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Click questions below to view answers:

What is an Isocyanate?

Answer: An isocyanate is any chemical that contains at least one isocyanate group in its structure. An isocyanate group is a group of atoms containing one nitrogen atom attached by a double bond to one carbon atom which, in turn, is attached by a second double bond to an oxygen atom (-N=C=O). A chemical containing two such groups is called a diisocyanate.

Common examples are toluene diisocyanate (TDI), hexamethylene diisocyanate (HDI) and diphenylmethane diisocyanate (MDI). These also are often called monomers because they can be made to react with one another and various other chemicals to form large chain-like chemicals called polymers. Prepolymers, such as Mondur® PF, are intermediate in size between the small diisocyanate monomers and the very large polymers. These also are often called polyisocyanates.

Is methylene isocyanate, which was involved in the Bhopal, India disaster, used in polyurethane products?

Answer: No. Due to its high volatility and extreme toxicity, methyl isocyanate (MIC) could not be used in polyurethane products. It is used as an intermediate in pesticides manufacturing. When nitrogen-rich materials, such as isocyanates, are decomposed under high heat conditions, however, recent test results have reported that methyl isocyanate may be generated.

How do various isocyanate products compare with regard to speed of evaporation (also called volatility)?

Answer: Among isocyantes, HDI and TDI evaporate faster than the other isocyanates listed below. Products which would be classified as very slow to evaporate are MDI (Mondur® M); polymeric MDI (Mondur® MR and Mondur® MRS); MDI prepolymers such as Mondur® PF; Desmodur® W diisocyanate; HDI polyisocyanates such as the Desmodur® N products; and the TDI polyisocyanates such as the Desmodur® CB products. In fact, the HDI- and TDI-based polyisocyanates used in coatings originally were developed to reduce the evaporation rate and thus to decrease the inhalation hazard during handling and use.

To illustrate the great difference in speed of evaporation, one can compare the room temperature vapor pressures of various materials. On a relative scale, if MDI is assigned a value of 1, the ease of evaporation (vapor pressure) numbers would be:

* Desmodur® N Polyisocyanate Isocyanurate trimer - 0.00052
* Biuret - 0.93
* Mondur® M (MDI) - 1
* Mondur® MR (polymeric MDI) - 1
* Desmodur® W diisocyanate - 1
* Desmodur® I (IPDI) - 48
* Desmodur® H (HDI) - 1,100
* Mondur® TD-80 (TDI) - 2,500
* Water - 1,800,000
* Solvent (methyl ethyl ketone) - 9,100,000
* Methyl isocyanate - 34,800,000

Is there cyanide in isocyanates or is cyanide given off during the normal use of isocyanate products?

Answer: Although the two chemical names are similar, no cyanide is used to make or is present in isocyanate products from Bayer. In addition, no cyanide will be released during the normal use of isocyanate products. However, hydrogen cyanide can be produced from isocyanates by heating to decomposition and/or burning. In fact, burning any nitrogen-containing material, even those which were not made from isocyanates, can produce some hydrogen cyanide. Even natural nitrogen-rich materials, such as wood and leather, can produce hydrogen cyanide when burned.

Are isocyanates dangerous when they are carried about in open containers at room temperature or during room-temperature pouring or mixing operations?

Answer: If the materials involved are the more volatile free monomer TDI (Mondur® TD, Mondur® TD-80 or Mondur® TDS) or free monomer HDI (Desmodur® H), open transfer of these materials at room temperature can result in airborne concentrations above the TLV or PEL. Therefore, care must be taken to prevent inhalation overexposure.

Further, care must be taken to prevent splashing onto the skin or into the eyes when any such open processing or use operation is taking place. From the standpoint of inhalation potential, the types of operations described in this question have a lower degree of hazard when the isocyanates involved are those which evaporate slowly, like MDI, MDI-based polyisocyanates, Desmodur® W, or the low free monomer polyisocyanates such as Desmodur® N and Desmodur® CB. Air sampling during many such operations has shown a low probability of airborne isocyanate concentrations exceeding the applicable TLV, PEL or Bayer guideline.

