration of a delivery mechanism is yet to be done in a geothermal borehole.

  4. Aliphatic polyesters: great degradable polymers that cannot do everything.

    PubMed

    Vert, Michel

    2005-01-01

    Nowadays the open and the patent literatures propose a large number of polymers whose main chains can be degraded usefully. Among these degradable polymers, aliphatic polyester-based polymeric structures are receiving special attention because they are all more or less sensitive to hydrolytic degradation, a feature of interest when compared with the fact that living systems function in aqueous media. Only some of these aliphatic polyesters are enzymatically degradable. A smaller number is biodegradable, and an even more limited number is biorecyclable. To be of practical interest, a degradable polymer must fulfill many requirements that depend very much on the targeted application, on the considered living system, and on living conditions. It is shown that aliphatic polyester structures made of repeating units that can generate metabolites upon degradation or biodegradation like poly(beta-hydroxy alkanoate)s and poly(alpha-hydroxy alkanoate)s are of special interest. Their main characteristics are confronted to the specifications required by various potential sectors of applications, namely, surgery, pharmacology, and the environment. It is shown that degradation, bioresorption, and biorecycling that are targets when one wants to respect living systems are also drastic limiting factors when one wants to achieve a device of practical interest. Finding a universal polymer that would be the source of all the polymeric biomaterials needed to work in contact with living organisms of the various life kingdoms and respect them remains a dream. On the other hand, finding one polymeric structure than can fulfill the requirements of one niche application remains a big issue.

  5. Decarboxylative Fluorination of Aliphatic Carboxylic Acids via Photoredox Catalysis

    PubMed Central

    Ventre, Sandrine; Petronijevic, Filip R.; MacMillan, David W. C.

    2016-01-01

    The direct conversion of aliphatic carboxylic acids to the corresponding alkyl fluorides has been achieved via visible light-promoted photoredox catalysis. This operationally simple, redox-neutral fluorination method is amenable to a wide variety of carboxylic acids. Photon-induced oxidation of carboxylates leads to the formation of carboxyl radicals, which upon rapid CO2-extrusion and F• transfer from a fluorinating reagent yield the desired fluoroalkanes with high efficiency. Experimental evidence indicates that an oxidative quenching pathway is operable in this broadly applicable fluorination protocol. PMID:25881929

  6. Aliphatic Polyethers: Classical Polymers for the 21st Century.

    PubMed

    Klein, Rebecca; Wurm, Frederik R

    2015-06-01

    Polyethers-polymers with the structural element (R'-O-R)n in their backbone--are an old class of polymers which were already used at the time of the ancient Egyptians. However, still today these materials are highly important with applications in all areas of our life, reaching from the automotive and paper industry to cosmetics and biomedical applications. In this Review, different aliphatic polyethers like poly(epoxide)s, poly(oxetane)s, and poly(tetrahydrofuran) are discussed. Special emphasis is placed on the history, the polymerization techniques (industrially and in academia), the properties, the applications as well as recent developments of these materials.

  7. In vitro interactions of biomedical polyurethanes with macrophages and bacterial cells.

    PubMed

    Visai, Livia; Rindi, Simonetta; Speziale, Pietro; Petrini, Paola; Farè, Silvia; Tanzi, M Cristina

    2002-01-01

    Three commercial medical-grade polyurethanes (PUs), a poly-ether-urethane (Pellethane), and two poly-carbonate-urethanes, the one aromatic (Bionate) and the other aliphatic (Chronoflex), were tested for macrophages and bacterial cells adhesion, in the presence or absence of adhesive plasma proteins. All the experiments were carried out on PUs films obtained by solvent casting. The wettability of these films was analysed by measuring static contact angles against water. The ability of the selected PUs to adsorb human fibronectin (Fn) and fibrinogen (Fbg) was checked by ELISA with biotin-labelled proteins. All PUs were able to adsorb Fn and Fbg (Fn > Fbg). Fn adsorption was in the order: Pellethane > Chronoflex > Bionate, the highest Fbg adsorption being detected onto Bionate (Bionate > Chronoflex > Pellethane). The human macrophagic line J111, and the two main bacterial strains responsible for infection in humans (Staphylococcus aureus Newman and Staphylococcus epidermidis 14852) were incubated in turn with the three PUs, uncoated or coated with plasma proteins. No macrophage or bacterial adhesion was observed onto uncoated PUs. PUs coated with plasma, Fn or Fbg promoted bacterial adhesion (S. aureus > S. epidermidis), whereas macrophage adhered more onto PUs coated with Fn or plasma. The coating with Fbg did not promote cell adhesion. Pellethane showed the highest macrophage activation (i.e. spreading), followed, in the order, by Bionate and Chronoflex. PMID:11939455

  8. Acid-promoted chemoselective introduction of amide functionality onto aromatic compounds mediated by an isocyanate cation generated from carbamate.