Is it true as a general rule that aliphatic diisocyanates are safer to work with than aromatic diisocyanates?

Answer: No. Comparisons of relative toxicity and hazard among chemical groups are very complex. The answers depend on comparisons in innate toxicity (ability to harm under a given set of test conditions), risk (probability of injury in a particular type of use situation), what end point is involved (e.g., irritation, sensitization, oral toxicity, etc.) and physical properties (e.g., speed of evaporation). When all of these factors and others come into play, it cannot be stated generally that aliphatic isocyanates are safer to work with than aromatic isocyanates.

How can isocyanate overexposure be controlled?

Answer: Good engineering controls such as local exhaust ventilation and enclosure of the operation where possible are the primary methods of control. In some cases, however, additional precautions such as the wearing of personal protective equipment (PPE) may be necessary.

Clothing and gloves (nitrile, neoprene or butyl rubber gloves are recommended, preferably of an intermediate thickness, e.g., > 10 mils) as well as respiratory protection often are needed in addition to engineering controls. This is especially so in inadequately ventilated environments where isocyanate-containing products are heated, sprayed, or otherwise aerosolized. In such cases, respiratory protection must be worn. The type of respiratory protection selected must comply with local regulations.

Because respirator guidelines can differ somewhat depending on the product involved, the reader is referred to the specific product?s material safety data sheet for further guidance.

Are air-purifying respirators ever appropriate in isocyanate work areas?

Answer: Yes. Where airborne isocyanate concentrations do not exceed 10 times the appropriate guideline or standard, an air-purifying respirator (APR) with organic vapor cartridges and particulate prefilter (P100) can give good protection. Of course, care must be taken to provide adequate eye protection, to ensure a good fit, and to employ a cartridge change-out schedule or use a cartridge with an end-of-service-life-indicator (ESLI).

Do isocyanates present a fire risk?

Answer: Unlike monoisocyanates, diisocyanates such as TDI, MDI, HDI, etc. and their prepolymers, have a relatively high flash point and are not normally considered flammable. However, they may burn if heated sufficiently. Some organizations list these diisocyanates as combustible materials that will burn in the presence of an existing fire or heat source and with adequate oxygen.

Any diisocyanate involved in a fire will evolve fumes in highly toxic concentrations (carbon monoxide, oxides of nitrogen, isocyanates and to some extent, hydrogen cyanide). Full ?emergency? equipment should be worn by all personnel dealing with such incidents; the use of self-contained breathing apparatus is essential.

Drums of diisocyanates involved in a fire, but not themselves on fire, should be sprayed with water to minimize the risk of a rupture. Suitable extinguishing agents include dry chemical powder, carbon dioxide, water and foam.

After the fire has been extinguished, the area should not be considered safe until a thorough inspection for residual diisocyanates has been carried out by qualified and properly protected personnel. Any suspect residues should be rendered harmless with liquid decontaminant. In all cases, refer to the MSDS for the specific isocyanate product involved.

What are the major human health effects of overexposure to isocyanate products?

Answer: Overexposure to isocyanate products can cause skin, eye, nose, throat and lung irritation. It also can lead to skin or respiratory sensitization. A third effect for which there is some evidence is a chronic (long-term) loss of lung function. For a more complete list of health effects and symptoms, material safety data sheets for the specific isocyanate products to be used should be consulted.

What is sensitization?

Answer: Sensitization is the body’s hyperreactive (allergy-like) response to a substance which has been touched or inhaled by a susceptible individual. Sensitization may develop as a result of a large single overexposure, for example, from a spill or accident, or from repeated overexposure at lower levels. A sensitized individual may then respond with skin reactions or asthma-like symptoms upon subsequent exposure to the same or even lower levels. For example: respiratory sensitization can result in a strong asthmatic response to future airborne exposures, even at levels well below the TLV.

Symptoms may include coughing, wheezing, tightness in the chest and shortness of breath. The skin sensitization reaction may include rash, itching, hives and swelling.

If people become sensitized, can they lose their isocyanate sensitivity after being removed from further exposure?

Answer: Sensitization can be either permanent or non-permanent. There have been documented cases in which individuals have lost their sensitivity to isocyanates based on direct challenge testing at levels below allowable limits. However, since such individuals may have an increased susceptibility to isocyanate sensitization, they should have no future contact with isocyanates.

Can sensitization be caused by skin contact or only by inhalation?

Answer: On rare occasions, skin contact with diisocyanates can lead to skin sensitization in some individuals and inhalation exposure can lead to respiratory sensitization in some individuals. In addition, there is some evidence from animal testing with diisocyanates that skin exposure can result in respiratory sensitization.

Is there any way to prescreen individuals to determine if they are likely to become sensitized to isocyanates?

Answer: There is no simple test which can be done to identify people most susceptible to sensitization. Applicants assigned to an isocyanate work area should undergo a preplacement physical evaluation. Special attention should be directed to diseases of the respiratory system or abnormal pulmonary function.

Each applicant should complete a medical, occupational and respiratory disease questionnaire. History of adult asthma, respiratory allergies such as severe hay fever, eczema, history of prior isocyanate sensitization, or lack of smell (anosmia) are possible reasons for medical exclusion from isocyanate areas.

In addition to the questionnaires, applicants should have a physical examination, including a thorough skin inspection, examination of the heart and lungs, and a baseline pulmonary function test.

While using or handling the diisocyanate product, emphasis should be placed on keeping all workers’ exposure consistently below the TLV, PEL or manufacturers’ guidelines. Workers also should be medically evaluated on an annual basis, with the frequency of pulmonary function testing dependent upon the workers’ potential for isocyanate exposure.

If a sensitized person (respiratory sensitization) is exposed to isocyanates, will the reaction be immediate or delayed?

Answer: Some will react with immediate asthma-like symptoms (e.g., coughing, wheezing, chest tightness, shortness of breath), some will not react until several hours after the exposure, and a third group will have both the immediate and the delayed reactions.

Can overexposure to isocyanates cause asthma?

Answer: Yes. Overexposure to isocyanates can cause sensitization which, in turn, can produce asthma. People who have been exposed to a single large concentration, or repeatedly exposed even at lower levels (above the TLV, PEL or manufacturers’ guidelines), may develop isocyanate sensitization. This, in turn, may cause them to react to future exposures at very low levels, even below the levels that might be considered safe for others.

In addition, there are reports that sensitized persons can develop a reactive airways condition which causes them to have asthma-like reactions from exposures to agents other than isocyanates. According to some reports, this condition may persist for several weeks, months or years after removal from futher isocyanate exposure. There is some evidence that the sooner a sensitization condition is identified and the person is removed from work with isocyanate products, the less likely that individual will be to experience the long-term reactive airways condition.

Can diisocyanates cause sterility, birth defects or reproductive problems?

Answer: Bayer is not aware of any scientific animal or human evidence that diisocyanates cause sterility, birth defects or reproductive problems. Studies using rats exposed to TDI, MDI or HDI by inhalation did not show any evidence of birth defects (teratology). Rats exposed, via inhalation, in a two-generation reproductive study for TDI and in a one-generation study for HDI did not show any affects on mating, gestation, or lactation.

Do isocyanates cause cancer?

Answer: [NOTE: UPDATE THIS FOR MDI IARC CLASSIFICATION!]
There is no evidence that diisocyanates cause cancer in humans. In animal tests, regulatory testing guidelines frequently result in the exposure of animals to concentrations many fold greater than those encountered in the workplace. Under such test conditions, nearly lifetime exposure of rats to HDI vapor did not cause cancer. In other similar studies of nearly lifetime exposure of rats to MDI aerosol, a small number of lung tumors were found.