    PubMed

    Sumita, Akinari; Kurouchi, Hiroaki; Otani, Yuko; Ohwada, Tomohiko

    2014-10-01

    Carbamates have been used as precursors of isocyanates, but heating in the presence of strong acids is required because cleavage of the C-O bond in carbamates is energy-demanding even in acid media. Direct amidation of aromatic compounds by isocyanate cations generated at room temperature from carbamoyl salicylates in trifluoromethanesulfonic acid (TfOH) was examined. Carbamates with ortho-salicylate as an ether group (carbamoyl salicylates) showed dramatically accelerated O-C bond dissociation in TfOH, which resulted in facile generation of the isocyanate cation. These chemoselective intermolecular aromatic amidation reactions proceeded even at room temperature and showed good compatibility with other electrophilic functionalities and high discrimination between N-monosubstituted carbamate and N,N-disubstituted carbamate. The reaction rates of secondary and tertiary amide formation were markedly different, and this difference was utilized to achieve successive (tandem) amidation reactions of molecules with an N-monosubstituted carbamate and an N,N-disubstituted carbamate with two kinds of aromatic compounds.

  9. Nasolacrimal Polyurethane Stent: Complications with CT Correlation

    SciTech Connect

    Pinto, Isabel T.; Paul, Laura; Grande, Carlos

    1998-11-15

    Purpose: To evaluate initial results in patients with epiphora secondary to obstruction of the nasolacrimal duct treated by placement of a polyurethane stent, and to discuss the technical problems and complications arising during the procedure, with visualization of the anatomy of the drainage apparatus using computed tomography (CT). Methods: We inserted 20 polyurethane Song stents under fluoroscopic guidance after dacryocystography in 19 patients with grade 3-4 epiphora caused by idiopathic obstruction of the nasolacrimal duct. CT scans were obtained following stent placement in all patients. Results: We focus on the technical problems and complications that arose during these procedures. During negotiation of the guidewire past the obstruction at the level of the junction of the duct with the lacrimal sac, the guidewire created a false passage in a posterior suborbital direction in two cases and towards the posterior midline in another. In all cases the guidewire was withdrawn and reinserted through the proper anatomic route without further difficulty or complications. In two cases the stent was improperly positioned wholly or partially outside the nasolacrimal system (one medially, one posteriorly). In one case the stent was removed and reinserted; in the other it remains in place and functional. CT was performed in all these cases to ensure proper anatomic alignment and determine what had gone wrong. The epiphora was completely resolved in 13 cases and partially relieved in four; there were three cases of stent obstruction. Epistaxis of short duration (1 hr) occurred in seven patients and headache in one. Conclusions: Treatment of epiphora with polyurethane stents is a technique that is well tolerated by patients and achieves a high success rate, yet problems in placement may be encountered. Though no major consequences for patients are involved, cognizance of such difficulties is important to avoid incorrect positioning of stents.

  10. Polyurethane Foam Impact Experiments and Simulations

    SciTech Connect

    Chhabildas, L.C.; Kipp, M.E.; Reinhart, W.D.; Wong, M.K.

    1999-06-17

    Uniaxial strain impact experiments have been performed to obtain shock compression and release response of a 0.22 g/cm{sup 3} polyurethane foam in a configuration where the foam impacts a thin target witness plate. Wave profiles from a suite of ten experiments have been obtained, where shock amplitudes range from 40 to 500 MPa. A traditional p-{alpha} porous material model generally captures the material response. A fully three-dimensional explicit representation of the heterogeneous foam structure modeled with numerical simulations recovers some of the high frequency aspects of the particle velocity records.