Evidence suggests that this increased incidence of tumors in the lungs is consistent with the prolonged irritation and accumulation of material resulting from the use of aerosolized MDI. In the absence of prolonged exposure to high aerosol concentrations of MDI leading to lung tissue irritation and damage, it is unlikely that tumor formation could occur.

For TDI, two types of cancer tests were conducted. The first study applied TDI liquid directly into the stomach of rats via a tube and tumors were found. Because the oral route is not the most relevant for human beings, another nearly lifetime study was conducted in rats using inhalation exposure to TDI vapor. This second study did not result in cancer. Other specialized studies to search for an explanation of the contradictory results of the two TDI cancer studies suggest that TDI given orally is converted, partly, to a known animal carcinogen.

Thus, from a regulatory perspective, HDI and MDI are not classified as carcinogens. TDI, based on the oral exposure study, is classified as an IARC Group 2B carcinogen (i.e., possibly carcinogenic to humans based on animal studies).

What should be done if an isocyanate comes in contact with a person's eyes?

Answer: Flush with large amounts of luke-warm water for at least 15 minutes, holding eyelids open all the time. Refer the affected individual to an ophthalmologist or other physician for immediate follow-up.

What should be done if an isocyanate contacts a person's skin?

Answer: Specific first aid information is available in the Material Safety Data Sheet (MSDS) for each Bayer MaterialScience isocyanate product. In general, the person should remove contaminated clothing immediately and wash the affected areas thoroughly with soap and water for at least 15 minutes.* Wash contaminated clothing thoroughly before reuse.

For severe exposures, the affected person should get under a safety shower, using the flushing action of the water to remove the bulk of the chemical, then remove contaminated clothing and wash skin with soap and water. Seek medical attention.

For lesser exposures, the individual should seek, medical attention if irritation develops or persists after the area is washed.

* Though soap and water will remove isocyanates from the skin, some studies have suggested that polypropylene glycol, a polyglycol-based cleanser, and corn oil may be more effective. While this may be true, there is concern as to the potential for these chemicals to also alter skin permeability, which could increase the rate of diisocyanate absorption; therefore, use of these chemicals should be limited.

What should be done in case of inhalation overexposure to an isocyanate?

Answer: The person should move to an area free from risk of further exposure. Oxygen or artificial respiration should be administered as needed, and medical attention should be obtained. Asthmatic-type symptoms may develop and may be immediate, or delayed up to several hours. Treatment is essentially symptomatic, and a physician should be consulted.

In the event of an acute asthma attack, seek immediate medical attention.

What should be done if a person ingests (swallows) an isocyanate material?

Answer: Vomiting should NOT be induced. Wash the mouth out with water, but, NOTHING SHOULD BE GIVEN BY MOUTH TO AN UNCONSCIOUS OR CONVULSING PERSON. A physician should be consulted.

What is a Threshold Limit Value (TLV)?

Answer: TLV stands for Threshold Limit Value. These values are used in some areas of the world to refer to airborne concentrations of substances, representing conditions under which it is believed that nearly all workers may be repeatedly exposed day after day without adverse effect.

TLVs are based on the best available information, but they should not be regarded as fine lines between safe and dangerous concentrations. They are not a relative index of toxicity.

Some individuals may be unusually susceptible and react to chemical concentrations lower than the TLV. For example, an individual may become "sensitized" to certain chemicals such as amines, epoxy resins or isocyanates and then react to concentrations below the TLV. Therefore, a TLV may not protect a sensitized individual.

These guidelines are recommended by the American Conference of Governmental Industrial Hygienists (ACGIH) and are followed in the USA and some other countries. For a more complete description, please read the current issue of Threshold Limit Values and Biological Indices published by the ACGIH (www.acgih.org).

What is a Permissible Exposure Limit (PEL)?

Answer: PEL stands for Permissible Exposure Limit and refers to airborne concentration standards established by the U.S. Occupational Safety and Health Administration (OSHA). These can be found in Title 29 of the Code of Federal Regulations (CFR), Section 1910.1000, or in one of the chemical-specific OSHA regulations. PELs are legally binding in the U.S.

Because many PELs are based on the ACGIH TLV, they are subject to many of the same limitations discussed in the previous question, "What is a TLV?" For example, compliance with a PEL may not protect a sensitized worker.

What is a Manufacturer's Exposure Guideline?

Answer: Some chemicals used in the workplace do not have a published TLV or PEL. For some of these, the manufacturer has suggested an airborne concentration guideline for worker exposure.

What is the best source of information concerning TLVs, PELs, or manufacturers' guidelines for Bayer's isocyanate products?

Answer: The current issue of the Bayer material safety data sheet (MSDS) available at www.baycareonline.com.

What gases can be generated when cutting or welding steel that is in contact with polyurethane foam, or has a polyurethane coating?

Answer: Gases or vapors evolved can include TDI, MDI, etc. (if they were used to make the polyurethane material) in addition to carbon monoxide, carbon dioxide, hydrogen cyanide, oxides of nitrogen and hydrocarbons. When welding or cutting steel in contact with polyurethane foam or coated with a polyurethane system, the worker may be exposed to decomposition products (metal fumes, gases or vapors, particulate) which vary depending on the type of process being used to weld or cut, the nature of the base metal and the type of polyurethane system. One or more of the following control procedures should be used for welding or cutting steel coated, or in contact with, a polyurethane system:

1. Use a power brush or grinding wheel to strip the polyurethane foam or coating from the steel in the vicinity where the cut or weld is to be made. A well-fitted dust resepirator with N95 or better filters, and eye protection, should be used while stripping the coating.

2. Use a local exhaust hood to remove fumes during the welding or cutting operation.

3. Use a fresh air supplied respirator during welding or cutting.

If I handle or use isocyanates, how would I know if I am being overexposed?

Answer: If you have isocyanate-caused eye irritation or respiratory irritation, you are being exposed to a concentration greater than the allowable limit. If you experience no effects, you still may be overexposed. The isocyanates have poor warning properties in that you cannot tell by your senses alone when you are exposed to levels exceeding the allowable limits (TLV, PEL, manufacturers' or other guidelines). For isocyanates, these values are lower than the odor threshold (lowest level at which it can be smelled) or the level at which irritation occurs.

What is a respirator?

Answer: A respirator is a protective facepiece, hood or helmet that is designed to protect the wearer against a variety of harmful airborne agents.

When is the use of respirators required in the workplace?

Answer: Consult the specific MSDS for recommendations. Also, local regulations may require use of specific repirators.

In the U.S for example, OSHA's respirator standard, 29 CFR 1910.134, requires the use of respirators to protect employees from breathing contaminated and/or oxygen-deficient air when effective engineering controls are not feasible, or while they are being instituted. Several other OSHA regulations also require the use of respirators.

How do you know which respirator to use for a particular application?

Answer: Respirators shall be selected on the basis of hazards to which the worker is exposed (i.e., particulates, vapors, oxygen-deficiency, or combination). Some country-specific regulations also require the use of certified respirators.

Why are formal respirator programs necessary?

Answer: Respirator programs increase the chances of using a respirator correctly. Also, formal respirator programs are required by regulation in certain countries.

Can employees check the fit of their own respirator?

Answer: Yes, employees using tight-fitting facepiece respirators are required to perform a user seal check each time they put on the respirator. They must use the procedures in Appendix B-1 of 29 CFR 1910.134 or procedures recommended by the respirator manufacturer that the employer demonstrates are as effective as OSHA's procedures. Note that a fit test is a method used to select the right size respirator for the user. A user seal check is a method to verify that the user has correctly put on the respirator and adjusted it to fit properly.

When is respirator fit testing required?