  11. Mechanical Characterization of Rigid Polyurethane Foams

    SciTech Connect

    Lu, Wei-Yang

    2014-12-01

    Foam materials are used to protect sensitive components from impact loading. In order to predict and simulate the foam performance under various loading conditions, a validated foam model is needed and the mechanical properties of foams need to be characterized. Uniaxial compression and tension tests were conducted for different densities of foams under various temperatures and loading rates. Crush stress, tensile strength, and elastic modulus were obtained. A newly developed confined compression experiment provided data for investigating the foam flow direction. A biaxial tension experiment was also developed to explore the damage surface of a rigid polyurethane foam.

  12. Polarized Raman spectra and intensities of aliphatic amino acids

    NASA Astrophysics Data System (ADS)

    Himmler, Hans J.; Eysel, Hans H.

    1989-01-01

    Raman spectra of aliphatic α- L-amino acids, glycine, alanine, and valine were re-investigated both in aqueous solution and deuterium oxide solution. The spectra were taken of the zwitterionic and of the completely deprotonated form of the amino acids. Spectra of leucine and isoleucine were studied in water at the isoelectric point. Spectra were recorded both with parallel and perpendicular polarization and the isotropic and anisotropic scattering components were isolated. The integrated intensities of CH stretch, CC stretch and carboxylate bend vibrations are discussed. Linear relations between the number of CC and CH bonds and the total scattered intensity in the appropriate spectral regions are observed. The sum over the carboxylate modes shows characteristic intensities for the first three members of the aliphatic amino acids. An increase of isotropic scattering of ϱ co 2 near 510 cm -1 with increasing chain length of the amino acid (or with increasing concentration) is interpreted as the result of micelle formation.

  13. Terrestrial ecotoxicity of short aliphatic protic ionic liquids.

    PubMed

    Peric, Brezana; Martí, Esther; Sierra, Jordi; Cruañas, Robert; Iglesias, Miguel; Garau, Maria Antonia

    2011-12-01

    A study of the ecotoxicity of different short aliphatic protic ionic liquids (PILs) on terrestrial organisms was conducted. Tests performed within the present study include those assessing the effects of PILs on soil microbial functions (carbon and nitrogen mineralization) and terrestrial plants. The results show that the nominal lowest-observed-adverse-effect concentration (LOAEC) values were 5,000 mg/kg (dry soil) for the plant test in two species (Lolium perenne, Allium cepa), 1,000 mg/kg (dry soil) for the plant test in one species (Raphanus sativus), and 10,000 mg/kg (dry soil) for carbon and nitrogen microbial transformation tests (all concentrations are nominal). Most of the median effective concentration values (EC50) were above 1,000 mg/kg (dry soil). Based on the obtained results, these compounds can be described as nontoxic for soil microbiota and the analyzed plants, and potentially biodegradable in soils, as can be deduced from the respirometric experiment. The toxicity rises with the increase of complexity of the PILs molecule (branch and length of aliphatic chain) among the three PILs analyzed. PMID:21935980

  14. Oxygen plasma modification of polyurethane membranes.

    PubMed

    Ozdemir, Yesim; Hasirci, Nesrin; Serbetci, Kemal

    2002-12-01

    Polyurethane membranes were prepared under nitrogen atmosphere by using various proportions of toluene diisocyanates (TDI) and polypropylene-ethylene glycol (P) with addition of no other ingredients such as catalysts, initiator or solvent in order to achieve medical purity. Effects of composition on mechanical properties were examined. In general, modulus and UTS values demonstrated an increase and PSBR demonstrated a decrease as the TDI/Polyol ratio of the polymer increased. Elastic modulus, ultimate tensile strength (UTS) and per cent strain before rupture (PSBR) values were found to be in the range of 1.4-5.4 MPa, 0.9-1.9 MPa, and 60.4-99.7%, respectively. Surfaces of the membranes were modified by oxygen plasma applying glow-discharge technique and the effect of applied plasma power (10 W or 100 W, 15 min) on surface hydrophilicity and on the attachment of Vero cells were studied. Water contact angle values of the plasma modified surfaces varied between 67 degrees and 46 degrees, demonstrating a decrease as the applied plasma power was increased. The unmodified material had 42-45 cells attached per cm(2). It was observed that as the applied power increased the number of attached cells first increased (60-70 cells/cm(2) at 10 W) and then decreased (27-40 cells/cm(2) at 100 W). These demonstrated that surface properties of polyurethanes can be modified by plasma-glow discharge technique to achieve the optimum levels of cell attachment. PMID:15348657

  15. Thermal Performance of Aircraft Polyurethane Seat Cushions

    NASA Technical Reports Server (NTRS)

    Kourtides, D. A.; Parker, J. A.