Answer: Fit testing of all negative or positive pressure tight-fitting facepiece respirators is often required prior to initial use, whenever a different respirator facepiece is used, and annually thereafter. An additional fit test should be done whenever there are changes in the user's physical condition that could affect respirator fit (e.g., facial scarring, dental changes, cosmetic surgery, or an obvious change in body weight). The employer should be fit tested with the same make, model, style, and size of respirator that will be used.

What can be done if an employee has a very small face and has trouble being fit tested for a respirator?

Answer: Manufacturers make several different sizes. Respirators may also vary in size from manufacturer to manufacturer. Users may be able to get a better fit by trying a respirator made by another manufacturer. In some cases, the use of powered air-purifying respirators may be appropriate. Employers must help employees find a suitable respirator.

What maintenance and care is required for respirators?

Answer: Generally, the employer provides for the cleaning and disinfecting, storage, inspection, and repair of respirators. Consult local regulations for specific requirements.

How long can a particulate respirator be used before it must be discarded?

Answer: Respirators with replaceable filters are reusable, and a respirator classified as disposable may be reused by the same worker as long as it functions properly. All filters must be replaced whenever they are damaged, soiled, or causing noticeably increased breathing resistance (e.g., causing discomfort to the wearer). Before each use, the outside of the filter material should be inspected. If the filter material is physically damaged or soiled, the filter should be changed (in the case of respirators with replaceable filters) or the respirator discarded (in the case of disposable respirators). Always follow the respirator filter manufacturer's service-time-limit recommendations.

Employers must develop standard operating procedures for storing, reusing, and disposing of respirators that have been designated as disposable and for disposing of replaceable filter elements.

How do you store a respirator that is used routinely?

Answer: Respirators must be stored to protect them from damage, contamination, dust, sunlight, extreme temperatures, excessive moisture, and damaging chemicals. They must also be packed or stored to prevent deformation of the facepiece and exhalation valve. A good method is to place them in individual storage bins. Keep in mind that respirator facepieces will become distorted and the straps will lose their elasticity if hung on a peg for a long time. Check for these problems before each use.

Storing the respirator in a plastic sealable bag after use is not considered a good practice. The respirator may be damp after use and sealing prevents drying and encourages microbial growth. If plastic bags are used, respirators must be allowed to dry before storage.

Are there specific storage requirements for storing emergency respirators?

Answer: Yes. Emergency respirators should be kept accessible to the work area and stored in compartments or in covers that are clearly marked as containing emergency respirators, and stored in accordance with any applicable manufacturer instructions.

Is training required before a respirator is used?

Answer: Generally, employers are required to provide training to employees who use respirators. The specific training requirements may vary depending on local regulations. Normally, the training should be comprehensive, understandable, and recur annually, and more often if necessary. This training should include at a minimum:

Why the respirator is necessary and how improper fit, use, or maintenance can compromise its protective effect
Limitations and capabilities of the respirator
Effective use in emergency situations
How to inspect, put on and remove, use and check the seals
Maintenance and storage
Recognition of medical signs and symptoms that may limit or prevent effective use
General requirements of local respirator standards

What can be done if employees find it difficult to talk with co-workers when wearing a respirator?

Answer: Some respirators may interfere with speech more than others. Consult your supplier for information about devices that enhance speech communication.

If employees have a beard or moustache, is their respirator still effective?

Answer: Tight-fitting facepiece respirators must not be worn by employees who have facial hair that comes between the sealing surface of the facepiece and the face or that interferes with valve function. Respirators that do not rely on a tight face seal, such as hoods or helmets, may be used by bearded individuals.

Can employees wear glasses while wearing a respirator?

Answer: Yes, but if an employee wears corrective glasses or goggles or other personal protective equipment, the employer must ensure that such equipment is worn in a manner that does not interfere with the seal of the facepiece to the face of the user. Kits are available from many respirator manufacturers that allow the mounting of prescription lenses inside the respirator.

If employees get a rash when they wear a respirator with a latex seal, how can this be prevented?