    1982-01-01

    Aircraft seat materials were evaluated in terms of their thermal performance. The materials were evaluated using (a) thermogravimetric analysis, (b) differential scanning calorimetry, (c) a modified NBS smoke chamber to determine the rate of mass loss and (d) the NASA T-3 apparatus to determine the thermal efficiency. In this paper, the modified NBS smoke chamber will be described in detail since it provided the most conclusive results. The NBS smoke chamber was modified to measure the weight loss of material when exposed to a radiant heat source over the range of 2.5 to 7.5 W/sq cm. This chamber has been utilized to evaluate the thermal performance of various heat blocking layers utilized to protect the polyurethane cushioning foam used in aircraft seats. Various kinds of heat blocking layers were evaluated by monitoring the weight loss of miniature seat cushions when exposed to the radiant heat. The effectiveness of aluminized heat blocking systems was demonstrated when compared to conventional heat blocking layers such as neoprene. All heat blocking systems showed good fire protection capabilities when compared to the state-of-the-art, i.e., wool-nylon over polyurethane foam.

  16. A review: fabrication of porous polyurethane scaffolds.

    PubMed

    Janik, H; Marzec, M

    2015-03-01

    The aim of tissue engineering is the fabrication of three-dimensional scaffolds that can be used for the reconstruction and regeneration of damaged or deformed tissues and organs. A wide variety of techniques have been developed to create either fibrous or porous scaffolds from polymers, metals, composite materials and ceramics. However, the most promising materials are biodegradable polymers due to their comprehensive mechanical properties, ability to control the rate of degradation and similarities to natural tissue structures. Polyurethanes (PUs) are attractive candidates for scaffold fabrication, since they are biocompatible, and have excellent mechanical properties and mechanical flexibility. PU can be applied to various methods of porous scaffold fabrication, among which are solvent casting/particulate leaching, thermally induced phase separation, gas foaming, emulsion freeze-drying and melt moulding. Scaffold properties obtained by these techniques, including pore size, interconnectivity and total porosity, all depend on the thermal processing parameters, and the porogen agent and solvents used. In this review, various polyurethane systems for scaffolds are discussed, as well as methods of fabrication, including the latest developments, and their advantages and disadvantages.

  17. Antimicrobial polyurethane thermosets based on undecylenic acid: synthesis and evaluation.

    PubMed

    Lluch, Cristina; Esteve-Zarzoso, Braulio; Bordons, Albert; Lligadas, Gerard; Ronda, Juan C; Galià, Marina; Cádiz, Virginia

    2014-08-01

    In the present study, plant oil-derived surface-modifiable polyurethane thermosets are presented. Polyol synthesis is carried out taking advantage of thiol-yne photopolymerization of undecylenic acid derivatives containing methyl ester or hydroxyl moieties. The prepared methyl ester-containing polyurethanes allow surface modification treatment to enhance their hydrophilicity and impart antimicrobial activity through the following two steps: i) grafting poly(propylene glycol) monoamine (Jeffamine M-600) via aminolysis and ii) Jeffamine M-600 layer complexation with iodine. The antimicrobial activity of the iodine-containing polyurethanes is demonstrated by its capacity to inhibit the growth of Staphylococcus aureus, and Candida albicans in agar media.

  18. [Synthesis, characterization and blood compatibility studies of waterproof breathable polyurethanes].

    PubMed

    Wang, Peng; Luo, Jianbin; Du, Minhui; He, Chengsheng; Fan, Cuirong; Zhong, Yinping

    2005-08-01

    Adopting the two-step method and changing the proportion between PEG (Polyethylene glycol) and PTMG (poly (tetrahydrofuran), we used the MDI (4,4'-diphenylmethane diisocyanate) and short chain extender BDO (1,4-butanediol) as hard segment, the PTMG and PEG as soft segment, and hence prepared a series of polyether-based thermoplastic polyurethanes. FTIR showed the structure character of these polyurethanes. The determination of mechanics property and water contact angles revealed their good mechanics properties and hydrophilicity. Blood compatibility was evaluated by hemolysis test and platelet adhesion test, which revealed their good hemocompatibility. So those polyurethanes may be of wide application in the future. PMID:16156261

  19. 40 CFR 721.10605 - Polyoxyalkylene ether, polymer with aliphatic diisocyanate, homopolymer, alkanol-blocked (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Polyoxyalkylene ether, polymer with..., polymer with aliphatic diisocyanate, homopolymer, alkanol-blocked (generic). (a) Chemical substance and... polyoxyalkylene ether, polymer with aliphatic diisocyanate, homopolymer, alkanol-blocked (PMN P-11-485) is...

  20. 40 CFR 721.10605 - Polyoxyalkylene ether, polymer with aliphatic diisocyanate, homopolymer, alkanol-blocked (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Polyoxyalkylene ether, polymer with..., polymer with aliphatic diisocyanate, homopolymer, alkanol-blocked (generic). (a) Chemical substance and... polyoxyalkylene ether, polymer with aliphatic diisocyanate, homopolymer, alkanol-blocked (PMN P-11-485) is...

  1. 40 CFR 721.7250 - Polyaziridinyl ester of an aliphatic alcohol (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... alcohol (generic). 721.7250 Section 721.7250 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.7250 Polyaziridinyl ester of an aliphatic alcohol (generic). (a... generically as a polyaziridinyl ester of an aliphatic alcohol (PMN P-01-97) is subject to reporting under...

  2. 40 CFR 721.7250 - Polyaziridinyl ester of an aliphatic alcohol (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... alcohol (generic). 721.7250 Section 721.7250 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.7250 Polyaziridinyl ester of an aliphatic alcohol (generic). (a... generically as a polyaziridinyl ester of an aliphatic alcohol (PMN P-01-97) is subject to reporting under...

  3. 40 CFR 721.7250 - Polyaziridinyl ester of an aliphatic alcohol (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... alcohol (generic). 721.7250 Section 721.7250 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.7250 Polyaziridinyl ester of an aliphatic alcohol (generic). (a... generically as a polyaziridinyl ester of an aliphatic alcohol (PMN P-01-97) is subject to reporting under...

  4. 40 CFR 721.7250 - Polyaziridinyl ester of an aliphatic alcohol (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... alcohol (generic). 721.7250 Section 721.7250 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.7250 Polyaziridinyl ester of an aliphatic alcohol (generic). (a... generically as a polyaziridinyl ester of an aliphatic alcohol (PMN P-01-97) is subject to reporting under...

  5. 40 CFR 721.9952 - Alkoxylated aliphatic diisocyanate allyl ether (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... allyl ether (generic). 721.9952 Section 721.9952 Protection of Environment ENVIRONMENTAL PROTECTION... New Uses for Specific Chemical Substances § 721.9952 Alkoxylated aliphatic diisocyanate allyl ether... identified generically as alkoxylated aliphatic diisocyanate allyl ether (PMN P-00-0353) is subject...

  6. 40 CFR 721.9952 - Alkoxylated aliphatic diisocyanate allyl ether (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... allyl ether (generic). 721.9952 Section 721.9952 Protection of Environment ENVIRONMENTAL PROTECTION... New Uses for Specific Chemical Substances § 721.9952 Alkoxylated aliphatic diisocyanate allyl ether... identified generically as alkoxylated aliphatic diisocyanate allyl ether (PMN P-00-0353) is subject...

  7. Preferences in removal of aliphatic and aromatic gasoline components by biofiltration under varied loading.

    PubMed

    Halecky, Martin; Paca, Jan; Kozliak, Evguenii I

    2012-01-01

    Removal of gasoline vapors from waste air was investigated in a bench-scale perlite biofilter for three aromatic-to-aliphatic mass ratios (62/38, 92/8 and 44/56) under different loads, varied by changing both the substrate inlet concentration and air flow rate. The measurement of concentration profiles along the bed height allowed for an assessment of interactions between the aromatic and aliphatic fractions of gasoline. Variations in both the inlet concentrations and empty bed residence time significantly influenced the removal of aliphatic gasoline components. Except for the lowest organic loads, the whole biofilter bed was required for achieving an acceptable removal efficiency of aliphatic hydrocarbons. The presence of large amounts of aromatics negatively impacted the removal of aliphatics. By contrast, the aromatic gasoline components were near-completely removed from any mixtures; the bulk of them were degraded in the first (out of three) biofilter section, even at high concentrations of aliphatic hydrocarbons. The observed effect was shown to be due to competitive interactions of aliphatic and aromatic components, which is consistent with the biological steps being rate limiting. Mass transfer, particularly for aliphatic components due to their high Henry's law constants, was shown to be rate-limiting under extreme scenarios, such as low loading rates and EBRT.