Answer: Users might have an allergy or sensitivity to the latex or its additives used in the manufacture of some respirators. Changing to a respirator using a silicone-based compound for the face seal, or a respirator that doesn't have a face seal (like a hooded PAPR) may solve the problem.

What is nanotechnology?

Answer: Imagine being able to see what real atoms and molecules look like as if they were laid out on a dish before you. Then, imagine sorting through the atoms and molecules, picking out the most perfect shapes, and putting them together to build tiny, perfect structures. This is what nanotechnology is all about. Equal parts science, artistry, and imagination, nanotechnology enables researchers to work with the smallest pieces of everything around us, atoms and molecules, to design and build things that could only once be imagined.

The unit of measure that applies to nanotechnology is the nanometer—one billionth of a meter. The graphic below should give you an idea of how small things are at the nanoscale:

How can nanotechnology improve our lives?

Answer: The ability to make things smaller and more efficiently has made huge differences in the way we live. For example, computers that used to fill entire buildings now fit into a pocket. And, surgical procedures that once required large incisions and long recovery periods can now be performed with very small incisions and instruments, which means less tissue damage, faster healing, and a lower chance of infection. So, by making the building blocks for computers, medical instruments, and many of the products we rely on every day through nanotechnology can ultimately lead to big improvements to our health, safety, and environment.

What kinds of nanotechnology products and applications are available right now and how are they better?

Answer: Many nanotechnology products are already available to us in a variety of forms: stain-resistant fabrics, sunscreens, and ultra-thin films are among the consumer products that have been improved through nanotechnology. Nanomaterials in plastics and composites make lighter, stronger, and more durable sports equipment, transport vehicles, and furniture.

As innovation progresses cost, consumption, waste, and pollution reductions will also become recognizable benefits.

What are carbon nanotubes?

Answer: Carbon forms like graphite and diamond have been known for many years, but the discovery that carbon could intentionally be made to form graphite sheets and cylinders was startling.

Scientists are finding ways to make carbon nanotubes (CNTs) with an amazing variety of diameters, lengths, and twisting patterns. To make things even more interesting, nanotubes can be made with open or closed ends, and with one layer (single walled carbon nanotubes (SWCNTs)) or two or more layers (multi-walled carbon nanotubes (MWCNTs)).

About 60,000 times thinner than a human hair, yet possibly up to several microns
(10-6m) in length and stronger than steel, carbon nanotubes could change the future of material science, medicine, and agriculture in unimaginable ways.

What are some of the possibilities offered by carbon nanotubes?

Answer: The fascination with carbon nanotubes doesn't end with lots of great shapes! Scientists have quickly learned that with varied structures come sensational properties like electrical and thermal conductivity, phenomenal strength, and flexibility. All this and incredible lightness too!

Envisioning a tiny nanotube is just the beginning—the possible benefits to people and the world may really have no end in sight. From miniaturized electronics, to better composite materials, we can look forward to making the every day things we rely on stronger, longer lasting, and more durable with less waste—better for us, better for the environment.

Is Bayer developing carbon nanotubes?

Answer: Since their re-discovery in the early 1990s, carbon nanotubes have generated a lot of excitement for their highly valuable and remarkable properties, but the cost of producing them was also extremely high—up to EUR 1000 per kilogram (about $1300 U.S.). And, fluctuating production quality prevented widespread, industrial scale use.

In 2005, scientists at Bayer MaterialScience in Germany developed an innovative new method for synthesizing carbon nanotubes. Bayer MaterialScience is marketing its Multi-Walled Carbon Nanotubes (MWCNTs) under the trade name Baytubes®. In addition to cost-effective production, and affordable quantities for industrial applications, BMS's discovery ensures consistent material quality and purity—greater than 95 percent.

Our pilot production plant in Germany currently has an annual capacity of 60 tons, making Bayer MaterialScience one of the top three MWCNT producers worldwide. We like to think of it as a small revolution in the field of nanotechnology!

What is the normal cleanup procedure for spills and is the cleaned-up material a hazardous waste?

Answer: The overriding principle is to protect people first, then prevent or minimize any environmental releases; lastly protect property and product. General steps are outlined below. Steps 7-13 generally apply only to small spills. For larger spills, call the supplier for assistance prior to Step 7.

Identify material(s).
Evacuate area and remove ignition sources. Size of evacuation area depends on type of material, temperature and size of spill.
Notify superior and others as necessary.
Put on Personal Protective Equipment (PPE):

Â Â â€¢Â Â Respirator (consult MSDS)

Â Â â€¢Â Â Face and eye protection

Â Â â€¢Â Â Permeation-resistant gloves

Â Â â€¢Â Â Permeation-resistant suit.
Control source (where applicable).
Dike the spill (where applicable).
Absorb and decontaminate with Oil-dry or similar absorbent decontaminating solution.

If the spill involves Desmodur WÂ®, a combination degreaser/monoethanol amine/water solution is recommended. Read Health and Safety Information: Desmodur WÂ®; Dicyclohexylmethane Diisocyanate for detailed clean-up procedure.
Remove, treat and discard absorbent/decontaminant mixture. After 15 minutes, shovel absorbent into steel drum and place outside (covered loosely) for 72 hours to allow completion of the isocyanate reaction. The isocyanate reacts with the water to produce a low toxicity polyurea. This material still may be a hazardous waste. For example, it may have a flash point less than 140Â°F if it contains an organic solvent. However, if the material spilled is a listed hazardous waste (e.g., TDI), cleanup residues and spent decontamination solutions also are hazardous wastes.
Decontaminate surface: Scrub with more decontaminant solution.
If the spill was monomeric TDI or HDI, the air should be sampled to ensure adequate dilution before normal operation resumes.
Decontaminate and remove protective equipment.
Properly dispose of isocyanate contaminated materials that cannot be decontaminated.
Return to normal operation.
Conduct accident investigation.

Can isocyanates be dangerous when spilled?

Answer: Yes. Spills of free monomer TDI or HDI are particularly hazardous with regard to inhalation because even at room temperature such spills can result in airborne concentrations above the TLV or PEL. In addition, care must be taken to prevent skin or eye contact. This is especially true with Desmodur W® diisocyanate which is a strong skin irritant and sensitizer.

Inhalation hazard varies depending on many factors including how easily that particular isocyanate evaporates, the volume of material spilled, how large an area is covered by the spilled material, the temperature of the spilled material and the amount of ventilation. Because it is hard to predict all of these factors, it is best to institute a standard spill cleanup procedure for all isocyanate spills.

What disposal method does Bayer recommend for isocyanate product wastes?

Answer: Bayer recommends incineration as the most cost-effective, technically feasible destructive technology.

Is it true that drums which contained isocyanate products are themselves hazardous waste?

Answer: Consult country-specific regulations for guidance. As an example, in the U.S., drums that contain material which is a listed hazardous waste or is hazardous by characteristic are also considered as hazardous wastes unless deemed legally "empty." For instance, a drum that contained TDI and is not "empty," would be considered a hazardous waste.

When is a drum that contained a hazardous waste considered empty?

Answer: Consult local regulations for guidance. In the U.S. an empty container is one that is "drip dry" ? i.e., one that has been emptied of all materials which can be removed using the practices commonly employed to remove materials from that type of container, e.g., pouring, pumping or aspirating.

Should empty chemical drums be given, donated, or sold to anybody?

Answer: No. It is the responsibility of the emptier to ensure that drums are transferred to a responsible party who will either properly recondition or destroy (e.g., puncture, crush) them to prevent reuse. Indiscriminately discarded drums could be converted wrongfully into barbecues, trash-burning barrels, etc., and this could result in injury.

Should a drum be destroyed or cut with a torch?

Answer: NO! Applying a flame or heat to a drum may result in explosive and/or toxic decomposition of residues. Drums should be cut or destroyed by mechanical means only.

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