  8. 40 CFR 721.2098 - Aliphatic polycarboxylic acid metal salt (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... salt (generic). 721.2098 Section 721.2098 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.2098 Aliphatic polycarboxylic acid metal salt (generic). (a) Chemical... as an aliphatic polycarboxylic acid metal salt (PMN P-01-7) is subject to reporting under...

  9. 40 CFR 721.2098 - Aliphatic polycarboxylic acid metal salt (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... salt (generic). 721.2098 Section 721.2098 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.2098 Aliphatic polycarboxylic acid metal salt (generic). (a) Chemical... as an aliphatic polycarboxylic acid metal salt (PMN P-01-7) is subject to reporting under...

  10. 40 CFR 721.2098 - Aliphatic polycarboxylic acid metal salt (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... salt (generic). 721.2098 Section 721.2098 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.2098 Aliphatic polycarboxylic acid metal salt (generic). (a) Chemical... as an aliphatic polycarboxylic acid metal salt (PMN P-01-7) is subject to reporting under...

  11. 40 CFR 721.2098 - Aliphatic polycarboxylic acid metal salt (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... salt (generic). 721.2098 Section 721.2098 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.2098 Aliphatic polycarboxylic acid metal salt (generic). (a) Chemical... as an aliphatic polycarboxylic acid metal salt (PMN P-01-7) is subject to reporting under...

  12. 40 CFR 721.2098 - Aliphatic polycarboxylic acid metal salt (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... salt (generic). 721.2098 Section 721.2098 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.2098 Aliphatic polycarboxylic acid metal salt (generic). (a) Chemical... as an aliphatic polycarboxylic acid metal salt (PMN P-01-7) is subject to reporting under...

  13. Laboratory study of isocyanic acid ions: Rotational spectroscopy of NCO-, H2NCO+, and HNCOH+

    NASA Astrophysics Data System (ADS)

    Lattanzi, Valerio; Gottlieb, Carl A.; Thaddeus, Patrick; Thorwirth, Sven; McCarthy, Michael C.

    2015-01-01

    We report detection of protonated isocyanic acid in two isomeric forms, H2NCO+ and HNCOH+, by high-resolution spectroscopy. The two ions were first observed at centimeter wavelengths by Fourier Transform (FT) microwave spectroscopy, in a discharge through HNCO heavily diluted in hydrogen in the throat of a supersonic nozzle. Spectroscopic constants derived from the two lowest rotational transitions of both isomers agree very well with those derived from theoretical structures computed at the coupled cluster level of theory. In the same molecular beam, the fundamental rotational transition of NCO- was observed with well-resolved nitrogen quadrupole hyperfine structure. Detection of NCO- and H2NCO+ in our beam was subsequently confirmed by observation of several millimeter-wave transitions in a low pressure discharge through cyanogen and water. The spectroscopic constants of NCO- obtained earlier by infrared laser spectroscopy are in good agreement with the highly accurate constants derived here. Owing to the high abundance of HNCO in many galactic molecular sources, both ions are excellent candidates for astronomical detection in the radio band.

  14. Time-programmed release of fluoroscein isocyanate dextran from micro-pattern-designed polymer scrolls.

    PubMed

    Egunov, Aleksandr I; Inaba, Ayano; Gree, Simon; Malval, Jean-Pierre; Tamura, Katsuhiro; Saito, Yukie; Luchnikov, Valeriy A

    2016-07-10

    In this article we present a relevant strategy for a non-trivial time-programmed release of water-soluble macromolecules from biocompatible μ-containers. The system is based on self-scrolled chitosan acetate (CA) fibers, encapsulated in a poly(dimethylsiloxane) matrix. Mass transfer between a fiber and the external environment takes place via the only opened extremity of the fiber. Fluoroscein isocyanate dextran (FID) is initially deposited at the inner surface of the CA fiber according to a programmed pattern. The FID molecules became mobile after the arriving of the swelling front, which propagates along the fiber's axis upon the immersion of the system in aqueous solution. Diffusion of the macromolecules into the environment is enabled by the open-tube geometry of the swollen part of the fiber, while a programmed kinetics of the drug release is due to patterning of the polymer film prior to rolling. The release of the macromolecules can be retarded by a few hours according to the placement of the FID spot with respect to the fibers orifice. A pulsatile release kinetics is demonstrated for a discrete pattern. A few millimeter spacing of the FID spots results in a few hours time interval between the release impulses. Random walk model is plugged in the effective diffusion coefficient for Fick's law and the release kinetics are simulated. PMID:27179634

  15. Hydrogen versus fluorine: effects on molecular structure and intermolecular interactions in a platinum isocyanate complex.

    PubMed

    Raven, William; Joschko, Thomas; Kalf, Irmgard; Englert, Ulli

    2016-03-01

    At the molecular level, the enantiomerically pure square-planar organoplatinum complex (SP-4-4)-(R)-[2-(1-aminoethyl)-5-fluorophenyl-κ(2)C(1),N][(R)-1-(4-fluorophenyl)ethylamine-κN](isocyanato-κN)platinum(II), [Pt(C8H9FN)(NCO)(C8H10FN)], and its congener without fluorine substituents on the aryl rings adopt the same structure within error. The similarities between the compounds extend to the most relevant intermolecular interactions, i.e. N-H...O and N-H...N hydrogen bonds link neighbouring molecules into chains along the shortest lattice parameter in each structure. Differences between the crystal structures of the fluoro-substituted and parent complex become obvious with respect to secondary interactions perpendicular to the classical hydrogen bonds; the fluorinated compound features short C-H...F contacts with an F...H distance of ca 2.6 Å. The fluorine substitution is also reflected in reduced backbonding from the metal cation to the isocyanate ligand. PMID:26942427

  16. Isocyanate Exposure Assessment Combining Industrial Hygiene Methods with Biomonitoring for End Users of Orthopedic Casting Products

    PubMed Central

    Pearson, Ronald L.; Logan, Perry W.; Kore, Anita M.; Strom, Constance M.; Brosseau, Lisa M.; Kingston, Richard L.

    2013-01-01

    Previous studies have suggested a potential risk to healthcare workers applying isocyanate-containing casts, but the authors reached their conclusions based on immunological or clinical pulmonology test results alone. We designed a study to assess potential exposure to methylene diphenyl diisocyanate (MDI) among medical personnel applying orthopedic casts using two different application methods. Air, dermal, surface, and glove permeation sampling methods were combined with urinary biomonitoring to assess the overall risk of occupational asthma to workers handling these materials. No MDI was detected in any of the personal and area air samples obtained. No glove permeation of MDI was detected. A small proportion of surface (3/45) and dermal wipe (1/60) samples were positive for MDI, but were all from inexperienced technicians. Urinary metabolites of MDI [methylenedianiline (MDA)] were detected in three of six study participants prior to both a ‘dry’ and ‘wet’ application method, five of six after the dry method, and three of six after the wet method. All MDA results were below levels noted in worker or general populations. Our conclusion is that the risk of MDI exposure is small, but unquantifiable. Because there is some potential risk of dermal exposure, medical personnel are instructed to wear a minimum of 5-mil-thick (5 mil = 0.005 inches) nitrile gloves and avoid contact to unprotected skin. This could include gauntlets, long sleeves, and/or a laboratory coat. PMID:23680587

  17. Organic-rich hybrid O/I systems based on isocyanate chemistry

    SciTech Connect

    Cuney, S. |; Gerard, J.F.; Pascault, J.P.Vigier, G.

    1996-12-31

    The isocyanate chemistry has been used to prepare, without adding any solvent, organic-rich hybrid O/I systems, {alpha}-{omega} hydroxy-terminated prepolymers (soft segments, denoted SS) can be end-capped with {gamma}-isocyanato propyl triethoxy silane ({gamma}-IPS), or previously reacted with a diisocyanate (DI) and then end-capped with {gamma}-amino propyl triethoxy silane ({gamma}-APS), or with {gamma}-amino propyl methyl diethoxy silane ({gamma}-APMDES). With this second pathway, a double distribution of molecules is present. The aim of this work is to investigate the morphologies and structural properties of different organic-rich hybrid organic/inorganic materials. Two types of {alpha}-{Omega} hydroxy prepolymers have been used: hydrogenated polybutadiene, HPBD, and polycaprolactone, PCL. The inorganic phase is obtained through the hydrolysis and condensation of the silane groups under acidic conditions and with [H{sub 2}O]/Si = 3. The nanometric silica-rich particles in the final morphologies, after a post-cure at 150 C, were also studied by means of SAXS measurements. Viscoelastic measurements show one or two main relaxation peaks depending on the phase separation process during reaction and the polarity of the initial SS. However for full crosslinked SS/{gamma}-IPS hybrid networks, the relaxed modulus does not depend on SS nature and it is well described by the affine network theory.

  18. Isocyanate-functionalized chitin and chitosan as gelling agents of castor oil.

    PubMed

    Gallego, Rocío; Arteaga, Jesús F; Valencia, Concepción; Franco, José M

    2013-06-03

    The main objective of this work was the incorporation of reactive isocyanate groups into chitin and chitosan in order to effectively use the products as reactive thickening agents in castor oil. The resulting gel-like dispersions could be potentially used as biodegradable lubricating greases. Three different NCO-functionalized polymers were obtained: two of them by promoting the reaction of chitosan with 1,6-hexamethylene diisocyanate (HMDI), and the other by using chitin instead of chitosan. These polymers were characterized through 1H-NMR, FTIR and thermogravimetric analysis (TGA). Thermal and rheological behaviours of the oleogels prepared by dispersing these polymers in castor oil were studied by means of TGA and small-amplitude oscillatory shear (SAOS) measurements. The evolution and values of the linear viscoelasticity functions with frequency for -NCO-functionalized chitosan- and chitin-based oleogels are quite similar to those found for standard lubricating greases. In relation to long-term stability of these oleogels, no phase separation was observed and the values of viscoelastic functions increase significantly during the first seven days of ageing, and then remain almost constant. TGA analysis showed that the degradation temperature of the resulting oleogels is higher than that found for traditional lubricating greases.

  19. Hydrogen versus fluorine: effects on molecular structure and intermolecular interactions in a platinum isocyanate complex.

    PubMed

    Raven, William; Joschko, Thomas; Kalf, Irmgard; Englert, Ulli

    2016-03-01

    At the molecular level, the enantiomerically pure square-planar organoplatinum complex (SP-4-4)-(R)-[2-(1-aminoethyl)-5-fluorophenyl-κ(2)C(1),N][(R)-1-(4-fluorophenyl)ethylamine-κN](isocyanato-κN)platinum(II), [Pt(C8H9FN)(NCO)(C8H10FN)], and its congener without fluorine substituents on the aryl rings adopt the same structure within error. The similarities between the compounds extend to the most relevant intermolecular interactions, i.e. N-H...O and N-H...N hydrogen bonds link neighbouring molecules into chains along the shortest lattice parameter in each structure. Differences between the crystal structures of the fluoro-substituted and parent complex become obvious with respect to secondary interactions perpendicular to the classical hydrogen bonds; the fluorinated compound features short C-H...F contacts with an F...H distance of ca 2.6 Å. The fluorine substitution is also reflected in reduced backbonding from the metal cation to the isocyanate ligand.

  20. Determination of methyl isocyanate in outdoor residential air near metam-sodium soil fumigations.

    PubMed

    Woodrow, James E; LePage, Jane T; Miller, Glenn C; Hebert, Vincent R

    2014-09-10

    The soil fumigant metam-sodium (CH3NHCS2Na) produces the bioactive respiratory irritant methyl isothiocyanate (MITC). Recent laboratory gas-phase oxidative studies indicate that MITC rapidly transforms to the more toxic methyl isocyanate (MIC) in the lower atmosphere. Inhalation exposure risks from MITC plus MIC may therefore be an occupational worker and/or bystander health concern. To address this concern, MIC was monitored, along with MITC, in outdoor residential air in Washington state during the peak fall metam fumigation season. XAD-7 cartridges, coated with 1-(2-pyridyl)piperazine, were developed to retain MIC as its stable substituted urea derivative. Of the 68 residential air measurements of MIC, 15 (22%) were observed to be above the California Environmental Protection Agency's chronic inhalation reference level of 1 μg/m(3), with an observed maximum MIC air concentration of 4.4 μg/m(3). This study indicates MIC air concentrations can be anticipated along with MITC in residential air where seasonal metam soil fumigant applications occur.